Welcome to the second clinical lecture. In this first part, we will discuss musculoskeletal disorders. This will be a rather long section, and then we'll be followed by skin disorders as the second part of the clinical medicine lecture. Alright, starting off with low back pain. It shouldn't come as any surprise that most of us will report an episode of low back pain during our lifetime, and breaking that down a little more, about a third of adults will report that they had an episode of low back pain in the past three months, so it's very common, very ubiquitous. The interesting thing to note is that only about 15 or 20 percent of those people with low back pain will seek medical attention. One major reason, which is germane to our points, is that they seek attention for low back pain because they were either injured at work, or they cannot perform the job, and they need medical treatment and possibly wage replacement. Low back pain is also expensive. It's the most common cause of work-related disability in people who are in the prime of their working years, and so therefore it represents an enormous cost to workers' compensation systems and to the general employment. About 10 percent of workers' comp claims are associated with 30 percent of the costs, and about a quarter of the cases account for 90 percent of the costs, so the important thing here is to identify cases early, particularly those that will go on to disability, and attempt to get them treated quickly, efficiently, and attempt to get them back and returned to work, because that's where the major costs lie. The next several slides will address risk factors for prolonged disability from low back pain. Many of them are risk factors for low back pain itself, particularly those in the workplace and the physical factors here, but most importantly, they represent causes of prolonged disability and of workers remaining out of work as a consequence of low back injury. Main workplace physical factors are, of course, heavy physical work, particularly lifting. When this is combined with twisting and bending, these are ergonomically poor postures, as are static work postures, and contribute to heavy loading on the spine, and consequently, they develop an onset of low back pain. It's very difficult to return people to work if these workplace factors remain in place, so not only are they causative, but they also represent, as I mentioned, risk factors for prolonged disability and remaining out of work. These can also be combined with low control over work. In other words, if you have to work at the pace of a machine or don't set the standards for your own working pace, you may not be able to return to work either because having to work fast or at the pace of a machine is going to increase back pain as you continue to work. Likewise, there's also individual physical factors amongst them. Age, the back and ligaments become much stiffer with age, and injury becomes more common. Physical fitness, particularly in light of the obesity epidemic these days, is a major risk factor for prolonged disability, and smoking also represents a cause of disability, probably because of its interference with the microvasculature and the blood supply to the lower back and its inhibition of recovery. In addition to the physical factors we saw in the previous slide, individual psychosocial factors become very important in whether people return to work or not or remain disabled. Many individuals will have particular pain beliefs in that movement that causes pain is deleterious or is in some ways furthering the injury. These have to be overcome in order to get people to move around and increase their physical activity. Many people are depressed. This can be a pre-existing condition or this can arise from prolonged spell at home, which is why enabling early or prolonged absence after injury can also be deleterious to recovery from low back pain. People tend to get depressed if they don't have structure, whether it's social or time-wise, as they do at work. Some people will have what's called a negative affective personality or catastrophizing. They can be like Eeyore and think that nothing is going to go right and everything is a disaster, and this also enables them to remain at home and consider themselves disabled. People may have considerable dissatisfaction with work, and if you can remain out of work or not go into a job that you hate or dislike the people at the work or that's monotonous and otherwise boring, you may have some gains through the benefit system in enabling you to stay at work, and there may be secondary gain at home also. So many of these psychosocial factors become very important, almost as important as the physical factors in prolonging people's remaining out of work from a back injury. Administrative factors, although we don't necessarily notice them quite as readily as we do some of the physical factors or even the psychosocial ones, can also play major roles in prolonging disability. In the workers' compensation system, a slow response or early claim rejection can lead to a lack of treatment or a delay in treatment. You should contrast this with what happens to people with a back injury who use their group health insurance, in which case you can oftentimes get them physical therapy, get them any needed testing, and they can progress fairly rapidly. By contrast, if you're waiting for a workers' comp claim to be accepted, it may be six weeks, two months, or more before you can get them the treatment that they need, and so this can lead to people sitting around without treatment. I mentioned earlier early and prolonged absence after injury, and I certainly have my own opinion on human resource people, but HR factors can be involved. Oftentimes, they are not amenable to providing modified work, recuperative jobs, or related types of work that could enable an injured worker to get fully back to work, and this causes early or a much more prolonged absence from work after an injury than perhaps it should be. Legal involvement is also a factor. Oftentimes, there's a need to demonstrate that the worker's been injured, and so proving an injury entails acting injured and taking on that sick role. In addition, there may be motivation to get an award as high as can be made available. Doctors themselves can also be responsible for problems in patients not returning to work. Overtesting, particularly series of imaging studies when there's no identifiable lesion or specific reason to obtain an imaging study, can lead to the patient being confused as to why imaging studies show nothing but why their back still hurts. Surgery also can disable people, not so much in treating specific lesions such as a disc herniation and a discrete radiculopathy, but oftentimes surgery for nonspecific back pain that goes on for six months to a year, and at some point the alternative or decision is made to operate, and those patients will probably not get better fairly rapidly. As well, many doctors, and I'm probably preaching of the converted in the occupational medicine setting, but many primary care physicians won't communicate to the workplace or to the patients the needs and attitudes that they need to take on vis-a-vis an injury or disability, and this involves rapid mobilization. In particular, oftentimes they will give the patient what they want, which is time away from work, which as we've seen in all the previous slides leads to sitting around the house, becoming depressed, not having a structure, and not having a job to go to, and probably becoming depressed as well. And so by all these tokens, doctors themselves can enable prolonged work absence and disability in addition. So moving on to the evaluation of low back pain, the first thing to do when a patient presents with a new onset of low back pain is to briefly evaluate the possibility that there's underlying systemic disease that needs other treatment, in other words, red flags. The main things to think of here are infections such as vertebral osteo or tuberculosis, immunologic disorders, and the possibility of cancer, particularly of metastases, if there's been a history of primary cancer or tumor. Additionally, red flags can encompass the cauda equina syndrome. Recall that the spinal column ends at about the L1 level, and below that is the cauda equina, which is grouped nerve roots passing down and out through the lumbar and sacral foramina. Any disc central compression, such as the lower disc in the picture on the right side, can result in central compression of multiple nerve roots. This is why we ask patients about incontinence, particularly bladder incontinence, but also fecal incontinence. And on examination, these patients may have saddle anesthesia in the area of the perineum and bilateral lower extremity neurologic deficits, such as bilateral weakness and loss of reflexes. You should also be alert to the possibility of a fracture if there's major trauma, fall from a height, so a regular age working person may be falling half a story, but also be very alert, as we have many elderly and older working patients, of the possibility that minor traumas, even just a slip and fall, may result in some type of a fracture in the older osteoporotic patient. Infection and tumors, as red flags I had mentioned before, if there's a history of intravenous drug abuse, they may have staphylococcal abscesses, or if there's a tubercular history, they may have tuberculous meningitis. So if you have history or high suspicion for those, particularly if they're accompanied by other signs of infection, they should be imaged or otherwise dealt with appropriately. A history of cancer may indicate the possibility of metastases. Also, as well, if the patient is age over 50, presents without history of a fall or a single provocative incident, and has other accompanying signs, such as weight loss. Interestingly, in the case of cancer, these patients are said to have pain that's worse when they're recumbent rather than standing and moving, which is the opposite of the pain that's described with a back injury from lifting. Now that said, most of the conditions that represent red flags, such as cancer or infection, represent only about 1% of the cases of new back pain presenting. The overwhelming majority is going to be mechanical low back pain, either from lifting or ongoing strain. Most of that, about three quarters or so, is going to be nonspecific low back pain. In other words, pain that doesn't have a specific localizing source. Disc herniations and radiculopathy are going to count for about 4% of the mechanical low back pain, and a kind of a grab bag of other conditions which will be causing low back pain, some of which may be either caused or aggravated by lifting or other activities in the workplace. I throw this slide up to jog your memory a little bit here with a couple of take-home points. Almost all disc herniations from lifting are going to be at the L5-S1 level or a few less, but a total of 95% between the two levels, L5-S1 or L4-L5 level. A few things to remember on physical examination. Pain on the L5 level, in other words, usually from an L4-5 disc herniation, but localizing to the nerve root, is going to produce pain down the lateral leg, but into the dorsal foot and on the great toe. Whereas by contrast, the S1 nerve root is going to be in the back of the thigh, down the lateral foot and the leg, and into the sole of the foot, and down as far as the little toe. A couple of other take-home points for the physical examination. You can screen these fairly well by having a patient heel walk and toe walk. These work a lot better, in my experience, than does manual muscle testing, because in these cases a patient has to support 150 or 200 pounds while heel and toe walking, and you will pick up much more subtle decrements in strength that way than on manual muscle testing. So if they're unable to keep their toes up on heel walking, that may be indicative of an L5 root lesion, and if they're unable to walk on their toes, again getting a sort of a decrement of strength, eventually walking flat on the floor, that may be indicative of an S1 nerve root lesion, along with all the other symptomatology, which is pain and other radicular symptoms extending down below the knee. The ankle jerk is usually diminished in an S1 lesion, and a knee jerk in an L4 lesion, at least for the purposes of the boards. There's said to be no reliable lesion, although you might see mildly diminished knee or ankle jerks in an L5 lesion. Of course, the next question after the examination and the question on the patient's mind is whether or not you're going to get an imaging study of the back, either an x-ray or a CT or MRI. I think most of us, and again here I'm preaching to the converted, is that we have a bias, and a good one too, not to image if there's no localizing signs, and certainly if there are no red flags. I'll throw up some numbers here. These aren't required knowledge, but just to give you an opportunity to see the extent of false positives. In one study that took a group of asymptomatic patients, in other words people whose backs felt fine, 90% had some form of degenerated or quote-unquote bulging discs, and actually a third of those people had what would be a demonstrably herniated disc on imaging, along with a lot of spinal stenosis. In a younger sample that was taken from a VA population, pretty much the same results obtained. About two-thirds had these degenerated or bulging discs, and again about a third had a disc protrusion. So the take-home point here is imaging throws up a lot of false positives, a lot of incidentalomas, and what you really want to do is image only if you have evidence that what you're looking at is going to be amenable to treatment in some other way, shape, or form than what you would normally do for a patient with non-specific low back pain. I'm going to take a very brief digression into the ACOM guidelines. This is not something you have to have at your fingertips, but many of the musculoskeletal recommendations are going to come with evidence ratings from the ACOM guidelines. An A-level of evidence means that there's high-quality evidence that oftentimes means randomized controlled trials or other strong evidence from studies in favor of it, or by contrast an A-level against an intervention means that there's high-quality evidence that it truly is ineffective or may cause more harm that outweighs the benefits. The remainder are B and C levels of recommendation, which are based on observational studies and case series. There's also a lot of I recommendations. This means that the panel had found there was insufficient evidence, but they may or may not recommend it depending on consensus data or other recommendations, or they may have an I-level recommendation against for the same reasons. So in the first slide of recommendations, here are the ACOM guidelines for imaging. Similar to what we saw earlier, the recommendations are to avoid imaging for the first month or so unless you find red flags on history and examination. If there are red flags, an x-ray can be recommended. For acute radicular symptoms, oftentimes you may want to go ahead and get an MRI or a CT scan fairly soon, particularly if there are severe findings, radicular signs, weakness, and consideration for surgery would be fairly strong. Aside from that, if there's subacute or mild radicular pain symptoms that go on for about four to six weeks, you can generally treat them with the same conservative therapy such as physical therapy, ambulation, and appropriate meds. And then if the symptoms persist, and again other measures such as surgery or epidurals are considered, then to go ahead and get the MRI after about four to six weeks. Aside from those questions of imaging, here's your first visit, obviously check for red flags, examination to ascertain whether there are acute or severe radicular signs or findings, and then getting the patient to understand that low back pain is frequent, that it does have an excellent prognosis, particularly if there's no specific lesion causing it, that it should not be debilitating on a long-term basis, and that maintenance of ordinary activities, such as an increase in ambulation and gentle stretching exercises, activities of daily living, and the like, can be maintained. So just to reiterate, recommendations for uncomplicated low back pain, number one is to avoid bed rest, as the muscles will weaken with prolonged bed rest over about five days to a week, and follow the visit with a gradual return to normal activities. The majority of patients will have a decrease in pain within four weeks, with about three quarters or more returning to work within four weeks, obviously the job should be modified a little bit within this, and about nine-tenths will return to work in three to six months. I'd like to also throw in a little anecdote here about a physical therapist that went to see a company manager or HR person to try and sell their services to the company, and what they told the company was, we will have 80% of your low back pain patients back to you within six to eight weeks working, and of course the HR manager thinks, oh hallelujah, this is fantastic, when can you start, and of course they could get those numbers and achieve those numbers just by having the patients do virtually anything, walk around, look on their phones, whatever they wanted to do, because that's really the natural history of uncomplicated low back pain, it's to get better, it's to get better a little bit on their own time, but the majority, as we see from these numbers, of back pain patients will get better relatively soon. A couple of additional points against bed rest, aside from acute spinal fracture, bed rest needs to be avoided. Yes, you can have the patient rest in bed for a day or two or rest on the couch, but the evidence is really good that after about two days they need to be up and mobilizing. Some additional study results are seen in this slide, resumption of normal activities is actually better than exercise, but both are better than more than two days bed rest, and another point to drive home to your patients is that light activity, albeit may hurt your back at some point, won't cause or lead to further injury in uncomplicated low back pain, so that's an important point to emphasize in the initial visit. Mainstay of treatment outlined here, non-steroidals for acute low back pain, and these get a strong level of recommendation, good evidence from controlled trials that they help, and moderate evidence, but still a good recommendation for its use in subacute, chronic, or post-operative low back pain. Non-steroidals can generally be combined with muscle relaxants, these also get a good level of evidence, although there's fewer controlled trials for that, hence the B-level of evidence, but they're still well-recommended. Many of the neurosurgeons prior to treating with surgery will give people a short pulse or dose of corticosteroids, such as prednisone, for acute radiculopathy, this does have a modest level of evidence, and probably some evidence that it helps, or at least helps the patients to manage or feel good. In most cases, these are people who eventually go on to surgery, so the point is more to kind of temporize the pain, rather than to absolutely treat the radiculopathy. And of course, preaching once again to the converted, we all know about limited use of opioids, and the recommendations are that these should be restricted to low back pain that's a consequence, or is accompanied by crush injuries, fractures, or other severe tissue damage, not non-severe acute low back pain, such as an acute back strain, where there hasn't been trauma, or other sort of tissue damage, and these should be limited to two weeks maximum, and need to be constantly reevaluated, as most of you know at this point. Moving on to some lesser-used medicines, or that may not be as familiar, capsaicin actually gets recommended for use in acute or subacute low back pain, I don't know how many of you use capsaicin, I haven't very much, and patients tend to dislike it because of the burning feeling on the initial couple of applications, but if they're able to work through that discomfort on initial application, it does get a reasonable level of evidence for efficacy. Similar in efficacy are tricyclics, like amitriptyline, and SNRIs, like duloxetine, and these get a good level of recommendation from randomized trials for chronic pain, there's less evidence that they're effective in acute or subacute pain, but you do see their use, and they are useful adjuncts to treating radiculopathy, particularly if surgery hasn't succeeded, or the patient's not a good candidate for it. Interestingly enough, distinct from the SNRIs, the SSRIs, the usual antidepressants, are not recommended, there's good evidence against their use in control of pain, now that doesn't mean that they can't be used to treat depression in people with ongoing low back pain, or chronic low back pain, but the expectation isn't that they're going to well treat the radiculopathy that occurs from low back pain, but they may be useful for depression. Since the discontinuation of recommendations for opioids, gabapentin and pregabalin have been used for treating radiculopathy, there's not a lot of good evidence for them one way or the other in chronic radicular pain, and so the ACOM guidelines have no recommendation one way or the other for their use in chronic radiculopathy, so it gets an eye level of recommendation with fundamentally no good recommendation for or against. Gabapentin may be useful for people who have chronic spinal stenosis and neurogenic claudication as an adjunct to that type of pain, and they both are recommended as there is evidence from trials for their use in perioperative pain. Beyond medicines, here's some recommendations for physical modalities, the guidelines indicate that low stress aerobic exercise should be begun once the pain will allow. Either chiropractic manipulation or physical therapy mobilization for acute or subacute low back pain is also recommended, and this gets people up and moving and may reduce their pain enough for them to become ambulatory and to partake in some of the exercises that will enable them to recover faster. After about two weeks, after the resolution of real acute or severe pain, conditioning exercises can be started. Massage has no recommendation for use in acute low back pain. It does get a low level of evidence in favor of its use for subacute and chronic low back pain. I think most of us find that most workers' compensation managers and insurance systems tend to be rather opposed to this sort of treatment, and it is a passive modality. In other words, it doesn't get the patient up and moving. It doesn't necessarily lead to great recovery, but it may result in some amelioration of the pain enough to get them up and exercising or otherwise ambulating. And traction, although it may have a theoretical basis, doesn't actually work, and so it's not recommended. Epidural steroids are useful in acute and subacute radicular low back pain. It gets an eye level of recommendation, but there's also a recommendation in favor of their using. One of the problems is that there aren't really any controlled trials or adequate trials of it with proper blinding and all the other nice things that go into making an adequate trial of it. So most of this information is gleaned from case series, but it becomes a useful adjunct, and I think many patients will prefer to undergo that in preference to surgery. So a reasonable recommendation, although an incomplete level of recommendation. There seems to be no recommendation about doing prognostic facet injections for low back pain. A jury is really still out of that, and there's no recommendation one way or the other. There's a lot of recommendations against a lot of other interventions. Many of these tend to be done by pain clinics or proceduralists, and so all these levels of evidence here are the levels against them. So there's a strong level of evidence against use of intradiscal steroids, moderate against radiofrequency neurotomy and prolotherapy, and all the other types of injections aside from the two that we see above, and IDAT, intradiscal electrothermy, or frying up the disc that's responsible. Also not recommended, although an eye level of recommendation as well. Most of you have used or come across the use of Waddell sign. These are physical examination findings that suggest that low back pain may not have a fully organic or specific anatomic location, but that psychosocial factors may be intruding and responsible for many of the pain responses that you see in a particular patient. So for example, a low back pain with axial loading, what this means is pressure down on top of the patient's head, which then leads to a complaint of pain in the lumbar or lower back region. The superficial tenderness to the skin, remember it's not the skin, but the muscles, bones, or other structures that are injured. So if you palpate just more superficially on the skin and the patient responds with grimacing or other pain attitudes, that also may be suggestive. The distracted straight leg raise is also very common. This is if the patient can raise their leg, bend their knee, or extend their knee all the way up to 90 degrees while seated, which means that their hip is in a 90 degree position, but not complain. Yet, when you put them supine and do a standard straight leg raising maneuver, they note pain at about 30 to 40 degrees. So this also may be contributory. Some of the other ones here are similar to what we've just described, the exaggerated pain response, such as grimacing and groaning, and non-anatomic or non-dermatomal symptoms. So Waddell designed these actually to help judge which patients were not likely to well benefit from surgery. In other words, if there was psychogenic overlay to the back pain, surgery probably wasn't going to completely fix or ameliorate low back pain. And so those persons would be poor surgical candidates. Fundamentally, what it means is you may want to look into psychogenic causes or other of the things that we earlier discussed about causes of low back pain disability, and perhaps seek some psychological intervention. It also should be remembered, as I mentioned down with a key here, is that this does not necessarily indicate malingering. Malingering is more conscious. Many of these findings are non-organic and psychogenic, but they may not necessarily have a conscious or specific outward behavioral motivation, as does malingering. So you have to keep that separate from simple non-organic low back pain signs. Very briefly in the ACOM guidelines, because we're not the ones who decide whether patients are going to have surgery, but we can think of these as indications for surgery or sending to the surgeon. If there's clearly evidence of nerve root compression after about a month to six weeks, indicating ongoing radiculopathy, obviously we'll have the surgeon see them. Individuals who have persistent spinal stenosis or neurogenic claudication should also get a surgical referral. They may or may not consider whether or not to have the surgery itself. When we talked about what else signs and also about disability, we talked about the fact that lumbar effusion can't be recommended for chronic nonspecific low back pain. This is likely to lead to continued ongoing disability, because the surgery probably doesn't really treat the localizable lesion, and therefore the outcomes are not necessarily going to be satisfactory. Disc replacements are not recommended. There was a vogue for them in recent years. I'm not sure whether that's died off or not now, but they are recommended, at least via the ACOM guidelines. So just in terms of the boards, what do you really, really need to know? Just a few major facts. More than 70% and probably much higher than that of back pain is going to be nonspecific low back pain. In other words, without a localizing or anatomic lesion or lumbar strain, essentially the same thing. Initially, the first thing you want to do is look for red flags during the history and examination, look for illnesses that may bear on the history of back pain, and then direct your physical exam to both those and to the possibility of a disc herniation and radiculopathy. You want to avoid immediate imaging, unless there are obviously red flags, or whether the patient hasn't improved in about four to six weeks, especially if signs and symptoms of radicular impingement still persist. And obviously, they're getting worse and worse, then you'll want to image them sooner. Patient really has to understand what the mainstay of treatment is, and that's slow progressive increase in activity and ambulation. Get them treated with medicines appropriately, help take the pain away, help manage their ability to increase ambulation, combine that with physical therapy if that's helpful, but you really want to mobilize them. And if they have signs of radiculopathy or bad radiculitis, obviously following imaging studies, they can be treated with epidural steroids and possibly surgery. So really sort of the mainstays of low back pain treatment, and again, the mainstay is going to be up and getting them moving. A little bit more on ergonomics is going to be presented in the physical hazards lecture. We're going to go through some controls very briefly. You want to avoid twisting or bending while bearing the load that puts unfavorable strains on the lumbar spine, as does bending or stooping below the knee level, particularly to lift or pick things up from that area. You want to avoid working outside an area that's close to the body and that requires deviation of the trunk for more than about 30 degrees. Lifting and repetitive pushing and pulling should definitely be limited to 50 pounds. In the physical hazards lecture, we'll see the NIOSH lifting equation, which starts off with a 51 pound maximum limit for repetitive lifting and goes downward from there depending on the characteristics of the work and the lifting. And any kind of heavy carrying should be kept, particularly if it's prolonged or repetitive to about 33% of the person's lean body weight. Back belts tend not to help or be useful. The best you can say is that they're preventive, like a string around the finger for a reminder not to bend at the waist, but to bend at the knees to pick and carry things up. You see them a lot in the DIY stores with the employees who wear them there. It may be helpful for them a little bit just to recall not to lift, but there really is no good evidence that they're preventives against low back pain and injury. All right, moving on from low back pain, we're going to discuss work-related musculoskeletal disorders of the upper extremity. These are typically anywhere from the hand, forearm, more proximal arm and shoulder and are usually the consequence of repetitive work with forceful movements or awkward hand postures or vibration. So it's got to consist of a combination of repetition plus one of these other factors. I think the main thing in looking at work-related musculoskeletal disorders of the upper extremity is to think very hard and clearly about a specific anatomic diagnosis. Although the title here says repetitive stress or strain disorders, I think that lumping them into one category keeps us from classifying them and most importantly affects treatment if you have specific localizing findings and can pin a specific anatomic diagnosis on the condition that's going to help you treat it and mainly also that's going to help you prevent it. So while we're calling it RSIs or CTDs, remember I think always to look at the specific type of diagnosis. Is it carpal tunnel syndrome? Is it de Quervain's? Is it some other specific disorder of the arm or hand? So we're going to lead off with probably the best known work-related upper extremity disorder carpal tunnel syndrome. This is entrapment of the median nerve in the anatomic compartment through which it runs the carpal tunnel and if you look at the picture over on the right-hand side you see that the carpal tunnel is very, very crowded. There are all the flexor tendons of the hand running through it along with the median nerve and so it can be very easily compressed by anything that causes swelling within the carpal tunnel. For the lower picture, I want to show you the distribution of the median nerve which is that it takes in primarily sensation in the thumb, index, middle finger and splits the fourth finger. The ulnar side is of course supplied by the ulnar nerve which takes care of the fifth finger and the other half of the fourth finger. It behooves us to remember that there are a lot of non-occupational causes of carpal tunnel syndrome and a number of very common disorders are associated with carpal tunnel. Two big ones I think to remember are diabetes and this can be both type 1 or type 2 diabetes, hypothyroidism which can be oftentimes subclinical or mildly symptomatic, obesity separate from type 2 diabetes and some other conditions, rheumatoid arthritis, amyloidosis and it occurs more frequently in pregnancy. Epidemiologically, carpal tunnel seems to have a predilection for women, about a 70 to 30% prevalence. It's not clear why this is, whether there are anatomic factors, whether there are hormonal factors involved or perhaps some diagnostic factors. Similar to what we noted on the last slide, there are clear occupational associations with repetition to which either force or awkward postures are applied. This means that many forceful, repetitive, stereotypical jobs, particularly in the meat packing and chicken boning industry are high risk for carpal tunnel syndrome. In these cases, the workers oftentimes pull a pullet down, slice it off with a knife, throw one side in one barrel and the other part in the other barrel and do that again and again. So they do this on a frequency of about every 6 to 10 seconds, which if you sort of add that up across an hour, across a day, across a week and across years, results in very extensive high frequency repetitive trauma to the hand and wrist. Other work includes carpentry and other hand tool use and manufacturing and assembly, particularly if workers are doing the same task repetitively on an assembly line. Clinically, the mainstay is a complaint of intermittent hand paresthesias in the median nerve distribution, which we went over in the previous slide. Usually patients will say that they interrupt sleep. They start to get nocturnal paresthesias first. They may awake with them in the morning. As it progresses, they get precipitants during the day. Anything that calls for flexing the hand, gripping a phone or driving, for example, can make the paresthesias occur in the hand. They will oftentimes say they get relief by shaking the affected hand and that's a great clinical sign for carpal tunnel syndrome if somebody first comes into your office. You want to remember that the median nerve is approximately 90% sensory. There are very few muscular branches of the nerve. It innervates the intrinsic muscles of the thumb, the thenar muscle, and the thenar eminence. This is the abductor pollicis brevis and the flexor pollicis brevis, as well as the opponents. Sometimes useful in the evaluation of carpal tunnel syndrome can be what's called a cat's hand diagram. This is a paper diagram that asks the patient to fill in areas where they feel numbness, pain, tingling, or decreased sensation. This can be helpful with the diagnosis depending on where the localization and distribution of these symptoms might be. For example, a pure carpal tunnel or a likely carpal tunnel case would be a sketch in of some of the pictures we saw in the preceding couple of slides. This diagram is something else altogether. This patient has colored in the pinky finger on both hands, nothing on the palmar side, and something going up and down the arm. So whatever this is, it's not carpal tunnel syndrome, but it can be useful if they do draw a picture that looks much like this. Here's a look at the predictive ability of various well-known tests for carpal tunnel syndrome, particularly the provocative tests like Tonell's and Phelan's that we're all used to. Cat's diagram that colors in the median nerve distribution, in other words a classic diagram or a probable CTS case, has a reasonably good sensitivity and specificity for a diagnosis of carpal tunnel syndrome, although the likelihood ratios over on the right side are still rather small. By contrast, the typical maneuvers that we usually do for CTS, Tonell's, which is tapping across the median nerve at the carpal tunnel, and Phelan's sign, which is flexion of the wrist for a period of time with reproduction of symptoms in the hand, have sensitivities and specificities that are really all over the map. They seem no better than chance if you look at some of these numbers here, and of course the likelihood ratios are low. They aren't particularly specific, in particular in many other conditions, or even just normal examinations on normal people may reproduce them. Thumb abduction might be a better sign, however, remember that we mentioned that the median nerve is primarily sensory, about 90%, so that any weakness arising from the thenar muscles is going to be a late sign of carpal tunnel syndrome, and they will likely have had symptoms much before then. So the most sensitive screen for carpal tunnel syndrome, using the results of nerve conduction tests as a gold standard, are a suggestive or a classic cat's hand diagram that looks like median neuropathy, plus the use of monofilament testing to demonstrate reduced sensation in the distal fingertips, particularly not in the pinky, which would be ulnar supplied, plus feelings of night discomfort, and that's going to be very sensitive and specific for prediction of whether somebody has carpal tunnel syndrome based on nerve conduction testing. Nerve conduction testing, as I mentioned in the last slide, is the gold standard for diagnosis of carpal tunnel syndrome, but remember that even this gold standard has about a 5% false negative rate, so you may have to use your clinical judgment as well for diagnosis. The numbers that present here aren't particularly important because most testing labs will give you their normative values and the interpretation of it, I'll just throw them up here for some illustration, but generally for the diagnosis of CTS, you want to see increased distal latency of the median nerve in either the motor or the sensory nerves, or both. What's oftentimes helpful is to compare the distal latencies from the median nerve with the ulnar nerve on the same side, the ipsilateral ulnar nerve of the same patient, and see if there's an increase in distal latency in the median nerve. This makes the patient their own control, and so therefore the results become a little more interpretable. EMGs will show denervation of the abductor pollicis brevis, which is innervated by the median nerve, and as I mentioned before, this is oftentimes a late finding, and so people who have positive EMGs will usually have severe nerve conduction tests indicative of fairly advanced carpal tunnel syndrome, and will likely need surgery. The ACOM guidelines don't recommend using ultrasound or MRI. They consider these as being no better than nerve conduction tests and EMGs for the diagnosis, so they have a B-level against use of ultrasound for diagnostics. Very briefly, a repetitive slide that indicates the occupational factors that aggravate carpal tunnel syndrome. Highly repetitive flexion and extension of the wrist, or repetitive work with gripping or forceful postures, and I mentioned before that poultry workers, meat packers, and fish packers are amongst the main workers who will go on to develop carpal tunnel syndrome, and a variety of others, such as assemblers and electricians using hand tools. Moving on to treatment of carpal tunnel syndrome, splinting is really the mainstay, and patients should really be splinted at nighttime or from the evening on to the nighttime at times of reduced activity. You really often don't want patients to wear splints at work. They tend to fight the splints while they're attempting to work, and that may lead to a secondary tendinitis or increased pain in and around the wrist as they try and move within the splint, so you want them to not be particularly active when they're wearing a splint, so mainly in the nighttime. Non-steroidals aren't recommended for treatment. Oftentimes the condition really isn't particularly painful, and there's not a lot of evidence that NSAIDs really work. They can certainly be used for post-operative pain after surgery. Work restrictions besides splinting are going to be important for ongoing treatment. You want to avoid the causative factors, particularly repetitive work that involves high-force hand gripping and pinch-type gripping, and avoid use of any vibrating handheld tools unless they're really damped. If splinting fails, many patients will move on to a corticosteroid injection, and this gets an A-level of recommendation for subacute and chronic carpal tunnel syndrome and an indeterminate recommendation for acute carpal tunnel syndrome. This can also be diagnostic, because if you have physical exams and preferably nerve conduction tests that show carpal tunnel syndrome, and you inject and you get a distinct improvement, that also becomes diagnostic as well as therapeutic. Most patients will improve with a corticosteroid injection. Some will go on to recur or relapse, and again, the steroid injection is also a good predictor of the success of surgery if a patient has to move on to surgery. So if you get a good result from a steroid injection and there's a recurrence, it's oftentimes predictive of a good outcome for surgery. They may require a second steroid injection, particularly if there's an attempt to avoid having surgery. Oral steroids work not quite as well as a steroid injection, probably because the injection is more localizing, but it can be recommended for patients who can't have or won't have injections or don't want to go on to surgery, and subsequently surgery for subacute or chronic carpal tunnel syndrome is recommended for people who clearly have positive EMGs, hypothenar muscle weakness. They have weakness in opposition and abduction of the thumb, or if they have positive nerve conduction tests and really intractable symptoms, and their numbness or pain in and around the area is particularly bothersome. Sometimes gets an indeterminate recommendation. It's not clear whether that's helpful or not. I'll say a brief few words about pronator teres syndrome. This is a mimicker of carpal tunnel syndrome and the sort of red herring that the boards tend to like. This is where the median nerve gets entrapped higher in the forearm, just distal to the elbow where the pronator teres divides and the median nerve runs through it. Overuse or hypertrophy of the pronator teres muscle is the cause of it, and this, as you might imagine, is somebody who's constantly pronating and supinating the arm, usually against force. So this would oftentimes be somebody using a wrench or a ratchet or a screwdriver. So as I say, the median nerve passes between the two heads of the muscle and it compresses farther up, much more proximal to the wrist. A couple of tricks to distinguish pronator teres syndrome from carpal tunnel syndrome. Percussion just distal to the antecubital fossa in the forearm will be fundamentally a, quote, Tenel sign in and around this area. It may be tender and it'll give them neuropathic symptoms down into the hand. So in the median nerve distribution, these individuals might have pinch weakness because this median nerve, prior to its passage to the carpal tunnel, innervates some extrinsic muscles of the thumb, the flexor pollicis longus, for example. And so they might get pinch weakness, which they don't necessarily have in carpal tunnel syndrome. And of course, nerve conduction testing, if you go above the wrist and the carpal tunnel and look at the arm above and below the elbow, you'll find more proximal findings related to the median nerve up in the forearm. So cubital tunnel syndrome or ulnar neuropathy at the elbow is the most likely ulnar neuropathic finding if that's what the patient presents with. The median nerve at the wrist in the carpal tunnel syndrome is fairly squashed within the carpal tunnel. By contrast, Ghion's canal, which is the tunnel in which the ulnar nerve passes through the wrist, is pretty capacious without a whole lot of other tendons running through it. Therefore, the ulnar nerve is more likely to be compressed in a smaller space on a much more mobile joint, which is the elbow. So if you see somebody with ulnar symptomatology paresthesias, particularly in the fourth and fifth fingers, this is more likely to be arising from the elbow than at the wrist. So as you might expect with the distribution of the ulnar nerve, these are people who will have decreased sensation in the fourth and fifth fingers. They'll have pain in the medial forearm, and they tend to get kind of funny bone feelings when they hit or put pressure on the elbow. You can reproduce this with a TINL sign via percussion across the cubital tunnel at the elbow. They may have tenderness in the ulnar groove as well as symptoms of medial epicondylitis. The ulnar nerve innervates a number of the extrinsic, sorry, of the intrinsic muscles of the hand, and so therefore, ulnar neuropathy is more likely to cause a motor neuropathy than is medial neuropathy or CTS. And you can test this in patients by asking them to abduct their fifth finger against the force of your hand. And if they're unable to do it, or they're weak, or they have hypothenar atrophy in that area, that may also be a good sign of ulnar nerve compression. Similar to what we saw in the preceding slides on pronators, Terry syndrome, workers at risk for cubital tunnel syndrome are those who repetitively torque their hands and arms, particularly using tools. So again, use of screwdrivers, wrenches, ratchets, and many power tools, particularly ones that have a kick to them and that repeatedly wrench the forearm. Diagnosis is usually made between the clinical presentation and by nerve conduction tests and EMGs. These will show slope conduction velocity across the elbow, so you want to measure conduction velocity above and below the elbow. And they may have reduced ulnar sensory and motor latency, though. There's a fair number more false positives. These can... Sorry, false negatives. False negatives is what I meant to say. This can be on the order of about 30% or more, which contrasted with carpal tunnel syndrome is not a very good yield. This has led to other modalities for an attempt to diagnose it, and in this case, ultrasound may actually be more useful and more sensitive than it is for carpal tunnel syndrome. So ACOM has no recommendation for or against the use of ultrasound, but it may be a useful adjunct, particularly if you've got clear clinical symptoms and a negative set of nerve conduction tests. EMGs, if they're positive, will pick up denervation in the intrinsic muscles of the hand, particularly in the hypothenar region and the abductor digitae quintae, which is what abducts the fifth finger, will show denervation. These are oftentimes patients who are hard to treat. You may want to get them elbow pads. You may get them something to keep them from fully rotating or flexing the elbow. Non-steroidals can be helpful. Corticosteroid injections usually are not, and in many cases, if these symptoms are bothersome or clearly if they're developing weakness in the handy intrinsics, they may need to go to surgery and have an ulnar nerve transposition away from the cubital tunnel. General principles of ergonomic controls for the upper extremity are to attempt to decrease the force and particularly the grip force that the hand uses. This picture illustrates a number of good ergonomic controls, although you can't decrease the weight here. What you're doing is decreasing torque on the hand and using a power grip. If you notice in the picture, the tool, the hand, the wrist, and the elbow are all in a straight line, and so there are no deviations or awkward postures. You can put on plastic handles or other things to increase frictions for lifting and also use some mechanical lifting devices so that people aren't constantly using their hands as lifting can be pretty useful. There's a picture of some more ergonomically designed tools. If you note the pair of pliers in the picture down in the lower left-hand corner, these are very differently aligned from a normal pair of pliers but allows a forceful grip, which is also keeping the wrist in line with the hand and providing additional power without the need to deviate the hand. So use better designed tools as well as optimum positions can be helpful. If people are using vibrating tools like jackhammers or grinders, damping materials, rubberized grips, also gloves can be useful in reducing vibration for those. Moving away from the entrapment neuropathies of the upper extremities, we're going to look at some of the tenderness and muscle disorders. The most common overuse injury in and around the area of the wrist is decorvains tenosynovitis or radial styloid tenosynovitis. This is seen in people who do a lot of pinch grasping, particularly if it's repetitive and forceful, or moving the thumb around a lot. We had an epidemic of this among pipetters who were using the old wheel and ratchet type of pipetting where the thumb had to move up and down frequently and if you do that yourself a little bit you can imagine how much that's going to strain that tendon. Any kind of pinch grip, however, may also contribute to the development of decorvains. So the pain here is over the radial styloid and the first dorsal compartment. This is in and around the anatomic snuff box and this contains the tendons of the extrinsic muscles of the thumb, particularly the ones that abduct and extend the thumb. The abductor pollicis longus and the extensor pollicis brevis, and when these become inflamed within the tendon sheath, pain develops in and around the wrist. A good maneuver for this is Finkelstein's test. Ask the patient to wrap their fingers and a fist around the thumb and then get the patient to ulnar deviate the hand and thumb essentially downward to the floor. This can be quite painful. If it's positive, find they jump off the examining seat and really complain of pain in there and that's a good positive test. Palpating around that area will also give you tenderness right along that right along the course of these two tendons. Treatment of this, aside from improving the work, so with our pipetters we got them electric pistol grip type pipetters and that put an end to the repetitive motion of the thumb, is to put them in a thumb spica splint. Sometimes non-steroidals can be useful and in many cases a corticosteroid injection relieves this greatly in conjunction with use of a thumb spica. Lateral epicondylitis is the most common tendinous condition of the elbow. You may also see it referred to as epicondylalgia. There's a lot of dispute, much heat and little light shed on it as to whether it's an inflammatory or degenerative condition. We won't get into this because the boards don't like this sort of controversy. All you need to know is that may be called by two different names. This occurs in a number of patients where there's gripping plus extensive and repetitive use of the forearm muscles. So gripping a hammer with forward and backward motion caused by extension and flexion of the elbow oftentimes causes it. And the main area affected is one of the extensor muscles called the extensor carpi radialis brevis or ECRB. This is the muscle that stabilizes the wrist and allows that hammer to stay in a stable position while at the same time you're straightening and flexing the elbow. This tends to fray the tendons in around where the muscle originates on the lateral epicondyle and fraying and maceration of the tendon start to occur with frequent use. It gets seen in a large number of workers, laborers. One of my own more memorable cases was a farmer hammering in fence post who presented very acutely with this condition. Anyone using hammers and a lot of twisting or torquing tools similar to other elbow disorders. We also had a big outbreak in ultrasonographers, particularly obstetric ultrasonographers. And if you think about this, the same motions really are apparent that the ultrasound probe has to be stabilized by the wrist while at the same time the elbow is being moved back and forth and generally is compressed with force against the patient's abdomen. So this then tends to lead to a number of similar cases and obstetric ultrasonographers and many of you may have seen similar cases. As I noted, there's a real long and boring debate on whether this is degenerative and inflammatory, but it doesn't really matter for our purposes here. Non-steroidals do help it. They can take acetaminophen if they've got a cardiovascular wrist. You want to restrict the work to reducing the amount of flexion extension, particularly with high force gripping at the hand and wrist that you saw in the last slide. The Velcro type elbow bands, which compress the extensor muscles of the forearms just distal to the lateral epicondyle can be useful. These mechanically take the force off the epicondyle itself and transfer them onto the muscle bellies and the band itself. Iontophoresis or use of a corticosteroid patch with ultrasound is actually quite useful for these workers who are affected by lateral epicondylitis. There's actually a B-level of evidence in its favor, as well as other physical therapy, particularly stretching and strengthening exercises. Many cases oftentimes go on to corticosteroid injections. The evidence in favor of that is rather indeterminate and it's not clear whether straight up conservative therapy, non-steroidals and elbow band, along with physical therapy or iontophoresis might not do better. Although in real severe, acutely painful cases, you can do the patient a lot of favors by reducing the pain rather quickly with a rapid injection. Moving on to the shoulder, the most likely problem we will see in clinical occupational medicine will be the rotator cuff tendinopathies. There can be an acute rotator cuff tear from a heavy lift in which pain abruptly develops or oftentimes a fall onto an outstretched arm will disrupt the tendon, sending the force back from the humerus into the shoulder joint and tearing the supraspinatus. More likely, you're going to see cases of chronic rotator cuff tendinopathies and partial tears. These are oftentimes a result of repeated reach and overhead work, especially load-bearing overhead work where the shoulder is moved at and above the shoulder joint level up and over the head and this compresses the rotator cuff within the shoulder joint. There's a number of age-related degenerative changes that many workers get and these can lead to impingement syndromes, they can lead to bone spurs, arthritis within the joint and these can actually aggravate the rotator cuff as well and cause further maceration of the tendons or even small tears themselves. The supraspinatus is the most common location of the three muscles in the rotator cuff to be affected. Treatment of shoulder tendinopathies is stepwise and progressive. If the patient doesn't have a positive drop sign indicating a full thickness tear and needs to go straight to surgery, you can start with treatment with non-steroidals and adjustment and modification of the work, particularly reductions in heavy lifting and lifting at and above shoulder level. Once acute pain is gone, they can be started on range of motion and strengthening exercises and at the same time or if there's lack of progression, a subacromial steroid injection can give them relief and as well speed healing. If they're not improved after four to six weeks, oftentimes the orthopedist oftentimes suggest x-rays with comparison to the opposite shoulder or an MRI if you suspect that there's a rotator cuff tear and that they will need surgery. Subsequent treatment for tears, larger partial thickness tears and certainly full thickness tears is directed towards repair of those tears and particularly in the older patient or one who's developed considerable arthritis, they may undergo subacromial decompression in some way shape or form in addition to any repair of the tears itself. Neck pain is much less common than low back pain but has a number of features in common with it. It's seen in a lot of the population but not nearly to the extent that low back pain develops and it's responsible for about eight percent of workers' compensation claims whereas low back pain is probably over twenty percent of all comp claims. You see some increased risk not only in manual workers but in office workers in whom poor ergonomic setups tend to kind of aggravate upper extremity disorders and it caused them to keep the neck in static positions and postures which aggravate pain. There are also psychosocial factors much the same as there are in low back pain that can lead to increased disability. I put up this slide to remind you of the distribution of the cervical nerves and their radiation mostly because in examination of disorders of the upper extremity you want to consider cervical nerve radiculopathy versus peripheral nerve compression. So for example compression of the c8 nerve at the neck may lead to paresthesias and weakness in the small finger which can also mimic ulnar neuropathy and by the same token c6 and c7 lesions affecting the thumb index and middle finger may be mistaken or present a diagnostic challenge vis-a-vis carpal tunnel syndrome. Of course most of these can be distinguished with nerve conduction testing but it also helps to have the clinical acumen and look at maneuvers of the neck as well as examination of the hand and arms to help differentiate them clinically on your initial exam. Red flags for the cervical spine are much the same as the lumbar spine. You also want to look at individuals who might have acute pain with progressive neurologic deficits because if there is evidence of a tumor cancer or of compression by say tuberculous meningitis there can be compression and myelopathy and this can affect the lower extremities as well so patients may have difficulty walking or gait disturbances if there's a central myelopathy in the cervical spine. But again much the same problems obtain if they've had previous neck surgery and increasing neurologic symptoms. Think again about a recurring disc. Similar to the lumbar spine MRI should be performed if there's red flags or if there's four to six weeks of radiculopathic type symptoms that are not improving with conservative therapy or in any way shape or form becoming worse. As you might expect given what we know about the lumbar spine the cervical spine imaging can have a high false positive rate as well so again ensure that your imaging and your symptomatology correlate before giving them a specific diagnosis. If there are no red flags and there's no evidence of cervical radiculopathy or radiculitis you should get people to again engage in their normal pre-injury activities and they can start low stress aerobic exercise immediately which is good for pain control in general terms. One of the real important mainstays of treatment of cervical spine disorders is to begin neck strengthening exercises. You want to delay these for several weeks after the acute injury such that the pain doesn't get in the way of performing their exercises and in early cases they might actually aggravate it a little bit more. But neck strengthening exercise become very important in the ongoing treatment and in particular in the prevention of further cervical spine disorders particularly the number of non-specific cervical spine disorders musculoskeletal ligamentis or other muscular disorders of the c-spine. A few of the ACOM guidelines and recommendations are presented here. As with the lumbar spine, non-steroidals are the main useful pharmacologic treatment for this. Cervical spine manipulation gets a B-level of evidence for. There's 50% or more of the studies which show some favorable outcomes in chiropractic manipulation. You want to be very careful in these cases, however, particularly in the older patient or someone who has vascular disease because the carotids may also become manipulated and you can break off a piece of plaque and send it on up to the middle cerebral artery and cause a stroke as a consequence of manipulation. So it pays to be much more wary of the patient's general medical condition in the case of the cervical spine vis-a-vis the lumbar spine. There's no good evidence that passive physical therapy helps. They need to use active modalities similar to the low back. You want to avoid bed rest, get them to engage in aerobic exercise, and as I mentioned in the prior slide, strengthening exercises for the neck once acute pain has diminished is very, very important in both treatment and prevention. And the last slide for musculoskeletal disorders treats injection therapies according to the ACOM guidelines. Epidural injections can also be recommended as they can for the lumbar spine. There's an indeterminate level of evidence, so this is a consensus recommendation rather than having much basis in controlled trials. Epidurals for chronic radicular symptoms and conditions of the cervical spine are not recommended, but this is also a consensus level or eye level of evidence in addition. So jury is still out with most of these treatments, but you can generally feel comfortable in sending subacute cases for epidural steroid injections. And similarly, again, to low back pain, many of the other procedural treatments for the cervical spine have recommendations against them. These include facet injections, prolotherapy, radiofrequency neurotomy, and botulinum toxin, which is good for torticollis or muscular spasm of the neck, but is not going to be useful for radicular signs or symptoms. So this ends the musculoskeletal disorders. The next section in the clinical occupational medicine is skin disorders, which will be the next recording.

musculoskeletal disorders

low back pain

work-related disabilities

early identification

proper treatment

risk factors

carpal tunnel syndrome

diagnosis

occupational associations

treatment options

neck pain