“Subjective physical disorder” is not an actual medical diagnosis or a validated  medical term. Nevertheless, it can be useful as a concept for understanding certain issues relevant to  disability evaluation.

            The term “subjective physical disorder” has been employed to refer to medical conditions  for which we have not identified specific findings on physical exam or laboratory tests that can reliably serve as proxy  measures of disease severity. This non-specificity  increase the reliance we must place on the patient’s self-reports of how they feel and function and the evaluation of their credibility through medical records and the opinion of their physicians.

            Migraine headache, tension headache, irritable bowel syndrome, irritable bladder syndrome, etc might also be considered as “subjective physical disorders”. However, this essay will focus here on fibromyalgia (FMS) and chronic fatigue syndrome (CFS), because of their prominence for disability claims.

            Clinical Differences between Fibromyalgia/Chronic Fatigue Syndrome and “traditional” causes of disability such as angina, emphysema, lumber disc disease, rheumatoid arthritis.

            Traditionally, disability insurance carriers have worked more  with

 “non-subjective” physical disorders. That is, condition for which it can be argued that certain   physical exam or lab findings might correlate fairly well with illness severity and/or performance limitation. 

             Thus, if a person claims disability because of severe angina it might be argued that we should see EKG abnormalities suggesting ischemia during the course of an exercise stress test. If severe emphysema, walking fast for 20 minutes should make them huff and puff. Chest x-ray and lung function tests should be abnormal. If a person has a disabling lumbar disc protrusion, we might expect to see the disc protrusion displayed on an MRI.  There might be limitation of motion while bending. Certain physical movements should increase pain. If a person were disabled due to rheumatoid arthritis, we might expect to find joint deformity, limited of motion, and. perhaps a high sedimentation rate–suggesting active inflammation.  

            The world would be simpler if we could apply similar reasoning  to every physical illness. However, we cannot.

            The American College of Rheumatology Criteria for the diagnosis of fibromyalgia requires one“subjective” along with one objective (actually, semi-objective) element. That is, the patient must complain of chronic wide spread pain affecting all 4 quadrants of the body and also report abnormal pain over at least 11 of 18 predesignated sites (known as tender points), when a standard quantifiable degree of pressure is applied to these sites. 

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            This tender point criteria is objective in the sense that we apply an “objective” degree or pressure, and might also observe wincing or other “objective”  signs of pain. However, it is also subjective in the sense that it requires the patient to report that they feel pain. Also tender point counts are not etched in stone. They may vary from day to day. And there is only a weak correlation between the number of tender points that are painful and disease severity and limitations of function. Indeed, the dividing line between fibromyalgia (11+ abnormal tender points) and chronic pain syndrome (10 or fewer tender points)–this dividing line is somewhat arbitrary. Diffuse fibromyalgia like pain with fewer than 11 tender points is called chronic pain syndrome. In principle, some  person with chronic pain syndrome could be so limited as to not be able to work, while others, with fibromyalgia, might well be able to carry on with their jobs.

            Why have medical specialists defined fibromyalgia using criteria that are in a large part “subjective”?

            Fibromyalgia’s defining symptom is wide spread chronic pain.  Symptoms, by definition, are and are meant to be “subjective”. They must therefore be based on a patient’s self-report. Thus, the criteria that define the illness requires that we depend on the patient’s self-reports. Unstated, but assumed, is that the validity of these reports depend, to a large degree, on the patient’s credibility. In clinical practice physicians have to make judgment about the truth and accuracy of their patients’ reports. We do this using a combination of  the physician’s medical judgment about the illness, the physician’s judgment about the patient’s character, the patient’s prior medical records, and how well the patient’s reports and actual life style match the known characteristics of their illness.

            These methods of evaluation all share elements of subjectivity i.e. requiring the patient’s self report, objectivity i.e. medical records, pharmacy presciption, old diaries, etc are objective documents, and partly an exercise of independent medical judgment i.e. are normally expected to become highly skilled at evaluating the credibility of their patients. Of course, as a rule, physicians tend to believe their patients–unless there is reason not to. A disability insurance company, of course, does not share this obligation. They can and should look critically at whether an individual claimants self reports are in fact true and accurate.

            Unfortunately, at present, we often have no standard “ruler”, “thermometer” or “tricoder” that  can objectively” measuring disease severity in fibromyalgia or chronic fatigue syndrome..  Such measures might become available in the future e.g. neuroimaging techniques that measure the activity of pain centers in the brain;  but for practical real world testing we’re not likely to have these anytime soon. .

            Fortunately, in research rather than “real world” practice settings scientists have made progress using objective means to validate the self-reports for patients with  “subjective physical disorders”. The data is especially strong for fibromyalgia, but is also fairly good for chronic fatigue syndrome.

            , These research studies “objectively” confirm that typical patients with fibromyalgia actually do perceive the pain they report. They also prove that fibromyalgia patients  perceive the pain they report at much lower levels of stimulus than do persons who are healthy. This increased sensitivity or pain augmentation has been given the name “neural sensitization”.  Neural sensitization is at its core a physical process, reflective of changes in the structure and function of the pain signaling pathways, primarily within the spinal cord and the brain. (The accompanying article discusses this research in some depth.)

            Think of the central nervous system’s pain signaling pathways as the volume knob on a radio. In fibromyalgia the volume is turned up to very high. Thus low level stimuli that causes only minor pain in “normal” persons, causes greater pain in persons among persons with fibromyalgia. The technical name for this amplification is hyperalgesia. Similarly, stimuli that normal individuals do not perceive as painful or distressing, are perceived as pain or paresthesia in the fibromyalgia patient. . The technical term for this is allodynia.  Anatomically, neural sensitization may reflect an increase in the size of pain transmitting nerve cells, neurotranmitter alterations, and increased  cross connecting  synapses among nerve cells that signal pain.

Functional MRI studies provide compelling support for the neural sensitization.

Both normal individuals and fibromyalgia patients show changes in the degree of blood flow in certain areas of the brain just at the time that they report feeling pain.  However, among fibromyalgia patients these regional blood flow changes occur at much lower levels of stimulus than they do for normals. Similar findings have been documented using other “imaging” tools including SPECT scan and cerebral evoked potentials.

            In addition to having a lower initial pain threshold, repeated stimulation causes pain intensity to

 increase more rapidly in fibromyalgia patients than similar stimulation increases pain in normals. Once the stimulus stops,  pain levels decline for both normal persons and those with fibromyalgia. However, pain fades more slowly among those with fibromyalgia.  With fibromyalgia, one can cause pain to continue without fading if one continues to apply a very mild level of further  stimulus. This same level of mild stimulation does not maintain pain when applied to normals.

            Fibromyalgia patients’ pain signaling differs from normals in other important ways.. For example, normal persons become temporarily less sensitive to pain shortly after they’ve exercised. With fibromyalgia we see the opposite. Fibromyalgia patients after exercise are more sensitive to painful stimuli, not less.

            The key studies that document neural sensitivity in fibromyalgia were independent of potential confounding factors including co-morbid depression, disability litigation or patient expectations.

             There is clear consensus in the fibromyalgia research and clinical community that neural sensitization is a major characteristic of  fibromyalgia. There is an up-regulation, augmentation or sensitization of the central nervous system’s pain signaling pathways. These physical changes can be measured in a research setting, but such testing is not  yet available for normal clinical evaluation.

            Thus, contrary to what we once imagined, the “end organ damage” of fibromyalgia is not primarily in the muscle, joints or in the peripheral nerves. Rather it lies within the pain signaling pathways of the spinal cord and the brain, targets that we don’t test with our standard exams. 

            2. How can we go from our general understanding of FMS and CFS, to apply this understanding to an individual patient?

            We knowing that, as a group,  fibromyalgia patients accurately report their pain. However, this does not tell us for sure whether any one specific individual with fibromyalgia is reporting accurately or truthfully.

            The number or intensity of tender point abnormalities does not tell us. A person can be very tender on a given day and still be able to work, or not too tender at all and still be disabled. Indeed, the sensitivity of tender points can vary from day to day. Psychological distress is one of many factors that can affect the pain sensitivity of tender points.

            Nor aside from tender points, are there any other physical exam findings or laboratory tests whose absence means that fibromyalgia is not present, or that it is mild versus severe. Thus, fibromyalgia patients typically have fairly normal muscle strength, no swelling of joints, normal range of motion, normal peripheral nerve examination, and normal interaction on the kind of “light” mental status examination that would typically be done by internists or neurologists.

            However, the opposite is not true. Sub-sets of fibromyalgia patients fairly often have specific physical exam or test abnormalities, that, when present, is evidence  that their disease is severe–although not necessarily disabling.

            Thus, a subset of patients with fibromyalgia (and chronic fatigue syndrome) have   abnormalities of blood pressure and/or heart rate, especially when they remain standing for an extended period. They may have orthostatic hypotension (low blood pressure with standing) and/or postural orthostatic tachycardia syndrome (POTS--heart rate increase with prolonged standing). To the degree that these conditions are substantial and fail to respond to medical  treatment, their presence can support a claim of disability. In contrast,  normal orthostatic findings cannot be used as proof that the disease is mild or not disabling.

            Another subset of patients with severe fibromyalgia and/or chronic fatigue syndrome   report cognitive difficulties–“brain fog”--decreased ability to concentrate and or think quickly, especially with complex or multi-tasked problems. Typically, these persons appear normal on standard office clinical and mental status examination. However, often, but not always, formal neurocognitive testing demonstrates defects consistent with their self-reports.  Formal neurocognitive testing should  be done in most cases where cognitive difficulties are a major reason why a person claims they cannot work.

 In some circumstances neurocognitive testing results can underestimate the degree of disability. Thus, patients typically appear for testing on their relatively “good” days, not on their worse days. Many patients “rest up” for several days before the day of testing so they can do their best effort. Plausibly, test scores might be lower on “bad” days, and/or if the “exertion” of testing had to be repeated 5 days a week for several weeks or months–as in a work setting–not just for one or two sessions. On the other hand, a specific test score that is substantially lower than that expected for a person of  high intelligence and substantial education, might still fall within the average range, despite the reduction caused by disease. In that case, the lower than expected score would be evidence of a substantial disease effect; but it would remain open for debate over how important that deficit would be with regard to a specific job and level of performance.

With regard of patients who complain of  “brain fog” but do not show deficits on cognitive testing, little research has been done with regard to the potential “mechanisms” involved in causing such symptoms. However, recent research suggests that the mental fatigue that these persons report may relate to the greater effort they require to concentrate. That is, they might do the test as well as others, but have to work much harder to do so. If one pushes on this long enough, increased fatigue and poor concentration might be the result.

Dr. Lange, a neuropsychologist at the New Jersey Medical School and her colleagues have made important contributions. Lange’s work is important enough to discuss in some detail ( Lange G, Steffner, J , Cook, D et. Al. Objective evidence of cognitive complaints in Chronic Fatigue Syndrome: A BOLD fMRI study of verbal working memory., NeuroImage 2005; 26: 513-524):

In her first studies patients with CFS but no psychological illness showed (on MRI) a significantly larger number of brain abnormalities on T2 weighted images than did persons who had CFS plus psychological illness. These “mentally healthy” CFS patients also showed more MRI abnormalities than did health controls. These “mentally healthy” CFS patients had mostly of small, punctuate, subcortical white matter hyperintensities, found predominantly in the frontal lobes. Lange wrote: This frontal lobe pathology could explain the more severe cognitive impairment previously reported in this subset of CFS patients. Thus, CFS patients have more anatomical changes in the brain than do healthy controls–independent of whether or not they also have psychological illness.

Lange et. al.  then extended her work to study chronic fatigue syndrome patients using functional MRI, a research imaging system that tracks changes in blood flow in different regions of the brain. Here, Lange all showed that patients with severe chronic fatigue syndrome, when challenged with a mental task, had to recruit many more areas of the brain to fulfill the task than did controls. This was true not only for patients with chronic fatigue syndrome who had abnormalities demonstrated on standard neuropsychological testing, but also on those who neurological test scores were normal.

This confirms that there is something wrong with brain function among chronic fatigue syndrome patients, that current standard neuropsychological tests may be unable to detect. In these patients, they are able to fulfill the initial challenge adequately in the short term, but have to exert substantially greater mental effort to do so. This is consistent with the clinical observation that many CFS patients can think clearly for short periods, but pay the price of increased symptoms and decreased function after prolonged effort.

Lange’s paper supports this view:

“Individuals with CFS appear to have to exert greater effort to process auditory information as effectively as demongraphically similar health adults. Our findings provide objective evidence for the subjective experience of cognitive difficulties in individuals with CFS.”

The Bottom Line: People with CFS might be able to accomplish a short term task fairly well, but they have to work harder to do so. Maintaining that extra effort for many hours at a time, repeated over many days–this might be expected to tend to “wear them out”.

Thus, Lange’s findings (and those of others) tends to support the accuracy of self-report for fibromyalgia patients as a group. Similar studies support the accuracy of self-report for groups of patients with fibromyalgia. This gives plausibility to the self-reports of an individual with these conditions who claims to be disabled. But, of course, the credibility of those claims for each individual has to be evaluated for that individual on its own merits.

            Conclusion: For many or most persons with fibromyalgia (and chronic fatigue syndrome), there is no physical examination sign or standard laboratory test result that we should expect to distinguish mild versus moderate versus severe disease. Therefore-- except for certain subgroups where cardiovascular or neurocognitive abnormalities are documented-- medical expert and insurance evaluators should not expect (or require) that the presence or absence of any specific “objective” finding reliably distinguish between a disabled and a non-disabled person with FMS/CFS.

             One patient/claimant can struggle through her job despite aching muscles and fatigue. Another patient/claimant cannot, and is limited to activity of say, just 3 hours a day. On standard physical exam, standard mental status exam, and standard lab tests, these two individuals are very likely to look the same. As of 2006, such standard exams lack the ability to tell these two individuals apart–despite their great difference in the their abilities and stamina for sustaining activity.          

            The non-conclusive nature of physical findings and laboratory tests, places an increased burden on the patient’s documented reported history–and its credibility–as the main means currently available for judging the capacity of an individual to sustain work.

            3. What reasons do persons with fibromyalgia and/or chronic fatigue syndrome usually give to support their belief that they are unable to work? This question is crucial because, to have face validity, any tool we decide to use to help us judge disability, has, at the very least to address the credibility of the specific claims that the patients are offering.

            In an idealized form these are the four most common scenarios described by patients with severe FMS/CFS. In practice, most patients  report a mix of three or all four of these scenarios.

            Scenario A. “My pain is bad even when I do nothing. However, if I am active for, say a half hour, –even if I am sitting-- my pain usually gets worse.   I might feel this immediately and  it might improve after a rest. I then go back to activity for another short period. However, if I repeatedly push my limits this way, the pain worsens more, accumulating with the total activity of the day. On most  days the total amount of time I can do even intermittent activity is very limited, e.g. a total of two to three hours. If I exceed these tight limits my pain usually flares for 24 hours or more. These flare-ups might begin several hours later or the next day (which is  common) or even several days later. If I push for several days in a row, then the delayed flare up will be much more severe, and will tend to last longer.”.

            Scenario B.  My fatigue and poor stamina keeps me from working. I feel tired and my stamina is poor even when I do little. However, if I do even light activities for, say, 30 minutes, my fatigue worsens further and my stamina declines.  If I keep pushing beyond these limits I become worse still. .  If I then rest for 30 minutes or so, I might be able to be active for another 30 minute. But on most days I’m good for only two or three hours a day of activity, even with breaks to rest.   If I do more, my fatigue often worsens,. These flare ups might last for 24 hours or more. The flare-up might begin  several hours later, or the next day or even  several days later. If I push for several days in a row, then the flare up will be much more severe, and will tend to last longer.”

             Scenario C. “My mental concentration is poor. If I do substantial mental or physical activity my ability to concentrate worsens. The more I do the worse I get. I used to be able to read technical articles and follow what’s happening in meetings. Now this is very difficult. I have to reread articles to try to understand them. I cannot pick up and retain facts in meetings. I do okay in normal conversations, but have trouble “finding” words. It’s especially hard for me to  think quickly, multi-task and doing complicated tasks.

            If I push to do cognitive work beyond my limits my mental concentration worsens (as does my pain and fatigue). . If I do to much physical activity, my cognitive abilities suffer. 

            If push my limits for one day, my concentration (and other symptoms) will be worse  later that day or the next. The more intensely, the longer, or the more often I push, the worse and the longer the flare up of symptoms  will likely be.

            D. Unpredictable Variability in Severity of Symptoms: I am pretty limited even on my relatively “good  days”; but,  I also have much worse than usual “ bad” days when I can do almost nothing at all. These very bad days may occur if I’ve pushed to much on the day before. But, they can also occur unpredictably, even if I watch myself.  On these bad days I can usually do little more than get out of bed. No major tasks are feasible.

            No expert on fibromyalgia or chronic fatigue syndrome doubts that a significant number of persons with these conditions legitimately experiences one or more of these scenarios. However, that fact with respect to a group, does not by itself tell us whether the claims made by any one individual are, in fact, true and accurate.  What tools do we have to help make this judgment with regard to a specific individual?

            4. How do physicians evaluate the severity of illness for patients with FMS/CFS when they present in the clinical setting?

            In normal clinical practice physicians usually make it a practice to believe what their patients tell them–unless and until they have reason to doubt them.

             One reason for doubt might be if the patient’s report are not consistent with the typical pattern of their disease. For example, it would be very atypical for a patient with FMS or CFS to feel typically 100% well and be highly active for weeks at a time, only to plunge back into severe illness for weeks at a time thereafter. Variation in symptoms from day to day or month to month is typical for severe FMS/CFS, but most the upswings are still fairly limiting. (Some CFS/FMS patients will refer to periods of  being “almost normal”. However, they usually see this in comparison to a very low baseline. Close questioning will usually reveal that their energy reserves are still limited.)

            Another reason for doubt might be information from the patient spouse, or other observer claiming that the patient habitually engages in activities that are inconsistent with their self-reports. For example, persons with disabling fatigue and pain due to FMS/ CFS cannot typically play vigorous singles tennis three times a week on a consistent or regular basis. (Such activity might be tolerated once in a while, but would typically flare up their symptoms later that day or the next.)

            Another reason that’s highly relevant to the individual’s credibility is the medical judgments of physicians who know the patient well. Physicians who have developed a relationship with a patient will typically develop a medical opinion about their reliability. 

By and large the judgment of a patient’s credibility made by long-term treating physician has more respect than does that of a physician who has seen the patient only once, or, if an opinion is based just on a review of the file–not all.

            In some charts one can often sense from the physician’s note whether or not the physician has any substantial reservations about the accuracy or truthfulness of the patient’s self-reports. However, in other charts, we cannot tell.

            One practical problem is that many physician’s notes are often not very detailed. As important, the physicians main focus is most on  issues other than quantifying the severity of symptoms or functional impairment.  We are often much more interested in making a diagnosis and recommending treatments, than in asking or writing down  how long a person can sit in a chair or type on a keyboard.

            Thus, a typical physician’s visit note might read something like:

                       Still tired and achy. Ultram helped  a little, but had to stop due to nausea  nausea. Will send to PT and perhaps try Cymbalta.

     This person’s illness might be mild, moderate or severe. One cannot tell from this note. If specifically asked to, the physician might have chosen to direct questions in a different way, toward assessing severity and function. However, in real world practice, other priorities take precedence. In an ideal world, physicians might directly quote the language of all their patients’ complaints. In practice, our notes are highly selective and condensed. Of course, one would not expect the dermatologist looking at a rash to ask about fatigue.

             Despite these limitations, the medical records remain the most important tool we have.

            When litigation occurs, these limitations cause a problem for both claimants and defense.

            If there is little or no mention of  functional limitations in the chart, one cannot necessarily conclude  that function was normal or that no limitations were reported.  Physicians may regard complaints about reduced function as more a vocational than medical concern.  We’re normally most concerned about a host of other issues.

            Another  practical problem is that many physicians don’t know enough about the normal pattern of fibromyalgia, such as the post-exertional flare phenomenon. We tend to only see what we look for, and only look for what we know. So, clinical records are often silent, on what, in litigation, may turn out to be very important points.  

            We also face problems due to the patient’s limitations as a communicator—e.g. limitations imposed by the duration of time allowed for a visit, the patient’s purpose for certain visits being unrelated to her FMS/CFS complaints.

            Please note: An important study extended observation on the flare-up phenomenon to include data on the cumulative effects of very modest degrees of exertion. ((Black C and McCully K Time course of exercise induced alterations in daily activity in chronic fatigue syndrome, Dynamic Medicine 2005, 4:10)

            Six individuals with chronic fatigue syndrome were given a daily walking programs of only 15 to 25 minutes a day with the hope of increasing their daily activity. Activity was measured by an accelometer worn at the waist. Initially these patients were able to increase their daily activity and were able to reach a daily level similar to that of sedentary controls. However, this increased exertion was also at the price of increasing CFS symptoms. Overall mood, daily fatigue and time spent each day with fatigue all worsened over the course of four weeks as the exercise program progressed.

            In order to further examine the idea of a “daily activity limit” a detailed analysis of each subject’s activity each day was performed...a distinct pattern was observed. During the first 4-10 (average of 7) days of exercise, our CFS subjects spent an average, approximately 23 minutes each day exercising. This indicates that the subjects were not only complying with the prescribed exercise, but also were able to reach the daily exercise target...However, over the final 3 weeks of prescribed exercise, the average time spent each day exercising fell to approximately 8 minutes per day...In contrast, sedentary control subjects responded to a similar daily walking program by increasing their total daily activity 25-30% for the first week, and were subsequently able to maintain this increase for three additional weeks.

            Unlike our initial interpretation that CFS subjects could maintain an activity increased over four weeks, it is now apparent that the CFS subjects were only able to sustain the prescribed increases in activity for 4-10 days. We believe the reduction in total daily activity levels, primarily from a reduction in time spent exercising, observed during the following 3 weeks were related to greater symptoms of fatigue. These results indicate that the CFS patients in the current study were more likely than controls to develop exercise intolerance.

            5. In a legal setting, how can we judge the validity of the patient’s reports? In particular, what is the validity of the FCE          

            Physicians in practice are predisposed to believe in the “good faith” of their patients. In the setting of litigation, a frequent issue becomes when is this assumption valid and when is it not? What tools can we use to evaluate whether what the patient now reports is truthful and accurate?

            Because physical exam and lab findings are usually not useful for measuring disease severity, one of the most important sources of relevant evidence is a thorough review of the patient’s medical records, both currently and in the past.  Do these “objective” document or contradict the patient’s reported claims? Are these records  1) consistent with the patient’s self report in their disability application? 2) self-consistent within and among different health records? 3) consistent with the pattern of illness typically seen among persons with severe FMS/CFS?

             Also from the records one can usually judge whether an adequate work up has been done for other potential causes of illness, and whether the patient has had an adequate course of standard treatment..

            In addition to the medical records other “objective” evidence can, in principle, be brought to bear. However, each has its potential weak points along with its strengths, and must be judged judiciously, and not be misused. For example: Information from the patient’s diary; testimony from family members, co-workers, neighbors; videotape surveillance.

            5. The special case of the Functional Capacity Evaluation (FCE)

            The FCE, as now done, asks a patient to light or moderate activities such as stooping, crawling, squeezing, balancing over a period of several hours. In some cases the testing is repeated on the next day. The examiner then uses the findings over these short periods of time to extrapolate out from this short term data to a judgment about how the subject would fare if similar levels of activity had to be sustained for eight hours a day, forty hours a week, week after week and month after month.

            For fibromyalgia and chronic fatigue syndrome is there a scientific or logical basis for making such extrapolations from such short term activity to any conclusion about the ongoing ability to sustain productive work. In brief, the answer has to be a very firm no.

            Please recall, the main reasons people with fibromyalgia and chronic fatigue syndrome claim they cannot work is because pushing past their physical limits causes symptoms to flare, typically with a delay of several hours or a day. They can often do a task for several hours, but if they do too much they then pay the price of being worse the next day. This is the delayed post-exertional flareup phenomenon. This is characteristic of patients with severe FMS/CFS.

These patients also report that their worsening with exertion tends to be cumulative. That is, five days of trying to push through causes much more severe and longer flare-ups than does just one day of over-doing. These patients also report that, unpredictably, they have days where they are even much worse, and can barely get out of bed. These are the reasons they claim they can’t work.

            Does the current FCE of short term activities even seek to address the accuracy of these self-reports. It does not attempt to do so. The current FCE is short term only, makes no effort to ask how the patient felt the next day, and makes no attempt to evaluate function that is in any way comparable to the 40 hours a week required for a job. (In reviewing the raw data in FCE  records I sometimes sees notation that the patient complained of feeling worse during or after the session. But almost never do the examiners refer to these complaints in forming their conclusions about what the patient can or cannot do. I have never seen a report where the examiner calls or visits the patient the next day to access for the expected post-exertional flare-up effects.)