Wednesday, November 28, 2007

Neuropsychology of Fatigue

Clinical neurophysiology of fatigue.

Journal: Clin Neurophysiol. 2007 Nov 24; [Epub ahead of print]

Authors: Zwarts MJ, Bleijenberg G, van Engelen BG.

Affiliations: University Medical Centre Nijmegen, Institute of
Neurology, 920 Department of Clinical Neurophysiology, PO Box 9101,
6500 HB Nijmegen, The Netherlands; Neuromuscular Centre Nijmegen,
Department of Neurology, Radboud University Nijmegen Medical Centre,
Nijmegen, The Netherlands.

NLM Citation: PMID: 18039594


Fatigue is a multidimensional concept covering both physiological and
psychological aspects. Chronic fatigue is a typical symptom of
diseases such as cancer, multiple sclerosis (MS), Parkinson's disease
(PD) and cerebrovascular disorders
but is also presented by people in
whom no defined somatic disease has been established. If certain
criteria are met, chronic fatigue syndrome can be diagnosed.

The 4-item Abbreviated Fatigue Questionnaire allows the extent of the
experienced fatigue to be assessed with a high degree of reliability
and validity. Physiological fatigue has been well defined and
originates in both the peripheral and central nervous system
. The
condition can be assessed by combining force and surface-EMG
measurements (including frequency analyses and muscle-fibre
conduction estimations), twitch interpolation, magnetic stimulation
of the motor cortex and analysis of changes in the readiness potential.

Fatigue is a well-known phenomenon in both central and peripheral
neurological disorders. Examples of the former conditions are
multiple sclerosis, Parkinson's disease and stroke. Although it seems
to be a universal symptom of many brain disorders, the unique
characteristics of the concomitant fatigue also point to a specific
relationship with several of these syndromes.

As regards neuromuscular disorders, fatigue has been reported in
patients with post-polio syndrome, myasthenia gravis, Guillain-Barré
syndrome, facioscapulohumeral dystrophy, myotonic dystrophy and
hereditary motor and sensory neuropathy type-I. More than 60% of all
neuromuscular patients suffer from severe fatigue, a prevalence
resembling that of patients with MS.

Except for several rare myopathies with specific metabolic
derangements leading to exercise-induced muscle fatigue, most studies
have not identified a prominent peripheral cause for the fatigue in
this population. In contrast, the central activation of the diseased
neuromuscular system is generally found to be suboptimal. The
reliability of the psychological and clinical neurophysiological
assessment techniques available today allows a multidisciplinary
approach to fatigue in neurological patients, which may contribute to
the elucidation of the pathophysiological mechanisms of chronic
fatigue, with the ultimate goal to develop tailored treatments for
fatigue in neurological patients.

The present report discusses the different manifestations of fatigue
and the available tools to assess peripheral and central fatigue.

* * *

As I've said in the past, and will certainly say again in the future, if I were to tell people that I had fatigue related to some accepted neurological disease like MS or polio, it would be considered perfectly normal and no one would DARE call me lazy.  But because I have CFS, the concept of "all blood tests are normal" precludes the doctors and judges realizing that neurology does not show up on blood tests.  The name alone is enough to brand me as "too lazy to work" without investigating why I have symptoms which cannot be faked.

Dr. Starlanyl suggests that if "all tests are normal" that means nothing more than that the right tests haven't been done.  Of course, her perspective is as a doctor who is also a patient, someone who knows she's not faking or imagining things, and not as a HMO doctor who sees his bonus reduced with every test he orders, for whom it is more lucrative to blame the patient than to order expensive neurological tests, MRIs, sleep studies, etc. looking for things that don't show up on basic first round blood tests.

I wanted a sleep study to prove that the doctors were wrong in asserting "sometimes we think we are awake when we are really asleep" -- if they had hard proof that I was only getting 2 hours sleep, something other than my claim that I laid awake till after 5 AM most nights, they might have addressed the severe sleep disturbance.  Instead, they tried to jolly me into believing that I was mistaken, and that the only reason to order a sleep study was for sleep apnea. 

Maybe they didn't want to lose their bonuses for keeping test expenses to a minimum, or maybe they didn't want to see the objective proof that there was something very wrong with my sleep pattern; either way, they continued to claim there's "no objective evidence" while refusing to investigate in ways that would create the necessary objective evidence to convince them that there were objective symptoms and not just the over-active imagination of a hypochondriac who'd found a way to avoid working.

And, for the record, I haven't found a way to avoid working -- I have been working in temp jobs and self-employment since losing my job for being too sick to work full-time.  If I were really just "too lazy to work" I wouldn't be doing that ... I'd be hanging out in upscale bars looking to seduce a Sugar Daddy.

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