Polioencephalitis and the Brain Fatigue Generator Model of Post-Viral Fatigue Syndromes

Fatigue is the most commonly reported and most debilitating Post-Polio Sequelae (PPS), affecting millions of polio survivors world-wide. Post-polio fatigue is associated with: (1) subjective reports of difficulty with attention, cognition, word-finding and maintaining wakefulness; (2) clinically significant deficits on neuropsychological tests of information processing speed and attention; (3) gray and white matter hyperintensities in the reticular activating system on magnetic resonance imaging of the brain; (4) neuroendocrine evidence of impaired activation of the HPA axis. Many of these findings are identical to those documented following a variety of viral encephalitides, including acute poliovirus infection, lethargic encephalitis, Iceland Disease, myalgic encephalomyelitis, and, most recently, Chronic Fatigue Syndrome. The clinical, historic, neuropsychologic, neuroanatomic and physiologic parallels between poliovirus infection, post-polio fatigue and post-viral fatigue syndromes (PVFS) will be explored in an attempt to describe the pathophysiology of PVFS. The disinhibition of a putative Brain Fatigue Generator will be implicated as a cause of the subjective symptoms and objective signs that accompany PVFS. The results of a pilot placebo-controlled study of a dopamine 2 receptor agonist to treat post-polio fatigue will also be described.