Faculty Bibliography

Fatigue is commonly reported in many neurologic illnesses, including multiple sclerosis, Parkinson disease, myasthenia gravis, traumatic brain injury, and stroke. Fatigue contributes substantially to decrements in quality of life and disability in these illnesses. Despite the clear impact of fatigue as a disabling symptom, our understanding of fatigue pathophysiology is limited and current treatment options rarely lead to meaningful improvements in fatigue. Progress continues to be hampered by issues related to terminology and assessment. In this article, we propose a unified taxonomy and a novel assessment approach to addressing distinct aspects of fatigue and fatigability in clinical and research settings. This taxonomy is based on our current knowledge of the pathophysiology and phenomenology of fatigue and fatigability. Application of our approach indicates that the assessment and reporting of fatigue can be clarified and improved by utilizing this taxonomy and creating measures to address distinct aspects of fatigue and fatigability. We review the strengths and weaknesses of several common measures of fatigue and suggest, based on our model, that many research questions may be better addressed by using multiple measures. We also provide examples of how to apply and validate the taxonomy and suggest directions for future research.

In the largest sample studied to date, we measured cognitive functioning in children and adolescents with pediatric multiple sclerosis (n = 187) as well as those with clinically isolated syndrome (n = 44). Participants were consecutively enrolled from six United States Pediatric Multiple Sclerosis Centers of Excellence. Participants had a mean of 14.8 +/- 2.6 years of age and an average disease duration of 1.9 +/- 2.2 years. A total of 65 (35%) children with multiple sclerosis and 8 (18%) with clinically isolated syndrome met criteria for cognitive impairment. The most frequent areas involved were fine motor coordination (54%), visuomotor integration (50%), and speeded information processing (35%). A diagnosis of multiple sclerosis (odds ratio = 3.60, confidence interval = 1.07, 12.36, P = .04) and overall neurologic disability (odds ratio = 1.47, confidence interval = 1.10, 2.10, P = .03) were the only independent predictors of cognitive impairment. Cognitive impairment may occur early in these patients, and prompt recognition is critical for their care.

Parainfectious disorders of the nervous system encompass those meningo-encephalo-radiculomyelitic conditions that are temporally associated with a systemic infection, antigenic stimuli, or toxin exposure, in the absence of evidence of direct neuronal infection or invasion of the central nervous system (CNS) or peripheral nervous system (PNS). Pathogenetic mechanisms can be due to immune-mediated processes (such as bystander activation, molecular mimicy) or the inciting insult can be due to toxic factors, as in the case of botulism. A myriad of clinical manifestations can occur including headache, seizures, and mental status changes, ranging from mood and behavioral disturbances to varying levels of alteration in consciousness. Focal neurological deficits can include aphasia, hemiparesis, or paraparesis. The PNS can also be affected leading to cranial nerve involvement, focal or multifocal neuropathies, and dysfunction of the autonomic nervous system. Diagnosis is based not only on the history, examination, laboratory, and neuroimaging data but also on epidemiological factors. The parainfectious disorders covered in this review are cat scratch disease, Lyme borreliosis, legionellosis, brucellosis, botulism, pertussis, and mycoplasma. Each is associated with a distinct organism, has both systemic and neurological manifestations, and has a different epidemiological profile.