Abstract
To determine if objective evidence of autonomic dysfunction exists from a group of Gulf War veterans with self-reported post-exertional fatigue, we evaluated 16 Gulf War ill veterans and 12 Gulf War controls. Participants of the ill group had self- reported, unexplained chronic post-exertional fatigue and the illness symptoms had persisted for years until the current clinical study. The controls had no self-reported post-exertional fatigue either at the time of initial survey nor at the time of the current study. We intended to identify clinical autonomic disorders using autonomic and neurophysiologic testing in the clinical context. We compared the autonomic measures between the 2 groups on cardiovascular function at both baseline and head-up tilt, and sudomotor function. We identified 1 participant with orthostatic hypotension, 1 posture orthostatic tachycardia syndrome, 2 distal small fiber neuropathy, and 1 length dependent distal neuropathy affecting both large and small fiber in the ill group; whereas none of above definable diagnoses was noted in the controls. The ill group had a significantly higher baseline heart rate compared to controls. Compound autonomic scoring scale showed a significant higher score (95% CI of mean: 1.72–2.67) among ill group compared to controls (0.58–1.59). We conclude that objective autonomic testing is necessary for the evaluation of self-reported, unexplained post-exertional fatigue among some Gulf War veterans with multi-symptom illnesses. Our observation that ill veterans with self-reported post-exertional fatigue had objective autonomic measures that were worse than controls warrants validation in a larger clinical series.
Highlights
About 7.7% of 11,441 survey respondents among a sample of 15,000 veterans after 1990–1991 deployment to Gulf War (GW) theater reported a variety of neurological symptoms in a population based study conducted in 1995 (Kang et al, 2000, 2002)
A follow up survey in year 2005 on these GW veterans showed that neuromuscular multi-symptoms such as post-exertional fatigue, dizziness, and tremor remained as medically unexplained (Kang et al, 2003, 2009; Blanchard et al, 2006)
Sophisticated neurophysiologic investigation in representative ill GW veterans showed that the unexplained neuromuscular complaints were not likely to be due to the primary muscle or neuromuscular junction abnormalities (Amato et al, 1997; Sharief et al, 2002)
Summary
About 7.7% of 11,441 survey respondents among a sample of 15,000 veterans after 1990–1991 deployment to Gulf War (GW) theater reported a variety of neurological symptoms in a population based study conducted in 1995 (Kang et al, 2000, 2002). A follow up survey in year 2005 on these GW veterans showed that neuromuscular multi-symptoms such as post-exertional fatigue, dizziness, and tremor remained as medically unexplained (Kang et al, 2003, 2009; Blanchard et al, 2006). Large fiber neuropathy screening showed the same occurrence rate in these veterans compared to non-deployed Gulf era controls, suggesting the need for investigating autonomic nervous system because the vague neuromuscular symptoms were likely to correlate to the small somatic or autonomic nerve fibers rather than large fibers (Jamal et al, 1996; Davis et al, 2004; Rose et al, 2004). Participants from the ill group had chronic post-exertional fatigue in the epidemiological survey conducted in 2005, and that many years later the post-exertional fatigue remained a chief complaint at the time of the current study conducted in 2011–2012. In the clinical context we searched for the presence of relevant clinical autonomic disorders through objective autonomic testing and compared the group differences on measures of cardiovascular function at both baseline and head-up tilt, and sudomotor function
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