Faculty Bibliography

BACKGROUND: Patients with chronic fatigue syndrome (CFS) and post-Lyme syndrome (PLS) share many features, including symptoms of severe fatigue and cognitive difficulty. OBJECTIVE: To examine the neuropsychiatric differences in these disorders to enhance understanding of how mood, fatigue, and cognitive performance interrelate in chronic illness. METHODS: Twenty-five patients with CFS, 38 patients with PLS, and 56 healthy controls participated in the study. Patients with CFS met 1994 criteria for CFS and lacked histories suggestive of Lyme disease. Patients with PLS were seropositive for Lyme disease, had met the Centers for Disease Control and Prevention criteria, or had histories strongly suggestive of Lyme disease and were experiencing severe fatigue that continued 6 months or more following completion of antibiotic treatment for Lyme disease. All subjects completed self-report measures of somatic symptoms and mood disturbance and underwent neuropsychological testing. All patients also underwent a structured psychiatric interview. RESULTS: Patients with CFS and PLS were similar in several somatic symptoms and in psychiatric profile. Patients with CFS reported more flulike symptoms than patients with PLS. Patients with PLS but not patients with CFS performed significantly worse than controls on tests of attention, verbal memory, verbal fluency, and motor speed. Patients with PLS without a premorbid history of psychiatric illness did relatively worse on cognitive tests than patients with PLS with premorbid psychiatric illness compared with healthy controls. CONCLUSIONS: Despite symptom overlap, patients with PLS show greater cognitive deficits than patients with CFS compared with healthy controls. This is particularly apparent among patients with PLS who lack premorbid psychiatric illness.

Multiple sclerosis (MS) patients often report that heat makes their symptoms worse. There is anecdotal evidence that the opposite, body cooling, may make MS symptoms better. The goal of this study was to determine whether core body temperature cooling compared to placebo treatment produced objective changes on the neurologic examination, and affected immune parameters, in MS patients. Eleven relapsing-remitting patients who reported heat sensitivity underwent cooling or sham cooling using a commercially available active liquid flow cooling garment. Clinical parameters of visual acuity, timed walk, muscle strength, and coordination, and immune parameters of cytokine production were examined one hour before and after treatment. Cooling produced a significant improvement in acuity, timed walk, and muscle strength compared to sham cooling. Cooling, but not sham cooling, also decreased cytokine production by MS peripheral blood cells. These results suggest that cooling can result in objective clinical improvements in several functional systems of heat sensitive MS patients. In addition to a clinical effect, cooling may also have an immune effect on MS.

The effects of cooling on sensory and cognitive processes were investigated in heat-sensitive multiple sclerosis (MS) patients and healthy control (HC) subjects. The Life-Support cooling jacket was used to lower core body temperature by one degree or more. Auditory event-related potentials and neuropsychological test performance were examined in both the cooled and the normal states. Eight MS patients and eight HC subjects underwent two hours of cooling on one day and two hours of sham cooling on another day (order counterbalanced across subjects). Cooling significantly slowed conduction speed in the auditory brainstem pathway of both groups. Cooling also delayed a longer latency sensory ERP (N100) in the MS patients, but not in the healthy controls. A cognitive evoked related potential measure (P300) was delayed in the MS patients but was not affected by cooling in either group. The MS patients had significantly poorer neuropsychological performance than HC subjects but performance on most of these tests was not affected by cooling. Since the electrophysiological and neuropsychological measures tapped a broad range of CNS functions and brain areas, the data suggest that the marked clinical improvement seen with cooling in heat-sensitive MS patients is not accounted for by facilitation of the sensory and cognitive processes of the CNS.