Neurology
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Periodic paralyses and paramyotonia congenita are rare disorders causing disabling weakness and myotonia. Mutations in sodium, calcium, and potassium channels have been recognized as causing disease. ⋯ Hypokalemic periodic paralysis, hyperkalemic periodic paralysis, and paramyotonia congenita may be distinguished based on clinical data. This series of 226 patients (127 kindreds) confirms some clinical features of this disorder with notable exceptions: In this series, patients without mutations had a less typical clinical presentation including an older age at onset, no changes in diet as a precipitant, and absence of vacuolar myopathy on muscle biopsy.
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To determine whether Gulf War veterans with neuromuscular symptoms that included weakness and fatigue had either 1) objective correlates for muscle weakness or fatigue; or 2) any etiologic explanation for such symptoms; and if so, 3) whether such objective measures or etiologic mechanisms were specific to Gulf War service. ⋯ Because complaints of weakness and fatigue in unwell servicemen do not correlate with actual weakness or fatigue, explanations for these symptoms must lie outside of the neuromuscular system. Increased lactate production during subanaerobic bicycle exercise reflects mitochondrial inefficiency, but it is unclear whether this reflects mitochondrial damage sustained during Gulf War service or inactivity secondary to ill health.