Inclusion body myositis - sensory dysfunction revealed with quantitative determination of somatosensory thresholds

In order to evaluate sensory function in inclusion body myositis (IBM), nine patients were subjected to sensibility screening and quantitative determination of somatosensory thresholds. Data were compared with results from electrophysiological examination and muscle biopsy. On sensibility screening all but one of the IBM patients had abnormal findings in hands and/or feet mostly affecting thermal sensibility. Vibratory thresholds were abnormal in five and thermal thresholds in four of the patients. Mean vibratory thresholds were significantly (P < 0.05) higher in the IBM patients when compared with the controls. Significantly increased heat pain thresholds were found in hands and feet when compared with the controls while thermal thresholds were normal. Nerve conduction velocities were decreased in three patients, EMG showed both myopathic and neuropathic abnormalities in six patients. Eight patients had neuropathic abnormalities on muscle biopsy. The sensory dysfunction found suggests an affection of peripheral nerves in IBM mainly affecting large diameter myelinated nerve fibres corroborating earlier findings of a peripheral neuropathy in IBM.