Multiple symmetric lipomatosis (MSL) is a rare disorder of middle life characterized by large nonencapsulated lipomas distributed around the neck, shoulders, and other axial regions. Neurologic involvement, particularly peripheral neuropathy, is frequent. The pathogenesis of the syndrome is still unknown, but ragged-red fibers are occasionally present in muscle of affected patients, suggesting a mitochondrial abnormality. We studied 11 unrelated patients with MSL by means of neurophysiology, muscle morphology, muscle biochemistry, Southern blot, and PCR analysis of mitochondrial DNA. All patients were men aged 41 to 63 years. Clinical or electrophysiologic signs of a sensorimotor polyneuropathy were present in nine patients, eight of whom had a history of alcoholism. In muscle biopsy specimens, the most prominent feature was pathologic subsarcolemmal aggregates of mitochondria. Biochemical analysis of respiratory chain enzymes revealed a moderate but significant decrease of cytochrome c oxidase activity as compared with age-matched controls. In one patient, Southern blot analysis showed multiple deletions of mitochondrial DNA. We conclude that mitochondrial dysfunction is common in MSL and may be based on identifiable defects in the mitochondrial genome.
Multiple symmetric lipomatosis (MSL) is characterized by a typical neck and shoulder distribution of subcutaneous lipomata and is often associated with polyneuropathy. Occasionally, the central nervous system (CNS) can be involved. Twelve of 14 patients in this retrospective study had clinical or electrophysiological evidence of a predominantly axonal polyneuropathy. Among those were 10 with alcohol abuse, but 2 patients without alcohol abuse also showed clinical or electrophysiological polyneuropathy. Clinical CNS involvement was present in 4 patients. CNS dysfunction was documented by evoked potentials in 8 subjects [prolonged latency or low amplitude of the motor response following cortical magnetic stimulation (4 patients), abnormal visually evoked potentials (4 patients) or somatosensory evoked potentials (SEP) (4 patients)]. These findings were compared to 10 chronic alcoholics without clinical signs of MSL. Five of these showed mild sensory neuropathy. Additionally, 2 also had delayed SEP latencies. Motor evoked potentials were normal in all controls. We propose that the multisystem involvement in MSL demonstrated here cannot be attributed to alcohol abuse alone. Biochemical studies have suggested mitochondrial dysfunction as the basis of the widespread neurological pathology in MSL.
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