Type 2 fiber predominance in Lambert-Eaton myasthenic syndrome.
Serial muscle biopsies in a noncarcinomatous case of Lambert-Eaton myasthenic syndrome (LEMS) have shown progressive atrophy and loss of type 1 fibers, resulting in overwhelming type 2 predominance. A similar abnormality was found in a single biopsy from a second case of LEMS without associated carcinoma. Review of the literature suggests that type 2 fiber predominance has been observed in at least one other biopsied case. Interference with transmitter release caused by anti-voltage-gated calcium channel antibodies may deprive type 1 muscle fibers of the low frequency discharge necessary to maintain their metabolic properties.
Squier
M
M
Department of Neuropathology, University of Oxford, Radcliffe Infirmary, United Kingdom.
Chalk
C
C
Hilton-Jones
D
D
Mills
K R
KR
Newsom-Davis
J
J
D000293:Adolescent; D000328:Adult; D001706:Biopsy; D004568:Electrodiagnosis; D004594:Electrophysiology; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D015624:Lambert-Eaton Myasthenic Syndrome / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009132:Muscles / Q000473:pathology* / Q000503:physiopathology