Friedreich's ataxia: electrophysiological and histological findings

Abstract

Electromyography was performed, and motor and sensory nerve conduction velocities were measured in 19 patients definitely affected by Friedreich's ataxia. Biopsy of the sural nerve was also performed in 9 patients. Most patients presented a moderate to severe loss of motor units, a significant increase in mean duration of motor unit potentials, and in the incidence of polyphasic potentials. Short-lasting spontaneous activity was rarely seen. Conduction velocity along the motor and sensory fibres of the median and tibial nerves was moderately slowed, while distal conduction time to muscle was significantly increased and the sensory orthodromically-evoked response markedly reduced. Intraoperative electrophysiological recordings obtained during biopsy of the sural nerve in 4 patients were consistent with the changes conventionally observed in the median, tibial and sural (6 patients) nerves. Quantitative histology revealed a reduced number of total myelinated fibres with a severe loss of large fibres, and a moderate loss of fibres of less than 7 microns in diameter. In teased nerve fibre preparations, the most evident abnormality consisted of fibres with uniformly short internodal length, while signs of remyelination were less prominent. Signs of active axonal degeneration were rarely observed in electron microscopy. Electrophysiological and histological findings were uniformly distributed, and the changes were neither related to the duration nor to the severity of the clinical condition.

Friedreich’s Ataxia: A New Mutation in Two Compound Heterozygous Siblings with Unusual Clinical Onset

“…They revealed considerable differences in the neuropathological features of the 2 siblings. In fact, patient 1 showed axonal loss and clear signs of de-and remyelination, as already reported in the literature [22,23] , whereas her brother had axonal neuropathy. Demyelination in patient 1 may also have been secondary to axonal atrophy.…”

Subclinical peripheral nerve involvement in patients with rheumatoid arthritis

“…Forty-six to 104 fibers, 7 pm or more in diameter and with at least 4 internodal segments, were teased in each nerve sample for morphometric evaluation. The results were compared with those obtained by Caruso and coworkers (22) in an age-matched group of normal control subjects.…”

Relation between trinucleotide GAA repeat length and sensory neuropathy in Friedreich's ataxia

“…The severity of myelinated fibre reduction seemed to increase with the patients’ age,15but it was not related to disease duration or severity 416 Said et al 17 suggested a slow dying back degeneration of abnormally developed sensory neurons.…”