Sustained atypical myokymia of the abductor pollicis brevis with a focal slowing of the median nerve motor axons at the wrist.
Clin Neurophysiol Pract
; 6: 36-40, 2021.
Article
em En
| MEDLINE
| ID: mdl-33490741
ABSTRACT
OBJECTIVE:
We report a case of sustained atypical myokymia associated with short bursts of neuromyotonic discharges involving the abductor pollicis brevis (APB) muscle and describe a useful way of detecting a focal slowing involving a small number of median nerve motor fibers with a concentric needle using the filter setting for single fiber electromyography (EMG). METHODS ANDRESULTS:
A 62-year-old woman developed right thumb twitches at regular interval of 1.7-3.3â¯s (0.6-0.3â¯Hz), which continued for more than four months. Muscle twitches remained the same during altered hand position, psychological stress, or sleep. A concentric needle inserted in the active zone of the APB muscle revealed myokymic bursts with a characteristic of neuromyotonic discharges. Inching study, stimulating at 5â¯mm increment along the median nerve and recording with a concentric needle using a filter setting for single fiber EMG, revealed a focal slowing of the motor fibers at a point 5-10â¯mm distal from the distal crease of the wrist, an entrapment site occasionally seen in the carpal tunnel syndrome. One injection of botulinum toxin type A eliminated the myokymia, which then recurred two and a half years later, showing less prominent muscle twitches.CONCLUSIONS:
Sustained atypical myokymia seen in our case represented bursts of neuromyotonic discharges originated from a focal demyelinating lesion involving a few median nerve motor fibers.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2021
Tipo de documento:
Article