Myokymia in obstetrically related brachial plexopathy

Area of Science:

• Neurology
• Clinical Electrophysiology

Background:

• Myokymic discharges are spontaneous, semirhythmic muscle potentials.
• These potentials are associated with various neurological conditions, including nerve compression and radiation-induced plexopathies.
• Myokymia has not previously been reported in obstetric brachial plexus palsies.

Purpose of the Study:

• To report the occurrence of myokymic discharges in children with obstetric brachial plexus palsies.
• To explore potential explanations for these findings in the context of birth-related nerve injuries.

Main Methods:

• Case study of two children with obstetric brachial plexus palsies.
• Serial electrophysiological assessments including electromyography (EMG).

Main Results:

• Myokymic discharges were identified in both children during later electrophysiological studies (at 10-11 months of age).
• These potentials were not present or noted in earlier assessments.

Conclusions:

• The presence of myokymic discharges in obstetric brachial plexus palsies is a novel finding.
• This may indicate ongoing recovery from birth-related nerve lesions or developmental alterations in axonal excitability.
• Axonal membrane hyperexcitability is proposed as a common pathway for myokymia across different etiologies.