Hemifacial spasm: clinical and electrophysiologic observations

Area of Science:

• Neurology
• Clinical Electrophysiology

Background:

• Hemifacial spasm (HFS) is characterized by involuntary facial muscle contractions.
• Clinical synkinesis is often observed in HFS but its objective measurement and diagnostic utility require further investigation.

Purpose of the Study:

• To objectively measure facial synkinesis in patients with hemifacial spasm (HFS).
• To evaluate the utility of electrodiagnostic synkinesis measurement in differentiating HFS from other facial movement disorders.

Main Methods:

• Clinical and electrodiagnostic evaluation of 23 patients with HFS.
• Objective measurement of facial synkinesis using simultaneous recording from orbicularis oculi and orbicularis oris muscles during supraorbital nerve stimulation.

Main Results:

• All HFS patients exhibited clinical synkinesis, with considerable variability.
• Facial nerve conduction and blink reflex latencies were normal in HFS.
• Objective synkinesis was measurable in all HFS patients.
• Synkinesis was also observed in aberrant regeneration after Bell palsy but not in other facial movement disorders.

Conclusions:

• Objective measurement of facial synkinesis is feasible in HFS.
• This electrodiagnostic method can help differentiate HFS from other facial movement disorders.
• The findings provide insights into the pathogenesis of HFS.