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Nonspastic hemifacial spasm confirmed by abnormal muscle responses
Shigeru Tani1, Mayuko Inazuka1, Tatsuya Maegawa1
1Department of Neurosurgery, Tokyo Women's Medical University Medical Center East, Tokyo, Japan.
Surgical Neurology International
|July 12, 2017
Summary
Hemifacial spasm can be diagnosed using abnormal muscle responses (AMR) even without visible facial movements. This finding suggests a new classification for nonspastic hemifacial spasm.
Area of Science:
- Neurology
- Neurosurgery
Background:
- Hemifacial spasm diagnosis traditionally relies on visual identification of involuntary orbicularis oculi movements.
- Abnormal muscle responses (AMR) offer an alternative diagnostic approach.
Observation:
- A 48-year-old man presented with left hemifacial spasm and subjective facial twitching, but no visible involuntary movements.
- MRI revealed compression of the left VIIth cranial nerve by the anterior inferior cerebellar artery (AICA), itself compressed by the vertebral artery.
- Abnormal muscle responses (AMR) were detectable, and hemifacial spasm was induced after AMR stimulation, despite the absence of visible spasms.
Findings:
- Hemifacial spasm can be diagnosed through AMR detection when not apparent on visual inspection.
- Microvascular decompression surgery resolved the patient's hemifacial spasm and abolished AMR-induced spasm.
- This case supports AMR as a diagnostic tool for specific hemifacial spasm presentations.
Implications:
- Suggests a new diagnostic category: nonspastic hemifacial spasm.
- Highlights the importance of electrophysiological assessment in diagnosing atypical hemifacial spasm.
- Microvascular decompression is an effective treatment for hemifacial spasm caused by neurovascular compression.
