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Superior oblique myokymia caused by vascular compression
Masato Hashimoto1, Kenji Ohtsuka, Yasuo Suzuki
1Department of Ophthalmology, Sapporo Medical University, School of Medicine, S-1, W-16, Chuo-Ku, Sapporo 060, Hokkaido, Japan. mashoyu5@beige.plala.or.jp
Summary
Superior oblique myokymia, a rare condition, was successfully treated by decompressing the trochlear nerve from a compressing superior cerebellar artery. This case highlights the effectiveness of surgical intervention for nerve compression syndromes.
Area of Science:
- Neuroscience
- Ophthalmology
- Neurosurgery
Background:
- Superior oblique myokymia is a rare condition causing involuntary twitching of the superior oblique muscle.
- Vascular compression of the trochlear nerve is an under-recognized etiology for this condition.
- Previous reports are limited, with only one similar case documented.
Observation:
- A 49-year-old male presented with an eight-year history of left superior oblique myokymia.
- Advanced magnetic resonance imaging (MRI) techniques, including SPGR and FIESTA, revealed a superior cerebellar artery branch compressing the left trochlear nerve at its root exit zone.
- Surgical exploration via posterior fossa craniotomy confirmed the vascular compression.
Findings:
- Surgical decompression using a Teflon pad effectively separated the artery from the trochlear nerve.
- Post-operative follow-up for one year showed complete resolution of the superior oblique myokymia.
- This report is the first to visually demonstrate the neuroimaging findings associated with this specific cause of superior oblique myokymia.
Implications:
- Vascular loops compressing cranial nerves are a significant cause of neurological symptoms.
- Advanced MRI sequences are crucial for diagnosing such compressions.
- Surgical decompression offers a potential cure for refractory superior oblique myokymia caused by vascular compression.