Vascular compression as a cause of superior oblique myokymia disclosed by thin-slice magnetic resonance imaging.
OBJECTIVE
To describe a case of superior oblique myokymia in which thin-slice magnetic resonance imaging (MRI) appeared to show vascular compression of the trochlear nerve.


METHODS
A 50-year-old woman presented with episodic monocular oscillopsia. Neuro-ophthalmologic examinations showed intermittent intorsional microtremor of her right eye, diagnosed as right superior oblique myokymia. Thin-slice (1.6 mm) MRI, using spoiled gradient recalled acquisition in the steady state, was employed to examine the trochlear nerve in its course through the ambient cistern.


RESULTS
Imaging disclosed a branch of the posterior cerebral artery immediately adjacent to the right trochlear nerve.


CONCLUSIONS
These magnetic resonance findings suggest that a cause of superior oblique myokymia may be vascular compression of the trunk of the trochlear nerve.
Hashimoto
M
M
Department of Ophthalmology, Sapporo Medical University, School of Medicine, Sapporo, Hokkaido, Japan.
Ohtsuka
K
K
Hoyt
W F
WF
D002536:Cerebral Arteries / Q000473:pathology*; D002561:Cerebrovascular Disorders / Q000150:complications / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D020385:Myokymia / Q000175:diagnosis* / Q000209:etiology; D009408:Nerve Compression Syndromes / Q000150:complications / Q000175:diagnosis*; D009801:Oculomotor Muscles / Q000294:innervation; D015840:Oculomotor Nerve Diseases / Q000175:diagnosis* / Q000209:etiology; D020432:Trochlear Nerve Diseases / Q000150:complications / Q000175:diagnosis*