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A. H. Kirk; Superior Oblique Myokymia as a Basilar Migraine Aura. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3003.
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To determine if there is a link between superior oblique myokymia (SOM) and migraine with aura and to suggest a mechanism whereby the brainstem spreading depression of a basilar migraine aura could cause SOM.Basilar migraine aura is a paroxysmal spreading depression caused by ion shifts in neurons in the brainstem and cerebellum. Basilar migraine auras include dysarthria, ataxia and vertigo.SOM is a train of very rapid, saccadic contractions of one superior oblique muscle causing bursts of shaking of one eye. Uninhibited firing of excitatiory neurons in the superior colliculus triggers firing in the excitatory burst neurons (EBN) of a saccade generator in the rostral interstitial nucleus of the midbrain reticular formation and the paramedian pontine reticular formation. This triggers saccadic firing in the trochlear nucleus.EBN are normally inhibited by glycinergic omnipause neurons in the pontine reticular formation and by brainstem GABAergic inhibitory neurons. In the cerebellum, inhibitory neurons in the vermis inhibit excitatory saccadic firing in the deep nuclei. Migraine spreading depression could inhibit these inhibitory neurons and allow the bursts of saccadic firing in the trochlear nucleus which cause SOMMigraine auras cease for years. This could account for the "success" of surgical treatments and the fact that SOM invariably disappears spontaneously.Gabapentin, which augments the inhibitory effect of GABAergic neurons, is an effective treatment for migraine and for SOM.
Between 1993 and 2009, 44 patients with SOM had detailed questioning about a history of migraine headaches and auras
Every one of 44 patients with SOM --36 women and 8 men-- had a history of migraine fulfilling all International Headache Society criteria. Every one had a history of migraine visual auras.
The 100% association of superior oblique myokymia with migraine with aura and the probability that spreading depression inhibits inhibitory neurons in the brainstem suggests that superior oblique myokymia is a basilar migraine aura
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