Superior oblique myokymia is an uncommon neurological condition caused by vascular compression of the trochlear nerve resulting in repeated, brief, involuntary episodes of movement of the eye.
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It has less commonly been associated with spasm of nystagmus and associated ocular motility deficits including skew deviation, oculomotor nerve palsy, trochlear nerve palsy and internuclear ophthalmoplegia.
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Patients with trochleitis typically experience a dull fluctuating aching over the trochlear region developing over a few days . Some may also feel occasional sharp pains punctuating the ache.
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Patients with an important supra-trochlear spur as in type B and D trochlear dysplasia and chronic instability are more reluctant to conservative and softtissue surgical treatment options.
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Patients with an important supra-trochlear spur as in type B and D trochlear dysplasia and chronic instability are more reluctant to conservative and softtissue surgical treatment options.
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To compensate for this, patients with trochlear nerve palsies tilt their heads to the opposite side, in order to fuse the two images into a single visual field.
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Netrin-1 has also been shown to act as a chemorepellent " in vivo " for trochlear motor axons that migrate dorsally away from the floor plate.
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Cranial nerve III ( the occulomotor nerve ) emerges ventrally from the midbrain, while the CN IV ( the trochlear nerve ) emerges out from the dorsal aspect of midbrain.
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Oddly, fibers from the trochlear nucleus cross over in the midbrain at the superior medullary velum and exit posteriorly, ( this is the only cranial nerve to do so ).
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Damages to these structures produce the ipsilateral presentation of paralysis or palsy due to the lack of cranial nerve decussation ( aside from the trochlear nerve ) before innervating their target muscles.
