Clinical picture

Demyelinating disease can produce isolated vertigo, but classical brainstem MS attacks combine vestibular symptoms with other ocular motor findings — internuclear ophthalmoplegia, gaze palsies, skew, vertical or torsional nystagmus, and cerebellar signs.

HINTS signature — central pattern

Head Impulse: typically normal (the peripheral apparatus is intact)
Nystagmus: often vertical, gaze-evoked direction-changing, or with INO features
Skew: may be present, especially with brainstem plaques

Trainee

Internuclear ophthalmoplegia

INO is caused by a lesion in the medial longitudinal fasciculus on the side of the impaired adducting eye. On lateral gaze the ipsilateral adducting eye is slow or fails to cross the midline, while the contralateral abducting eye shows dissociated nystagmus. Bilateral INO in a young patient should raise strong suspicion of MS.

Clinician

Imaging and workup

MRI of the brain and craniocervical junction with FLAIR and post-contrast T1 sequences. Look for periventricular, juxtacortical, infratentorial, and spinal cord lesions. CSF examination for oligoclonal bands. The McDonald criteria are the diagnostic framework; HINTS findings alone are insufficient¹².