Neurology case: spontaneous jump-torsion nystagmus due to medial bulbar infarction

71-year-old man presenting with acute dizziness and right-sided paresthesia
.
Examination reveals spontaneous torsional nystagmus (beating to the left at the upper pole of the eye [top pole]) with a slight up-jumping component (video), right-sided weakness, and loss
of sensation in the right hemisphere.
MRI of the brain shows acute left medial bulbar infarction (Figure).

Upbeat-torsional nystagmus is usually caused by selective damage to the vertical semicircular canal access in the medial longitudinal tract (MLF) of the medulla oblongata, often resulting in ipsilateral beating torsional nystagmus
.
Notably, MLF extraneous lesions in the combined arm (brachium conjunctivum) and ventral tegmental tracts can produce similar results (Figure).

Although upward jumping torsional nystagmus is more commonly observed in benign paroxysmal positional vertigo of the posterior semicircular canal, it is induced by the Dix-Hallpike manoeuvre rather than sustained or spontaneous.

(Fig.
: Diffusion-weighted imaging [DWI] showed high signals in the anterior and paramedian [A, arrow] of the left medulla oblongata, combined with the corresponding apparent diffusion coefficient [ADC] performance [B, arrow] to consider diffusion limitation, indicating acute infarction; Pathway imaging[C] adapted from Gold's vertical semicircular canal pathway; MLF and extracentral localization of MLF for spontaneous upward jumping torsional nystagmus; The patient's ischaemic stroke is indicated by lightning in the MLF pathway; BC = binding arm; VTT = ventral tegmental bundle; MLF = medial longitudinal bundle; SVN = vestibular nucleus; LVN = lateral vestibular nucleus; MVN = medial vestibular nucleus; IV = trochlear nucleus; III = oculomotor nucleus; INC=Cajal interstitial nucleus)

(Video: Spontaneous torsional nystagmus [upper pole beating to the left] with a slight upward jump component and unidirectional torsional nystagmus with top pole beating to the left during left and right partial gaze)

References

Hale DE, Green KE.
Teaching Video NeuroImage: Spontaneous Upbeat-Torsional Nystagmus From Medial Medullary Infarction.
Neurology.
2021 Dec 7; 97(23):e2355-e2356.