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Upbeat Nystagmus917-5
Eye Movements
Upbeat nystagmus in primary gaze
Horizontal gaze evoked nystagmus left > right
No nystagmus on downgaze
Saccadic pursuit in all directions.
Square wave jerks
Dysmetria
Marked saccadic hypermetria
Right gaze to center overshoot (hypermetria) taking the eyes almost fully to the left
Left gaze to center (hypermetria) taking the eyes almost fully to the right
Upgaze to center hypermetria
Downgaze to center hypermetria
Present in primary gaze usually increases on upgaze
Slow phases may have linear-, increasing-, or decreasing-velocity waveforms
Poorly suppressed by visual fixation of a distant target
Clinical Features of Upbeat Nystagmus
Clinical Features of Upbeat Nystagmus
Convergence may increase, suppress or convert to downbeat nystagmus
Associated with abnormal vertical vestibular and smooth-pursuit responses, and saccadic intrusions (square-wave jerks) that produce a bow-tie nystagmus
Localizes to the Caudal Medulla with the lesion affecting the perihypoglossal group of nuclei including:
nucleus intercalatus
nucleus of Roller
nucleus of pararaphales
Upbeat Nystagmus
More rostral brainstem lesions may interrupt the ventral tegmental tract
containing projections from the vestibular nuclei that receive inputs from the
anterior semicircular canal
or
Involve the brachuim conjunctivum in the rostral pons and medulla.
Upbeat Nystagmus
Etiology of Upbeat Nystagmus
Infarction of medulla or cerebellum and superior cerebellar peduncle
Wernicke’s encephalopathy
Multiple sclerosis
Tumors of the medulla, cerebellum or midbrain
Cerebellar degeneration or anomalies
Etiology of Upbeat Nystagmus
Brainstem encephalitis
Creutzfeldt-Jacob disease
Bechet’s syndrome
Meningitis
Thalamic arteriovenous malformation
Transient finding in infants
Clinical Features of Torsional Nystagmus
Torsional jerk nystagmus (minimal vertical or horizontal components) present with eye close to central position.Slow phases may have linear-, increasing-, or decreasing-velocity waveformsPoorly suppressed by visual fixation of a distant targetExacerbated by changes in head position or vigorous head shaking
Leigh JR and Zee DS. The Neurology of Eye Movements 4th Edition. Oxford University Press, New York 2006 with permission
Clinical Features of Torsional Nystagmus
May be suppressed by convergenceOften occurs in association with ocular tilt reaction or unilateral internuclear ophthalmoplegiaMay be precipitated or modulated by vertical smooth pursuit movements.
Leigh JR and Zee DS. The Neurology of Eye Movements 4th Edition. Oxford University Press, New York 2006 with permission
Etiology of Torsional Nystagmus
Syringobulbia, with or without syringomyeliaArnold-Chiari malformationBrainstem stroke (e.g., Wallenberg’s syndrome)Arteriovenous malformation in the brainstem or middle cerebellar peduncle
*Often occurs in association with the ocular tilt reaction and unilateral internuclear ophthalmoplegia.
Leigh JR and Zee DS. The Neurology of Eye Movements 4th Edition. Oxford University Press, New York 2006 with permission
Etiology of Torsional Nystagmus
Brainstem tumorMultiple sclerosisOculopalatal tremor (“myoclonus”)Head traumaCongenital
References
The Neurology of Eye Movements, 4th Edition, Oxford University Press, New York, 2006.
Tilikete C. Koene A. Nighoghossian N, Vighetto A, Pelisson. Saccadic lateropulsion in Wallenberg syndrome: a window to access cerebellar control of saccades? Exp Brain Res 2006;174(3):555-565.
Tilikete C, Hermier M, Pelisson D, Vighetto A. Saccadic lateropulsion and upbeat nystagmus: disorders of caudal medulla. Ann Neurol. 2002 Nov;52(5):658-62.
http://library.med.utah.edu/NOVEL