Vertical pendular nystagmus1
Synchronous rhythmic movements of the pharynx, face, tensor tympani, vocal cords,
shoulders, and respiratory muscles2
1. Pathogenesis of vertical pendular nystagmus: results from involvement of the Triangle of Guillain and
Mollaret, which consists of:
■ Red nucleus in the midbrain (which projects to the inferior olivary nucleus via the central tegmental tract)
■ Inferior olivary nucleus in the medulla (which projects to the contralateral dentate nucleus via the olivocerebellar tract in the inferior cerebellar peduncle)
■ Contralateral dentate nucleus in the cerebellum (which projects to the red nucleus via the superior cerebellar
Hypertrophic degeneration of inferior olivary nucleus (which contains increased acetylcholine-esterase reaction
product) is necessary but not sufficient for the genesis of the nystagmus
2. Pathogenesis of palatal tremor: results from rostral cerebellar or brainstem damage that denervates the dorsal
cap of inferior olivary nucleus.


Pendular nystagmus and palatal tremor may arise In lesions of the Guillain-Mollaret triangle, and may be associated with hypertrophy of the inferior olive on MRI. Pendular nystagmus may have delayed development due to denervation hypersensitivity, as occurs in patients with strokes affecting the structures of the triangle.  Following a brainstem lesion affecting the central tegmental tract, new electronic coupling via gap junctions (connexins) between cells in the inferior olive leads to synchronous firing of inferior olivary neurons, which negatively impacts the cerebellum and leads to maladaptive learning1.
It is likely that these oscillations in MS occur primarily because of dysfunction of brainstem and cerebellar connections and instability of the neural integrator. Brainstem lesion burden tends to be high, and the majority of patients with MS with acquired pendular nystagmus have additional signs of cerebellar disease1.




  1. Rucker JC. Nystagmus and Saccadic Intrusions. Continuum (Minneap Minn). 2019;25(5):1376-1400.