Alternating Skew Deviation due to Hemorrhage in the Cerebellar Vermis

Abstract

A 76-year-old Japanese woman with essential hypertension and diabetes mellitus abruptly presented with nausea, dizziness, an occipital headache, truncal ataxia, gaze-evoked nystagmus and alternating skew deviation (ASD) with abducting eye hypertropia. Cranial computed tomography demonstrated hemorrhage in the cerebellar vermis and its vicinity. These symptoms gradually resolved within three weeks. This is the first reported case of ASD secondary to cerebellar hemorrhage without hydrocephalus. The vertical misalignment of the eyes during the right-sided gaze was consistently larger than during the left-sided gaze. We speculated that bilateral and asymmetrical damage to the utricular pathway due to the bilateral involvement of the nodulus and uvula might have caused the ASD.

Alternating Skew Deviation from Traumatic Intracranial Hypotension

“…Zee has proposed that in patients with cerebellar disease, there is an imbalance in otolithocular pathways and a loss of the normal correction for the differences of pulling direction and strength of the extraocular muscles as the eyes change position in the orbit. 5 Our patient, along with some other reported associations, particularly Arnold-Chiari malformation, 2 cerebellar vermis haemorrhage 10 and idiopathic intracranial hypertension, 6 might suggest that some of this dysfunction is related to the anatomic distortion that occurs with a pressure differential between intracranial and intraspinal spaces with downward shifting of brainstem and/or cerebellar structures. …”

“…Other reported causes have included cervicomedullary junction disease (e.g., Arnold-Chiari, basilar invagination, or platybasia), cerebellar or spinocerebellar degeneration, posterior fossa involvement with infarct, haemorrhage, tumour, encephalitis, trauma or demyelination, Wernicke encephalopathy, lithium toxicity, Joubert syndrome, a rare motor neuronopathy, anti-glutamic acid decarboxylase (GAD) antibody syndrome, paraneoplastic syndrome, syringomyelia/syringobulbia, tentorial herniation, or idiopathic intracranial hypertension. 1,2,[5][6][7][8][9][10][11] One might argue that the diplopia in our patient is coincidental to the intracranial hypotension, since it did not disappear after treatment. However, the timing of the onset simultaneous to the rest of the clinical presentation, and the partial improvement along with the partial improvement on MRI, favours the intracranial hypotension as the cause of the alternating skew deviation.…”