Unilateral asterixis, thalamic astasia and vertical one and half syndrome in a unilateral posterior thalamo-subthalamic paramedian infarct: An interesting case report

Isolated astasia caused by a localized infarction in the suprathalamic white matter

A 73‐year‐old woman with essential hypertension and diabetes mellitus abruptly developed astasia. There were no other neurological abnormalities. Cranial diffusion‐weighted magnetic resonance imaging demonstrated a localized infarction in the right‐sided suprathalamic white matter. Under antiplatelet agent and rehabilitation, the patient became asymptomatic within 4 days. This is a first reported case of isolated astasia due to a suprathalamic white matter infarction. We speculated that disruption of the connection from the ventrolateral nucleus of the thalamus to the posterior cingulate gyrus and/or supplementary motor area might cause astasia.

Asterixis

Asterixis is a type of negative myoclonus characterized by irregular lapses of posture of various body parts. It is an uncommon but important sign in clinical neurology. Initially described as a "liver flap," its utility encompasses a galaxy of neurological and nonneurological situations. Asterixis has a rich history. Despite being described over 70 years ago, its exact pathogenesis remains unknown. Its significance as a tool for the evaluation and prognosis of encephalopathies has been suggested. This review presents its history, clinical implications and its significance.

Skew deviation: clinical updates for ophthalmologists

PURPOSE OF REVIEW

This article discusses the current approach in diagnosing skew deviation, as well as recent findings in the lesion localization.

RECENT FINDINGS

Skew deviation can be defined as vertical misalignment of the eyes that does not map to any of cyclovertical muscles, in association with neurologic symptoms and signs and with posterior fossa lesion. It can be differentiated from trochlear nerve palsy by the direction of ocular torsion and the change in the degree of vertical deviation with upright and supine head position. It is commonly caused by ischemia of the posterior paramedian pons, medial thalamus, or cerebellum. Other less common mechanism being demyelinating lesion, mass effect, infection, hemorrhage, or intracranial hypertension. When the vestibular nuclei are involved, skew deviation may occur with acute vestibular syndrome. Ground-in or Fresnel prism may alleviate diplopia in relatively small vertical deviation; however, patient with larger deviation or with the presence of ocular torsion may benefit from surgery of the cyclovertical muscles.

SUMMARY

Skew deviation can be appropriately diagnosed from the nature of the ocular torsion and the vertical deviation, along with the presence of lesion involving posterior paramedian pons and/or medial thalamus.