Which physical findings are characteristic of vertebrobasilar stroke?

Updated: Mar 03, 2020
  • Author: Vladimir Kaye, MD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Answer

Answer

Common clinical findings observed in more than 70% of patients with vertebrobasilar stroke include an abnormal level of consciousness, as well as hemiparesis or quadriparesis, which usually is asymmetric. Pupillary abnormalities and oculomotor signs are common, and bulbar manifestations, such as facial weakness, dysphonia, dysarthria, and dysphagia, occur in more than 40% of patients.

Oculomotor signs usually reflect the involvement of the abducens nucleus; the horizontal gaze center located in the pontine paramedian reticular formation (PPRF), contiguous to the abducens nucleus; and/or the medial longitudinal fasciculus (MLF). Lesions to these structures result in ipsilateral lateral gaze or conjugate gaze palsy.

See the images below.

Lesion of the medial longitudinal fasciculus (MLF) Lesion of the medial longitudinal fasciculus (MLF) resulting in internuclear ophthalmoplegia (INO). (Courtesy of BC Decker Inc.)
Center for vertical gaze and pathways involved in Center for vertical gaze and pathways involved in vertical eye movement (Courtesy of Cranial Nerves--Anatomy and Clinical Comments. BC Decker Inc; Toronto. 1988)
Illustration of afferent (CN V) and efferent (CN V Illustration of afferent (CN V) and efferent (CN VII) limbs of the blink reflex. (Courtesy of BC Decker Inc.)
Vestibular reflex illustrating horizontal eye move Vestibular reflex illustrating horizontal eye movements only. (Courtesy of BC Decker Inc.)
Visceral motor component of CN III and pathways in Visceral motor component of CN III and pathways involved in pupillary constriction. (Courtesy of BC Decker Inc.)

Ocular bobbing is described as a brisk, downward movement of the eyeball with a subsequent return to the primary position. This deficit localizes the lesion to the pons. Other reported signs of pontine ischemia include ataxia and tremor associated with mild hemiparesis. The signs described can occur in different combinations, presenting a diagnostic challenge in lesion localization.


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