Radiology Resident's Case of the Week

Vertebral Artery Dissection

Bao Nguyen, M.D.
Peer Review Status: Internally Reviewed by Daniel Crosby, M.D.

Imaging:

The head CT shows a large area of hypodensity in the right posterior cerebellar hemisphere consistent with an infarct.

The spin-echo MRI images confirm a right cerebellar infarct in the vascular distribution of the posterior inferior cerebellar artery (PICA).

In contradistinction to the left vertebral arteriogram , there is a segmental region of luminal irregularity along the distal right vertebral artery associated with several intraluminal filling defects, consistent with recannalized thrombus at a site of arterial dissection.

Diagnosis:
Right vertebral artery dissection with associated right posterior inferior cerebellar artery (PICA) territory infarct.

Etiology/Epidemiology/Pathophysiology:
Besides trauma, various causes of vertebral artery dissection have been reported, including drug abuse, hypertension, migraine, vasculopathy, cervical manipulation and sudden vigorous activity. But whatever the underlying etiology, the pathophysiologic insult of any arterial dissection is the sudden intrusion of blood into the arterial wall which results in the creation of a false lumen which may occlude the vessel or propogate thrombus.

Patients with vertebral artery dissection may present with minor symptoms such as headache and neck pain, but severe and catastrophic neurologic deficits occur if crucial branch vessels become occluded. The PICA territory includes not only the posterior inferior cerebellum, the cerebellar tonsil and ipsilateral vermis, but also the posterolateral portion of the medulla, which can be involved in a clinical entity known as the Wallenberg Syndrome.

Miscellaneous:
The Wallenberg Syndrome is a clinical manifestation of an infarct in the lateral medulla, characterized by a combination of contralateral sensory deficits affecting the trunk and extremities, and ipsilateral sensory and motor deficits affecting the face and cranial nerves. The clinical manifestations are broad but include ipsilateral ataxia, facial pain, dysphagia, loss of taste, vertigo, nausea, nystagmus, diplopia, Horner's syndrome, hiccups and contralateral pain and temperature loss.

Key Referrences:

1. Adams, Raymond and Victor, Maurice. Principles of Neurology. 4th ed. 1989. McGraw-Hill Information Services Company. New York.
2. Osborn, Ann. Diagnostic Neuroradiology. 1994. Mosby. St. Louis.

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