Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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April 6, 2009
Hypoplasia of the Internal Carotid Artery with Intercavernous Anastomosis and Congenital Horner Syndrome
- Congenital absence or hypoplasia of an ICA is extremely rare. It may be associated with congenital Horner syndrome, and iris heterochromia occurs when there is interruption of the sympathetic pathway during the first year of life resulting in a light-colored iris.
- Congenital absence or hypoplasia is usually asymptomatic because of collateral circulation from the contralateral ICA or vertebrobasilar system via the circle of Willis.
- Less commonly, the collateral circulation is supplied by intercavernous anastomotic vessels connecting the intracranial portions of the ICAs.
- There are two hypotheses concerning the anomalous intercavernous communcations. One is that they are abnormal anastomosis of two fetal trigeminal arteries; the other focuses on hypertrophy of normally developing vessels including the primitive maxillary , inferior hypophyseal or capsular and preexisting medial rami from the cavernous ICAs.
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