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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February 18, 2016
Ruptured Pontine Arteriovenous Malformation
- Background:
- The pons is an unusual location for brain AVMs. Approximately 10% of all brain AVMs are located in the posterior fossa, and the minority of them are located primarily in the pons. Prognosis is poor in these patients due to the difficult surgical and endovascular access. Radiosurgery has changed the prognosis as it allows for nidal obliteration in a much less invasive manner.
- Key Diagnostic Features:
- Pontine haemorrhage in a patient with no other risk factors and no evidence of an underlying mass lesion on MR imaging requires angiographic evaluation to rule out an AV shunt (DAVF or AVM).
- Differential Diagnosis:
- Pontine cavernous malformation: Low-T2 rim, significant blooming artifact, intralesional or perilesional hemorrhage. May be associated with a DVA.
- Capillary telangectasia: There are no reports of an acute hematoma secondary to this type of lesion.
- Dural AV fistula: The differential diagnosis requires a DSA
- Hemorrhagic tumor (primary vs. secondary): Usually shows a disproportionate amount of edema compared to the hematoma
- Treatment:
- Radiosurgery is the treatment of choice.
- Endovascular techniques carry a high risk due to the small size of the afferent arteries and the small safety margin for liquid embolic material injection.
- Surgical access to the dorsal pons for AVM resection is highly challenging.
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