Chiari malformation type I with concomitant persistent trigeminal artery -- report of an unusual case and a review of the current literature.

BACKGROUND: Chiari malformation type I is a stenosis of the subarachnoid space at the level of the foramen magnum due to a small posterior fossa and herniation of the cerebellar tonsils. We present here the unusual case of a Chiari malformation in conjunction with a persistent trigeminal artery and hypoplasia of the basilar artery, also known as a Saltzman anomaly. CASE REPORT: A 34-year-old female physician presented with recurrent headaches, bilateral weakness of deltoid muscles and numbness of the fingertips 3 to 5. A cranial MRI revealed a descent of the cerebellar tonsils to the level of C2 and a supracerebellar cyst. During surgery, a decompressive suboccipital craniectomy was performed. The supracerebellar cyst was fenestrated and the cerebellar tonsils were resected bilaterally. Two days after surgery the patient developed cranial nerve dysfunction and a right-sided hemiparesis. Cerebral angiography revealed a Saltzman type 1 anomaly with persistent primitive trigeminal artery and hypoplasia of the basilar artery. DISCUSSION: This is the first report in the literature about the coincidence of both unusual anomalies. The latest literature of both rare anatomy and the unusual clinical course will be discussed.