ANTERIOR TRANSLOCATION OF LANGUAGE IN PATIENTS WITH LEFT CEREBRAL ARTERIOVENOUS MALFORMATION

We studied seven patients with left cerebral atriovenous malformation (AVM) with superselective arterial injection of anesthetics during ang iography to determine whether there was translocation of some language functions to other regions in the ispilateral hemisphere. All patient s were right handed. With a catheter inserted into each target vessel, patients underwent aphasia examination in an A-B-A design: (A) baseli ne, no anesthetic; (B) 1 minute after anesthetic injection; and (A) 12 minutes after injection (when its effects had dissipated). The result s showed that six of seven patients had no significant aphasia at base line or 12 minutes after anesthetic injection. One patient had a mild conduction aphasia at baseline and after anesthetic effects had dissip ated. In the six patients with temporoparietal AVM, anesthetic injecti ons into vessels in the lower division of the middle cerebral artery ( MCA) not feeding the AVM (e.g., the left angular artery) produced a wi de range of language function-from conduction aphasia to dense Wernick e's syndromes. When upper division MCA vessels were injected (e.g., th e prefrontal branch), all developed a major aphasic disorder with sign ificant comprehension defects. A seventh patient with a frontal opercu lar AVM had a mild anemia, semantic paraphasias, and decreased word-li st generation when the prefrontal branch was injected. Her comprehensi on, however, was intact. These data show that patients with posterior cerebral AVM can show language abnormalities where such deficits are n ot typically seen after acute brain injury. These findings support a p osterior-to-anterior extension of some language skills under condition s of brain disease.