Arteriovenous malformation and diaschisis.

We investigated the haemodynamic dysfunction and secondary thalamic and brainstem atrophy in 24 patients with angiographically proven cerebral arteriovenous malformations (AVM) and no clinical history of cerebral haemorrhage. Cerebral blood flow (CBF) was measured by the method using either stable Xenon or single photon emission computerized tomography (SPECT). Morphological changes in the thalamus and brainstem were evaluated by magnetic resonance imaging (MRI). Two factors are considered to influence hypoperfusion in the ipsilateral cerebral and contralateral cerebellar hemisphere and secondary atrophy of the thalamus and brainstem. One is the size of the nidus and the other is the involvement of the basal ganglia. It is presumed that continuous haemodynamic stress over a long period of time may cause irreversible histological changes in areas remote from the lesion, especially in the AVM which demonstrates involvement of the basal ganglia or a large nidus.