Congenital middle fossa arachnoid cysts may cause global brain ischaemia: A study with Tc-99-hexamethylpropyleneamineoxime single photon emission computerised tomography scans

Three children with middle fossa arachnoid cysts, presenting with non-speci fic symptoms and otherwise well, were investigated before and after surgery with magnetic resonance and Tc-99-hexamethylpropyleneamineoxime single pho ton emission computerised tomography scans, to assess the effect of the cys ts on cerebral blood flow. All patients had evidence of a reduction in cere bral blood flow at presentation, even in the hemisphere contralateral to th e middle fossa cyst, implied by perfusion defects seen centrally in the dee p white matter of both cerebral hemispheres. After successful surgical exci sion of the cyst, the perfusion defects disappeared. This was associated wi th general improvement of pre-existing non-specific symptoms. These finding s indicate that middle fossa arachnoid cysts may cause global impairment of brain function by interfering with its blood supply. This does not support the generally held view that such cysts are benign in nature when 'asympto matic'. Copyright (C) 2001 S. Karger AG, Basel.