Temporal lobe arachnoid cyst-attention deficit disorder syndrome: role of the electroencephalogram in diagnosis.

I report three childhood cases of temporal lobe arachnoid cyst in association with attention deficit hyperactivity disorder (ADHD). The cysts were identical in location, situated in the left middle cranial fossa, and involved the medial aspect of the temporal lobe. The diagnosis by MRI was determined following EEGs obtained because of headaches, episodes suggestive of partial seizures or tremors, and abnormal neurologic signs. The etiology of the cysts appeared to be developmental and not related to trauma or hemorrhage. EEGs showed focal epileptiform or slow wave abnormalities involving the left temporal region and correlating with the location of the structural temporal fossa lesions. Surgery was not advised, and headaches resolved after dietary modification or when methylphenidate medication for ADHD was discontinued. The relation of the arachnoid cyst to the headaches is not definitely determined, but a causal association with the ADHD is considered plausible because of coincidental learning and language disabilities that might be explained by temporal lobe and sylvian region pathology. This appears to be the first report of the association of ADHD and temporal fossa arachnoid cyst in children. The EEG is a valuable diagnostic test in patients with ADHD complicated by headaches, seizures, or focal neurologic signs. Future cases of arachnoid cyst involving the temporal lobe and diagnosed because of headache or seizures should be investigated psychologically for associated attention deficits and learning disabilities.