Sphenoidal electrodes: their use and value in the electroencephalographic investigation of complex partial epilepsy.

The diagnostic value of sphenoidal electrode EEG recordings in patients with seizures characteristic for epilepsy with complex partial symptomatology was assessed in a study comprising 404 patients; 71.3% of the patients had seizures with automatisms and amnesia, and 28.7% had psychic seizures with subjective phenomena such as hallucinations and illusions. A total of 59.6% of the patients had diagnostic EEG changes in routine waking or sleep EEG. In sphenoidal EEG recording including thiopenthone activation, diagnostic changes were found in 40.5% of the patients without specific changes in waking or sleep EEG, the chance of a positive finding being more than five times higher in patients with automatisms than patients with psychic seizures. Apart from cases where surgical treatment of temporal lobe epilepsy is considered, sphenoidal electrode EEG recording, including intravenous thiopenthone activation, should be performed in patients with seizure phenomena raising suspicion of epilepsy with complex partial symptomatology but where waking and sleep EEGs fail to demonstrate specific abnormalities.