LANGUAGE FUNCTION FOLLOWING SUBDURAL GRID-DIRECTED TEMPORAL LOBECTOMY

The purpose of the study was to determine the extent to which a tempor al resection may be undertaken without producing risk to temporal lang uage areas. Patients undergoing craniotomy and placement of a subdural electrode array (SEA) for evaluation of intractable epilepsy were stu died to determine the variability of distance of temporal language cor tex from the temporal pole. Hemisphere dominance was determined by int racarotid sodium amytal injection. Temporal lobe speech arrest (SA) wa s mapped with a 64 contact point SEA. Thirty-one patients had left dom inant hemisphere SEAs. Thirty had SA 5 cm to 9 cm from the temporal po le (median 7 cm). One had SA at 3 cm. Twenty-one patients subsequently had temporal lobectomy (TL). Mean extent of resection was 5.7 cm (ran ge 3 to 9 cm). In 18 TL patients who had neuropsychometric evaluation of language function pre- and post-surgery, there was no significant d eterioration. Thirty-nine patients had right non-dominant SEAs placed. Eighteen had TL. Thirteen of these had pre- and post-surgery language evaluation and there was no significant change. Comparison of preoper ative scores showed significant superiority of the right non-dominant group over the left dominant group for naming. TL up to 5 cm without s timulation mapping of language areas would be safe in the majority of cases, but one subject (3%) had SA mapped anterior to this and a small number of cases may therefore be at risk to language function followi ng a 5 cm TL. Extensive lateral resections up to 9 cm are possible wit h preservation of language function with stimulation cortical mapping.