Intraoperative direct cortical stimulation motor evoked potentials: Stimulus parameter recommendations based on rheobase and chronaxie.

Objective: To determine optimal interstimulus interval (ISI) and pulse duration (D) for direct cortical stimulation (DCS) motor evoked potentials (MEPs) based on rheobase and chronaxie derived with two techniques.

Methods: In 20 patients under propofol/remifentanil anesthesia, 5-pulse DCS thenar MEP rheobase and chronaxie with 2, 3, 4 and 5ms ISI were measured by linear regression of five charge thresholds at 0.05, 0.

Diagnostic yield of stereotactic brain biopsy.

Objective: To evaluate the diagnostic yield, accuracy, and safety of frame-based stereotactic brain biopsy procedures.

Methods: A retrospective study of all pathologically diagnosed intracranial lesions, using frame-based stereotactic guided brain biopsy procedures performed at King Faisal Specialist Hospital and Research Centre (KFSH&RC), Riyadh, Kingdom of Saudi Arabia between 1993 and 2005 was conducted. Medical charts, radiological studies, and pathological slides were reviewed.