Theodore H. Schwartz, Brian Ho, Charles J. Prestigiacomo, Jeffrey N. Bruce, Neil A. Feldstein, and Robert R. Goodman
Object. Ventricular size often shows no obvious change following third ventriculostomy, particularly in the early postoperative period, making postoperative evaluation difficult without expensive and often invasive testing in patients with equivocal clinical responses. The authors hypothesized that performing careful volumetric measurements would show decreases in size within the first 3 weeks after surgery.
Methods. Volumetric measurements were calculated from standard 3 × 3—mm axial computerized tomography (CT) scans obtained immediately before and 3 and 21 days after surgery. Two independent investigators measured third ventricular volume in a series of 16 patients and lateral ventricular volume in 10 of the patients undergoing stereotactically guided endoscopic third ventriculostomy for noncommunicating hydrocephalus.
Fifteen patients were symptomatically improved at the time the follow-up scan was obtained. Third ventricular volume decreased in all patients by a mean of 35% (range 7.8–95.1%) and lateral ventricular volume decreased in all patients by a mean of 33% (range 4.5–80.3%). The degree of change correlated with the length of preoperative symptoms (p <0.005). The one patient who experienced no improvement showed no decrease in third ventricular volume. In seven of 10 patients, the decrease in third ventricular volume exceeded the decrease in lateral ventricular volume. Repeated measurements indicated that the 95% confidence interval for the authors' calculations varied around the mean by 2.5% for third ventricular volume and 1.2% for lateral ventricular volume. Long-term outcome was excellent, with only one case of delayed failure. The mean follow-up duration was 12 months.
Conclusions. Volumetric measurements calculated from standard CT scans will show a demonstrable decrease in ventricular volume soon after successful third ventriculostomy and can be helpful in assessing patients postoperatively. Although the third ventricle may exhibit a greater decrease, the lateral ventricular measurements are more accurate. Patients with more indolent symptoms show the smallest change.
Theodore H. Schwartz, Orrin Devinsky, Werner Doyle, and Kenneth Perrine
Object. Although it is known that 5 to 10% of patients have language areas anterior to the rolandic cortex, many surgeons still perform standard anterior temporal lobectomies for epilepsy of mesial onset and report minimal long-term dysphasia. The authors examined the importance of language mapping before anterior temporal lobectomy.
Methods. The authors mapped naming, reading, and speech arrest in a series of 67 patients via stimulation of long-term implanted subdural grids before resective epilepsy surgery and correlated the presence of language areas in the anterior temporal lobe with preoperative demographic and neuropsychometric data.
Naming (p < 0.03) and reading (p < 0.05) errors were more common than speech arrest in patients undergoing surgery in the anterior temporal lobe. In the approximate region of a standard anterior temporal lobectomy, including 2.5 cm of the superior temporal gyrus and 4.5 cm of both the middle and inferior temporal gyrus, the authors identified language areas in 14.5% of patients tested. Between 1.5 and 3.5 cm from the temporal tip, patients who had seizure onset before 6 years of age had more naming (p < 0.02) and reading (p < 0.01) areas than those in whom seizure onset occurred after age 6 years. Patients with a verbal intelligence quotient (IQ) lower than 90 had more naming (p < 0.05) and reading (p < 0.02) areas than those with an IQ higher than 90. Finally, patients who were either left handed or right hemisphere memory dominant had more naming (p < 0.05) and reading (p < 0.02) areas than right-handed patients with bilateral or left hemisphere memory lateralization. Postoperative neuropsychometric testing showed a trend toward a greater decline in naming ability in patients who were least likely to have anterior language areas, that is, those with higher verbal IQ and later seizure onset.
Conclusions. Preoperative identification of markers of left hemisphere damage, such as early seizure onset, poor verbal IQ, left handedness, and right hemisphere memory dominance should alert neurosurgeons to the possibility of encountering essential language areas in the anterior temporal lobe (1.5–3.5 cm from the temporal tip). Naming and reading tasks are required to identify these areas. Whether removal of these areas necessarily induces long-term impairment in verbal abilities is unknown; however, in patients with a low verbal IQ and early seizure onset, these areas appear to be less critical for language processing.