STEREOTAXIC BIOPSY OF NONPOLAR TUMORS IN THE DOMINANT HEMISPHERE - A PROSPECTIVE-STUDY OF EFFECTS ON LANGUAGE FUNCTIONS

A prospective study of patients undergoing computerized tomography (CT )-guided stereotactic biopsy of nonpolar tumors in the dominant hemisp here was undertaken to determine if stereotactic biopsy caused a deter ioration of language functions. Language was assessed using the Wester n Aphasia Battery (WAB) and the Boston Naming Test (BNT) before and af ter a biopsy sample was obtained. Of 16 patients studied, five (31%) w ere dysphasic preoperatively. After the biopsy the Aphasia Quotient (A Q), derived from the WAB, had significantly deteriorated in four (80%) of these patients, whereas in the fifth it remained relatively unchan ged. One of these patients with an extensive infiltrating hemispheric oligoastrocytoma subsequently recovered normal language function after radiotherapy. In 10 of the 11 patients who had normal language functi on preoperatively there were no deleterious changes after biopsy in ei ther the WAB subtest or BNT scores. In the other patient whose WAB sco re was normal preoperatively, there was a significant deterioration in postoperative AQ. This patient, who declined steroid therapy before a nd after biopsy, had a glioblastoma multiforme in Wernicke's area. A p ostoperative CT scan revealed no changes from what was shown on preope rative scan. This clinical study shows that CT-guided stereotactic bio psy of nonpolar tumors in the dominant hemisphere using the Brown-Rebe rts-Wells system and the Sedan-Nashold biopsy cannula carries a 9% ris k (95% confidence intervals 0-26%) of impairing language functions if the patient is not dysphasic preoperatively. If the patient is dysphas ic preoperatively, there is a very high risk of aggravating the dyspha sia with stereotactic biopsy.