STEREOTAXIC BIOPSY OF BRAIN-STEM MASS LESIONS

BACKGROUND Appropriate therapy of brainstem lesions is guided by accurate diagnosis. Because the majority of brainstem lesions are not amenable to surgical resection, stereotactic biopsy is an attractive method of obtaining pathological tissue. METHODS We reviewed the medical records of all patients who underwent stereotactic biopsy of brainstem mass lesions at our institution by the senior author (WAF) over a 10-year period ending in December 1993. RESULTS Twenty-four patients ranging in age from 3 to 68 years underwent stereotactic biopsy of mass lesions of the brainstem. Sixteen lesions were located primarily in the pens, 7 in the midbrain, and 1 in the medulla. Twenty-two of the biopsies were approached transfrontally and two were approached via the suboccipital transcerebellar route. Pathological diagnosis was made in 23 of the 24 patients. The histologic diagnosis was astrocytoma in 16 patients, metastasis in 3, lymphoma in 1, germinoma in 1, chordoma in 1, progressive multifocal leukencephalopathy in 1, and was nondiagnostic in 1. Complications included 1 case of increased hemiparesis, 1 case of obstructive hydrocephalus, and I death. Six patients were less than 20 years of age and in each of these patients the preoperative diagnosis was astrocytoma. In ail of these patients the pathology revealed astrocytoma. In the adult patients the pathology was more varied, with 7 of the 18 patients having tumors or pathology other than astrocytoma. CONCLUSIONS The data suggest that, in adult patients, brainstem lesions are of varied pathology and stereotactic biopsy can provide adequate tissue for diagnosis. The data also suggest that the diagnosis of brainstem glioma in children can often be made without submitting the patient to the risk of surgery.