Stereotactic Transcerebellar Approach to Pontine Lesions through the Middle Cerebellar Peduncle

A stereotactic approach to the pons through the middle cerebellar peduncle based on MR studies was used to biopsy 18 patients. The stereotactic coordinates and angles were defined with reference to three orthogonal planes (midsagittal, IVth ventricular floor and pontomedullary junction). The pathological diagnoses were in keeping with clinical outcome and comprised five highgrade astrocytomas, three low-grade astrocytomas, two glioblastomas multiforme, two oligodendrogliomas, two primitive neuroectodermic tumours, two lymphomas, one medulloblastoma, and one tuberculosis. This approach provides a high yield of positive histological diagnoses with little morbidity (transient neurological deficits in two cases) and thereby avoids inappropriate therapy.