Stereotaxy of third ventricular masses.

Posterior third ventricular masses are uncommon and posterior intraventricular masses are rare. Intraventricular and paraventricular lesions are difficult to differentiate in this region and present particular problems of diagnosis and treatment. Uncertain radiology and frequently confusing histology make treatment planning difficult. The first requirement of histological confirmation of the speculative pathology is best achieved by stereotactic biopsy rather than craniotomy exposure and biopsy, the mortality and morbidity for each being compared. The problem of CSF pathway obstruction can be dealt with by aspiration of the mass or CSF diversion; solid tumours frequently require a definitive shunting procedure while other lesions may not.