Dade Lunsford

Currently, microsurgical resection of acoustic neuromas by an experienced, multidisciplinary team is thought to be the treatment of choice. During the past 20 years stereotactic radiosurgery has been used as an alternative to surgical removal. To compare the results of both microsurgery and stereotactic radiosurgery, we conducted a study of 87 patients with unilateral, previously unoperated acoustic neuromas with an average diameter less than 3 cm treated by the neurosurgical service during 1990 and 1991. Preoperative patient characteristics and average tumor size were similar between the treatment groups. State of the art microsurgical or radiosurgical techniques were used by experienced surgeons in both treatment groups. The treatment groups were compared based on cranial nerve preservation, tumor control, postoperative complications, patient symptomatology, length of hospital stay, total management charges, effect on employment status, and overall patient satisfaction. Stereotactic radiosurgery was more effective in preserving normal postoperative facial function (P < 0.05), and hearing preservation (P < 0.03) with less treatment associated morbidity (P < 0.01). Effect on preoperative symptoms were similar between the treatment groups. Postoperative functional outcomes and patients' satisfaction of their tumor management were greater after stereotactic radiosurgery when compared to the microsurgical group, although they did not reach statistical significance (P = 0.07 and P = 0.10, respectively). Patients returned to independent functioning sooner after stereotactic radiosurgery (P < 0.001). Hospital length of stay and total management charges were less in the radiosurgical group (P < 0.001). When compared to microsurgical removal, stereotactic radiosurgery proved to be an effective and less costly management strategy of unilateral acoustic neuromas less than 3 cm in diameter. For many acoustic neuroma patients, stereotactic radiosurgery should be offered as an alternative management strategy.

Appropriate treatment for intracranial mass lesions depends upon accurate histological diagnosis. Although both advanced generation computed tomographic and magnetic resonance scanners can detect small lesions within the brain stem, only the combination of these advanced imaging tools with stereotactic instrumentation permits safe and accurate pathological diagnosis of such lesions. We present the results of 13 operations performed on 12 patients with mass lesions of the pons and mesencephalon. A definitive diagnosis was obtained in all patients. Aspiration of necrotic tumors (3 patients), neoplastic or benign cysts (2 patients), and chronic hematomas (2 patients) resulted in immediate neurological improvement in 7 of these 12 patients. No morbidity or mortality related to surgery occurred in this series. Both the preoperative clinical and radiographic diagnoses were erroneous in 6 patients so that accurate histological diagnosis indeed altered subsequent therapy. A transfrontal approach to the midbrain and a transcerebellar approach to the lateral pons are described. The importance of accurate diagnosis, the possibility of definitive therapy in selected patients, and the encouraging benefits and safety of stereotactic surgery indicate that empiric treatment of mass lesions of the midbrain and pons is no longer justified.

A therapeutic computed tomographic (CT) scanner uniquely dedicated to surgical usage allowed intraoperative CT imaging during precise resections of glial brain tumors in three patients. Intraoperative CT scanning provided accurate tumor localization, superior contrast and spatial resolution of the lesion, and cross sectional anatomy of the entire brain. Further development of intraoperative CT guidance will allow safer or even complete removal of some previously unresectable brain tumors.

Computed tomography (CT) has become the first modality to provide the patient's self-brain map for stereotactic neurosurgery. This paper describes our development of a nearly artifact-free stereotactic frame designed for CT imaging. The surgical procedure is performed within the CT scanner itself. The scanner's computer, via a new software program, spatially integrates the new stereotactic frame with the CT images of the patient and with the scanner gantry to provide rapid coordinate determinations, calculate potential probe trajectories, obtain target accuracy within 1 mm, and observe for any procedural complications. Our initial clinical experience with this system is described.

The technique and results of treatment of tic douloureux by percutaneous retrogasserian glycerol rhizotomy ( PRGR ) were assessed in a series of 112 patients. All patients were refractory to or intolerant of medical therapy. Many of these patients had recurrent pain despite such surgical treatment as microvascular decompression (21%) or one or more percutaneous radiofrequency thermal rhizotomies (19%). The follow-up duration after glycerol rhizotomy ranged from 4 to 28 months. At the final assessment, 67% had complete pain relief; 23% were improved, with pan relieved by minimal drug therapy; and 10% had poor results with unsatisfactory pain relief even with medications. Before the final assessment, 19 patients required a second PRGR because of an initially suboptimal injection (10%) or recurrent pain (16.9%). Seventy-three per cent had no demonstrable change in facial sensation after operation. H akanson 's original procedure based on anatomic verification by cisternography provided precise localization, required no intraoperative stimulation or lesion generators, and allowed varied anesthetic options during operation. In contrast to thermal rhizotomy, PRGR offers patients relief of painful tic douloureux without altering facial sensation in most cases.