✓ The author reviews the molecular genetics, pathology, and cell kinetics of meningiomas and the role that regional multiplicity in the dura mater may play in their recurrence. Malignant and radiation-induced meningiomas are discussed, with summaries of series of 60 patients with frankly malignant lesions treated over a period of 22 years at the University of California, San Francisco, and of 10 patients with meningiomas induced by high-dose radiation therapy. Reviewing a 23-year series of 140 patients with subtotally removed meningiomas who were treated postoperatively with radiation, the author recommends that, with meticulous technique, irradiation is effective in preventing the regrowth of subtotally removed benign meningiomas and of all malignant meningiomas. Adoption of both the microscopical cytological grading system proposed by Jääskeläinen's group in Helsinki and the classification of operations proposed by Donald Simpson is also recommended. Wide removal of dura adjacent to meningioma reduces the risk of recurrence, and determination of the bromodeoxyuridine labeling index provides a valid basis for planning treatment and follow-up evaluations. Increased awareness is necessary for early recognition of radiation-induced meningiomas in patients at risk for developing such tumors. For meningiomas in such sites as the parasellar region and the posterior fossa, conservative removal of tumor followed by irradiation is advocated in preference to a radical operation that may cause neurological injury without being curative.
The Richard C. Schneider Lecture
Charles B. Wilson
The Herbert Olivecrona Lecture
Charles B. Wilson
✓ The author reviews his experience with surgical treatment of 1000 pituitary tumors, the majority of which were endocrine-active. The criteria of grading, the microsurgical technique used, and the postoperative results are presented. The mortality rate was 0.2% overall, with no deaths in the group of 774 patients with endocrine-active adenomas.
Significance of the Small Lumbar Spinal Canal: Cauda Equina Compression Syndromes Due to Spondylosis
Part 3: Intermittent Claudication
Charles B. Wilson
Charles S. Cobbs and Charles B. Wilson
✓ The authors present a rare entity, an intrasellar cavernous hemangioma that on neuroimages mimicked a nonfunctioning pituitary macroadenoma in a patient with a known orbital hemangioma. Such lesions can grow extraaxially within the dural sinuses, particularly the cavernous sinus, and present like tumors. A better understanding of the neuroimaging, clinical, and anatomical features of these lesions may prevent difficulties in management.
Joshua B. Bederson and Charles B. Wilson
✓ Outcome after 252 posterior fossa explorations for the treatment of trigeminal neuralgia was determined by a retrospective review. Patients with distortion of the fifth nerve root caused by extrinsic vascular compression underwent microvascular decompression, those with no compression underwent partial sensory rhizotomy, and those with vascular contact but no distortion of the nerve root underwent decompression and rhizotomy. The mean follow-up period was 5.1 years. An excellent (75%) or good (8%) clinical outcome was achieved in 208 patients; 13 patients (5%) experienced little or no pain relief. Thirty-one patients (12%) suffered recurrent trigeminal neuralgia an average of 1.9 pain-free years after operation; recurrence continued at a rate of approximately 2% per year thereafter. Reoperation for recurrent or persistent pain provided excellent or good results in 85% of reoperated patients, but partial sensory rhizotomy was required in most of these patients. Outcome was affected by previous surgical procedures. A previous percutaneous radiofrequency lesion was associated with a significantly greater incidence of fifth nerve complications and a worse outcome after posterior fossa exploration. Because of this finding, the authors recommend that percutaneous radiofrequency rhizolysis be reserved for patients who have failed posterior fossa exploration or who are not candidates for surgery. Patients with compressive nerve root distortion and a short duration of symptoms before surgery had a significantly better outcome than patients with a longer duration of symptoms. In contrast, there was no relationship between the duration of symptoms and outcome of patients without nerve root distortion. Vascular decompression may cause dysfunction of the trigeminal system in tic douloureux, but in patients who remain untreated for long periods an intrinsic abnormality develops that may perpetuate pain even after microvascular decompression. Posterior fossa exploration is recommended as the procedure of choice for patients with trigeminal neuralgia who are surgical candidates.
Mitchel S. Berger and Charles B. Wilson
✓ Epidermoid cysts originating in the paramedian basal cisterns of the posterior fossa are congenital lesions that grow to a large size through slow accumulation of desquamated epithelium. These lesions grow between and ultimately displace cranial nerves, vascular structures, and the brain stem, causing a long course of progressive neurological deficits. The onset of symptoms usually occurs during the fourth decade of life. Epidermoid cysts are easily diagnosed with computerized tomography scans, which characteristically show a low-density extra-axial pattern. The primary surgical objective is to decompress the mass by evacuating the cyst contents and removing nonadherent portions of the tumor capsule; portions of the capsule adherent to vital structures should be left undisturbed. Aseptic meningitis is the most common cause of postoperative morbidity, and its incidence may be minimized by intraoperative irrigation with steroids followed by systemic therapy with dexamethasone. Symptomatic recurrences that occur many years after surgery should be managed with conservative reoperation.
Peter Dyck and Charles B. Wilson
✓ A woman presented with a mass in the left groin, which was later shown to be a sliding hernia. A bony sacral defect prompted investigation, which uncovered a massive anterior sacral meningocele. Examination, including ultrasonography and myelography, is discussed, and a surgical approach proposed.
Neil A. Martin and Charles B. Wilson
✓ In a consecutive operative series of 115 intracranial arteriovenous malformations (AVM's), 16 occupied the medial occipital region. Typically, the patients with medial occipital AVM's presented with bleeding, often accompanied by homonymous visual field deficit, or with migrainous headache. The malformations were supplied principally by branches of the posterior cerebral artery. Through an occipital craniotomy, a surgical approach along the junction of the falx and tentorium provided access to the arteries feeding the AVM and facilitated excision of the malformation. There were no deaths in the series. The incidence of visual field deficit after the operation varied, but in only five cases was the visual field worsened postoperatively. All patients who had a history of intractable headache were cured or improved after surgery. These lesions are favorably situated for surgical treatment.
Sinsuke Hukuda and Charles B. Wilson
✓ Maximal tolerable compression was produced in 28 dogs by advancing a screw through the anterior portion of the C-5 vertebral body into the spinal canal until limb weakness occurred. Chronic vascular insufficiency was established in the cervical cord of 17 dogs by blocking or ligating the spinal and vertebral arteries and their branches in various combinations. Vascular insufficiency was also established in combination with maximal compression. Neurological, microangiographic, and histological findings in all groups of dogs were compared. Dogs in the last group with the most severe injury had more abnormal findings in surface vessels than did all other dogs. When the dogs were bled to the point of weakness, that point also appeared soonest in the last group. From these findings, the authors conclude that the effects of vascular insufficiency and compression are additive and that this may be an explanation of the clinical signs in patients with cervical spondylotic myelopathy who appear to have relatively slight mechanical compression.