The role of spinal fusion in surgery for lumbar spinal stenosis: a review.

The authors undertook a review of the literature and analysis of the local surgical experience for lumbar stenosis to define the role of simultaneous arthrodesis in the treatment of patients undergoing decompression for spinal stenosis. The restrained use of spinal fusion is recommended in spinal stenosis surgery because of the coexisting medical problems in the elderly patient population and the higher associated complication rate with spinal fusion and instrumentation. A spinal fusion is recommended when decompression is performed in an area of segmental instability as manifested by gross movement on flexion--extension radiographs; when the decompression coincides with an area of degenerative instability, as with scoliosis or spondylolisthesis; or when the decompression creates an iatrogenic instability by the disruption of the posterior elements. The use of spine instrumentation as an adjunct to fusion is recommended when an area of degenerative instability shows evident gross instability or has had additional destabilizing procedures, such as a discectomy or a facetectomy. Spinal fusion is not recommended for a routine decompressive laminectomy for lumbar stenosis or in the case of stable degenerative deformities. New fusion techniques may improve the outcome and decrease the morbidity associated with contemporary methods of spinal fusion and instrumentation.

A clinical and neuropathologic study of silk suture as an embolic agent for brain arteriovenous malformations.

PURPOSE: To evaluate the safety and efficacy of silk suture as an agent for preoperative embolization of cerebral arteriovenous malformations. METHODS: Clinical and histopathologic results were analyzed in six patients who underwent embolization of cerebral arteriovenous malformations using silk suture in combination with other agents. RESULTS: Three of the patients treated with silk hemorrhaged after embolization, and two of these patients died. Neuropathologic analysis of four patients showed acute perivascular inflammation, sometimes quite severe. CONCLUSIONS: The inflammatory response to silk may explain its effectiveness in producing vascular occlusion. However, a fulminate vasculitis theoretically can predispose to delayed hemorrhage. Other problems with silk include the pressure required to inject the agent and the inability to determine the final site of deposition of the silk. Although other embolic agents may share some of these potential difficulties, we feel that the disadvantages outweigh the advantages of silk as an embolic agent.

Long-term evaluation of decompressive surgery for degenerative lumbar stenosis.

One-hundred patients who had undergone decompressive surgery for lumbar stenosis between 1980 and 1985 were evaluated as to their long-term outcome. Four patients with postfusion stenosis were included. A 5-year follow-up period was achieved in 88 patients. The mean age was 67 years, and 80% were over 60 years of age. There was a high incidence of coexisting medical diseases, but the principal disability was lumbar stenosis with neurological involvement. Results were categorized as either a surgical success or a failure, depending upon the achievement of preset goals within the context of lifestyle and needs. There were no perioperative complications. Initially there was a high incidence of success, but recurrence of neurological involvement and persistence of low-back pain led to an increasing number of failures. By 5 years this number had reached 27% of the available population pool, suggesting that the failure rate could reach 50% within the projected life expectancies of most patients. Of the 26 failures, 16 were secondary to renewed neurological involvement, which occurred at new levels of stenosis in eight and recurrence of stenosis at operative levels in eight. Reoperation was successful in 12 of these 16 patients, but two required a third operation. The incidence of spondylolisthesis at 5 years was higher in the surgical failures (12 of 26 patients) than in the surgical successes (16 of 64). Spondylolisthetic stenosis tended to recur within a few years following decompression. To forestall recurrences, it is suggested that stabilization be carried out at levels of spondylolisthetic stenosis and the initial decompression include adjacent levels of threatening symptomatic stenosis. However, the heterogenicity of this patient population, with varying patterns and levels of symptomatic stenosis, precludes application of rigid surgical protocols.

Reliability of left and right indicators in CT scanning of the head. Case report.

A case is described in which incorrect preliminary programming of a computerized tomography (CT) machine caused transposition of the left- and right-side indicators in a CT scan, which led to craniotomy on the normal side. The possible mechanism for this is incorrect pre-scan programming of the CT scanner with respect to patient positioning in the scanner gantry. This error, although unlikely, is still possible with the present generation of CT scanners.

Positional vertigo and the cerebellar vermis.

A patient with lower and posterior vermis hematoma presented with truncal ataxia; paroxysmal, positional, downbeating nystagmus; and saccade dysmetria. Drainage of the hematoma resulted in complete resolution of all signs and symptoms.

Childhood medulloblastoma presenting with hemorrhage.

Cerebellar hemorrhage is rare in childhood, and is usually the result of trauma or a ruptured arteriovenous malformation. We report acute subarachnoid hemorrhage as the presenting manifestation of medulloblastoma and review the atypical presentation and causes of cerebellar hemorrhage in infants and children.

Cerebral arteriovenous malformations. Indications for and results of surgery, and the role of intravascular techniques.

To address the problems of surgical risk versus natural risk associated with cerebral arteriovenous malformations (AVM's), and the role of the intravascular operative approach, the authors have assessed a 20-year experience with 450 patients. Results of direct surgery in 90 patients indicate that for the smaller AVM's (Grades I and II), mortality and morbidity rates are lower than a reasonably projected natural risk. Hence, these patients are candidates for surgery in most instances. However, for more extensive AVM's (Grades III and IV), consideration of anticipated future years of exposure to natural risk and the location of the AVM in the brain are necessary for determining operability. In general, neither seizures nor incipient focal neurological dysfunction alone are indications for surgery, and the risks of disability or death from hemorrhage after the fifth decade of life are probably less than the surgical risks by present operative techniques. Considering the usual age of patients at the time of diagnosis, it is estimated that surgical risk is currently less than the natural risk for about 65% to 70% of all AVM patients. The categories of AVM's in which the angiographic effectiveness of the intravascular approach is the greatest correspond to the same categories of AVM's that can be surgically removed with low risk. The intravascular approach is most useful for management of large AVM's causing progressive neurological dysfunction or as a preliminary step to surgery in selected cases in which access to major feeding arteries is difficult. The authors believe that the future of the intravascular approach should be directed toward transforming large inoperable AVM's into operable ones, but that the overall capability for this with acceptable risk is uncertain at present.

Cervical myelopathy due to atlantoaxial and subaxial subluxation in rheumatoid arthritis.

Four patients aged 41 to 73 years, who had had rheumatoid arthritis for eight to 25 years, had signs and symptoms of cervical myelopathy and radiculopathy due to either atlantoaxial dislocation with herniation of the odontoid through the foramen magnum, or subluxation of the middle to lower cervical vertebrae. Spastic paraparesis or quadriparesis, severe nuchal immobility and pain, and flaccid paresis of the upper limbs necessitated anterior medullary decompression and posterior cervical fusion. Postmortem examination disclosed old ischemic necrosis, atrophy, and gliosis in the low medulla and cervical cord. Anterior and posterior gray horns and contiguous posterior and lateral funiculi bore the brunt of the damage. Ascending and descending wallerian degeneration and atrophy of the cervical nerve root were evident. In three cases, anterior spinal or radicular arteries demonstrated intimal fibrosis with moderate stenosis; two cases depicted chronic phlebitis or subarachnoid vessels. Previous reports have infrequently provided evidence of a vasculopathy.

Dissecting aneurysm of intracranial vertebral artery: case report and review of literature.

A spontaneous dissecting aneurysm of the intracranial portion of the dominant right vertebral artery presented as massive subarachnoid hemorrhage, excruciating headache, and respiratory arrest in a 57-year-old white man with a history of systemic hypertension. He died on the 3rd day. Postmortem examination revealed a dissecting hemorrhage extending for 2.1 cm along the artery; rupture of the intima, media, and adventitia could be demonstrated. The intramural accumulation of blood in the proximal segments appeared to be related to retrograde dissection within a media weakened by cystic degeneration. Accumulation of pools of mucoid ground substance was also demonstrated in other intracranial and extracranial arteries. Hemodynamic stresses due to arterial hypertension and physical exertion may have played a contributory role in the etiopathogenesis of this uncommon form of cerebrovascular accident. A comprehensive literature review permits a comparison of supratentorial and infratentorial dissecting aneurysms; vertebral and basilar artery dissections are presented in tabular form.

Estimate of the incidence and importance of circulatory breakthrough in the surgery of cerebral arteriovenous malformations.

Severe hemorrhagic brain swelling has been described occasionally in patients with cerebral AVMs after surgical interruption for feeding arteries, surgical excision, and embolization. The proposed mechanism is an abrupt increase in perfusion pressure in the vasculature of the normal adjacent brain which has lost its capacity to autoregulate. The term circulatory breakthrough has been adopted to describe this. The authors found its incidence to be 3 in 66 patients in a surgical series, but lesser degrees of circulatory breakthrough in smaller lesions may have accounted for most of mortality and morbidity that was encountered. Its importance in embolization is less certain because of the possibility of infarction. It is proposed that better control of this problem by presurgical embolization, surgical staging, and graduated degrees of induced hypotension postsurgery may be necessary if the larger cerebral AVMs are to be excised with mortality and morbidity less than the natural history.

Subarachnoid hemorrhage secondary to an aneurysm of the ascending pharyngeal artery: case report.

The authors report a patient presenting with subarachnoid hemorrhage (SAH) secondary to one of two saccular aneurysms arising from the dural branches of the ascending pharyngeal artery. The aneurysms were obliterated by surgery without complications. Satisfactory visualization of the aneurysms required selective external carotid angiography with magnification and subtraction. This case emphasized the need to include the external carotid system in conventional four-vessel angiography for evaluation of patients with SAH.

Removal of occipital arteriovenous malformations with sparing of visual fields.

Two patients with occipital lobe arteriovenous malformation (AVM) underwent two-stage resection of their lesions. The intervals between operations were eight and 12 days. Prior to surgery, the patients had normal neuro-ophthalmologic examination results and both experienced a reversible homonymous hemianopsia after the initial, partial resection of the AVM. Frequent seizures with visual hallucinations developed in the early postoperative period, with gradual improvement of the visual field defect. The pattern and duration of visual disturbances and the nature of the visual field defects in each patient had similar characteristics. The second operation with complete resection of the AVMs left normal visual fields.

Embolization of segments of the circle of Willis and adjacent branches for management of certain inoperable cerebral arteriovenous malformations.

Most large cerebral arteriovenous malformations (AVM's) in the territories of the penetrating arteries arising from the circle of Willis, including the proximal anterior, middle, and posterior cerebral arteries, have been considered untreatable. However, the pattern of collateral circulation which accompanies these lesions presents the possibility of completely occluding certain segments of the circle of Willis and adjacent major branches without producing infarction distally in the cerebral hemisphere or in the critical areas occupied by the AVM itself. The ensuing reduction of arterial pressure within the AVM may reduce the likelihood of hemorrhage or progressive enlargement. Four patients in whom this was accomplished in whole or in part by embolization are described. In one patient, infarction did ensure but the potential for collateral circulation had been restricted by the passage of emboli into the pericallosal artery. In the others, angiographic filling of the lesion was considerably reduced without worsening of their neurological deficits. One patient had recovery of neurological loss following the procedure, and another was slightly improved. Over follow-up periods of up to 28 months there have been no recurrent hemorrhages or further progression of neurological deficits. However, final assessment of the efficacy of this procedure will require longer follow-up intervals and additional patients.

Cavernous hemangioma of optic chiasm, optic nerves and right optic tract. Case report and review of literature.

Diminishing right ocular visual acuity for three weeks in a 30 year old man was confirmed by examination. Bilateral scotomata and bitemporal hemiachromatopsia indicated a chiasmal lesion; reduced visual acuity and Marcus Gunn pupil of the right eye and left relative temporal hemianopia indicated asymmetric involvement. Erythrocytes in the CSF verified a suspected subarachnoid bleed; contrast-enhanced CAT scan demonstrated a suprasellar mass. A cystic, multiloculated, bluish mass distorted the right optic nerve, tract, and chiasm. A hematoma was evacuated and biopsy revealed a cavernous hemangioma of the right optic nerve. Post-operatively, visual acuity has recovered in the right eye but a left homonymous temporal hemianopia has developed.

Anatomical grading of supratentorial arteriovenous malformations for determining operability.

After the study of over 300 angiograms of supratentorial cerebral arteriovenous malformations (AVM's), the authors have formulated an anatomical grading scheme of I to IV to correspond to the degrees of surgical difficulty for total obliteration. The grading is based upon the number of directly participating arteries for which there is a standardized nomenclature. Occasionally, allowance for clinical grading, in addition to this anatomical grading, must be made. Also, for the anticipation of morbidity, but not mortality, the location of the lesion is important. The authors present the postoperative results in a series of 49 patients to demonstrate the clinical usefulness of the grading scheme.