THE POSTERIOR APPROACH TO A SERIES OF GLOMUS (TYPE-II) INTRAMEDULLARYSPINAL-CORD ARTERIOVENOUS-MALFORMATIONS

OBJECTIVE: Intramedullary spinal cord arteriovenous malformations (AVM s) are comprised of those AVMs which in either glomus or nidal form ar e found partially or entirely within the substance of the spinal cord. An effort to subdivide these lesions into either glomus Type II or ju venile Type III spinal cord AVMs has underscored the diffuse, unresect able nature of the latter but has done little to suggest a logical man agement paradigm for the more well-defined, low-flow glomus lesion. ME THODS: To address this shortcoming, 15 cases of glomus Type II spinal AVMs were identified from a larger series of a variety of spinal AVMs. Computed tomography, magnetic resonance imaging, and superselective a ngiography rendered the anatomic diagnosis of these lesions accurate i n all cases. All lesions were approached posteriorly via a standard la minectomy, with the goal of total extirpation, and all patients underw ent immediate postoperative angiography to verify cure. In the vast ma jority of cases, patients underwent follow-up imaging to confirm the d urability of this cure, and long-term outcome was determined using bot h a subjective quality of life assay and a functional grading scale. A ge, sex, mode of presentation, and radiographic features were subseque ntly analyzed with respect to functional outcome. RESULTS: Most glomus spinal AVMs presented with a rapid cascade of signs and symptoms (73% ), often caused by subarachnoid hemorrhage (60%) and often leading to significant neurological deficits (47%). Initially, 14 of 15 patients (94%) were angiographically cured of their malformations. The remainin g patient was neurologically improved after a 90% resection, and follo w-up angiography demonstrated that the residual was thrombosed. Howeve r, not uncommonly, follow-up angiography and magnetic resonance imagin g revealed recurrences, with three of the patients who underwent delay ed imaging (23%) demonstrating new draining veins. Fortunately, in eac h case, the recurrence was asymptomatic. Therefore, the long-term cure rate (mean follow-up, 8.5 yr; range, 1-17 yr) was 80%, with no subseq uent bleeding or progression of symptoms. Outcomes were generally good , with six patients (40%) demonstrating objective improvement, eight ( 53%) being neurologically stable, and one (7%) being worse. Sixty-six percent were independent, 20% required moderate assistance, and 14% re mained entirely dependent. There were no deaths. Patients possessing l esions,with large direct feeders off the anterior spinal artery and oc cupying a primarily anterior position in the cord fared somewhat worse , as did those with rapidly progressing symptomatology in the absence of subarachnoid hemorrhage. However, even in those with preserved or i mproved function, chronic pain was a significant problem, affecting on e-third of all patients. Chronic pain was especially common in young w omen who had presented with significant preoperative pain that respond ed poorly to all subsequent therapeutic manipulations. CONCLUSION: Wit h careful evaluation of high-quality superselective angiography and th e judicious use of preoperative embolization, posterior surgical appro aches can deliver results comparable with those achieved for other ben ign intramedullary lesions in terms of long-term cure (80%), control o f symptom progression (100%), and good functional outcome (86%). Despi te these results, chronic dysesthetic pain syndromes are not uncommon and continue to present a significant management problem.