Spinal arteriovenous malformations: Is surgery indicated?

PURPOSE: To identify clinico-radiological distinguishing features in various types of spinal arteriovenous malformations (AVM) with an aim to define the role of surgical intervention.

MATERIALS AND METHODS: Hero's modified Di Chiro classification differentiated four types of spinal AVMs on digital subtraction angiogram (DSA) in 74 patients: I. Dural arteriovenous fistulae (n = 35, 47.3%); II. Glomus/intramedullary (n = 13, 17.6%); III. Juvenile/metameric (n = 4, 5.4%); and, IV. Ventral perimedullary fistula (n = 21, 28.4%). A patient with extradural AVM remained unclassified. Demographic profiles, DSA features and reason for surgical referral were recorded. Statistical comparison of discrete variables like gender, spinal cord level, presentation and outcome was made using Chi-square test; and, continuous variables like age, feeder number, duration of symptoms and number of staged embolizations by one way analysis of variance with Boneferoni post hoc comparison. Embolization alone (n = 39, 52.7%), surgery alone (n = 16, 21.6%), and combined approach (n = 4, 5.4%) were the treatments offered (15 were treated elsewhere).

RESULTS: Type I-AVM occurred in significantly older population than other types (P = 0.01). Mean duration of symptoms was 13.18 ± 12.8 months. Thoracic cord involvement predominated in type-I and III AVMs (P = 0.01). Number of feeding arteries were 1 in 59.7%; 2 in 29.0%; and, multiple in 11.3% patients, respectively. Staged embolization procedures in type-III AVM were significant (P < 0.01). Surgical referral was required due to: Vessel tortuosity/insufficient parent vessel caliber (n = 7); residual AVM (n = 4); low flow AVM (n = 3); and, multiple feeders (n = 2). Check DSA (n = 34) revealed complete AVM obliteration in 26 and minor residual lesion in eight patients. Neurological status improved in 26 and stabilized in 25 patients.

CONCLUSIONS: Differentiating between Type I-IV AVMs has a significant bearing on their management. Surgical intervention should be considered as an important adjunct/alternative to therapeutic embolization.