2007, Number 4
Med Sur 2007; 14 (4)
Dynamic definition of critical diameter in arteriovenous malformations for the treatment with radiosurgery gamma
Del Valle R, Rodríguez D, Zenteno M, Jaramillo J, De Anda S, Gamiño I, Ortiz J, Pérez M
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ABSTRACTIntroduction: Thirty years of cumulative experience worldwide indicate complete obliteration rates from 35% to 90% volume dependant. Objective: To propose a strategy to increase the obliteration rate for arteriovenous malformations (AVMs) through the dynamic definition of the critical zone, which is the hydrodynamically most sensitive target volume for radiosurgical gamma knife. Methods: We used a digital counter to measure several stages of the frame-by-frame circulation times of AVMs. 44 patients were treated using dynamic measurement planning to define the critical zone, including criteria that categorize the type of AVM: fistulous vs plexiform or mixed; Spetzler–Martin classification grades III 28, IV 14, V 2; with single treatments 37, repeated radiosurgery 4, or prospective stage radiosurgery 3. Endovascular therapy in 50% and superselective angiography in 34%. The preembolization AVM volume was up to 120 mL, with a critical zone target volume of up to 15 mL for single treatments, mean volume 8.5 mL, and 28 mL for prospectively staged radiosurgery. The marginal radiation dose 18–22 Gy, mean dose 20 Gy. Results: Digital subtraction angiography was performed in 36 patients 1–10 years after treatment. Complete obliteration was observed in 33 patients, including 12 grade IV and one grade V. The repeated radiosurgery group showed 100% complete obliteration. Neurological complications were observed in 7.5% of patients after preradiosurgery embolization. There was no mortality. Conclusion: Dynamic definition of the AVM critical zone might increase the obliteration rate, even in complex AVMs, allowing the treatment of smaller volumes off the recruitment vessels (pseudonidus).