Surgical Treatment for Late Complications following Gamma Knife Surgery for Arteriovenous Malformations

Abstract

Background: To establish the surgical indications and strategy for late complications following gamma knife surgery (GKS) for arteriovenous malformations (AVMs). Methods: Ten male and 7 female patients aged 17–52 years (mean 28.0 years) were retrospectively identified among 686 patients who underwent GKS for AVM at our hospital. Ten patients showed cyst formation (group A), 2 patients had expanding hematoma (group B), and 5 patients had both cyst and expanding hematoma (group C). Results: The mean nidus volume was 10.1 ml (range 0.1–36 ml), and the mean prescription dose at the nidus margin was 19.9 Gy (range 18–28 Gy). Complete obliteration of the nidus was obtained in 12 patients, partial obliteration in 4, and no change in 1. Cyst formation (group A) was asymptomatic in 5 patients, and symptomatic in 5 patients, manifesting as headache, hemianopia, aphasia, and motor weakness. Expanding hematoma (groups B and C) was associated with surrounding brain edema and was symptomatic in all 7 patients. Cyst opening in 1 patient and placement of an Ommaya reservoir in 2 patients were necessary in group A. Both patients in group B underwent craniotomy. Four of the 5 patients in group C required craniotomy. Another patient in group C was lost to follow-up and the final outcome was unknown. Conclusions: Cyst formation is one of the late complications of GKS for AVM. Some cysts show spontaneous regression but others gradually increase in size and become symptomatic, although relatively large asymptomatic cysts are also known. Predicting the future course of a cyst is difficult. Surgery such as placement of an Ommaya reservoir should be considered for symptomatic cases. Expanding hematoma always increases in size and becomes symptomatic, so removal by craniotomy is necessary. Surrounding brain edema decreases rapidly after surgery and neurological symptoms quickly resolve.

Stereotactic radiosurgery for arteriovenous malformations after Onyx embolization: a case-control study

“…7,11,28 Embolization decreases the volume of the AVM nidus, permitting a higher radiosurgical dose to be delivered to the smaller nidus. This approach is believed to lead to less morbidity 31,59,69 and a higher obliteration rate following SRS. 27 In addition, embolization can reduce the risk of AVM rupture by eliminating intranidal aneurysms and reduce the flow in shunting vessels by blocking the high-flow fistulas.…”

Proposed mechanism for cyst formation and enlargement following Gamma Knife Surgery for arteriovenous malformations

“…If the cyst apparently increases in size and becomes symptomatic, surgery is indicated. 19 Placement of an Ommaya reservoir under local anesthesia is recommended for such cases. 10 Neurological symptoms tend to improve immediately after aspiration of the cyst content.…”

Ruptured de novo Aneurysm following Gamma Knife Surgery for Arteriovenous Malformation: Case Report

“…The pros and cons of GKS for AVM have been documented in many previous studies [14,15,16,17]. The demanding latency period from surgery to complete obliteration and radiation-induced changes are major disadvantages of the use of GKS for AVM [15,18,19,20,21,22,23,24,25,26,27].…”

“…The demanding latency period from surgery to complete obliteration and radiation-induced changes are major disadvantages of the use of GKS for AVM [15,18,19,20,21,22,23,24,25,26,27]. Vasculopathy-related lesions, such as cysts, vessel occlusions, and aneurysms, are relatively late-onset problems of using GKS for AVM.…”