Pathological characteristics of cyst formation following gamma knife surgery for arteriovenous malformation

• Published in: Acta neurochirurgica Vol. 157; no. 2; pp. 293 - 298
• Main Authors: Shuto, Takashi, Yagishita, Saburo, Matsunaga, Shigeo
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.02.2015; Springer Nature B.V
• Subjects: Adolescent; Adult; Aged; Arteriovenous Fistula - surgery; Clinical Article - Vascular; Cysts - etiology; Cysts - pathology; Female; Humans; Interventional Radiology; Intracranial Arteriovenous Malformations - surgery; Male; Medicine; Medicine & Public Health; Middle Aged; Minimally Invasive Surgery; Neurology; Neuroradiology; Neurosurgery; Radiation Injuries - pathology; Radiosurgery - adverse effects; Radiosurgery - methods; Surgical Orthopedics; Young Adult; Complication; Arteriovenous malformation; Radiosurgery; Cyst; Gamma knife
• ISSN: 0001-6268; 0942-0940
• DOI: 10.1007/s00701-014-2298-z

Background The pathological characteristics of cyst development after gamma knife surgery (GKS) for arteriovenous malformation (AVM) were analysed. Method Sixteen male and 12 female patients aged 17–67 years (mean 31.3 years) were retrospectively identified among 868 patients who underwent GKS for AVM at our hospital. The pathological characteristics of the reddish nodular lesion and chronic encapsulated expanding haematoma associated with cyst following GKS for AVM were examined. Results Cyst was associated with chronic encapsulated expanding haematoma in 13, and with nodular lesion in 12 patients. The nidus volume at GKS was 0.1–36 ml (median 6.0 ml), and the prescription dose at the nidus margin was 18–25 Gy (median 20 Gy). Cyst formation was detected from 1.1 to 16 years (mean 7.3 years) after GKS. Seven of the 12 patients with nodular lesion underwent surgery. Ten of the 13 patients with expanding haematoma underwent surgical removal of expanding haematoma. Histological examination was possible in 17 cases. Dilated capillary vessels with wall damage such as hyalinisation and fibrinoid necrosis, marked protein exudation and haemorrhage were the most common findings. Brain parenchyma was observed among the dilated vessels in some cases. Structureless necrotic tissue was not evident. Conclusions The present study suggests that enhanced nodular lesion on magnetic resonance imaging and chronic encapsulated expanding haematoma associated with cyst may have common aetiopathology caused by late radiation effects, mainly consisting of dilated capillary vessels with wall damage. Massive protein exudation from such damaged capillary vessels is important in cyst development.