Gamma knife surgery in the treatment of intracanalicular vestibular schwannomas

Abstract

Objective According to the literature, gamma knife surgery (GKS) is a promising method for intracanalicular vestibular schwannoma (IVS) management, providing excellent tumor growth control rates (91%‐100%) and good hearing preservation rates (41%‐76%), but this evidence originates primarily from a small series of patients. The aim of this study was to present the outcomes of GKS in the largest group of patients with IVS studied to date, with particular emphasis on the long‐term outcomes of treatment. Methods The study included 136 consecutive patients with unilateral IVS, who underwent GKS in 2011‐2015. Mean age of the patients was 54 ± 12.6 years. All patients were operated on with a 192‐source cobalt‐60 gamma knife unit. All patients had complete follow‐up documentation and the mean duration of the follow‐up was 52 ± 13.8 months (6‐83 months). Neurological status (facial and trigeminal nerve), hearing and instability/dizziness presence were determined prior to GKS, immediately after the procedure, and during the follow‐up visits. Results Tumor growth control was obtained in 124/136 (~91.2%) patients. Hearing improvement was observed in 32/136 (23.5%) patients, and there was a distinct cluster of 9 patients (6.6%) regaining serviceable hearing after GKS, whereas in 36 patients (26.5%) was stable. Four patients developed facial nerve dysfunction, including 3 periodic hemifacial spasm and 1 partial paresis, which resolved spontaneously within 12 months of GKS. None of the operated patients showed new, debilitating neurological deficits, including trigeminal sensory disturbances or hydrocephalus. Conclusions GKS is a highly effective treatment for IVS, associated with low morbidity and good tumor growth control.

Evaluation of Brainstem Subcortical Auditory Pathways with Diffusion Tensor Imaging After Gamma Knife Radiosurgery in Intracanalicular Vestibular Schwannoma

“…Evaluating the volumetric changes in tumor after radiosurgery is an important indicator of response to treatment 2,15 . Some authors reported that tumor control was achieved in 91.1% of the patients followed up approximately 4.5 years after radiosurgery in patients with ICVS 2 . In our study, there was a significant decrease in the tumor volume and a shrinkage in tumor size in 58.82% of the patients treated with ICVS.…”

“…To evaluate the true response after radiosurgery, it should be clearly demonstrated whether there is growth in tumor volume by successive follow-up MRIs. It is recommended to be followed up by MRI every 6 months for up to 5 years after radiosurgical treatment 2,8,12,16 .…”

Makroskopische und mikroskopische Veränderungen des N. vestibulocochlearis nach Gamma-Knife-Therapie

“…Bei intrameatalen Vestibularisschwannomen stellen radiochirurgische Therapien wie Gamma-Knife oder CyberKnife etablierte Modalitäten dar, welche in den meisten Fällen eine Tumorkontrolle er-möglichen, gute Chancen eines Hörerhalts haben und nur selten mit Komplikationen verbunden sind [1,3]. Eine operative Versorgung nach radiochirurgischer Vorbehandlung ist nur in wenigen Fällen nötig [9].…”

Intracanalicular vestibular schwannomas. Observation, radiosurgery or microsurgery – what to choose?

“…У 4 пациентов возникла дисфункция лицевого нерва, в том числе 3 эпизодических гемифациальных спазма и 1 частичный парез, которые регрессировали полностью в течение 12 мес после радиохирургического лечения. Ни у одного из пациентов не было выявлено новых неврологических нарушений, в том числе дисфункции тройничного нерва или гидроцефалии [30]. В исследовании A. Niranjan и соавт.…”