Gamma Knife Radiosurgery for Arteriovenous Malformations: Long-term Follow-up Results Focusing on Complications Occurring More than 5 Years after Irradiation

Arteriovenous malformation (AVM) with a small nidus located in the cortical eloquent areas is difficult to surgically resect without neurological complication, but is a suitable target for stereotactic radiosurgery (SRS). However, lesions with large nidus volume or with deeply located nidus are difficult to safely treat, even by SRS. To explore the optimal treatment strategies for such high-grade cerebral AVM, we reviewed treatment outcomes of SRS using gamma knife surgery (GKS) for patients with high-grade AVM at our institute and in published reports. Although lesions in the thalamus and the brainstem carried higher risk of morbidity after SRS, accumulation of technical knowledge and experience about SRS and technological advances in dose planning have enabled safer treatment of AVM in these locations. Large AVM presents another challenge to SRS treatment. Multimodal treatment, including surgery and endovascular treatment, should be considered. In this setting, staged SRS using GKS or CyberKnife may achieve safer treatment of large cerebral AVM. Further progress in SRS is anticipated to enhance the treatment efficacy for high-grade cerebral AVM while reducing treatment morbidity.

Section: Srs For Avmmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Role of Stereotactic Radiosurgery in the Treatment of High-Grade Cerebral Arteriovenous Malformation

Hanakita

Koga

Shin

et al. 2012

“…The incidence of cyst formation varies between 2% and 30%. 14,20,38) Delayed cyst formation following GKRS in 1203 consecutive patients with arteriovenous malformations was related to the duration of the follow-up period. 20) The incidence of cyst formation was 3.6% in cases with follow-up period over 5 years.…”

Section: Discussionmentioning

confidence: 99%

Serious Adverse Effects of Gamma Knife Radiosurgery for Mesial Temporal Lobe Epilepsy

Kawamura

Onishi

Kohda

et al. 2012

Gamma knife radiosurgery (GKRS) for mesial temporal lobe epilepsy (MTLE) has been proposed as an alternative to surgical resection. We report serious adverse effects of the treatment after follow-up periods over 9 years in 11 patients treated with GKRS between 1997 and 2000. The target volume of the entorhinoamygdalohippocampectomy area was 4.8-17.1 ml. Marginal dose of 20-25 Gy to the 50% isodose was delivered. One patient was drowned after suffering seizure 7 months after GKRS. Two patients did not show any reduction in seizure frequency over 9 and 18 months. Both patients requested open surgery and became seizure-free postoperatively. Four of the other eight patients were classified as Engel's class I within 4 years after GKRS. One of the four patients experienced symptomatic radiation-induced cerebral edema transiently, one developed radiation necrosis and required surgery 5 years after GKRS, and one developed cognitive impairment with hemiparesis 10 years after GKRS. Magnetic resonance (MR) imaging showed a large cyst in the irradiated temporal lobe. This patient recovered fully after the cyst excision. Only one patient became seizure-free and antiepileptic drug-free without symptomatic radiation-induced complications. However, MR imaging revealed abnormal enhancement, cyst formation, and diffuse white matter change in the irradiated temporal lobe 9 years after GKRS. GKRS for MTLE causes adverse effects of delayed seizure remission and symptomatic radiationinduced complications. Therefore, GKRS cannot be considered as an ideal alternative to surgery for MTLE. Long-term follow-up studies including MR imaging with contrast medium are required for the patients even after successful control of seizures.

“…79) Deeply located arteriovenous malformations cause devastating hemorrhage, 20,34,122,135,145) and are associated with higher morbidity and mortality compared with superficial lesions. 47,141,148) Although the morbidity rates for deep arteriovenous malformation are 12% to 19% and higher than those for arteriovenous malformations in other parts of the brain, which were 2.7% to 8%, 48,69,97,129) gamma knife radiosurgery is a good treatment of choice, considering the high morbidity of surgical removal for these lesions. 122) Delayed complications such as hemorrhage from obliterated arteriovenous malformations, chronic encapsulated expanding hematoma, and delayed cyst formation occurred even more than 10 years after the treatment.…”

Section: Vascular Lesionsmentioning

confidence: 99%

“…122) Delayed complications such as hemorrhage from obliterated arteriovenous malformations, chronic encapsulated expanding hematoma, and delayed cyst formation occurred even more than 10 years after the treatment. 64,148) Since arteriovenous malformations are predominantly found in the younger population, it is important to carefully follow up patients after treatment for a long period.…”

Section: Vascular Lesionsmentioning

confidence: 99%

Role of Gamma Knife Radiosurgery in Neurosurgery: Past and Future Perspectives

Koga

Shin

Saito

2010

The gamma knife was the first radiosurgical device developed at the Karolinska Institute in 1967. Stereotactic radiosurgery using the gamma knife has been widely accepted in clinical practice and has contributed to the development of neurosurgery. More than 500,000 patients have been treated by gamma knife stereotactic radiosurgery so far, and the method is now an indispensable neurosurgical tool. Here we review long-term outcomes and development of stereotactic radiosurgery using the gamma knife and discuss its future perspectives. The primary role of stereotactic radiosurgery is to control small well-demarcated lesions such as metastatic brain tumors, meningiomas, schwannomas, and pituitary adenomas while preserving the function of surrounding brain tissue. The gamma knife has been used as a primary treatment or in combination with surgery, and some applications have been accepted as standard treatment in the field of neurosurgery. Treatment of cerebral arteriovenous malformations has also been drastically changed after emergence of this technology. Controlling functional disorders is another role of stereotactic radiosurgery. There is a risk of radiation-induced adverse events, which are usually mild and less frequent. However, especially in large or invasive lesions, those risks are not negligible and pose limitations. Advancement of irradiation technology and dose planning software have enabled more sophisticated and safer treatment, and further progress will contribute to better treatment outcomes not only for brain lesions but also for cervical lesions with less invasive treatment.