Microsurgical resection
Microsurgical resection is a primary treatment modality for cerebellar AVMs, particularly those that are located within the cerebellopontine angle. The “backdoor resection” technique has had high success rates, achieving complete angiographic obliteration in 92% of the cases (1).
This technique is effective for small and compact AVMs, with a better neurological outcome in 79% of the patients (1).
For safer surgical resection, preoperative embolization is done to reduce the size and vascularity of the AVM (2).
Characteristics of cerebellar AVMs
Cerebellar AVMs account for 7–15% of all intracranial AVMs approximately and are more prone to rupture (1, 3). In a study of patients with cerebellopontine angle AVMs, around 76% of the patients had presented with hemorrhage (1). The cerebellar AVMs have a complex angioarchitecture and usually involve multiple arterial feeders and superficial venous drainage, which complicates the treatment (3).
Endovascular treatment
Endovascular treatment is another modality of treatment for AVMs, especially for AVMs with complicated angioarchitecture (3).
Endovascular treatment is a feasible technique and has shown an acceptable therapeutic outcome with a favorable Glasgow Outcome Scale score in 81.7% of the patients upon discharge (3).
Endovascular treatment has a risk of intraoperative and postoperative bleeding which can give rise to serious complications (3).
Combined treatment strategies
Usually, large or complex cerebellar AVMs require combined endovascular and surgical techniques. A multimodal approach involving the combined technique is proven to be effective by demonstrating favorable outcomes without any major complications (4).
Grading systems
Traditional systems of grading, including the Spetzler-Martin grading system, have been traditionally used to grade the risk of AVMs, while newer grading schemes have been proposed and developed that better predict outcomes for cerebellar AVMs (5).
The classification by de Oliveira introduces the size, location, and involvement of the dentate nucleus, providing a more detailed risk assessment (2).
Furthermore, a new grading system proposed by Nisson et al. includes factors such as preoperative neurological status and venous drainage that give a better prognosis compared with the older systems (5).
Classification and risk assessment
Cerebellar AVMs are categorized according to the size, location, and involvement of critical structures such as the dentate nucleus. The de Oliveira classification system is especially useful for assessing risk and guiding treatment strategies (2).
Arteriovenous malformations with mixed superficial and deep locations and those involving the dentate nucleus carry higher surgical risks and require very careful planning (2).
Whereas microsurgical resection and EVT are effective in their own right, the treatment is generally selected based on the nature of the AVM and the status of the patient concerned. Cerebellar AVMs are complex lesions and thus require an approach that is individualized based on the specific features of the malformation at hand, usually by multimodal strategies to optimize outcomes and minimize risks.
The bottom line is that cerebellar AVMs represent some of the most complex challenges with regard to treatment because of their highly demanding anatomy and elevated risk of hemorrhage. Based on a combined strategy of microsurgical resection and endovascular techniques, advanced grading systems can provide a suitable approach for optimizing patient outcomes. However, each case should be managed based on specific considerations regarding the unique features of the AVM and associated vascular lesions.
| Video 1. Cerebellar AVM excision: Surgical Video https://youtu.be/o4RzTQ5O_6o |
In this video, we present an 18-year-old boy with altered sensorium. CT brain showed cerebellar hematoma, and CT angiography showed left cerebellar AVM, SM Grade 3. He underwent emergency suboccipital decompressive craniotomy and evacuation of hematoma, and after 6 weeks, he was evaluated with DSA and underwent microsurgical resection of cerebellar AVM. The patient is now recovered.
References
1. Hanalioglu S, Graffeo CS, Srinivasan VM, Ibrahim S, Garcia JH, Koester SW, et al. Arteriovenous malformations in the cerebellopontine angle: assessment of the “backdoor resection” technique and microsurgical results in 38 patients. J Neurosurg. (2024) 1–14. doi: 10.3171/2024.3.jns231271
2. Almefty R, Essayed W, Al-Mefty O. Multimodality resection of Oliveira Type IIIC* cerebellar AVM: A distinct entity. Surg Neurol Int. (2022) 13:163. doi: 10.25259/SNI_217_2022
3. Piao J, Luan T, Wang Y, Yu J. Imaging characteristics and endovascular treatment strategy for cerebellar arteriovenous malformations. Med Int (Lond). (2021) 1:5. doi: 10.3892/mi.2021.6
4. Loof de Amorim B, Wainberg RC, Paz-Archila JA, Lessa SS, Bustamante Vargas GM, Bocca LF, et al. Combined treatment for a hemispheric cerebellar AVM. Neurosurg Focus Video. (2021) 4:V14. doi: 10.3171/2020.10.FOCVID2069
5. Nisson PL, Fard SA, Walter CM, Johnstone CM, Mooney MA, Tayebi Meybodi A, et al. A novel proposed grading system for cerebellar arteriovenous malformations. J Neurosurg. (2020) 132:1105–15. doi: 10.3171/2018.12.JNS181677
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