Intra-operative neurophysiological monitoring as an adjunct to resection of eloquent cerebral arteriovenous malformations: a retrospective cohort study

Arteriovenous malformations (AVM) carry a risk of haemorrhage and may also cause epilepsy or ischaemic steal phenomenon. Surgical resection leads to high rates of lesion obliteration but resection of AVMs located in eloquent cortex is associated with high rates of morbidity. The aim of this study was to assess the outcomes following surgical resection of AVMs in eloquent cortical locations with the use of intra-operative neuro-monitoring (IoNM). A prospectively maintained database of AVM resections between 2012 and 2023 was reviewed. Data describing demographic details, AVM characteristics and outcomes of patients who underwent surgical resection of AVMs located in eloquent areas with IoNM were extracted. Functional status was assessed using the modified Rankin scale (mRS). 191 patients underwent resection of an AVM, of which 10/191 (5%) underwent resection with IoNM. 7/10 patients were female and the median age was 40 years (range 25-57). 5/10 (50%) of the AVMs were ruptured. The AVM was completely resected in 10/10 (100%) of cases. New neurological deficits occurred in 6/10 (60%) with no permanent neurological deficits observed. The median period of follow-up was 12 months (range 2-46) and the functional status of every patient improved or remained stable compared to their preoperative status. IoNM may be a useful intra-operative adjunct during the resection of AVMs located within eloquent cortical areas. The use of IoNM should be considered when attempting surgical resection of AVMs located in eloquent cortical areas.