Visual techniques in microsurgery for intra-cranial arteriovenous malformations

Arterio-venous malformations (AVMs) are anomalous shunts between the arterial and venous systems, acting as a major risk factor for intra-cerebral haemorrhage, seen in 38%–71% of patients harbouring the pathology. Current techniques in the management of AVMs include observation, microsurgery, embolisation and radiosurgery, or combination therapy. AVMs are classically categorised based on the Spetzler-Martin grading and it is generally accepted that Grades I and II are best managed by microsurgical resection. To discuss the technique of astute visual inspection of AVM malformations on the operating table in microsurgical management of AVMs, and the surgical importance and significance of the valuable inferences derived from this routine. It is of utmost importance to visually distinguish between the arterial and venous ends of the nidus, and this can be effectively accomplished through eyeballing techniques by looking at the appearance of the vessels and noticing its colour, thickness, and underlying blood; and the variations in the turgor pressure of the nidus with changes in compression of the arterial and venous ends. It is equally important to visually identify the safe and effective plane to approach the target lesion by identifying the gliotic plane, the discoloured vertex of the underlying haematoma, or the widened subarachnoid spaces. Microsurgical resection is a definite mode of treatment of intra-cranial AVMs and flawless execution of surgery is vital. Eyeballing techniques must be aimed at correctly identifying the nature of the lesion and creating a mind-map before setting out to manipulate the AVM. A good initial visual inspection and survey is a crucial measure of safety and efficiency in AVM surgery.