Almost 5% of individuals who undergo MRI scanning of the brain for unrelated symptoms (for example headaches and hearing loss), harbour asymptomatic vascular abnormalities namely aneurysms, arterio-venous malformations (AVMs) and cavernomas.
An aneurysm is the most frequently encountered asymptomatic pathology. It is literally reminiscent of a balloon at a point where a blood vessel in the brain divides, and has the risk of bursting, causing a subarachnoid haemorrhage (SAH). We generally tend to keep under regular surveillance the majority of incidentally found aneurysms. This is based on the knowledge that (i) very few aneurysms are likely to bleed and cause a SAH, and (ii) treating them has potentially significant risks. There are, however, subgroups that we recommend treatment for, especially individuals who (i) have large aneurysms, (ii) are hypertensive, (iii) smoke, (iv) have relatives with aneurysms that have caused a SAH and (v) when their aneurysm enlarges whilst under surveillance. Every individual with an aneurysm will be discussed with a team of interventional neuroradiologists (these are the specialists who put coils in aneurysms to stop them from causing a haemorrhage) at a multidisciplinary team setting (MDT). Pertinent aspects such as (i) whether to treat an aneurysm, (ii) how to treat it (with coils or surgery), and (iii) how often to repeat the scans in patients that are kept under surveillance (and ensure that they are not enlarging), are comprehensively addressed by a team of national experts.
Arteriovenous malformations and cavernomas are less common pathologies. They can, however, cause additional problems apart from a haemorrhage, most frequently seizures. The same principles applicable to aneurysms guide our decision making in the management of these lesions. As stated above, these individuals will be discussed at an MDT with interventional neuroradiologists (who treat AVMs with gluing), neuro oncologists (who employ stereotactic radiosurgery for their elimination) and neurologists specializing in the epidemiology of these lesions. Again, pertinent aspects such as (i) whether to treat an AVM or cavernoma (ii) how to treat it (with surgery, gluing, stereotactic radiosurgery, or a combination of these), (iii) how to manage associated symptoms such as seizures, are comprehensively addressed by a team of national experts.