Investigations and treatment
MRI brain with contrast showed a right cerebellopontine solid-cum-cystic contrast-enhancing lesion (Fig. 1). Findings were consistent with a nerve sheath tumor, and a provisional diagnosis of vestibular schwannoma was made.
The patient was then electively admitted for surgical management. Following pre-operative assessments and anaesthesia clearance, he underwent elective right retro-sigmoid craniotomy and resection of the lesion. Post-procedure, the patient was received in a vitally stable condition in the recovery room, where he was initially drowsy but arousable, and later shifted to a special care unit for further neurological monitoring. He developed odynophagia, hoarseness of voice, and right upper extremity monoparesis, which was managed conservatively. He was shifted to the ward bed and mobilized out of bed. Post-operative MRI brain with contrast showed significant reduction in surrounding oedema and mass effect (Fig. 2). On the third day following surgery, he was discharged in stable condition and on medication.
However, the patient presented again on the tenth day following surgery with complaints of drowsiness and seizure-like episode. His repeat CT brain showed a craniotomy site-resolving hematoma. Acute infarcts in bilateral occipital, left parietal lobes, bilateral cerebellar hemispheres, and left basal ganglia were noted on CT, which are rare to occur. An MRI of the brain with contrast showed extradural collection over the right cerebellar hemisphere. This collection caused a mass effect and partially effaced the fourth ventricle. A large, dilated, tortuous vascular channel was found within the central part of the collection, most likely a vertebral artery pseudoaneurysm showing possible communication with the right sigmoid sinus (Fig. 3). Pseudoaneurysm of the right vertebral artery and arteriovenous fistula was confirmed with a CT angiogram (Fig. 4).
After that, the patient was scheduled for DSA and endovascular intervention. Briefly, his right femoral artery was punctured, and a 6 Fr sheath was placed by Seldingers technique. Angiographic images were acquired by cannulating both vertebral arteries. The right vertebral angiogram showed a large pseudoaneurysm being filled by a rent in the V3 segment of the right vertebral artery and draining directly into the distal part of the right sigmoid sinus, representing an arteriovenous fistula (Fig. 5). The rent in the vertebral artery was measuring 2.9 mm, with the sac of the pseudoaneurysm measuring 58 x 53 mm. Subsequently, a 6F guiding catheter was advanced into the right vertebral artery across the pseudoaneurysm over a glide wire, and the glide wire was exchanged with a 0.014 BMW microwire. Afterwards, a covered stent measuring 4 mm by 20 mm was placed over a microwire through a Fargo guiding catheter, and the entire system was readjusted to place the covered stent across the pseudoaneurysm (Fig. 6). The post-procedure run showed complete exclusion of pseudoaneurysm with adequate distal flow into the basilar artery and reflux into the left vertebral artery (Fig. 7).