Introduction
Vestibular schwannomas, also known as acoustic neuromas, are
intracranial, extra-axial nerve sheath tumors that grow slowly and
originate from the Schwann cells, investing the vestibular part of the
vestibulocochlear nerve (1). When these tumors enlarge, they eventually
take up a significant portion of the cerebellopontine angle, which
frequently results in symptoms like tinnitus, vertigo, and hearing loss.
Schwannomas are solitary in 90% of the instances and are categorized as
grade 1 benign tumors by the World Health Organization. Acoustic
neuromas reportedly occur in 0.6-1.9 individuals per 100,000 population
(2).
The patient’s age, their neurological state, the size, and other
features of the tumor influence the treatment plan. Radiation therapy,
stereotactic radiosurgery, and microsurgery are available as treatment
alternatives. Microsurgical resection is the gold standard for treating
large vestibular schwannomas (3). It is frequently carried out utilizing
the trans-labyrinthine, middle cranial fossa, or retro-sigmoid
approaches (4).
Any size of vestibular schwannomas can be removed with the retro-sigmoid
approach; however, with this surgical intervention, there is a risk of
mortality and postoperative complications in 0.2% and 22% of patients,
respectively (5). These complications include facial nerve damage,
trigeminal nerve dysfunction, aggravated gait associated with damage to
the cerebellum, CSF leaks, and meningitis (6). A very unusual side
effect of retro-sigmoid craniotomy is postoperative AV fistulas, which
take time to appear clinically (7) (8). Similarly, the vertebral artery
may inadvertently be harmed, even though it is beyond the surgical
field, because of its abnormal course and loss of anatomical landmarks
(9) (10).
It is very rare in the literature to find vertebral artery
pseudoaneurysm and AV fistula formation between the vertebral artery and
sigmoid sinus (11). Such lesions typically follow either penetrating
trauma or iatrogenic trauma (12) (13). Surgical correction has
historically been the preferred course of treatment for such lesions.
Alternative endovascular techniques have also been introduced that allow
selective occlusion of the vascular injury (14). Both methods do,
however, require sacrificing the vertebral artery. Another alternative
endovascular approach is the use of a covered stent or flow diverting
stent, which maintains vessel patency (15) (16). Herein, we report a
unique case of iatrogenic pseudoaneurysm and arteriovenous fistula in
Pakistan that was successfully treated with a covered stent.