Mastoid Epidermoid Tumor and Associated Dural Arteriovenous Fistula with Venous Sinus Occlusion

Background

Dural arteriovenous fistula (DAVF) is an abnormal vascular connection between arterial and venous channels within dura mater. Although DAVFs have been linked to other types of intracranial tumors, this is the first case reporting the association between DAVF and an epidermoid tumor.

Case Description

A middle-aged patient with chronic headache presented with Borden type II DAVF draining into the right transverse sigmoid junction and was also found to have an epidermoid tumor over the right mastoid. The patient underwent staged embolization of the fistula through both transvenous and transarterial routes. Continuous intraoperative venous pressure monitoring confirmed marked reduction in intracranial venous pressure, and the patient's symptoms completely resolved. However, the fistula still remained. The residual DAVF was then surgically disconnected, and the epidermoid tumor was resected in the same procedure.

Conclusions

This case demonstrates a DAVF can be associated with an epidermoid tumor. Tumor can compromise the venous outflow, which can then lead to intracranial venous hypertension and development of the DAVF. Venous pressure monitoring offers an objective method to verify resolution of venous hypertension, which might correlate with resolution of clinical symptoms.

Introduction

Intracranial dural arteriovenous fistulas (DAVFs) are abnormal vascular connections between dural arteries and dural veins, which represent 10%−15% of all arteriovenous malformations.1, 2 While the majority of these lesions are idiopathic, some of them are associated with thrombosis of dural sinuses, aneurysms, or trauma.2, 3, 4, 5 Venous hypertension also plays a role in the formation of DAVFs through changes in flow hemodynamics.6, 7

Although previous reports described the association between DAVFs and intracranial tumors such as meningioma,8, 9, 10, 11, 12, 13, 14 hypothalamic hamartoma,¹⁵ and pituitary adenoma,¹⁶ there are no existing reports demonstrating an association between epidermoid tumors and DAVFs. Despite the benign nature of epidermoid tumors, a surgical excision may be indicated as these tumors have a tendency to grow over time and can compress surrounding neurovascular structures leading to symptoms.17, 18, 19 Haussen et al²⁰ suggested continuous pressure monitoring might be a useful modality during an embolization of arteriovenous malformation in a swine model. Similarly, we were able to continuously monitor venous pressure during embolization of DAVF, which offered an objective measurement of venous pressure during treatment. We were able to successfully treat this complex DAVF in 3 stages: transvenous, transarterial, and an open surgical disconnection of DVF and removal of epidermoid to achieve a complete obliteration of DAVF.