Introduction

In reference to cavernous sinus fistulas (CSFs) causing pulsating exophthalmos, Walter Dandy (1937) wrote: “The study of carotid-cavernous aneurysm – the clinical ensemble – the variation and capricious results of treatment – have been told and retold, and most admirably. Medical literature can scarcely claim more accurate and thorough studies than upon this subject.”

More than 70 years later, a similar statement can be made relating to a subgroup of CSFs, the arteriovenous shunts between small dural branches arising from the external and internal carotid arteries and the cavernous sinus, also called dural cavernous sinus fistulas (DCSFs). Indeed much has been written about these fistulas, which were recognized relatively late as a separate entity among CSFs, and which can be clinically perplexing and sometimes quite difficult to diagnose or to treat. The cure of patients, on the other hand, is one of the most rewarding in the spectrum of modern neuroendovascular treatments.

The initial angiographic descriptions by Castaigne et al. (1966), Newton and Hoyt (1970) and

Djindjan et al. (1968) focused mainly on their peculiar arterial supply, which later became the basis for a widely used anatomic classification (Barrow et al. 1985).

The cavernous sinus itself represents a rather complex venous reservoir, embedded in the base of the skull and traversed by the cavernous carotid artery and four cranial nerves. It functions as a confluens, receiving multiple cerebral and intracranial afferent veins (tributaries) and drains into various efferent veins or dural sinuses.

Despite numerous studies, etiology, pathophysiology and clinical course of these fistulas are to date only partially understood.

Because the arteriovenous shunts develop within the dural walls of the cavernous sinus (CS), their flow is usually directed towards the superior

ophthalmic vein (SOV), causing signs and symptoms very similar, albeit milder, to those observed in patients with direct high-flow carotid cavernous fistulas (CCFs).

Significant improvements in angiographic imaging technology over the last 15 years, such as the introduction of three-dimensional digital subtracted angiography (3D-DSA), have resulted in better understanding of the specific arterial and venous anatomy, opening the doors for novel treatment options. In combination with the advances made in endovascular tools and devices, transvenous occlusion using various transfemoral or percutaneous access routes has become increasingly popular.

Numerous case reports and small case series have been published, creating a wealth of information in the medical literature. However, the data scattered through journals of various clinical disciplines namely neuroradiology, neurosurgery, neurology and ophthalmology.

Regarding therapeutic options for patients with CSFs, Hamby (1966) stated: “The best possibility theoretically would be to induce thrombosis that would close the sinus completely. This appears to be hardly possibly, by currently known techniques, in the face of the tremendous arterial inf low of blood”. This concept was reiterated by Mullan (1974), and 40 years later, transvenous occlusion (TVO) techniques play a dominant role in the management of patients with DCSFs. Because TVO of DCSFs can often be performed successfully today with high efficacy and low morbidity, it has widely replaced microneurosurgery. On the other hand some controversy about its proper indication, associated complication rates and the use of therapeutic alternatives persists.

The purpose of this monograph was to collect and discuss much of the radiological and imaging information available. It aims to summarize and

facilitate access to currently existing knowledge on these complex, incompletely understood, and sometimes challenging lesions.

Views and opinions stated below reflect personal experience in clinical and endovascular management of patients with DCSFs, demonstrating the evolution of minimal invasive techniques, particularly the increasing use of transvenous approaches to the CS.

Insights into all aspects of these interesting cerebrovascular lesions, including their anatomy, etiology, classification, clinical presentation, imaging techniques and hemodynamics, are provided. Various current treatment options and their role in patient management are described, such as conservative management, manual compression, controlled hypotension, radiosurgery, surgery, but foremost endovascular therapy.

Percutaneous catheterization techniques are covered in greater detail with great emphasis on transvenous access routes and the progress that has been made since Halbach et al. (1989) published the first relevant series.

This volume is intended as a reference and a guide for neuroradiologists, neurosurgeons, neurologists and ophthalmologists, who see patients with DCSFs in their practice.

References

Dandy W (1937) Carotid-cavernous aneurysms (pulsating exophthalmos). Zentralbl Neurochir 2:77–206

Castaigne P, Laplane D, Djindjian R, Bories J, Augustin P (1966) Spontaneous arteriovenous communication between the external carotid and the cavernous sinus. Rev Neurol (Paris) 114:5–14

Newton TH, Hoyt WF (1970) Dural arteriovenous shunts in the region of the cavernous sinus. Neuroradiology 1:71–81 Djindjian R, Cophignon J, Comoy J, Rey J, Houdart R (1968)

Neuro-radiologic polymorphism of carotido-cavernous fistulas. Neurochirurgie 14:881–890

Djindjian R, Manelfe C, Picard L (1973) External carotid-cav- ernous sinus, arteriovenous fistulae: angiographic study of 6 cases and review of the literature. Neurochirurgie 19:91–110

Newton TH, Hoyt WF (1968) Spontaneous arteriovenous fistula between dural branches of the internal maxillary artery and the posterior cavernous sinus. Radiology 91:1147–1150

Barrow DL, Spector RH, Braun IF, Landman JA, Tindall SC, Tindall GT (1985) Classification and treatment of spontaneous carotid-cavernous sinus fistulas. J Neurosurg 62:248–256

Hamby W (1966) Carotid-cavernous fistula. Springfield Mullan S (1974) Experiences with surgical thrombosis of in-

tracranial berry aneurysms and carotid cavernous fistulas. J Neurosurg 41:657–670

Halbach VV, Higashida RT, Hieshima GB, Hardin CW, Pribram H (1989) Transvenous embolization of dural fistulas involving the cavernous sinus. AJNR Am J Neuroradiol 10:377-383