In a small retrospective series, most cranial nerve palsies resolved completely within 6 months.
Endovascular transvenous embolization is a safe and effective treatment for cavernous sinus dural arteriovenous fistulas, although it results in cranial nerve palsy in about 20% of cases, according to research published online May 2, 2019, ahead of print in the Journal of NeuroInterventional Surgery. Fortunately, as the authors point out, these palsies are usually self-limiting in nature.
“Cavernous sinus dural arteriovenous fistulas (CS DAVFs) are abnormal shunt flow between arteries from the internal and external carotid arteries and the CS at the sinus wall,” write Su Hwan Lee, MD (Seoul National University Hospital, South Korea), and colleagues. “The CS is the most common location of DAVFs, together with transverse-sigmoid sinus. CS DAVFs present with various symptoms, such as diplopia, ptosis, eyeball pain, hyperemia, visual disturbances, and seizures.”
Endovascular embolization using a transvenous approach (TVE) is the most frequently used treatment for CS DAVFs, but Lee et al note that there have been some reports of new-onset cranial nerve palsy (CNP).
“Some patients or physicians are frustrated by the occurrence of new CNPs, even after the successful embolization of CS DAVFs,” coauthor Won-Sang Cho, MD (Seoul National University Hospital), told Neurovascular Exchange in an email. “They are prone to consider it a treatment failure or incomplete treatment, and some physicians are [quick] to plan additional tests and repeat treatments.” As a result, he said, it is important to understand the incidence, causes, types, and natural course of CNPs.
Sixth CNP Most Common Presentation
Lee et al retrospectively analyzed data on 121 patients treated in their institution between April 2004 and August 2016. They evaluated baseline characteristics, radiologic results, clinical outcome, and newly occurring CNPs after treatment. Among these patients, angiographic follow-up data were available for 104 lesions and clinical follow-up data were available for 130 lesions.
Angiographic results revealed an overall partial:complete obliteration ratio of 87.5% at the final follow-up, with a deteriorated/no change:improved ratio of 96.9%. New CNPs occurred in 19.8%, and most were of mixed or sixth CNP etiology. Of these, 90% were completely recovered within 6 months.
On multivariate analysis, pretreatment cranial nerve symptoms and complete obliteration immediately after treatment were significant preventive factors for new CNPs. Embolization in the posterior compartments of the cavernous sinus was a significant risk factor for development of CNPs (OR 5.15; 95% CI 1.71-15.47).
To Neurovascular Exchange, Cho said that the best way to avoid CNPs is to “to embolize just the fistular point focally, not the whole or cavernous sinus or some compartments, especially the posterior compartment. The second way is to embolize the whole or some compartments loosely. Coverage of the fistular inner surface of CS is important, but too much compact embolization should be avoided.”
Nevertheless, the main finding of this study is that, “the sixth CNP is the most common, and most of them are resolved within 6 months without specific remedy,” said Cho. Thus, the authors conclude that, “Endovascular intervention was satisfactory in patients with CS DAVFs.”
What remains unclear, added Cho, is the cause of delayed CNP. This series reported only one case, but Cho said coauthor Hyun-Seung Kang, MD (Seoul National University Hospital), has experienced a few others.
Lee SH, Cho W-S, Kang H-S, et al. Newly occurring cranial nerve palsy after endovascular treatment of cavernous sinus dural arteriovenous fistulas. J NeuroIntervent Surg. 2019;Epub ahead of print.
Cho and Lee report no relevant conflicts of interest.