A case of isolated transverse sigmoid sinus dural arteriovenous fistula in which ipsilateral sensory neural hearing loss developed after transvenous embolization—letter to the editor

Abstract

Dear Sir, We would like to report a rare complication after transvenous embolization (TVE) of an isolated transverse sigmoid sinus (TSS) dural arteriovenous fistula (dAVF). A 72-year-old male complaining of right pulsatile tinnitus was referred to our hospital. A bruit was identified in the post-auricular region on the right side. There were no neurological deficits. Diagnostic angiography demonstrated a dAVF fed by branches of the occipital and posterior auricular artery and ending in an isolated transverse sigmoid sinus (Fig. 1a). The venous phase of the right common carotid angiography demonstrated absence of opacification of the diseased sinuses and of the ipsilateral inferior petrosal sinus (IPS) and jugular Bulb (JB) (Fig. 1b). TVE was performed under general anesthesia. A microcatheter was navigated to the diseased sinus via contralateral approach. This segment of sinuses was packed with detachable microcoils (GDC®/Targets Therapeutics, Fremont, CA, USA). Final control angiography showed complete obliteration of the shunt (Fig. 2). The pulsatile tinnitus disappeared immediately after the procedure. On postoperative day 1, the patient complained of dizziness, but MR with diffusion weighted images showed no abnormal findings. The dizziness improved within 10 days. After 10 days of hospitalization, a sudden hearing loss occurred in the right ear. Puretone audiography revealed a sensory neural hearing loss (SNHL) of 40 dB. A tentative diagnosis of sudden SNHL (SSNHL) was made by the ENT specialists. Intravenous drip infusion of corticosteroids and low molecular dextrin was initiated. Two weeks later, hearing loss had improved with 15 dB. To the best of our knowledge, no previous reports have described SNHL after TVE of a dAVF. When considering the etiology of the hearing loss in our case, two aspects must be discussed. First it should be made out whether this SNHL occurred incidentally or as a consequence of the procedure. Secondly, if the embolization caused the SNHL, the potential pathogenesis and clinical significance of the SNHL should be investigated. If the hearing loss was coincidental, the diagnosis of SSNHL would be the most likely diagnosis. Nevertheless, in the literature, the incidence of SSNHL is reported as low as 5–20/100,000 person-years [1, 2]. Moreover, it is highly unlikely that ipsilateral SSNHL would occur incidentally within 10 days after TVE. Therefore, it seems more likely that this SNHL has arisen as a consequence of the procedure. Although various reports have described SNHL caused by anesthesia [3], radiation [4], and contrast medium administration [5], these potential causes of hearing loss seem not to match for our case. Therefore, we considered that TVE itself must be responsible for this SNHL. Anatomically, the inner ear has two main venous drainage routes: the vein of the vestibular aqueduct (VVAQ) draining into the vertical portion of the sigmoid sinus or superior petrosal sinus (SPS); and the vein of cochlear aqueduct (VCAQ) draining into the JB or the caudal end of the IPS (Fig. 3a) [6]. Watanabe et al. reported the precise venous drainage of the inner ear in guinea pigs [7]. They reported the presence of minor collateral vessels between the VCAQ and the mucoperiosteal veins of the middle ear, which act as collateral channels in the event of venous congestion of the inner ear [7]. S. Yamauchi (*) :A. Nishio Department of Neurosurgery, Hokuto Hospital, 7-5 Inada, Obihiro, Hokkaido 080-0033, Japan e-mail: ymailadd@silver.ocn.ne.jp