Congenital Retrosigmoid Cholesteatoma: Case Series and Literature Review.

BACKGROUND: This study aimed to discuss 3 cases of congenital cholesteatoma located posterior to the sigmoid sinus, with no/minimal involvement of mastoid, and compare them with cases presented in the literature to better define this rare entity. METHODS: Retrospective chart analysis of 3 congenital cholesteatomas located posterior to the sigmoid sinus treated surgically in 2 skull-base centers and literature review. Though congenital cholesteatoma can arise outside the middle ear, only a few cases presenting in the retrosigmoid occipital bone have been described earlier. RESULTS: In all 3 patients, there was a delay in the presentation, as symptoms were nonspecific or lacking, leading in 1 case to severe complications. Computed tomography and magnetic resonance imaging, especially diffusion-weighted imaging scans, allowed accurate diagnosis and surgical planning. Surgery happened to be challenging due to the tight adherence of the cholesteatoma to the thinned dural surface. Complete excision was achieved in all the cases. CONCLUSION: Congenital cholesteatoma located posterior to the sigmoid sinus is a rare entity and is even more exceptional after a critical review of the literature. Complete excision is quintessential to prevent intradural extension or infection. The most important surgical issue is the management of the posterior fossa dura and the sigmoid sinus. We recommend meticulous dissection with slow peeling of the epithelial lining from the dura. Bipolar coagulation of the dura may help in avoiding recidivism. Moreover, cerebrospinal fluid (CSF) leak during dissection has to be avoided as long as possible, because the loss of tension of the already thinned dura makes its peeling particularly difficult.

Cochlear Patency after Translabyrinthine and Retrosigmoid Vestibular Schwannoma Surgery.

OBJECTIVES: To assess the incidence and onset of cochlear obliteration after translabyrinthine and retrosigmoid vestibular schwannoma surgery. MATERIALS AND METHODS: We retrospectively identified a consecutive series of eighty ears in eighty vestibular schwannoma patients who were treated via a translabyrinthine or retrosigmoid approach by a single neuro-otological surgical team in a tertiary referral center from May 2011 to January 2018. Postoperative, high- resolution T2-weighted turbo spin echo three-dimensional magnetic resonance (MR) images of the posterior fossa were evaluated at the level of the membranous labyrinth and internal auditory canal. Perilymphatic patency of the vestibule, basal, and apical cochlear turns were scored and classified as patent, hypointense, partially obliterated, or completely obliterated. RESULTS: Twenty-five vestibular schwannomas were treated with surgery via a translabyrinthine approach, and fifty-five were treated using a retrosigmoid approach; of these, 8% and 65%, respectively, showed no signs of perilymphatic alterations in the basal or apical turns, while 84% and 20%, respectively, showed partial or complete obliteration in the basal or apical turns with a mean postoperative interval of 127 and 140 days, respectively. All the patients who underwent multiple MR scans and had a completely patent perilymphatic system on the first postoperative scan remained patent during subsequent scans; 16% of the patients showed worsened perilymphatic appearance. The onset of cochlear obliteration occurred within 2-7 months in most translabyrinthine patients. CONCLUSION: These findings may support the need for simultaneous cochlear electrode or dummy implantation in translabyrinthine surgery. Second-stage implantation could be feasible in cases where a retrosigmoid approach is used; however, the implantation should be considered within the initial months to avoid cochlear obliteration. Findings on the first postoperative MR could indicate the need for intensified MR follow-up and may even predict the occurrence of cochlear obliteration.