• Nilesh K Desai, Lindsay Young, Mario A Miranda, Joe Walter Kutz, Peter S Roland, and Timothy N Booth.
• Department of Radiology, Division of Neuroradiology, Emory University School of Medicine and Children's Healthcare of Atlanta, Georgia 30322, USA. nilesh.k.desai@emory.edu
• Otolaryngol Head Neck Surg. 2011 Dec 1;145(6):992-8.

ObjectivesPontine tegmental cap dysplasia (PTCD) is a rare congenital malformation. Clinical and imaging findings in 3 patients and the authors' experience with bilateral cochlear implantation in 1 patient are described.Study DesignRetrospective review.SettingTwo tertiary medical centers.Subjects And MethodsThree patients were evaluated by an otolaryngologist and underwent magnetic resonance imaging (MRI) of the temporal bones and brain. High-resolution computed tomography (CT) scanning of the temporal bones was performed in 2 patients. Imaging findings of the brain, the presence and course of resolvable cranial nerves, the membranous labyrinth, and internal auditory canals were reviewed. Clinical data were reviewed.ResultsAll patients demonstrated typical brain characteristics of PTCD. Mild, bilateral cochlear dysplasia was noted in 2, and all had a normal vestibular labyrinth. The cochleovestibular nerves were universally absent bilaterally. The facial nerves were subjectively deficient bilaterally in 1 patient, unilaterally in the second patient, and normal in the third. An accessory canal for the seventh cranial nerve, referred to as a duplicated internal auditory canal, was present in all patients. Auditory brainstem response testing revealed profound bilateral sensorineural hearing loss in all of the patients; none suffered facial weakness. A single patient underwent bilateral cochlear implantation with only minimal response.ConclusionThe authors report 3 cases of PTCD with emphasis on imaging of the seventh and eighth cranial nerves and clinical neurotologic findings. All patients manifested duplicated internal auditory canals, a previously unreported finding in PTCD. Bilateral profound sensorineural hearing loss is due to absence of the cochleovestibular nerve. Prognosis for cochlear implantation is poor.

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