BACKGROUND:. Pulsatile tinnitus (PT) caused by venous sinus diverticulum is a relatively common, potentially incapacitating condition. Although treatmen

Lee JY, et al. J Clin Neurol. 2020 Apr;16(2):277-284. https://doi.org/10.3988/jcn.2020.16.2.277

Severe to profound sensorineural hearing loss (SNHL) requires cochlear implantation (CI) for auditory rehabilitation. Etiologic diagnoses can contribute to candidacy selection and decision-making regarding the timing of successful CI. However, few studies have been performed to address the etiologic spectrum of severe SNHL in the population where there is no consanguineous marriage and the majority of SNHL cases are sporadic in small sized families. The authors sought to comprehensively understand the etiologies of Korean cochlear implantees by incorporating the targeted resequencing of 204 candidate deafness genes (TRS-204) and a phenotype-driven candidate gene approach. Ninety-three that consented to molecular genetic testing and underwent at least one molecular genetic test were included. Patients with a characteristic Phenotypic marker were subject to Sanger sequencing to detect variants in corresponding candidate genes. The rest of patients without any prominent phenotype were tested on GJB2. Next, TRS-204 was applied in GJB2-negative cases without any phenotypic marker. In addition, the sibling recurrence-risk of SNHL among families with non-diagnostic genotypes after TRS-204 was performed to gain insight of etiologies in non-diagnostic cases. Overall, we could find causative variants in 51 (54.8%) of the 93 cochlear implantees. Thirty (32.3%) probands could be diagnosed by direct Sanger sequencing of candidate genes selected by their phenotypes. GJB2 sequencing added 10 subjects to the group with a diagnostic genotype. TRS-204 could detect a causative variant from additional 11 cases (11.8%). We could not detect any pathogenic deletion or duplication on 204 target genes. The sibling recurrence-risk of SNHL among 42 genetically undiagnosed families with 0.03 (1/38) was significantly lower than among genetically diagnosed recessive families with 0.19 (7/37). Despite that the majority of severe or more degree of SNHL occurs sporadically in Koreans, at least 54.8% of such cases that were willing to join the genetic study in the Korean population are monogenic Mendelian disorders with convincing causative variants. This study also indicates that a substantial portion of unsolved cases after applying our current protocol are predicted to have non-genetic or complex etiology rather than a Mendelian genetic disorder involving new genes beyond the 204 target genes.

Thinning or dehiscence of the superior semicircular canal may occur on the middle cranial fossa floor or adjacent to the superior petrosal sinus (SPS). However, no symptomatic cases of superior canal dehiscence by SPS have been previously described. A 45-year-old woman presented with left-side pulsating tinnitus, autophony and disequilibrium. Examination showed conductive hearing loss and decreased threshold of vestibular evoked myogenic potential in the left side. Sound and vibration stimuli and positive pressure insufflations into the left ear evoked mainly torsional nystagmus instead of vertical-torsional nystagmus. High-resolution temporal bone CT revealed a dehiscence of the superior canal close to the common crus, which was encased by SPS. Symptoms and signs resolved after plugging the dehiscence through a middle fossa approach. Deep groove of SPS may cause superior canal dehiscence close to the common crus, and costimulation of the superior and posterior canals may explain the mainly torsional nystagmus induced by sound and vibration stimuli.