Clinical Implications of the Association Between Temporal Bone Tegmen Defects and Superior Semicircular Canal Dehiscence

Abstract

Objective: To discuss the clinical implications of the association between temporal bone tegmen dehiscence (TD) necessitating surgical correction and the adjacent dehiscent superior semicircular canal (SSCD). Study Design: Retrospective. Setting: Tertiary referral center. Patients: Sixteen patients with idiopathic TD, with or without SSCD, requiring surgical correction. Interventions: Corrective surgery for TD. High-resolution temporal bone-targeted computed tomography. Main Outcome Measures: The impact of the minimal distance between TD and SSCD or the arcuate eminence on the choice of surgical approach to TD. Results: The patients’ median age was 58 years and 5 were males. The median body mass index was 31.8 kg/m2. The average distance from the TD and the SSC was 4.9 mm (range 2.1–14.2 mm). Three of the 14 patients who were operated via a temporal craniotomy to fix a cerebrospinal fluid-leaking TD required plugging of an asymptomatic SSCD due to its close proximity (3–5 mm) to the defect, and two of them had relatively protracted vestibular recuperation. Two patients were operated via a transmastoid approach for sealing a cerebrospinal fluid-leaking TD coexisting with a bilateral asymptomatic SSCD. No patient had a hearing loss. Conclusion: The close proximity of a TD and an SSCD might not allow selective exposure. As a result, asymptomatic SSCD may become symptomatic during TD correction via the temporal craniotomy approach. The need to plug an asymptomatic SSCD that is proximal to a TD should be factored in planning for surgery and rehabilitation. The choice of surgical approach (middle fossa vs. transmastoid) could be influenced by this relationship, especially in cases of bilateral lesions.

Predictive Factors for Concurrent Tegmen Dehiscence in Superior Canal Dehiscence Syndrome

“…Since superior semicircular canal dehiscence (SCD) syndrome (SCDS) was first described by Minor et al (1) in 1998 as a constellation of unique audiovestibular symptoms arising from thin or dehiscent bone overlying the superior semicircular canal (SSC), many reports have emerged that demonstrate an increased radiographic prevalence of concurrent tegmen tympani (TTD) or tegmen mastoideum dehiscence (TMD) in SCDS (2)(3)(4)(5)(6). An interesting but as yet unresolved question about SCDS surrounds the pathogenesis of this syndrome, and in particular, if thin or dehiscent superior semicircular canal represents a congenital or acquired defect, or some combination of both.…”

Dural Contact to the Malleus Head in Patients with Superior Semicircular Canal Dehiscence (SSCD): Case Series and Review of SSCD and Tegmen Defects

“…26 It has been speculated that the brain itself may seal off the SSCD, especially in the setting of increased intracranial pressure. 27 Although this does not explain the hearing difference between ears in our patient series, it raises the question as to whether the ear with the DCMH is somehow affected more by the increased intracranial pressure due to the lower and dehiscent tegmen.…”

Asociación entre dehiscencia del canal semicircular superior y dehiscencia del tegmen tympani. Revisión narrativa cronológica

“…Handzely cols., en 2018, reiteraron la importancia de la realización de tomografía computarizada para buscar dehiscencias del canal previo al tratamiento quirúrgico de una dehiscencia del tegmen, debido a que, tras la intervención de tegmen mediante craneotomía vía temporal, una dehiscencia del canal semicircular superior asintomática no detectada podría tornarse sintomática. Además, la elección del tipo de abordaje quirúrgico (vía transmastoidea o a través de la fosa craneal media) po-dría estar influenciada por esta asociación, especialmente en hallazgos de lesiones bilaterales 19 . Kouy cols., en 2018, realizaron un estudio piloto para ver si la hipertensión intracraneal estaba involucrada en la asociación de ambas dehiscencias, concluyendo que no existía vinculación alguna entre la hipertensión intracraneal, obtenida mediante punción lumbar, con la ero-sión del tegmen y la presencia de dehiscencia del canal semicircular superior, presentes en 24 de los 121 casos estudiados (19,8%), de los cuales ninguno cumplió criterios de presión intracraneal elevada (presión de apertura superior a 25 cmH 2 O) 20 .…”