Persistent Positional Vertigo in a Patient with Partial "Auto-Plugged" Superior Semicircular Canal Dehiscence: A Case Study

Abstract

A 73-year-old female was referred to our department for persistent left anterior benign paroxysmal positional vertigo refractory to multiple repositioning procedures and training physiotherapist exercises. The audiovestibular assessment and high resonance computed tomography of the petrosal bone confirmed the presence of a 5.4 mm large paucisymptomatic left anterior semicircular canal dehiscence. The connection between the 2 apparently distinct neurotological entities in the same patient was further sustained by additional imagery. T2-weighted and 3-dimensional labyrinthine sequences confirmed the presence of a partially "auto-plugged" superior semicircular canal dehiscence which progressively entrapped greater otolith particles proximal to the cupula of the superior semicircular canal.

Figure 1. a,b.

(a) Left-sided mixed hearing loss with an air-bone gap of 40 dB at 250 Hz; (b) lower than normal cVEMPs at 60 dB. Left cVEMPs amplitudes were significantly greater when compared to the right cVEMPs. cVEMPs, cervical vestibular evoked myogenic potentials.

Figure 2. a,b.

High-resolution computed tomography (HRCT) scan of the petrous bone showing (a) a right-sided measured 3.8 mm “near dehiscence” of the SSC and (b) (left ear) a left-sided 5.4 mm large dehiscence of the SSC. SSC, superior semicircular canal.

Figure 3. a,b.

(a) Three-dimensional high-resolution MRI of the labyrinth. Narrowing and partial stenosis of the membranous duct of the left superior semicircular canal (right) matching the SSCD area; Fusion imaging between 3D T2 FLAIR and T2 Driven Equilibrium (DRIVE) confirming the narrowing left SSC (left); (b) (3D HR MRI) of the labyrinth confirming a narrowing at 0.5 mm of the SSC (for a normal diameter of about 1.2 mm)—multiaxial 3D plane view. SSCD, superior semicircular canal dehiscence; FLAIR, fluid-attenuated inversion recovery; 3D HR MRI, three-dimensional high-resolution magnetic resonance imaging.