Long-term results of middle fossa plugging of superior semicircular canal dehiscences: clinically and instrumentally demonstrated efficiency in a retrospective series of 16 ears

Abstract

The objective of this study is to report the surgical outcome after middle fossa approach (MFA) plugging in patients suffering from a superior semi-circular canal dehiscence (SCD) syndrome. This is a retrospective case review. Tertiary referral center. Sixteen ears in 13 patients with a SCD syndrome suffering from severe and disabling vestibular symptoms with a bony dehiscence on CT scan >3 mm and decreased threshold of cervical vestibular evoked potentials (cVEMPs). We assessed preoperatively: clinical symptoms, hearing, cVEMPs threshold, size of dehiscence and videonystagmography (VNG) with caloric and 100 Hz vibratory tests. Postoperatively, we noted occurrences of neurosurgical complication, evolution of audiological and vestibular symptoms, and evaluation of cVEMP data. Tullio’s phenomenon was observed in 13 cases (81.3 %) and subjectively reported hearing loss in seven (43.7 %). All patients were so disabled that they had to stop working. No neurosurgical complications were observed in the postoperative course. In three cases (16.6 %), an ipsilateral and transitory immediate postoperative vestibular deficit associated with a sensorineural hearing loss (SNHL) was noted, which totally resolved with steroids and bed rest. All patients were relieved of audiological and vestibular symptoms and could return to normal activity with a mean follow-up of 31.1 months (range 3–95). No patient had residual SNHL. cVEMPs were performed in 14 ears postoperatively and were normalized in 12 (85.7 %). Two of the three patients operated on both sides kept some degree of unsteadiness and oscillopsia. MFA plugging of the superior semi-circular canal is an efficient and non-hearing deteriorating procedure.

Effectiveness of Transmastoid Plugging for Semicircular Canal Dehiscence Syndrome

“…25 Canal plugging procedures involve occlusion of the lumen of the canal. 1,6,7,[12][13][14][15][17][18][19][20][21][22]28 Most investigations suggest that canal plugging has a higher success rate than canal resurfacing 25 ; however, lack of consensus regarding a metric for operative success and inconsistent reporting of surgical complications preclude a strong recommendation regarding a single surgical technique at this time. 3 Regarding the present study, our results seem at least comparable to middle fossa canal plugging and superior to resurfacing or capping techniques for symptom control and low-frequency hearing improvement.…”

“…2,7 Computed tomography (CT) imaging of the temporal bone identifies absent or thinned bone overlying the superior canal, and this area of decreased cochlear input impedance provides the basis for the ''thirdwindow hypothesis,'' in which clinical findings are explained by abnormal shunting of acoustic energy through the hypercompliant area of bony dehiscence. [8][9][10] Multiple clinical studies have demonstrated that surgical intervention can provide relief of clinical symptoms, 1,6,7,[11][12][13][14][15][16][17][18][19][20][21][22][23] although no technique or approach has yet shown superior outcomes across the literature. [3][4][5]24,25 Studies continue to be limited based on the small sample size reported, making conclusions regarding operative technique difficult to assess.…”

Heterogeneity in Reported Outcome Measures after Surgery in Superior Canal Dehiscence Syndrome—A Systematic Literature Review

“…SNHL was reported in a minority of cases (3/16) (19). Another study did not report thresholds, but described a general improvement of AC with an average of 10 ± 23 dB HL (21).…”

“…Outcome measures included: the SRT (19), the Word Recognition Score (20), and the Speech Discrimination Score (13, 23). …”

Impact of Superior Canal Dehiscence Syndrome on Health Utility Values: A Prospective Case-Control Study

“…The subgroup analysis of the case group did not reveal any statistically significant differences comparing bilateral to unilateral SCDS patients and patients who opted for surgery compared to patients who chose a conservative approach. Surgery has the potential to improve symptoms such as autophony, and pulsatile tinnitus ( 14 , 15 , 29 ). However, these symptoms are not measured by HUI, because it is a generic HRQoL instrument.…”