Congenital Membranous Stapes Footplate Producing Episodic Pressure-Induced Perilymphatic Fistula Symptoms

Clinical course of five patients definitively diagnosed with idiopathic perilymphatic fistula treated with transcanal endoscopic ear surgery

Objectives

An idiopathic perilymphatic fistula (PLF) can be difficult to diagnose because patients present with sudden sensorineural hearing loss (SSHL) and/or vestibular symptoms without any preceding events. In such cases, we currently test for cochlin-tomoprotein (CTP) to confirm the diagnosis of idiopathic PLF because CTP is only detected in the perilymph. In this study, we report the clinical course of five patients definitively diagnosed with idiopathic PLF who underwent PLF repair surgery using transcanal endoscopic ear surgery (TEES).

Patients and methods

Five patients were initially treated with intratympanic dexamethasone for SSHL, at which time a CTP test was also performed (preoperative CTP test). Due to refractory hearing loss and/or fluctuating disequilibrium, PLF repair surgery using TEES was performed to seal the oval and round windows using connective tissue and fibrin glue. These patients were diagnosed with definite idiopathic PLF based on pre- or intra-operative CTP test results (negative, < 0.4 ng/mL; intermediate, 0.4-< 0.8 ng/mL; and positive, > 0.8 ng/mL). We evaluated pre- and intra-operative CTP values, intraoperative surgical findings via a magnified endoscopic view, and pre- and post-operative changes in averaged hearing level and vestibular symptoms.

Results

Pre- and intra-operative CTP values were positive and intermediate in three patients, positive and negative in one patient, and negative and positive in one patient. None of the patients had intraoperative findings consistent with a fistula between the inner and middle ears or leakage of perilymph. Only two patients showed a slight postoperative recovery in hearing. Four patients complained of disequilibrium preoperatively, of whom two had resolution of disequilibrium postoperatively.

Conclusion

A positive CTP test confirms PLF in patients without obvious intraoperative findings. The CTP test is considered more sensitive than endoscopic fistula confirmation. We consider that CTP test results are important indicators to decide the surgical indication for idiopathic PLF repair surgery. In our experience with the five cases, two of them showed improvements in both hearing and vestibular symptoms.

Objective Assessment of Perilymphatic Fistula in Cases of Postoperative Vertigo after Cochlear Implantation by Cochlin Tomoprotein (CTP)

OBJECTIVE

Vertigo is a quite frequent complication after cochlear implantation. Perilymphatic fistula (PLF) is assumed to be one cause of this problem. Cochlin tomoprotein (CTP) is a newly introduced marker for PLF. The present aim was to evaluate the rate of positive CTP testing in cases of newly occurring vertigo after cochlear implantation.

MATERIALS AND METHODS

Twelve patients with vertigo after cochlear implantation and a revisional electrode-sealing procedure underwent intraoperative rinsing of their middle ear. The sample was evaluated for CTP with monoclonal antibody testing. Sixteen controls from six CI patients were taken.

RESULTS

4 out of 12 (33%) cases showed positive CTP testing, indicating that a PLF could be evaluated. In all of the positive CTP cases, surgery decreased the vertigo symptoms. A relation between the subjective visual assessment of a fistula and a positive CTP value was not observed. Controls confirmed the value of the testing.

DISCUSSION

CTP detection objectively shows that PLF can occur in patients with vertigo after CI.

Assessing the efficacy of perilymphatic fistula repair surgery in alleviating vestibular symptoms and associated auditory impairments

Perilymph Fistula (PLF), abnormal communication between the fluid-filled space of the inner ear and the air-filled space of the middle ear, is a significant cause of vestibular and auditory symptoms. This is a retrospective study of 22 cases treated with PLF repair surgery, selected based on our surgical indication. We analyzed the characteristics of these 22 cases and evaluated the efficacy of PLF repair surgery in treating vestibular and auditory symptoms. Cases with antecedent events had significantly shorter intervals before surgery. The postoperative recovery from vestibular symptoms following PLF repair surgery was strikingly rapid, with 82% of cases demonstrating marked improvement within a week, even in chronic cases. Despite the notable absence of a control group in the study, the marked improvements in vestibular symptoms and substantial reductions in Dizziness Handicap Inventory (DHI) scores suggest that the observed benefits are attributable to the surgical intervention. Further, timely surgery showed improvements in hearing, with some benefits also seen in late-stage surgeries. Using the perilymph-specific protein Cochlin-tomoprotein (CTP) as a diagnostic biomarker, we could prove that PLF could be responsible for disequilibrium and related auditory disturbances in these patients. A new hypothesis is proposed that the chronic disequilibrium experienced by many PLF patients is due to enhanced mobility of the utricle and not to endolymphatic hydrops. Further research is needed to fully elucidate PLF's symptoms and treatment efficacy using the surgical indication we developed.

Proposal for a Unitary Anatomo-Clinical and Radiological Classification of Third Mobile Window Abnormalities

Introduction: An increased number of otic capsule dehiscence (OCD) variants relying on the third window pathomechanism have been reported lately. Therefore, a characterization of the anatomical structures involved and an accurate radiological description of the third window (TW) interface location have become essential for improving the diagnosis and appropriate therapeutic modalities. The purpose of this article is to propose a classification based on clinical, anatomical, and radiological data of third mobile window abnormalities (TMWA) and to discuss the alleged pathomechanism in lesser-known clinical variants.

Materials and Methods: The imaging records of 259 patients who underwent, over the last 6 years, a high-resolution CT (HRCT) of the petrosal bone for conductive hearing loss were analyzed retrospectively. Patients with degenerative, traumatic, or chronic infectious petrosal bone pathology were excluded. As cases with a clinical presentation similar to those of a TW syndrome have recently been described in the literature but without these being confirmed radiologically, we thought it necessary to be integrated in a separated branch of this classification as “CT - TMWA.” The same goes for certain intralabyrinthine pathologies also recently reported in the literature, which mimic to some extent the symptoms of a TW pathology. Therefore, we suggest to call them intralabyrinthine TW-like abnormalities.

Results: Temporal bone HRCT and, in some cases, 3T MRI of 97 patients presenting symptomatic or pauci-symptomatic, single or multiple, unilateral or bilateral OCD were used to develop this classification. According to the topography and anatomical structures involved at the site of the interface of the TW, a third-type classification of OCD is proposed.

Conclusions: A classification reuniting all types of TMWA as the one proposed in this article would allow for a better systematization and understanding of this complex pathology and possibly paves the way for innovative therapeutic approaches. To encompass all clinical and radiological variants of TMWA reported in the literature so far, TMWAs have been conventionally divided into two major subgroups: Extralabyrinthine (or “true” OCD with three subtypes) and Intralabyrinthine (in which an additional mobile window-like mechanism is highly suspected) or TMWA-like subtype. Along these subgroups, clinical forms of OCD with multiple localization (multiple OCD) and those that, despite the fact that they have obvious characteristics of OCD have a negative CT scan (or CT – TMWA), were also included.