The significance of the human endolymphatic sac and its possible role in Menière's disease

Comparison of vestibular aqueduct visualization on computed tomography and magnetic resonance imaging in patients with Ménière's disease

BACKGROUND

The vestibular aqueduct (VA) serves an essential role in homeostasis of the inner ear and pathogenesis of Ménière's disease (MD). The bony VA can be clearly depicted by high-resolution computed tomography (HRCT), whereas the optimal sequences and parameters for magnetic resonance imaging (MRI) are not yet established. We investigated VA characteristics and potential factors influencing MRI-VA visibility in unilateral MD patients.

METHODS

One hundred patients with unilateral MD underwent MRI with three-dimensional sampling perfection with application optimized contrasts using different flip angle evolutions (3D-SPACE) sequence and HRCT evaluation. The imaging variables included MRI-VA and CT-VA visibility, CT-VA morphology and CT-peri-VA pneumatization.

RESULTS

The most frequent type of MRI-VA and CT-VA visualization was invisible VA and continuous VA, respectively. The MRI-VA visibility was significantly lower than CT-VA visibility. MRI-VA visibility had a weak positive correlation with ipsilateral CT-VA visualization. For the affected side, the MRI-VA visualization was negatively correlated with the incidence of obliterated-shaped CT-VA and positively with that of tubular-shaped CT-VA. MRI-VA visualization was not affected by CT-peri-VA pneumatization.

CONCLUSION

In patients with MD, the VA visualization on 3D-SPACE MRI is poorer than that observed on CT and may be affected by its osseous configuration. These findings may provide a basis for further characterization of VA demonstrated by MRI and its clinical significance.

Comparison of radiological abnormalities between the jugular bulb and the vestibular aqueduct in patients with Ménière's disease

Objective

Anatomical variations of the inner ear may contribute to the development of Ménière's disease (MD), which is a complex inner ear disorder histopathologically characterized by idiopathic endolymphatic hydrops (ELH). Abnormalities of the vestibular aqueduct (VA) and the jugular bulb (JB) have been suggested as predisposing factors. Yet, few studies have investigated the correlation between JB abnormalities and VA variations as well as its clinical relevance in these patients. In this retrospective study, we investigated the differences in the incidence of radiological abnormalities of the VA and JB in patients with definite MD.

Methods

Anatomical variations of JB and VA were evaluated based on high-resolution CT (HRCT) in a series of 103 patients with MD (93 unilateral cases and 10 bilateral cases). JB-related indices included JB anteroposterior and mediolateral diameter, JB height, JB type regarding to Manjila classification system, and incidences of JB diverticulum (JBD), JB related inner ear dehiscence (JBID), and inner ear adjacent JB (IAJB). VA-related indices included CT-VA visibility, CT-VA morphology (funnel, tubular, filiform, hollow, and obliterated-shaped type), and peri-VA pneumatization. Radiological indices were compared between MD ears and control ears.

Results

Radiological JB abnormalities were comparable between MD ears and control ears. As for VA-related indices, the CT-VA visibility was lower in MD ears than in control ears (p = 0.004). The distribution of CT-VA morphology was significantly different between MD and control ears (p = 0.013), with a higher proportion of obliterated-shaped type in MD ears (22.1%) than in control ears (6.6%).

Conclusion

Compared with JB abnormalities, the anatomical variations of VA are more likely to be an anatomically predisposing factor for MD.

Efficacy of Resection of Lateral Wall of Endolymphatic Sac for Treatment of Meniere's Disease

Background

To explore the long-term efficacy and safety of resection of the lateral wall of the endolymphatic sac for the treatment of intractable Meniere's disease (MD) as an alternative surgical procedure for treating this disorder.

Methods

Data from 73 patients who were referred to our hospital and diagnosed with unilateral MD between January 2015 and June 2019 were retrospectively analyzed in this study. Seventy-three patients who had frequent vertigo even after receiving standardized conservative treatment for at least half a year underwent resection of the lateral wall of the endolymphatic sac. Vertigo control and auditory function were assessed. Pure tone audiometry, caloric test, and vestibular evoked myogenic potential were performed to evaluate audiological and vestibular functions. The post-operative follow-up duration was more than 2 years.

Results

Among the 73 patients (male 34 cases, female 39 cases; age 20–69 years, average 51.4), vertigo was controlled effectively for 66 cases (90.4%) after 2 years of follow-up; 45 cases (61.6%) were completely controlled, and 21 cases (28.8%) were substantially controlled in this study. The patients of 16.4% had hearing loss with more than 10 dB change based on the four-tone average (0.5, 1, 2 and 3 kHz). No patient had a facial nerve weakness, cerebrospinal fluid leakage, or other complications.

Conclusion

Resection of the lateral wall of the endolymphatic sac, which can effectively control vertiginous symptoms in intractable MD patients, represents an effective and safe therapy for this disease. Resection of the lateral wall of the endolymphatic sac is expected to be used as an alternative treatment for MD.

A comparison of endolymphatic duct blockage, endolymphatic sac drainage and endolymphatic sac decompression surgery in reversing endolymphatic hydrops in Meniere's disease

Background

To explore the differences between endolymphatic duct blockage, endolymphatic sac drainage and endolymphatic sac decompression surgery in the reversal of endolymphatic hydrops (EH) in patients with intractable Meniere’s disease (MD).

Methods

A total of 27 MD patients receiving endolymphatic duct blockage surgery (n = 10), endolymphatic sac drainage surgery (n = 9) and endolymphatic sac decompression surgery (n = 8) underwent gadolinium-enhanced inner ear magnetic resonance imaging (MRI) scans prior to, 2 weeks after and at > 12 months following surgery.

Results

In the group with endolymphatic duct blockage, the second MRI revealed no changes in EH, whereas the third MRI revealed a reversal of vestibular EH in 3 patients and a downgrading of cochlear hydrops in 2 of these 3 patients, who presented with an improvement in their hearing and complete control of vertigo. In the group with endolymphatic sac drainage, the second MRI showed a reversal of EH in 4 patients, and no changes in EH in the remaining 5 patients, whereas the third MRI showed that those 4 patients who presented with a reversal of EH at the second MRI stage remained unchanged except a recurrence of vestibular hydrops in 1 patient. All 4 patients exhibited a complete control of vertigo, but hearing improved in 1, worsened in 1 and remained unchanged in 2. In the group with endolymphatic sac decompression, both the second and third MRI examination revealed no reversal of EH.

Conclusions

The present study has shown that both endolymphatic duct blockage surgery and endolymphatic sac drainage surgery have the potential to reduce EH in certain MD patients, but none of the patients receiving endolymphatic sac decompression surgery showed reversal of their EH.

Graphical Abstract

Recent surgical options for vestibular vertigo

Vertigo is not a well-defined disease but a symptom that can occur in heterogeneous entities diagnosed and treated mainly by otolaryngologists, neurologists, internal medicine, and primary care physicians. Most vertigo syndromes have a good prognosis and management is predominantly conservative, whereas the need for surgical therapy is rare, but for a subset of patients often the only remaining option. In this paper, we describe and discuss different surgical therapy options for hydropic inner ear diseases, Menière's disease, dehiscence syndromes, perilymph fistulas, and benign paroxysmal positional vertigo. At the end, we shortly introduce the most recent developments in regard to vestibular implants. Surgical therapy is still indicated for vestibular disease in selected patients nowadays when conservative options did not reduce symptoms and patients are still suffering. Success depends on the correct diagnosis and choosing among different procedures the ones going along with an adequate patient selection. With regard to the invasiveness and the possible risks due to surgery, in depth individual counseling is absolutely necessary. Ablative and destructive surgical procedures usually achieve a successful vertigo control, but are associated with a high risk for hearing loss. Therefore, residual hearing has to be included in the decision making process for surgical therapy.

Long-term outcomes of endolymphatic sac shunting with local steroids for Meniere's disease

OBJECTIVES

To evaluate the long-term efficacy of endolymphatic sac shunt techniques with and without local steroid administration.

STUDY DESIGN

Retrospective case series and patient survey.

SETTING

Tertiary university hospital.

PATIENTS

Meniere's disease (MD) patients that failed medical therapy and subsequently underwent an endolymphatic sac shunt procedure. All patients had definitive or probable MD and at least 18-months of follow-up.

INTERVENTIONS

Three variations on endolymphatic sac decompression with shunt placement were performed: Group A received no local steroids, Group B received intratympanic dexamethasone prior to incision, and Group C received dexamethasone via both intratympanic injection and direct endolymphatic sac instillation.

MAIN OUTCOME MEASURE(S)

Vertigo control, hearing results, and survey responses.

RESULTS

Between 2002 and 2013, 124 patients with MD underwent endolymphatic sac decompression with shunt placement. 53 patients met inclusion criteria. Groups A, B, and C had 6 patients, 20 patients, and 27 patients, respectively. Mean follow-up was 56months. Vertigo control improved in 66%, 83%, and 93% of Groups A, B, and C. Functional level improved for Group B (-2.0) and Group C (-2.2) but was unchanged in Group A. Pure-tone average and speech discrimination scores changed by +22dB and -30%, +6dB and -13%, and +6dB and -5% in Groups A, B, and C. The long-term hearing results were significantly better with steroids (Groups B and C) according to the AAO-HNS 1995 criteria but did not meet significance on non-parametric testing.

CONCLUSIONS

Endolymphatic sac shunt procedures may benefit from steroid instillation at the time of shunt placement.

Endolymphatic sac surgery for Ménière's disease: a systematic review and meta-analysis

OBJECTIVE

To analyze current endolymphatic surgery techniques and quantify their efficacy in controlling vertigo and maintaining hearing in the short and long term.

DATA SOURCES

A comprehensive literature search using the PubMed-NCBI database from 1970 to 2013.

STUDY SELECTION

Articles on sac decompression and mastoid shunt (with and without silastic) were included. Included studies had to report data using the 1985 or 1995 American Academy of Otolaryngology-Head and Neck Foundation (AAO-HNS) guidelines, describe surgical technique in detail, include a minimum of 10 patients, and have minimum 12 months of follow-up.

DATA EXTRACTION

Endpoints were vertigo control and hearing preservation using AAO-HNS guidelines. Analysis included short-term (>12 mo) and long-term (>24 mo) follow-up.

DATA SYNTHESIS

Data analysis was performed using MedCalc 12.7.0. Each article was weighted according to the number of patients treated. Analysis of pooled proportion was performed, and Freeman-Tukey transformation was used to correct for probable variance. A t test (of proportions) was performed to compare differences between groups.

CONCLUSION

Endolymphatic sac surgery (sac decompression or mastoid shunt) is effective at controlling vertigo in the short term (>1 yr of follow-up) and long term (>24 mo) in at least 75% of patients with Ménière's disease who have failed medical therapy. Sac decompression and mastoid shunting techniques provide similar vertigo control rates. Mastoid shunting, with and without silastic, also provides similar vertigo control rates. Non-use of silastic, however, seems to maintain stable or improved hearing in more patients compared to silastic sheet placement. The data suggest that, once the sac is opened, placing silastic does not add benefit and may be deleterious.

Endolymphatic duct blockage: a randomized controlled trial of a novel surgical technique for Ménière's disease treatment

OBJECTIVES

To compare the effectiveness of the endolymphatic duct blockage (EDB) and the endolymphatic sac decompression (ESD) to control Ménière's disease symptoms and to evaluate their effect on hearing level.

STUDY DESIGN

Prospective nonblinded randomized study.

SETTING

Tertiary medical center.

SUBJECTS AND METHODS

Fifty-seven patients affected by a refractory Ménière's disease were included out of which 22 underwent an ESD and 35 underwent an EDB. Five periods of follow-up were considered: 0 to 1 week, 1 week to 6 months, 6 to 12 months, 12 to 18 months, and 18 to 24 months. Mean outcome measurements consisted of vertigo control, tinnitus, aural fullness, instability, and hearing level. Hearing level was evaluated using pure-tone average (PTA) and speech discrimination score (SDS).

RESULTS

There was no significant difference between the 2 groups in the number of vertigo spells per months preoperatively (P = .153). Twenty-four months postoperatively, 96.5% of the EDB group had achieved a complete control of vertigo spells against 37.5% of the ESD group with a statistically significant difference (P = .002). There was a better control of tinnitus and aural fullness with EDB (P = .021 and P = .014, respectively). There was no statistically significant difference in hearing level preoperatively (P = .976) and 24 months postoperatively (P = .287) between the 2 groups. Hearing level was preserved in each group with no significant difference between the preoperative and the postoperative levels (P > .05).

CONCLUSION

EDB is more effective than the traditional ESD in controlling the symptoms of Ménière's disease. It is a novel surgical technique with promising results for a complete treatment of Ménière's disease. There are no significant complications or adverse effect.

The outcome of patients with ménière’s disease

Ménière’s disease is a frequent vestibular disease that occurs predominantly in the fourth decade of life. Diagnosis is mostly medical and is based on findings of vertigo, sensorineural hearing loss, tinnitus and aural fullness. Aim: To study the clinical findings of Ménière’s disease: age, duration of vertigo, tinnitus, hearing loss and aural fullness, and unilateral or bilateral involvement. Method: a retrospective study included 39 patients with a diagnosis of Ménière’s disease confirmed by electrocochleography, who were seen at a neuro-otology referral centre. Patients underwent a clinical examination, audiometry and bilateral transtympanic electrocochleography. Patients were separated into 2 groups: bilateral Ménière’s disease and unilateral Ménière’s disease. Results: The mean age was 42.9 years; 72.5% were female. Fluctuation of hearing loss occurred in 54.5% of cases, and 65.7% had frequent attacks of vertigo. Bilateral disease was observed in 33.3%. The onset of the disease was earlier in the bilateral group (33.7 years) compared to the unilateral group (p= 0.0013). Duration of disease, tinnitus, hearing loss and aural fullness were similar between groups. Conclusion: Patients with bilateral Ménière’s disease had symptoms earlier than patients with unilateral disease. There was no difference between the groups in duration of disease and associated symptoms.

Measles virus in otosclerosis and the specific immune response of the inner ear

Histologic and immunohistochemical studies of otosclerotic lesions have shown that there is a chronic inflammatory reaction of the otic capsule with bone resorption resulting from vascular invasion accompanied by inflammatory cells. During the active lytic stage of otosclerosis, paramyxoviral structures have been identified by electron microscopy and measles virus antigen expression by immunohistochemistry. Recently, measles virus related sequences have been detected in tissue of otosclerotic lesions. Because the otosclerotic focus has a close relation to the perilymphatic space, the expression of measles virus antigens within it should represent an immunologic challenge to the immune system of the endolymphatic sac. In this study, measles virus specific antibodies were detected in all of the perilymph samples from 19 patients suffering from otosclerosis, and the relative amount of these IgG antibodies was much higher than in serum samples of the same patients or in perilymph of control patients. These findings support the hypothesis that measles viruses play an crucial role in the pathogenesis of otosclerosis.