Comparison of electronystagmography results with dynamic posturography findings in patients with vestibular schwannoma

A Proposal for Comprehensive Audio-Vestibular Test Battery Protocol for Diagnosis and Follow-Up Monitoring in Patients with Vestibular Schwannoma Undergoing Surgical Tumor Removal

Background: A vestibular schwannoma (VS) is a benign tumor, causing audiological and vestibular symptoms. This study aimed to propose a comprehensive audio-vestibular test battery protocol for diagnosis and follow-up monitoring in patients with unilateral VSs undergoing surgical removal. Methods: The detailed interpretation of audiological and vestibular findings was presented in two example cases. The surgery was performed through the middle cranial fossa (#1) and translabyrinthine approach (#2). The participants were evaluated with tonal, speech, and impedance audiometry, ABR, caloric test, vHIT, cVEMP, oVEMP, SOT, and DHI. Patient and tumor characteristics were retrieved from the patient's history. Results: In the postoperative period, the reduction in gain of the lateral semicircular canal was observed in the vHITs of both patients. The DHI in case #1 increased after surgery, while it decreased in case #2. The improvement in postural performances compared to the preoperative SOT (CON 5, CON 6, composite score) and immediately after the procedure was observed. Conclusions: A specific diagnostic protocol is necessary to compare the results of different surgical techniques and approaches. Diagnostic tests performed before the surgery should be repeated within a specific time frame during postoperative follow-up to enable the comparison of results. The proposed protocol can help us better understand the processes ongoing during tumor growth and postoperative vestibular compensation.

Evaluation of Vestibular Function in Diagnosis of Vestibular Schwannomas

Vestibular schwannomas (VS) are benign tumors of the vestibular nerve. The common first symptoms are hearing loss and tinnitus, followed by imbalance, vertigo, and facial nerve involvement. The subjective symptoms of VS patients are not consistent with the severity of vestibular lesions and the results of vestibular tests, which often interfere with clinicians' diagnoses. Thus, the main screening and diagnostic methods for VS are audiometry and magnetic resonance imaging (MRI), ignoring the evaluation of vestibular function at the source of pathological lesions. With the development and improvement of vestibular evaluation technology and its wide application in the clinic, modern vestibular examination technology can reflect the severity and frequency of vestibular lesions and compensation from multiple perspectives, providing an objective basis for the diagnosis and treatment of vestibular diseases. In this report, we review the results and characteristics of vestibular tests in VS patients and further clarify the clinical value of vestibular function assessment in the diagnosis and treatment of VS.

The Antwerp Vestibular Compensation Index (AVeCI): an index for vestibular compensation estimation, based on functional balance performance

PURPOSE

To create an index that is a measure of the amount of vestibular compensation and for which only functional balance performance is needed.

METHODS

The medical charts of 62 eligible peripheral vestibular dysfunction (PVD) patients were analyzed retrospectively. To be included, the following vestibulo-ocular reflex (VOR) and balance performance data had to be available: (1) caloric and sinusoidal harmonic acceleration test (SHA) and (2) standing balance sum-eyes closed (SBS-EC), Timed Up and Go Test and Dynamic Gait Index. Patients were divided into three groups: normal caloric- and SHA test (group 1), abnormal caloric- and normal SHA test (group 2, PVD compensated) and abnormal caloric- and SHA test (group 3, PVD uncompensated). Next to the use of non-parametric tests to study the VOR and balance variables, logistic regression was used to identify the balance measures that predict whether PVD patients were compensated or uncompensated. This resulted also in the construction of a continuous measure representing the degree of compensation.

RESULTS

Logistic regression identified SBS-EC and age to classify uncompensated from compensated patients with sensitivity of 83.9% and specificity of 72.4%. Then an index was created, called the Antwerp Vestibular Compensation Index, AVeCI = - 50 + age × 0.486 + SBS-EC × 0.421. A patient belongs to the uncompensated group when AVeCI < 0 and to the compensated group when AVeCI > 0, with respective group means of - 5 and 5.

CONCLUSION

AVeCI stages the degree of compensation of PVD patients and can serve to evaluate rehabilitation effects.

Relationship of Vertigo and Postural Instability in Patients With Vestibular Schwannoma

Objectives

Growth of vestibular schwannomas (VS) causes progressive vestibular symptoms and postural instability. Since the tumor grows slowly, compensation of decaying vestibular input may decrease subjective symptoms of dizziness. This study aims to estimate the relationship of subjective vestibular symptoms and objective postural instability in patients with VS.

Methods

A retrospective review of 18 patients newly diagnosed with VS and with subjective vertigo symptoms was performed. The results of vestibular function tests including the sensory organization test (SOT) using computerized dynamic posturography, caloric test, and self-report measures of subjective dizziness handicap (Dizziness Handicap Inventory) and visual analogue scale were compared according to the onset of vertigo symptoms.

Results

In VS patients, SOT showed decreased equilibrium score for all vestibular function related conditions, condition (C) 5 and 6, and composite (COMP) score. COMP scores were not correlated with visual analogue scale or Dizziness Handicap Inventory scores. Acute onset group included six patients and insidious onset group, 12 patients. Equilibrium scores for C5 and C6, and COMP scores were lower for insidious onset group, but the difference was not statistically significant.

Conclusion

Our findings confirmed postural instability is prevalent in VS patients. SOT parameters did not differ significantly between acute onset and insidious onset groups, but increased tumor size and canal weakness were noted in the insidious onset group. Clinicians should consider that postural instability is likely present even in patients who do not complain of acute vertigo, and appropriate counseling should be discussed with the patients.

Efficacy of CDP and ENG in Detecting Balance Impairment Associated With Cerebral White Matter Changes

OBJECTIVE

To examine the relationship between white matter changes (WMCs) and abnormal balance test results on computerized dynamic posturography (CDP) and electronystagmography (ENG). Also, to compare the utility of CDP with ENG for this purpose.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary care referral center.

PATIENTS

A retrospective review of 137 subjects was conducted. The CDP and ENG results were compared between patients with (80) and without (57) WMCs as detected byT2/fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI).

MAIN OUTCOME MEASURES

CDP analysis consisted of both sensory organization test (SOT) and motor control test (MCT) results, and ENG analysis included positional, oculomotor, and bithermal caloric testing. Multivariate logistic regression was performed to control for age and hearing loss discrepancies between the two groups.

RESULTS

Ninety three percent of patients with WMCs had an abnormal CDP result, as compared with 44% of patients lacking WMCs (p < 0.001). Eighty six percent of patients with WMCs had an abnormal ENG, as did 81% of patients without WMCs (p = 0.435). Multivariate regression analysis maintained that an abnormal CDP result was significantly associated with WMCs when controlling for age and hearing loss (p < 0.001).

CONCLUSION

These findings suggest that patients with cerebral small-vessel ischemic changes are significantly more likely to have an abnormal balance result as detected by CDP, than by ENG. Hence, CDP may be a better study to identify and document patients who have balance dysfunction associated with this central finding. Such identification will permit additional evaluation and treatment based on objective confirmation of balance dysfunction, in this group of balance-impaired subjects who may have normal ENG's.

Bilateral Vestibular Hypofunction: Insights in Etiologies, Clinical Subtypes, and Diagnostics

Objective

To evaluate the different etiologies and clinical subtypes of bilateral vestibular hypofunction (BVH) and the value of diagnostic tools in the diagnostic process of BVH.

Materials and methods

A retrospective case review was performed on 154 patients diagnosed with BVH in a tertiary referral center, between 2013 and 2015. Inclusion criteria comprised (1) imbalance and/or oscillopsia during locomotion and (2) summated slow phase velocity of nystagmus of less than 20°/s during bithermal caloric tests.

Results

The definite etiology of BVH was determined in 47% of the cases and the probable etiology in 22%. In 31%, the etiology of BVH remained idiopathic. BVH resulted from more than 20 different etiologies. In the idiopathic group, the percentage of migraine was significantly higher compared to the non-idiopathic group (50 versus 11%, p < 0.001). Among all patients, 23.4% were known with autoimmune disorders in their medical history. All four clinical subtypes (recurrent vertigo with BVH, rapidly progressive BVH, slowly progressive BVH, and slowly progressive BVH with ataxia) were found in this population. Slowly progressive BVH with ataxia comprised only 4.5% of the cases. The head impulse test was abnormal in 94% of the cases. The torsion swing test was abnormal in 66%. Bilateral normal hearing to moderate hearing loss was found in 49%. Blood tests did not often contribute to the determination of the etiology of the disease. Abnormal cerebral imaging was found in 21 patients.

Conclusion

BVH is a heterogeneous condition with various etiologies and clinical characteristics. Migraine seems to play a significant role in idiopathic BVH and autoimmunity could be a modulating factor in the development of BVH. The distribution of etiologies of BVH probably depends on the clinical setting. In the diagnostic process of BVH, the routine use of some blood tests can be reconsidered and a low-threshold use of audiometry and cerebral imaging is advised. The torsion swing test is not the “gold standard” for diagnosing BVH due to its lack of sensitivity. Future diagnostic criteria of BVH should consist of standardized vestibular tests combined with a history that is congruent with the vestibular findings.

Preoperative prediction of vestibular schwannoma's nerve of origin with posturography and electronystagmography

CONCLUSION

Chances of hearing preservation are better in patients with vestibular schwannoma (VS) from the superior vestibular nerve (SVN) than from the inferior vestibular nerve (IVN). Pathologic posturography and electronystagmography (ENG) findings are more common in schwannomas from the SVN compared with tumors from the IVN. In this way, computerized dynamic platform posturography (CDPP) and ENG contribute to predict the nerve of origin of VS and can be used indirectly as a prognostic factor for hearing preservation.

OBJECTIVES

To test whether preoperative CDPP or ENG results contribute to predict the nerve of origin in VS and also to evaluate the influence of the nerve of origin on hearing preservation.

METHODS

Eighty-nine patients with VS originating from the IVN and 22 patients with VS from the SVN were included. Hearing loss due to surgery was calculated on postoperative and preoperative audiograms. Caloric response was measured by ENG and condition 5 and 6 score were recorded by CDPP before surgery.

RESULTS

Hearing loss due to surgery was significantly lower in patients with tumors from the SVN than from the IVN (p = 0.011). Pathologic results in preoperative ENG (p < 0.0001) and CDPP (p = 0.025) were significantly more frequent in subjects with SVN than with IVN schwannomas.