Preoperative balance control compensation in patients with a vestibular schwannoma: does tumor size matter?

Effect of vestibular loss on head-on-trunk stability in individuals with vestibular schwannoma

The vestibulo-collic reflex generates neck motor commands to produce head-on-trunk movements that are essential for stabilizing the head relative to space. Here we examined the effects of vestibular loss on head-on-trunk kinematics during voluntary behavior. Head and trunk movements were measured in individuals with vestibular schwannoma before and then 6 weeks after unilateral vestibular deafferentation via surgical resection of the tumor. Movements were recorded in 6 dimensions (i.e., 3 axes of rotation and 3 axes of translation) using small light-weight inertial measurement units while participants performed balance and gait tasks. Kinematic measures differed between individuals with vestibular schwannoma (at both time points) and healthy controls for the more challenging exercises, namely those performed in tandem position or on an unstable surface without visual input. Quantitative assessment of the vestibulo-ocular reflex (VOR) revealed a reduction in VOR gain for individuals with vestibular schwannoma compared to control subjects, that was further reduced following surgery. These findings indicated that the impairment caused by either the tumor or subsequent surgical tumor resection altered head-on-trunk kinematics in a manner that is not normalized by central compensation. In contrast, we further found that head-on-trunk kinematics in individuals with vestibular schwannoma were actually comparable before and after surgery. Thus, taken together, our results indicate that vestibular loss impacts head-on-trunk kinematics during voluntary balance and gait behaviors, and suggest that the neural mechanisms mediating adaptation alter the motion strategies even before surgery in a manner that may be maladaptive for long-term compensation.

Regional differences in patient-reported outcomes as a proxy of healthcare practices for Americans living with vestibular symptoms

BACKGROUND

Geographical location is known to affect health outcomes; however, evidence regarding whether location affects healthcare for persons suspected to have vestibular dysfunction is lacking.

OBJECTIVE

To investigate whether location affects healthcare seeking and outcomes for adults with symptoms of vestibular pathology.

METHODS

We assessed for regional disparities associated with demographics, diagnosis, chronological factors, and financial expenditures from Americans who participated in the Vestibular Disorders Association registry (N = 905, 57.4±12.5 years, 82.7% female, 94.8% White, and 8.1% Hispanic or Latino). Respondents were grouped per geographical regions defined by the United States Census Bureau.

RESULTS

There were no significant between-region differences for age (p = 0.10), sex (p = 0.78), or ethnicity (p = 0.24). There were more Asian respondents in the West versus the Midwest (p = 0.05) and more Black respondents in the South versus the West (p = 0.05). The time to first seek care was shorter in the Northeast (17.3 [SD = 49.5] weeks) versus the South (42.4 [SD = 83.7] weeks), p = 0.015. The time from the first healthcare visit to receiving a final diagnosis was shorter in the Northeast (46.5 [SD = 75.4] weeks) versus the South (68.9 [SD = 89.7] weeks), p = 0.015. Compared to the Midwest, fewer respondents in the Northeast reported "no" out-of-pocket financial impact, p = 0.039.

CONCLUSIONS

Geographical location affects healthcare seeking and outcomes for persons suspected to have vestibular dysfunction.

Head movement kinematics are altered during balance stability exercises in individuals with vestibular schwannoma

Background

Balance stabilization exercises are often prescribed to facilitate compensation in individuals with vestibular schwannoma (VS). However, both the assessment and prescription of these exercises are reliant on clinical observations and expert opinion rather than on quantitative evidence. The aim of this study was to quantify head motion kinematics in individuals with vestibular loss while they performed commonly prescribed balance stability exercises.

Methods

Using inertial measurement units, head movements of individuals with vestibular schwannoma were measured before and after surgical deafferentation and compared with age-matched controls.

Results

We found that individuals with vestibular schwannoma experienced more variable head motion compared to healthy controls both pre- and postoperatively, particularly in absence of visual input, but that there was little difference between preoperative and postoperative kinematic measurements for our vestibular schwannoma group. We further found correlations between head motion kinematic measures during balance exercises, performed in the absence of visual input, and multiple clinical measurements for preoperative VS subjects. Subjects with higher head motion variability also had worse DVA scores, moved more slowly during the Timed up and Go and gait speed tests, and had lower scores on the functional gait assessment. In contrast, we did not find strong correlations between clinical measures and postoperative head kinematics for the same VS subjects.

Conclusions

Our data suggest that further development of such metrics based on the quantification of head motion has merit for the assessment and prescription of balance exercises, as demonstrated by the calculation of a “kinematic score” for identifying the most informative balance exercise (i.e., “Standing on foam eyes closed”).

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.

Gross-total versus near-total resection of large vestibular schwannomas. An institutional experience

OBJECTIVE

We will report our experience of the surgical treatment of large vestibular schwannomas (VSs).

PATIENTS, MATERIALS AND METHODS

We conducted a retrospective study of patients operated on for Koos grade IV VS between 2007 and 2015 at the Department of Neurosurgery, Emergency County Hospital, Târgu Mureş, Romania. We studied the general preoperatory clinical data, the preoperative and postoperative facial nerve status, preoperative hearing on the affected side, and any postoperative complications, including death.

RESULTS

Sixty-six cases were included in our study. The mean age was 52.95 years and 66.7% (n=44) of the sample were female. All patients had suffered from tinnitus and this had been followed by loss of serviceable hearing on the affected side in 89.4% (n=59) of cases. Preoperative facial palsy was found in 53% (n=35) of patients. The mean tumor size was 40.35 mm. Gross-total resection (GTR) was achieved in 24 (36.36%) cases, while near-total resection (NTR) was obtained in 42 (63.64%) cases. New-onset facial palsy or degradation of the preoperative facial deficit occurred in 12 (18.18%) cases, most of whom were patients with a GTR (n=9, 37.5%). This was statistically significant. There were no significant postoperative differences between the GTR and NTR groups. There was one death in the GTR group.

CONCLUSIONS

We conclude that near-total tumor removal provides good surgical results and better postsurgical quality of life for patients when compared to gross-total tumor resection. Therefore, this should be the end goal of the resection of large VSs.

Predicting Potential of Rapid Tumor Growth in Small to Medium Vestibular Schwannomas on the Basis of Sway Assessed Using Posturography

OBJECTIVE

The relationship between quantitative posturography results and growth of vestibular schwannomas (VSs) during conservative management has not been studied. We aimed to clarify the relationship between the presence of disequilibrium based on posturographic measurement and VS growth.

METHODS

This retrospective, single-center study included 53 patients with VSs (Koos stage I or II) managed conservatively after initial diagnosis. Radiographic progression was considered present if 20% volumetric growth was observed over the imaging interval. Posturography was performed at initial diagnosis, and sway velocity (SV) and sway area were calculated. Tumor growth-free survival was estimated using the Kaplan-Meier method.

RESULTS

Mean follow-up period was 2.87 ± 2.58 years, up to tumor growth detection or last follow-up magnetic resonance imaging. Tumor growth incidence was 40.8% and 61.2% at 2 and 5 years, respectively. Cerebellopontine angle extension and SV with eyes open were related to tumor growth. Tumor growth-free survival of patients with cerebellopontine angle extension and patients with intracanalicular tumor at 2 years was 37.3% and 76.4%, respectively. Tumor growth-free survival of patients with SV >2.06 cm/second and patients with SV ≤2.06 cm/second at 2 years was 30.8% and 68.9%, respectively. The Cox hazard model demonstrated a significant risk for future tumor growth with SV >2.06 cm/second (relative risk, 2.475; 95% confidence interval, 1.11-5.37, P = 0.027).

CONCLUSIONS

We demonstrated a positive correlation between SV with eyes open and future tumor growth. Posturographic data are objective and quantitative; thus, SV may be a potential predictor of future growth of VSs.

The prediction of the tumor size of a vestibular schwannoma by clinical performance and vestibular function tests

PURPOSE

To investigate the relationship between vestibular schwannoma (VS) size and the dysfunction and compensation of the vestibular system.

METHODS

One hundred fifty-two patients with unilateral VS were investigated using multiple auditory-vestibular function tests such as audiometry, sensory organization test (SOT), caloric test, cervical vestibular-evoked myogenic potential (cVEMP) test, and ocular VEMP (oVEMP) test.

RESULTS

In this study, 89% of patients with unilateral VS had mild to severe hearing loss on the involved side. All patients showed higher threshold values or no response in the cVEMP and oVEMP tests, which both exhibited a lower response rate on the affected side than on the unaffected side. Patients with a tumor size ≥ 30 mm had significantly lower equilibrium scores for condition 5 and condition 6 of the SOT, which were associated with vestibular dysfunction, higher rates of canal paresis in the caloric test, and lower response rates in the cVEMP and oVEMP tests on the affected sides, compared with the results of patients with a tumor size ≤ 14 mm and patients with a tumor size of 15-29 mm.

CONCLUSIONS

A diameter > 30 mm may be the critical threshold at which vestibular function is affected and vestibular compensation is interfered with by a VS tumor. Functional performance of the vestibular system can help clinicians predict the size of a tumor and provide a basis for the development of treatment protocols.

A missing piece? Neuropsychiatric functioning in untreated patients with tumors within the cerebellopontine angle

PURPOSE

To date, little is known about neuropsychiatric symptoms in patients with tumors within the cerebellopontine angle (CPA). These, however, might be of clinical relevance. Aim of this study was thus to assess possible impairment in cognition, elevation in mood symptoms, and fatigue in this specific patient group.

METHODS

Forty-five patients with an untreated CPA tumor (27 vestibularis schwannoma, 18 meningioma) were tested within a cross-sectional observational study in a single institution prior to neurosurgical treatment. Patients were administered a multifaceted battery comprising of widely-used tests for assessment of neuropsychiatric functioning.

RESULTS

The majority of the included patients (69%) showed neurocognitive impairment, most frequently in the areas of attention and visuo-motor speed (e.g., alertness) (62%) as well as visuo-construction (44%). Impaired structural integrity of the brain stem was accompanied by more serious neurocognitive deficits. About one-third of the sample reported clinically relevant depression and/or anxiety and an even higher proportion (48%) described high levels of fatigue. Cognitive and affective symptoms as well as fatigue contributed significantly to patients' Quality of Life, indicating the clinical relevance of neuropsychiatric symptoms in patients with CPA tumors.

CONCLUSIONS

Although patients with untreated CPA tumors often suffer from devastating and prominent physical symptoms, neuropsychiatric problems are also frequent. Including these aspects in the routine clinical assessment and initiating treatment accordingly might thus improve clinical management of the patients and improve Quality of Life.

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.

Dynamical analysis of balance in vestibular schwannoma patients

The analysis of the complexity of postural fluctuations is a recent method for assessing postural control. Complexity relates to the irregularity of the center of pressure time series and characterizes the ability of postural control to meet a changing environment. In our study, we used the sample entropy (SampEn) parameter to evaluate the complexity of postural sway velocity time series in patients with vestibular schwannoma (n=19) compared to healthy controls (n=20), using the sensory organization test. Patients performed postural assessments three days before surgical ablation of the tumor, then three times after surgery, at eight, thirty, and ninety days. The control group underwent posturographic tests only once. Our results demonstrated that SampEn values distinguished both groups before surgery only in postural tasks where vestibular afferences significantly contribute to maintaining balance. We also found an immediate decrease of complexity after the surgical resection of the tumor. Our results are in line with the theory of complexity loss of physiological systems stating that reducing the number of their structural components or altering their coupling leads to a decrease in complexity. Finally, our findings showed that progressive restoration of complexity over time was such that no difference was found between the two groups ninety days after surgery, due to the implementation of central adaptive mechanisms and the substitution by other sensory afferences. Thus, the SampEn parameter can highlight the postural effects of vestibular pathology, and complexity analysis appears to be a valuable tool for investigating the temporal structure of CoP time series.

Prediction of Balance Compensation After Vestibular Schwannoma Surgery

Background Balance compensation after vestibular schwannoma (VS) surgery is under the influence of specific preoperative patient and tumor characteristics. Objective To prospectively identify potential prognostic factors for balance recovery, we compared the respective influence of these preoperative characteristics on balance compensation after VS surgery. Methods In 50 patients scheduled for VS surgical ablation, we measured postural control before surgery (BS), 8 (AS8) days after, and 90 (AS90) days after surgery. Based on factors found previously in the literature, we evaluated age, body mass index and preoperative physical activity (PA), tumor grade, vestibular status, and preference for visual cues to control balance as potential prognostic factors using stepwise multiple regression models. Results An asymmetric vestibular function was the sole significant explanatory factor for impaired balance performance BS, whereas the preoperative PA alone significantly contributed to higher performance at AS8. An evaluation of patients' balance recovery over time showed that PA and vestibular status were the 2 significant predictive factors for short-term postural compensation (BS to AS8), whereas none of these preoperative factors was significantly predictive for medium-term postoperative postural recovery (AS8 to AS90). Conclusions We identified specific preoperative patient and vestibular function characteristics that may predict postoperative balance recovery after VS surgery. Better preoperative characterization of these factors in each patient could inform more personalized presurgical and postsurgical management, leading to a better, more rapid balance recovery, earlier return to normal daily activities and work, improved quality of life, and reduced medical and societal costs.