Vertigo in Vestibular Schwannoma Patients Due to Other Pathologies

Paroxysmal Positional Nystagmus in Acoustic Neuroma Patients

The association between acoustic neuroma and positional vertigo with paroxysmal positional nystagmus is relatively rare, but, when present, it certainly represents a challenge for the otoneurologist. There are few reports in the literature on this particular issue, and some questions are still unanswered, particularly regarding the characteristics of positional nystagmus that may distinguish between a true benign paroxysmal vertigo and a positional nystagmus associated with the tumor. We present the videonystagmographic patterns of seven patients with acoustic tumor who had paroxysmal positional nystagmus and analyzed its features. A concomitant true benign paroxysmal positional vertigo may be present during the follow-up of a non-treated patient, as the paroxysmal positional vertigo may be the first symptom of the tumor, and it may show characteristics that are very similar to a posterior semicircular canal canalolithiasis or a horizontal canal "heavy or light cupula". The possible mechanisms are discussed.

Endolymphatic Hydrops in the Setting of Vestibular Schwannoma: A Temporal Bone Study

HYPOTHESIS

Vestibular schwannoma (VS) may be associated with endolymphatic hydrops (EH). EH may account for symptomatology in a subset of patients with VS.

BACKGROUND

Presenting symptoms of VS and EH overlap, and MRI evaluation of the membranous labyrinth in some patients with VS demonstrates EH. The aim of the current study is to evaluate whether EH is present in temporal bones of patients with VS.

METHODS

The NIDCD and House Temporal Bone Laboratory at UCLA Eccles database was queried for the diagnosis of "acoustic neuroma." Exclusion criteria included concomitant ear disease and surgery. Temporal bones were analyzed for EH of the basal, middle, and apical turns and vestibule. Premortem audiometric and clinical data were gathered.

RESULTS

Of 43 human temporal bones with VS, 6 met inclusion criteria. All temporal bones demonstrated VS that was undisturbed by surgery. Three of six demonstrated EH of at least one cochlear turn as well as vestibular hydrops. Three patients had severe to profound hearing loss. One patient carried a diagnosis of Menière's disease.

CONCLUSIONS

EH is demonstrated in the setting of VS in human temporal bones. EH may be one mechanism of hearing loss and dizziness in patients with VS.

PROFESSIONAL PRACTICE GAP AND EDUCATIONAL NEED

The underlying mechanisms of symptoms of VS may be multifactorial. The association of EH in some patients with VS would modify our clinical approach to management.

LEARNING OBJECTIVE

To discover if EH may be associated with VS.

DESIRED RESULT

To broaden understanding of pathophysiologic mechanisms in patients with VS.

LEVEL OF EVIDENCE

Level IVIRB Approved: UCLA IRB No. 10-001449.

Vestibular Schwannoma Presenting as Acute Vertigo Mimicking Vestibular Neuritis

Vestibular schwannoma (VS) is commonly accompanied by hearing loss, tinnitus, and dizziness and tends to be chronically progressive in nature. We report a case of VS presenting as left vestibular neuritis (VN) in a previously healthy 57-year-old patient. Right-beating horizontal-torsional spontaneous nystagmus was observed, and the bedside head impulse test revealed a left catch-up saccade. The bithermal caloric test showed left canal paresis, and pure-tone audiometry revealed an average threshold of 22.5 dB bilaterally. Brain magnetic resonance imaging (MRI) demonstrated a 0.7-cm enhancing mass in the left internal auditory canal, consistent with VS. The patient was administered with high-dose systemic corticosteroids and vestibular suppressants with antiemetic, which relieved acute vertigo. Although dizziness in VS is chronically progressive in nature, VS may present as an acute vestibular syndrome that mimics VN. VS should be considered a potential cause of acute vestibular syndrome, and thorough neurological examination with MRI may be helpful for accurate diagnosis.

Impact of Social Determinants of Health on Stereotactic Radiotherapy for Vestibular Schwannoma

OBJECTIVES/HYPOTHESIS

Linear accelerator (LINAC) and Gamma Knife (GK) are common stereotactic radiation therapies for treating vestibular schwannoma (VS). There is currently limited literature examining specific demographic and socioeconomic factors, which influence the type of stereotactic radiation therapy a patient with VS receives.

STUDY DESIGN

Retrospective database review.

METHODS

The National Cancer Database was queried for cases of VS between 2004 and 2016. Patient demographic characteristics were compared using chi-squared and t-tests between GK and LINAC treated groups. Multivariate regression analysis was performed to assess predictors of stereotactic radiation therapy received.

RESULTS

Of the 6,208 included patients, 5,306 (85.5%) received GK and 902 (14.5%) received LINAC. The mean age of GK patients was significantly lower than that of LINAC patients (58.0 vs. 59.7, P < .001). Individuals treated with GK had greater proportions of private insurance (P < .001) and incomes greater than $63,332 (P = .003). A greater proportion of GK patients were treated in academic centers (P < .001), in high-volume facilities (P < .001), in metropolitan areas (P < .001), and in the Northeastern United States (P < .001). On multivariate logistic regression analysis, region, metropolitan area, facility type, tumor size, and distance traveled by patients independently predict receipt of GK versus LINAC.

CONCLUSION

Differences in patient demographics and other social determinants of health influence choice of GK versus LINAC therapy for VS patients. Future studies focused on addressing barriers to care, which may influence postprocedural quality of life and clinical outcomes associated with these two treatments are necessary to better understand the impact of these social differences.

LEVEL OF EVIDENCE

4 Laryngoscope, 2022.

Outcomes of Initial Observation Versus Upfront Microsurgical Resection for Small to Medium-sized Vestibular Schwannomas

OBJECTIVE

To assess postoperative outcomes and predictive factors of patients observed prior to microsurgery and those undergoing upfront resection for small and medium-sized VS.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary referral center.

PATIENTS

VS patients who had microsurgery from 2003 to 2018 for tumors up to 2.5 cm.

MAIN OUTCOME MEASURES

Postoperative outcomes including facial nerve function and interventions, complications, extent of resection, and salvage therapy.

RESULTS

Of 220 patients, 120 were initially observed, and 100 pursued upfront microsurgery. There was no significant association between initial observation and upfront microsurgery for postoperative facial nerve function at 2 to 3 weeks (p = 0.18) or 12 months (p = 0.5), facial nerve intervention (p = 0.5), major/minor complications (p = 0.48/0.63), recurrence (p = 0.8), subtotal resection (p = 0.6), or salvage therapy (p = 0.9). Time from initial consultation to surgery did not significantly impact outcomes. Intrameatal tumors were more likely to be observed (odds ratios [OR] 2.93; 95% CI 1.53-5.63; p = 0.001). Patients with larger tumor volume (OR 0.52; 95% CI 0.37-0.72; p < 0.0001), brainstem compression (OR 0.28; 95% CI 0.09-0.91; p = 0.03), or higher PTA were less likely to undergo observation (OR 0.99; 95% CI 0.97-0.997; p = 0.02). On multivariable analysis, predictive factors for observation were smaller tumor volume (OR 0.53; 95% CI 0.38-0.75; p < 0.001), lower PTA (OR 0.99; 95% CI 0.98-0.999; p = 0.04), and diabetes (OR 2.54; 95% CI 0.95-6.83; p = 0.06).

CONCLUSIONS

Patients with worse hearing, larger tumor volume, and brainstem compression were more likely to pursue upfront microsurgery. A watchful waiting period does not appear to worsen outcomes and can be considered for patients with better hearing and smaller tumors without brainstem compression.

Contralesional High-Acceleration Vestibulo-Ocular Reflex Function in Vestibular Schwannoma

Impairment of ipsilesional vestibulo-ocular reflex (VOR) function is well described in vestibular schwannoma (VS) and a correlation between gain of the VOR and tumor size has been suggested. Bilateral VOR impairment may also occur in VS patients, but its mechanisms are poorly understood. We sought to explore the effect of unilateral VS on ipsilesional and contralesional high-acceleration VOR function using video head impulse testing, and evaluate potential factors responsible for contralesional VOR impairment.

MATERIALS AND METHODS

Chart review in tertiary referral center of patients with unilateral VS, who completed neurotological examination and vestibular function testing.

RESULTS

One hundred one patients (mean age 57.4 yrs) were included. Maximal tumor diameter ranged from 0.3 to 5.0 cm. Forty one patients had evidence of brainstem compression from VS on magnetic resonance imaging (MRI). Ipsilesional and contralesional VOR impairment was present in 81 (80%) and 44 (43%) patients, respectively. Bilateral VOR impairment was seen in 42 (42%) patients. Bilateral VOR impairment correlated with tumor size. Presence of brainstem compression was associated with reduced ipsilesional VOR gain, but not contralesional VOR gain.

Vestibular neuronitis in a vestibular schwannoma patient

This is a unique presentation of an acute vestibular syndrome (AVS) caused by vestibular neuronitis (VN) of a vestibular nerve (CNVIII) already affected by vestibular schwannoma (VS). A 48-year-old patient, formerly diagnosed with an intracanalicular VS, presented with AVS. The patient underwent clinical and neurotological examination including video Head Impulse Test and a 4-hour delayed-enhanced 3D-FLAIR MRI using intravenous gadolinium. Clinical and neurotological findings were consistent with VN of the CNVIII formerly diagnosed with VS. A 4-hour delayed-enhanced 3D-FLAIR MRI showed significant enhancement of the labyrinth also indicating VN of the same nerve affected by VS. Pragmatic corticosteroid therapy and vestibular exercises were applied resulting in satisfactory recovery of the patient. As vestibular symptoms are common in VS patients, investigating another cause of dizziness and vertigo in VS patients can be marginalized. Nevertheless, VS presenting as AVS is very unusual. VN should not be overlooked as a possible cause of acute vertigo in a patient previously diagnosed with VS.

Comparison of test results from two separate video head impulse test systems in a cohort of patients diagnosed with a unilateral vestibular schwannoma

PURPOSE

Video head impulse testing (vHIT) is a relatively new technology enabling evaluation of vestibular function. The aim of this study was to compare the test results from two separate vHIT systems in a group of patients diagnosed with a unilateral vestibular schwannoma (VS) with regards to sensitivity, specificity and inter-examiner differences.

METHODS

Forty-two patients were examined with two separate vHIT systems: EyeSeeCam^® (system A) and ICS Impulse^® (system B), by one of two examiners. All six semicircular canals (SCCs) were tested under standardized conditions, and strict criteria were set up for post-test interpretation.

RESULTS

With the majority of test parameters, the two test systems were in agreement. Vestibular deficits were found in 40.5% (system A) to 45% (system B) of patients with a VS on the tested side; corresponding to a positive predictive value (PPV) of 86.4% (system B) to 94.4% (system A). The specificity was 97.6% for system A and 92.9% for system B. An overall agreement between the two vHIT systems measured as kappa was computed to be 0.61. There were no significant inter-examiner differences. When testing the vertical SCCs, a tendency of too high mean gain values was seen with system A but not with system B.

CONCLUSION

In patients with unilateral VS, vHIT is a test with moderate sensitivity and high specificity in regard to identification of a vestibular deficit. There were no significant differences in test results between the two vHIT systems.

Vestibular Migraine Following Radiosurgery for Vestibular Schwannoma

Vestibular schwannoma (VS) is associated with dizziness and vertigo during all stages of treatment. This report describes a patient who presented with a one-year history of intermittent motion sickness, dizziness, headache, imbalance, and nausea. MRI showed a right-side VS in the cerebellopontine angle and internal auditory canal. The patient elected to undergo Gamma Knife radiosurgery for treatment. Within two to three months, she continued to experience recurring dizziness, vertigo, neck stiffness, and head pressure. She was referred for neurotology evaluation, which led to a diagnosis of vestibular migraine (VM). Her vestibular reflexes were intact. Subsequently, she was treated with diet modification and low-dose venlafaxine. She reported dramatically improved dizziness and vertigo symptoms at six-month follow-up. VM is a very common cause of dizziness that should always be included in the differential diagnosis, even in VS patients.