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Background and Purpose: A variant of benign paroxysmal positional vertigo (BPPV) involves the subjective report of vertigo without the coinciding nystagmus. This presentation includes truncal retropulsion when sitting up from the ipsilesional provocative test (ie, Dix-Hallpike), which we term type 2 BPPV. The primary objective of this study is to prospectively determine the prevalence and describe the clinical course of type 2 BPPV. We offer a theoretical explanation for the absence of nystagmus. Methods: Prospective, observational study carried out in 2 tertiary hospitals. One hundred eighty patients (134 women, 46 men) met the inclusion criteria and were included between January 10, 2018, and October 30, 2019. Efficacy of physical therapy maneuvers was determined at 1-week follow-up. Three-dimensional reconstructions of the planes of the semicircular canal cupula from histological preparations are offered as evidence for the theoretical explanation. Results: One-third of the patients met the criteria for type 2 BPPV; the remainder had typical posterior or horizontal semicircular canal involvement. Symptoms from type 2 BPPV were longer in duration yet responded favorably to physical therapy maneuvers. Upon repeat testing, 19 patients treated for posterior canalithiasis developed a slight, persistent positional downbeat nystagmus in the Dix-Hallpike position that we propose as evidence the otoconia entered the short arm of the posterior semicircular canal. Discussion and Conclusions: Our data and 3-dimensional rendering suggest the report of vertigo, yet absent nystagmus in type 2 BPPV is from otoconia aligning with the gravitoinertial vector during provocative testing that precludes cupular stimulation. Type 2 BPPV appears to be a common and treatable form of vertigo. Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A372). [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Background and Purpose: A crossover, double-blinded randomized controlled trial to investigate once-daily incremental vestibulo-ocular reflex (VOR) adaptation (IVA) training over 2 years in people with stable and chronic peripheral vestibular hypofunction. Methods: Twenty-one patients with peripheral vestibular hypofunction were randomly assigned to intervention-then-control (n = 12) or control-then-intervention (n = 9) groups. The task consisted of either x1 (control) or IVA training, once daily every day for 15 minutes over 6-months, followed by a 6-month washout, then repeated for arm 2 of the crossover. Primary outcome : vestibulo-ocular reflex gain. Secondary outcomes : compensatory saccades, dynamic visual acuity, static balance, gait, and subjective symptoms. Multiple imputation was used for missing data. Between-group differences were analyzed using a linear mixed model with repeated measures. Results: On average patients trained once daily 4 days per week. IVA training resulted in significantly larger VOR gain increase (active: 20.6% ± 12.08%, P = 0.006; passive: 30.6% ± 25.45%, P = 0.016) compared with x1 training (active: −2.4% ± 12.88%, P = 0.99; passive: −0.6% ± 15.31%, P = 0.68) (P < 0.001). The increased IVA gain did not significantly reduce with approximately 27% persisting over the washout period. x1 training resulted in greater reduction of compensatory saccade latency (P = 0.04) and increase in amplitude (P = 0.02) compared with IVA training. There was no difference between groups in gait and balance measures; however, only the IVA group had improved total Dizziness Handicap Inventory (P = 0.006). Discussion and Conclusions: Our results suggest IVA improves VOR gain and reduces perception of disability more than conventional x1 training. We suggest at least 4 weeks of once-daily 4 days-per-week IVA training should be part of a comprehensive vestibular rehabilitation program. Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A356). [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Background and Purpose: This was a double-blinded randomized controlled study to investigate the effects of once-daily incremental vestibulo-ocular reflex (VOR) training over 1 week in people with chronic peripheral vestibular hypofunction. Methods: A total of 24 patients with peripheral vestibular hypofunction were randomly assigned to intervention (n = 13) or control (n = 11) groups. Training consisted of either x1 (control) or incremental VOR adaptation exercises, delivered once daily for 15 minutes over 4 days in 1 week. Primary outcome : VOR gain with video-oculography. Secondary outcomes : Compensatory saccades measured using scleral search coils, dynamic visual acuity, static balance, gait, and subjective symptoms. Between-group differences were analyzed with a linear mixed-model with repeated measures. Results: There was a difference in the VOR gain increase between groups (P < 0.05). The incremental training group gain increased during active (13.4% ± 16.3%) and passive (12.1% ± 19.9%) head impulse testing (P < 0.02), whereas it did not for the control group (P = 0.59). The control group had reduced compensatory saccade latency (P < 0.02). Both groups had similarly improved dynamic visual acuity scores (P < 0.05). Both groups had improved dynamic gait index scores (P < 0.002); however, only the incremental group had improved scores for the 2 walks involving head oscillations at approximately 2 Hz (horizontal: P < 0.05; vertical: P < 0.02), increased gait speed (P < 0.02), and step length (P < 0.01) during normal gait, and improved total Dizziness Handicap Inventory (P < 0.05). Conclusions: Our results suggest incremental VOR adaptation significantly improves gain, gait with head rotation, balance during gait, and symptoms in patients with chronic peripheral vestibular hypofunction more so than conventional x1 gaze-stabilizing exercises. Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A336). [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Background and Purpose: Convergence of the eyes during head rotation increases the gain (eye velocity/head velocity) of the vestibulo-ocular reflex (VOR). We sought to know whether convergence would increase the VOR gain (mean + SD) in unilateral vestibular hypofunction (UVH). Methods: Vestibulo-ocular reflex gain during ipsi- and contralesional horizontal head rotation at near (15 cm) and far (150 cm) targets was measured in 22 subjects with UVH and 12 healthy controls. Retinal slip was estimated (retinal slip index [RSI]) as the difference between ideal VOR gain (no retinal slip) and the actual VOR gain. Results: Convergence did not significantly enhance VOR gain for ipsilesional rotation (mean difference, 0.04; 95% confidence interval [CI], −0.01 to 0.09), near viewing (0.77 ± 0.34) versus far viewing (0.72 ± 0.29), yet the VOR gain during contralesional rotation was greater for near viewing (1.20 ± 0.23) than for far viewing (0.97 ± 0.21; mean difference, 0.23; 95% CI, 0.13-0.32). In the 36% of subjects with recovery of their ipsilesional VOR gain, the vergence effect trended to recover (far VOR gain: 1.06 ± 0.17 vs near VOR gain 1.16 ± 0.21; mean difference, 0.10; 95% CI, −0.02 to 0.22). Ipsilesional head rotation induced greater retinal slip for near (RSI = 0.90 ± 0.34) targets than for far targets (RSI = 0.35 ± 0.29; mean difference, 0.56; 95% CI, 0.51-0.61). Discussion and Conclusions: The convergence-mediated VOR gain enhancement is preserved during contralesional but impaired during ipsilesional head rotation. Recovery of ipsilesional passive VOR gain does not equate to restored convergence enhancement, although it did increase ∼10%. These data suggest head motion viewing near targets will increase retinal slip, which warrants consideration as a gaze stability exercise for subjects with UVH. Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A325). [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Background and Purpose: Both central (eg, brain stem, cerebellum) and peripheral (eg, vestibular, fourth cranial nerve palsy) etiologies can cause a vertical misalignment between the eyes with a resultant vertical diplopia. A vertical binocular misalignment may be due to a skew deviation, which is a nonparalytic vertical ocular misalignment due to roll plane imbalance in the graviceptive pathways. A skew deviation may be 1 component of the ocular tilt reaction. The purposes of this article are (1) to understand the pathophysiology of a skew deviation/ocular tilt reaction and (2) to be familiar with the examination techniques used to diagnose a skew and to differentiate it from mimics such as a fourth cranial nerve palsy. Summary of Key Points: The presence of a skew deviation usually indicates a brain stem or cerebellar localization. Vertical ocular misalignment is easily missed when observing the resting eye position alone. Recommendations for Clinical Practice: Physical therapists treating patients with vestibular pathology from central or peripheral causes should screen for vertical binocular disorders. [ABSTRACT FROM AUTHOR]

Background and Purpose: Unilateral incremental vestibulo-ocular reflex (VOR) adaptation (IVA) increases the VOR gain (= eye/head velocity) for head rotations to one side by ∼10%. Prior IVA studies involved setting the initial VOR training gain demand at the subject's starting value (= 1 in a healthy subject), with the gain preset to increment by 0.1 every 90 seconds over 15 minutes, defined as Static IVA. We determined whether a dynamically calculated gain demand (= "actual gain" + 0.1) would result in greater adaptation, defined as Dynamic IVA. Methods: Using a hybrid video-oculography and StableEyes training system, we measured the active (self-generated head impulse) and passive (imposed, unpredictable head impulse) VOR gain in 8 healthy subjects before and after 15 minutes of Static (ie, preset) and Dynamic IVA training consisting of active, leftward and rightward, horizontal head impulses (peak amplitude 15°, peak velocity 150°/s, and peak acceleration 3000°/s2). We also measured the active VOR gain during training. Results: The VOR gain increase toward the adapting side was ∼5% larger after Dynamic compared with Static IVA training (Dynamic: 13.9% ± 5.2%, Static: 9.4% ± 7.3%; P < 0.05). Discussion and Conclusions: Our data suggest that 17°/s retinal image slip (due to the 0.1 gain difference between demand and actual gain) is sufficient to drive robust VOR adaptation. The implications for vestibular rehabilitation are that Dynamic IVA training not only produces better VOR adaptation but also allows more flexible training, for example, training can be spread over several smaller time blocks, without undoing prior adaptation. [ABSTRACT FROM AUTHOR]

Background and Purpose: Deciphering the cause for a persistent, direction-changing geotropic nystagmus can be difficult. Migraine and light cupula are two possible causes, though can be confused with benign paroxysmal positional vertigo (BPPV) affecting the horizontal semicircular canal. In migraine, the persistent geotropic nystagmus tends to be slow; in light cupula, the nystagmus has been illustrated to beat in the direction opposite that of prone positioning. Case Description: Here we describe a patient with initial occurrence then recurrence of a high velocity (≥30 deg/sec), persistent direction-changing geotropic nystagmus and vertigo with an intensity variable based on head position, which was difficult to manage. This patient did not have migraine. The case presented uniquely as it was unlikely due to canalithiasis of the horizontal semicircular canal yet the presentation was not clearly related to the light cupula phenomena either. Intervention: In this case, the physical therapist attempted to use the barbeque roll canalith repositioning maneuver (CRM) even though the direction-changing geotropic nystagmus was persistent. The nystagmus did not resolve during the clinic visit. Outcomes and Discussion: The persistent, high velocity geotropic nystagmus resolved within 1 week, however, this resolution was likely spontaneous and not due to the CRM intervention. Our case suggests that physical therapists assessing persistent geotropic nystagmus should wait long enough for the nystagmus to stop (~2 minutes), test for fatigue by repeating the positional nystagmus tests, incorporate a head flexion component as part of the positional testing, and attempt to identify a null point. [ABSTRACT FROM AUTHOR]

The article reports on research which was conducted to develop and validate a scale to grade near-fall and fall events on the basis of their severity represented by the use of health care resources which could be used to standardize fall reporting in clinical and research settings. Researchers were able to develop a scale called the illustrated 4-point Hopkins Falls Grading Scale and found it to be valid and reliable.

Objective: To establish intrarater and interrater reliability of the Vestibular Autorotation Test (VAT) (Western Systems Research Inc., Pasadena, CA) in a clinical sample of individuals reporting dizziness. Study Design: Ninety-eight patients with reports of dizziness referred for vestibular function testing performed repeated trials of horizontal VAT. A subsample of 49 individuals repeated the test for a second rater. Results: Approximately 66% of subjects were unable to meet the performance criterion of six consecutive trials where data was displayed at frequencies ≥3.9 Hz with coherence values held constant trial to trial. There was a good level of intrarater reliability for gain independent of the effects of practice (intraclass correlation coefficient [ICC] = 0.78 [95% confidence interval [CI]: 0.69-0.87] to 0.95 [(95% CI: 0.93-0.97]). A significant difference in intrarater reliability was found when the first three trials were compared to the last three trials for phase (ICC ranged from 0.04 [95% CI: 0.00-0.31] to 0.96 [95% CI: 0.93-0.97]) and asymmetry (ICC ranged from 0.39 [95% CI: 0.17-0.56] to 0.73 [95% CI: 0.32-0.81]) particularly at frequencies ≥4.3 Hz. Interrater reliability was good to excellent across all variables at frequencies ≤3.9 Hz. Conclusions: Many patients had difficulty performing the VAT. The reliability estimates for phase and asymmetry, but not gain, were significantly affected by practice. Careful attention to patient preparation, instruction, and test monitoring including sufficient patient practice before data collection are likely to be critical factors to ensure quality data. [ABSTRACT FROM AUTHOR]

Background and Purpose: Vestibular rehabilitation strategies including gaze stabilization exercises have been shown to increase gain of the angular vestibulo-ocular reflex (aVOR) using a retinal slip error signal (ES). The identification of additional ESs capable of promoting substitution strategies or aVOR adaptation is an important goal in the management of vestibular hypofunction. Position ESs have been shown to increase both aVOR gain and recruitment of compensatory saccades (CSs) during passive whole body rotation. This may be a useful compensatory strategy for gaze instability during active head rotation as well. In vestibular rehabilitation, the imaginary target exercise is often prescribed to improve gaze stability. This exercise uses a position ES; however, the mechanism for its effect has not been investigated. We compared aVOR gain adaptation using 2 types of small position ES: constant versus incremental. Methods: Ten subjects with normal vestibular function were assessed with unpredictable and active head rotations before and after a 20-minute training session. Subjects performed 9 epochs of 40 active, high-velocity head impulses using a position ES stimulus to increase aVOR gain. Results: Five subjects demonstrated significant aVOR gain increases with the constant-position ES (mean, 2%; range, -18% to 12%) compared with another 5 subjects showing significant aVOR gain increases to the incremental-position ES (mean, 3.7%; range, -2% to 22.6%). There was no difference in aVOR gain adaptation or CS recruitment between the 2 paradigms. Discussion and Conclusion: These findings suggest that some subjects can increase their aVOR gain in response to high-velocity active head movement training using a position ES. The primary mechanism for this seems to be aVOR gain adaptation because CS use was not modified. The overall low change in aVOR gain adaptation with position ES suggests that retinal slip is a more powerful aVOR gain modifier. [ABSTRACT FROM AUTHOR]

The article discusses various reports on vestibular rehabilitation published within the issue including one about the use of vibrotactors in neurologic physical therapy, another on the treatment effectiveness in patients with mild traumatic brain injury related to blunt and one on the differences among treatment paradigms.

Objective: To generate normative values for performance on the modified Romberg Test of Standing Balance on Firm and Compliant Support Surfaces stratified by age, sex, and race/ethnicity and to determine fall risk associated with different levels of performance., Study Design: National cross-sectional survey., Setting: Ambulatory examination centers., Patients: U.S. adults 40 years and older who participated in the 2001-2004 National Health and Nutrition Examination Survey (n = 5,086)., Interventions: Time to failure on the modified Romberg Test of Standing Balance on Firm and Compliant Support Surfaces., Main Outcome Measures: History of falling in the previous 12 months., Results: We observed that the time to failure decreased with increasing age across all sex and race/ethnicity categories. We found that once individuals went below a time to failure of 20 seconds, there was a significant greater than 3-fold increase in the odds of falling. In general, participants crossed the 20-second threshold at the age of 60 to 69 years., Conclusion: We established nationally representative normative values for performance on the modified Romberg test and noted differences in the rates of change across demographic groups. In addition, we demonstrated the fall risk associated with different levels of performance. These data will aid the clinician in interpreting and risk stratifying their patient's performance on this postural test.

Objective: To prospectively assay the vestibular and oculomotor systems of blast-exposed service members with traumatic brain injury (TBI)., Study Design: Prospective, nonblinded, nonrandomized descriptive study., Setting: Tertiary care facility (Department of Defense Medical Center)., Patients: Twenty-four service members recovering from blast-related TBI sustained in Iraq or Afghanistan., Interventions: Focused history and physical, videonystagmography (VNG), rotational chair, cervical vestibular-evoked myogenic potentials, computerized dynamic posturography, and self-report measures., Results: Vestibular testing confirms a greater incidence of vestibular and oculomotor dysfunction in symptomatic (vestibular-like dizziness) personnel with blast-related TBI relative to asymptomatic group members. VNG in the symptomatic group revealed abnormal nystagmus or oculomotor findings in 6 of 12 subjects tested. Similarly, rotational chair testing in this group revealed evidence of both peripheral (4/12) and central (2/12) vestibular pathology. By contrast, the asymptomatic group revealed less vestibular impairment with 1 of 10 rotational chair abnormalities. The asymptomatic group was further characterized by fewer aberrant nystagmus findings (4/12 abnormal VNGs). Computerized dynamic posturography testing revealed no significant differences between groups. Self-report measures demonstrated differences between groups., Conclusion: Vestibular function testing confirms a greater incidence of peripheral vestibular hypofunction in dizzy service members with blast-related TBI relative to those who are asymptomatic. Additionally, oculomotor abnormalities and/or nystagmus consistent with central involvement were present in 10 of the 24 study participants tested. The precise cause of these findings remains unknown.

Objective: Patients with diabetes are at increased risk both for falls and for vestibular dysfunction, a known risk factor for falls. Our aims were 1) to further characterize the vestibular dysfunction present in patients with diabetes and 2) to evaluate for an independent effect of vestibular dysfunction on fall risk among patients with diabetes., Study Design: National cross-sectional survey., Setting: Ambulatory examination centers., Patients: Adults from the United States aged 40 years and older who participated in the 2001-2004 National Health and Nutrition Examination Survey (n = 5,86)., Interventions: Diagnosis of diabetes, peripheral neuropathy, and retinopathy., Main Outcome Measures: Vestibular function measured by the modified Romberg Test of Standing Balance on Firm and Compliant Support Surfaces and history of falling in the previous 12 months., Results: We observed a higher prevalence of vestibular dysfunction in patients with diabetes with longer duration of disease, greater serum hemoglobin A1c levels and other diabetes-related complications, suggestive of a dose-response relationship between diabetes mellitus severity and vestibular dysfunction. We also noted that vestibular dysfunction independently increased the odds of falling more than 2-fold among patients with diabetes (odds ratio, 2.3; 95% confidence interval, 1.1-5.1), even after adjusting for peripheral neuropathy and retinopathy. Moreover, we found that including vestibular dysfunction, peripheral neuropathy, and retinopathy in multivariate models eliminated the significant association between diabetes and fall risk., Conclusion: Vestibular dysfunction may represent a newly recognized diabetes-related complication, which acts as a mediator of the effect of diabetes mellitus on fall risk.

Objective: Vestibular adaptation exercises have been shown to improve gaze stability during active head rotation in individuals with vestibular hypofunction. Little is known, however, of the types of eye movements used during passive head rotation and their effect on gaze stability in individuals with vestibular hypofunction. The primary purpose of this study was to determine differences in oculomotor strategies and their effect on stabilizing gaze during ipsilesional passive and active head rotations in vestibular hypofunction., Patients: Subjects with unilateral (n = 4) and bilateral (n = 3) vestibular hypofunction and healthy subjects (n = 4) based on bithermal caloric and rotational chair testing., Intervention: Diagnostic., Main Outcome Measure: Head and eye velocity and position data measured with scleral search coil., Results: Subjects with unilateral and bilateral vestibular hypofunction generated 3 types of gaze-stabilizing eye movements with ipsilesional head impulses: slow vestibular ocular reflex, compensatory, and corrective saccades. The types of eye movements generated during active and passive head impulses were highly individualized. Gaze position error was reduced when compensatory saccades were recruited as part of the gaze-stabilizing strategy., Conclusion: Rehabilitation for individuals with vestibular hypofunction should identify individuals' unique gaze stability preferences and attempt to facilitate compensatory saccades.