Effect of timing delay between visual and vestibular stimuli on heading perception.

Heading direction is perceived based on visual and inertial cues. The current study examined the effect of their relative timing on the ability of offset visual headings to influence inertial perception. Seven healthy human subjects experienced 2 s of translation along a heading of 0°, ±35°, ±70°, ±105°, or ±140°. These inertial headings were paired with 2-s duration visual headings that were presented at relative offsets of 0°, ±30°, ±60°, ±90°, or ±120°. The visual stimuli were also presented at 17 temporal delays ranging from -500 ms (visual lead) to 2,000 ms (visual delay) relative to the inertial stimulus. After each stimulus, subjects reported the direction of the inertial stimulus using a dial. The bias of the inertial heading toward the visual heading was robust at ±250 ms when examined across subjects during this period: 8.0° ± 0.5° with a 30° offset, 12.2° ± 0.5° with a 60° offset, 11.7° ± 0.6° with a 90° offset, and 9.8° ± 0.7° with a 120° offset (mean bias toward visual ± SE). The mean bias was much diminished with temporal misalignments of ±500 ms, and there was no longer any visual influence on the inertial heading when the visual stimulus was delayed by 1,000 ms or more. Although the amount of bias varied between subjects, the effect of delay was similar.NEW & NOTEWORTHY The effect of timing on visual-inertial integration on heading perception has not been previously examined. This study finds that visual direction influence inertial heading perception when timing differences are within 250 ms. This suggests visual-inertial stimuli can be integrated over a wider range than reported for visual-auditory integration and may be due to the unique nature of inertial sensation, which can only sense acceleration while the visual system senses position but encodes velocity.

Rapid antibiotic susceptibility testing using resazurin bulk modified screen-printed electrochemical sensing platforms.

Urinary tract infections (UTIs) are one of the most common types of bacterial infection. UTIs can be associated with multidrug resistant bacteria and current methods of determining an effective antibiotic for UTIs can take up to 48 hours, which increases the chances of a negative prognosis for the patient. In this paper we report for the first time, the fabrication of resazurin bulk modified screen-printed macroelectrodes (R-SPEs) demonstrating them to be effective platforms for the electrochemical detection of antibiotic susceptibility in complicated UTIs. Using differential pulse voltammetry (DPV), resazurin was able to be detected down to 15.6 µM. R-SPEs were utilised to conduct antibiotic susceptibility testing (AST) of E. coli (ATCC® 25922) to the antibiotic gentamicin sulphate using DPV to detect the relative concentrations of resazurin between antibiotic treated bacteria, and bacteria without antibiotic treatment. Using R-SPEs, antibiotic susceptibility was determined after a total elapsed time of 90 minutes including the inoculation of the artificial urine, preincubation and testing time. The use of electrochemistry as a phenotypic means of identifying an effective antibiotic to treat a complicated UTI offers a rapid and accurate alternative to culture based methods for AST with R-SPEs offering an inexpensive and simpler alternative to other AST methods utilising electrochemical based approaches.

Common causation and offset effects in human visual-inertial heading direction integration.

Movement direction can be determined from a combination of visual and inertial cues. Visual motion (optic flow) can represent self-motion through a fixed environment or environmental motion relative to an observer. Simultaneous visual and inertial heading cues present the question of whether the cues have a common cause (i.e., should be integrated) or whether they should be considered independent. This was studied in eight healthy human subjects who experienced 12 visual and inertial headings in the horizontal plane divided in 30° increments. The headings were estimated in two unisensory and six multisensory trial blocks. Each unisensory block included 72 stimulus presentations, while each multisensory block included 144 stimulus presentations, including every possible combination of visual and inertial headings in random order. After each multisensory stimulus, subjects reported their perception of visual and inertial headings as congruous (i.e., having common causation) or not. In the multisensory trial blocks, subjects also reported visual or inertial heading direction (3 trial blocks for each). For aligned visual-inertial headings, the rate of common causation was higher during alignment in cardinal than noncardinal directions. When visual and inertial stimuli were separated by 30°, the rate of reported common causation remained >50%, but it decreased to 15% or less for separation of ≥90°. The inertial heading was biased toward the visual heading by 11-20° for separations of 30-120°. Thus there was sensory integration even in conditions without reported common causation. The visual heading was minimally influenced by inertial direction. When trials with common causation perception were compared with those without, inertial heading perception had a stronger bias toward visual stimulus direction.NEW & NOTEWORTHY Optic flow ambiguously represents self-motion or environmental motion. When these are in different directions, it is uncertain whether these are integrated into a common perception or not. This study looks at that issue by determining whether the two modalities are consistent and by measuring their perceived directions to get a degree of influence. The visual stimulus can have significant influence on the inertial stimulus even when they are perceived as inconsistent.

Superior Semicircular Canal Dehiscence Syndrome.

Superior canal dehiscence syndrome (SCDS) is a vestibular disorder caused by a pathologic third window into the labyrinth that can present with autophony, sound- or pressure-induced vertigo, and chronic disequilibrium among other vestibulocochlear symptoms. Careful history taking and examination in conjunction with appropriate diagnostic testing can accurately diagnose the syndrome. Key examination techniques include fixation-suppressed ocular motor examination investigating for sound- or pressure-induced eye movements in the plane of the semicircular canal. Audiometry, vestibular evoked myogenic potentials, and computed tomography confirm the diagnosis. Corrective surgical techniques can be curative, but many patients find their symptoms are not severe enough to undergo surgery. Although a primarily peripheral vestibular disorder, as first-line consultants for most dizziness complaints, neurologists will serve their patients well by understanding SCDS and its role in the differential diagnosis of vestibular disorders.

Effect of range of heading differences on human visual-inertial heading estimation.

Both visual and inertial cues are salient in heading determination. However, optic flow can ambiguously represent self-motion or environmental motion. It is unclear how visual and inertial heading cues are determined to have common cause and integrated vs perceived independently. In four experiments visual and inertial headings were presented simultaneously with ten subjects reporting visual or inertial headings in separate trial blocks. Experiment 1 examined inertial headings within 30° of straight-ahead and visual headings that were offset by up to 60°. Perception of the inertial heading was shifted in the direction of the visual stimulus by as much as 35° by the 60° offset, while perception of the visual stimulus remained largely uninfluenced. Experiment 2 used ± 140° range of inertial headings with up to 120° visual offset. This experiment found variable behavior between subjects with most perceiving the sensory stimuli to be shifted towards an intermediate heading but a few perceiving the headings independently. The visual and inertial headings influenced each other even at the largest offsets. Experiments 3 and 4 had similar inertial headings to experiments 1 and 2, respectively, except subjects reported environmental motion direction. Experiment 4 displayed similar perceptual influences as experiment 2, but in experiment 3 percepts were independent. Results suggested that perception of visual and inertial stimuli tend to be perceived as having common causation in most subjects with offsets up to 90° although with significant variation in perception between individuals. Limiting the range of inertial headings caused the visual heading to dominate the perception.

Effect of eye position during human visual-vestibular integration of heading perception.

Visual and inertial stimuli provide heading discrimination cues. Integration of these multisensory stimuli has been demonstrated to depend on their relative reliability. However, the reference frame of visual stimuli is eye centered while inertia is head centered, and it remains unclear how these are reconciled with combined stimuli. Seven human subjects completed a heading discrimination task consisting of a 2-s translation with a peak velocity of 16 cm/s. Eye position was varied between 0° and ±25° left/right. Experiments were done with inertial motion, visual motion, or a combined visual-inertial motion. Visual motion coherence varied between 35% and 100%. Subjects reported whether their perceived heading was left or right of the midline in a forced-choice task. With the inertial stimulus the eye position had an effect such that the point of subjective equality (PSE) shifted 4.6 ± 2.4° in the gaze direction. With the visual stimulus the PSE shift was 10.2 ± 2.2° opposite the gaze direction, consistent with retinotopic coordinates. Thus with eccentric eye positions the perceived inertial and visual headings were offset ~15°. During the visual-inertial conditions the PSE varied consistently with the relative reliability of these stimuli such that at low visual coherence the PSE was similar to that of the inertial stimulus and at high coherence it was closer to the visual stimulus. On average, the inertial stimulus was weighted near Bayesian ideal predictions, but there was significant deviation from ideal in individual subjects. These findings support visual and inertial cue integration occurring in independent coordinate systems.NEW & NOTEWORTHY In multiple cortical areas visual heading is represented in retinotopic coordinates while inertial heading is in body coordinates. It remains unclear whether multisensory integration occurs in a common coordinate system. The experiments address this using a multisensory integration task with eccentric gaze positions making the effect of coordinate systems clear. The results indicate that the coordinate systems remain separate to the perceptual level and that during the multisensory task the perception depends on relative stimulus reliability.

Perception of combined translation and rotation in the horizontal plane in humans.

Thresholds and biases of human motion perception were determined for yaw rotation and sway (left-right) and surge (fore-aft) translation, independently and in combination. Stimuli were 1 Hz sinusoid in acceleration with a peak velocity of 14°/s or cm/s. Test stimuli were adjusted based on prior responses, whereas the distracting stimulus was constant. Seventeen human subjects between the ages of 20 and 83 completed the experiments and were divided into 2 groups: younger and older than 50. Both sway and surge translation thresholds significantly increased when combined with yaw rotation. Rotation thresholds were not significantly increased by the presence of translation. The presence of a yaw distractor significantly biased perception of sway translation, such that during 14°/s leftward rotation, the point of subjective equality (PSE) occurred with sway of 3.2 ± 0.7 (mean ± SE) cm/s to the right. Likewise, during 14°/s rightward motion, the PSE was with sway of 2.9 ± 0.7 cm/s to the left. A sway distractor did not bias rotation perception. When subjects were asked to report the direction of translation while varying the axis of yaw rotation, the PSE at which translation was equally likely to be perceived in either direction was 29 ± 11 cm anterior to the midline. These results demonstrated that rotation biased translation perception, such that it is minimized when rotating about an axis anterior to the head. Since the combination of translation and rotation during ambulation is consistent with an axis anterior to the head, this may reflect a mechanism by which movements outside the pattern that occurs during ambulation are perceived.

The influence of head and body tilt on human fore-aft translation perception.

The tilt-translation ambiguity occurs because acceleration due to translation cannot be differentiated from gravitational acceleration. Head tilt can occur independent of body tilt which further complicates the problem. The tilt-translation ambiguity is examined for fore-aft (surge) translation with head and/or body orientations that are tilted in pitch 10° forward or backward. Eleven human subjects (six female), mean age 40 years participated. Conditions included no tilt (NT), head and body tilt (HBT), head only tilt (HOT), and body only tilt (BOT). The fore-aft stimulus consisted of a 2 s (0.5 Hz) sine wave in acceleration which a maximum peak velocity of 10 cm/s. After each stimulus, the subject reported the direction of motion as forward or backward. Subsequent stimuli were adjusted to determine the point at which subjects were equally likely to report motion in either direction. During the HBT, responses were biased such that upward pitch caused a neutral stimulus to be more likely to be perceived as forward and downward pitch caused the stimulus to be more likely to be perceived as backward. The difference in the point of subjective equality based on the direction of tilt was 3.3 cm/s. During the BOT condition, the bias with respect to the direction of body tilt was in a similar direction with a difference in PSE 1.6 cm/s. During HOT and NT, there was no significant bias on fore-aft perception. These findings demonstrate that body tilt shifts the PSE of fore-aft direction discrimination while head tilt has no influence.

Psychometrics of inertial heading perception.

BACKGROUND: Inertial self-motion perception is thought to depend primarily on otolith cues. Recent evidence demonstrated that vestibular perceptual thresholds (including inertial heading) are adaptable, suggesting novel clinical approaches for treating perceptual impairments resulting from vestibular disease. OBJECTIVE: Little is known about the psychometric properties of perceptual estimates of inertial heading like test-retest reliability. Here we investigate the psychometric properties of a passive inertial heading perceptual test. METHODS: Forty-seven healthy subjects participated across two visits, performing in an inertial heading discrimination task. The point of subjective equality (PSE) and thresholds for heading discrimination were identified for the same day and across day tests. Paired t-tests determined if the PSE or thresholds significantly changed and a mixed interclass correlation coefficient (ICC) model examined test-retest reliability. Minimum detectable change (MDC) was calculated for PSE and threshold for heading discrimination. RESULTS: Within a testing session, the heading discrimination PSE score test-retest reliability was good (ICC = 0. 80) and did not change (t(1,36) = -1.23, p = 0.23). Heading discrimination thresholds were moderately reliable (ICC = 0.67) and also stable (t(1,36) = 0.10, p = 0.92). Across testing sessions, heading direction PSE scores were moderately correlated (ICC = 0.59) and stable (t(1,46) = -0.44, p = 0.66). Heading direction thresholds had poor reliability (ICC = 0.03) and were significantly smaller at the second visit (t(1,46) = 2.8, p = 0.008). MDC for heading direction PSE ranged from 6-9 degrees across tests. CONCLUSION: The current results indicate moderate reliability for heading perception PSE and provide clinical context for interpreting change in inertial vestibular self-motion perception over time or after an intervention.

Limited interaction between translation and visual motion aftereffects in humans.

After exposure to a moving sensory stimulus, subsequent perception is often biased in the opposite direction. This phenomenon, known as an aftereffect, has been extensively studied for optic flow stimuli where it is known as the visual motion aftereffect (MAE). Such visual motion can also generate the sensation of self-motion or vection. It has recently been demonstrated that fore-aft translation in darkness also produces an aftereffect. The current study examines the interaction between visual MAE and vestibular translation aftereffects. Human subjects participated in a two-interval experiment in which the first interval (adapter) was visual, translation, or both combined congruently or in conflict. Subjects identified the direction of the second (test) interval of either visual or translation using a forced-choice technique. The translation adapter had no influence on visual test stimulus perception, and the visual adapter did not influence vestibular test stimulus perception in any subjects. However, congruent visual and translation induced a significantly larger perceptual bias on the translation test stimulus than was observed for a translation only adapter. The congruent adapter caused the MAE to be diminished relative to a visual only adapter. Conflicting visual and vestibular adapters produced an aftereffect similar to that seen when the single adapting stimulus was the same modality as the test stimulus. These results suggest that unlike visual and translation stimuli whose combined influence on perception can be predicted based on the effects of each stimulus individually, the effects of combined visual and translation stimuli on aftereffects cannot be predicted from the influences of each stimulus individually.

Roll aftereffects: influence of tilt and inter-stimulus interval.

A theme in sensory perception is that exposure to a stimulus causes perception of subsequent stimuli to be shifted in the opposite direction. Such phenomenon is known as aftereffect and has been extensively described in the visual system as well as recently described for the vestibular system during translation. It is known from aviation studies that after a maneuver in roll, pilots can experience a false perception of roll in the opposite direction. The magnitude and duration of this effect as well as the potential influence of the gravity vector have not previously been defined. In the current paper this roll aftereffect (RAE) is examined in response to whole-body roll about an earth-horizontal axis in eight healthy human subjects. The peak velocity of a 0.5-s-duration roll was varied based on previous responses to find the point where subjects perceived no motion. Without a preceding stimulus, the starting position (upright, 9° left, or 9° right) did not influence roll perception. The RAE was measured in a completely dark room using an adapting (first interval) stimulus consisting of 9° of roll over 1.5 s (peak velocity, 12°/s), delivered 0.5, 3, or 6 s prior to test (second interval) stimulus. A significant RAE was seen in all subjects. Half a second after the adapting stimulus, a test stimulus had to be on average 1.5 ± 0.4°/s in the opposite direction to be perceived as stationary. When the subject remained upright after the adapting stimulus, the RAE diminished with time, although it remained significantly larger at 3 and 6 s when the subject remained tilted after the adapting stimulus. These data demonstrate that roll perception can be influenced by small preceding stimuli and tilt causes a persistence of the RAE.

Fore-aft translation aftereffects.

A general theme in sensory perception is that exposure to a stimulus makes it seem more neutral such that perception of subsequent stimuli is shifted in the opposite direction. The visual motion aftereffect (MAE) is an extensively studied example of this. Although similar effects have been described in other sensory systems, it has not previously been described in the vestibular system. Velocity storage has been extensively studied in the vestibular system and suggests a persistence of perception in the direction of the initial movement. The current study sought to determine how motion perception is influenced by prior movement in darkness. Thirteen human subjects (mean age 41, range 21-68) underwent whole-body fore-aft translation. The threshold of vestibular motion discrimination perception was measured using a single interval (1I) of motion lasting 0.5 s in which subjects identified their direction of motion as forward or backward using an adaptive staircase. The translation aftereffect (TAE) was measured in 2-interval (2I) experiments: The adapting stimulus moved 15 cm in 1.5 s (peak velocity 20 cm/s, peak acceleration 42 cm/s(2)). After a fixed inter-stimulus interval (ISI) of 0.5, 1.0, 1.5, or 3 s, a second stimulus lasting 0.5 s was delivered and the subject identified the perceived direction of the second test stimulus. The test stimulus was determined using an adaptive staircase. The ISI was constant within the block, but adapting stimuli directions were randomly interleaved. During the 1I condition, the response bias was near zero in all subjects. With a 2I stimulus, 8 of 13 subjects demonstrated a significant bias. At an ISI of 0.5 s, a minority of subjects demonstrated a bias in the same direction as the adapter. When the ISI was 1, 1.5, or 3 s, all subjects who demonstrated a significant TAE had one in the opposite direction of the adapter, similar to that seen for MAE. When averaged across subjects, the TAE was significant with ISIs of 1.0 s and above. These findings demonstrate that perception of vestibular stimuli depends on prior motion. This has important implications for understanding and quantifying vestibular perception.

Suprathreshold asymmetries in human motion perception.

Detection of asymmetries has been a mainstay of using vestibular reflexes to assess semicircular canal function. However, there has been relatively little work on how vestibular stimuli are perceived. Suprathreshold vestibular perception was measured in 13 normal healthy controls by having them compare the relative sizes of two yaw (vertical-axis rotation) or sway (right-left translation) stimuli. Both stimuli were 1.5 s in duration with a staircase used to adjust the relative size of the stimuli to find a pair of stimuli perceived as equal. Motion stimuli were delivered in darkness using a hexapod motion platform, and visual stimuli simulating motion were presented on a screen in the absence of platform motion. Both same direction (SD) and opposite direction (OD) stimuli were delivered in separate runs. After a two-interval stimulus, subjects reported which movement they perceived as larger. Cumulative distribution functions were fit to the responses so that the relative magnitudes of the two stimuli perceived as equal could be determined. For OD trial blocks, a directional asymmetry index was calculated to compare the relative size of perceived rightward and leftward motion. For all trial blocks, a temporal asymmetry index (TAI) was used to compare the relative size of the first and second intervals. Motion OD stimuli were perceived as equal in all subjects in yaw and all but one in sway. For visual OD stimuli, two subjects had slightly asymmetric responses for both sway and yaw. The TAI demonstrated asymmetry in 54% in yaw, in which the second interval was perceived to be larger in all but one subject who had an asymmetry. For sway, only two subjects had a significant asymmetry. Visual stimuli produced a similar rate of asymmetry. The direction and magnitude of these asymmetries were not significantly correlated with those seen for motion stimuli. Asymmetries were found in a fraction with the TAI in SD stimuli for motion in yaw (42%) and sway (33%), as well as for vision in yaw (60%) and sway (43%). The precision at discriminating SD motion stimuli decreased significantly with age, but there was no difference in OD motion or visual stimuli.

Comparative study of the analysis of seized samples by GC-MS, 1H NMR and FT-IR spectroscopy within a Night-Time Economy (NTE) setting.

Rapid analysis of surrendered or seized drug samples provides important intelligence for health (e.g. treatment or harm reduction), and custodial services. Herein, three in-situ techniques, GC-MS, 1H NMR and FT-IR spectroscopy, with searchable libraries, are used to analyse 318 samples qualitatively, using technique specific library-based searches, obtained over the period 24th - 29th August 2019. 259 samples were identified as consisting of a single component, of which cocaine was the most prevalent (n = 158). Median match scores for all three techniques were ≥ 0.84 and showed agreement except for metformin (n = 1), oxandrolone (identified as vitamin K by IR (n = 4)), diazepam (identified as zolpidem by FT-IR (n = 2)) and 2-Br-4,5-DMPEA (n = 1), a structural isomer of 2C-B identified as a polymer of cellulose (cardboard) by FT-IR. 51 samples were found to consist of two or more components, of which 49 were adulterated cocaine samples (45 binary and 4 tertiary samples). GC-MS identified all components present in the 49 adulterated cocaine samples, whereas IR identified only cocaine in 88 % of cases (adulterant only = 12 %). The breakdown for 1H NMR spectroscopy was all components identified (51 %), cocaine only (33 %), adulterant only (10 %), cocaine and one adulterant (tertiary mixtures only, 6 %).

A Protocol for Imaging of Cochlear Implantation.

OBJECTIVES: Correct electrode placement is a challenge of cochlear implant surgery, which occurs because electrode position cannot be directly visualized. This work aims to 1) develop a protocol for a practical, consistent, single view plain radiograph able to be used to confirm cochlear implantation, 2) confirm its usefulness on patients, and 3) confirm its usefulness for identifying misplaced electrodes in cadaveric ears. STUDY DESIGN: Imaging procedure and quality improvement initiative. SETTING: Tertiary academic hospital. PATIENTS: Cadaveric ears, and patients undergoing cochlear implantation. INTERVENTIONS: An intraoperative imaging protocol was developed specifying patient head position, machine position, and exposure setting. This was tested to confirm proper cochlear implantation in patients, including one revision case. This technique allowed the electrode placement to be reliably identified in patients of all ages. Its usefulness for identifying maligned electrodes (partial insertion, and insertion into the vestibule or hypotympanum) was confirmed using four cadaveric hemi-heads. MAIN OUTCOME MEASURES: Ability to accurately identify correct or incorrect electrode insertion based on radiographic images. RESULTS: After adjusting radiographic exposure to account for the embalming process of the cadaveric heads, this new protocol was confirmed to be able to identify incorrect placement. This was also successfully used to confirm proper placement of cochlear implants in patients. CONCLUSIONS: Following a standardized radiographic protocol for cochlear implantation is a quick and easy method for checking electrode position.Supplemental Digital Content, http://links.lww.com/MAO/B253.

Facemasks Block Lower Visual Field in Youth Ice Hockey.

Wearing a facemask (FM) reduces the spread of COVID-19, but it also blocks a person's lower visual field. Many new public safety rules were created in response to COVID-19, including mandated FM wearing in some youth sports like youth ice hockey. We hypothesized that FM wearing in youth hockey players obstructs the lower field of view and may impact safety. Youth hockey players (n = 33) aged 12.03 (1.6) years button press when they saw an LED on the floor turn on in two conditions (wearing FM or no FM) in random order. An interleaved one-up/one-down two-alternative-forced-choice adaptive staircase design was used. Visual thresholds were calculated for each condition and participant. The visual angle threshold (VAT) was determined using standing eye height and the linear distance from the tip of the skates to the visual threshold. Paired t-tests determined whether mask wearing changed the VAT. We modeled the probability a player could see the puck on their stick in four distinct scenarios to estimate the potential impact of FM wearing during hockey play. The average unmasked VAT (11.4 degrees) was significantly closer to the skates than the masked VAT (20.3 degrees) (p < 0.001). Our model indicated a significant reduction in ability to visualize the puck using peripheral vision when more upright while wearing a FM. FM wearing compromised their lower visual field, suggesting a downward head tilt may be necessary to see the puck. Playing ice hockey while wearing a FM may lead to unsafe on-ice playing conditions due to downward head tilt to see the puck.

Iatrogenic thoracic outlet syndrome secondary to vertical expandable prosthetic titanium rib expansion thoracoplasty: pathogenesis and strategies for prevention/treatment.

BACKGROUND: An innovative treatment for thoracic insufficiency syndrome involves a vertical expansion of the chest wall through a horizontal chest wall osteotomy maintained by a distraction device (vertical expandable prosthetic titanium rib or VEPTR). Upper-extremity neurovascular dysfunction has been reported after expansion. The purposes of this study are to identify potential etiologies for compression of the brachial plexus after expansion thoracoplasty and to suggest strategies to reduce the incidence of this complication. METHODS: A simulated VEPTR procedure was performed on 8 fresh cadaveric specimens. Manometric measurements were taken in the 3 anatomic regions of the thoracic outlet after thoracotomy and rib distraction were performed. Confirmation of the location of compression was performed by placing barium-impregnated putty along the course of the brachial plexus and evaluating the effect of expansion using video fluoroscopy. A midclavicular osteotomy was then performed and video fluoroscopy repeated. RESULTS: A 20% increase in pressure was seen in the costoclavicular region of the thoracic outlet after expansion. Constriction of the midclavicular region of the thoracic outlet between the first rib and clavicle was confirmed using the putty model. Midclavicular osteotomy alleviated this region of compression. CONCLUSIONS: Expansion thoracoplasty with the VEPTR procedure causes increased pressure in the costoclavicular region of the thoracic outlet. A midclavicular osteotomy may be one method to alleviate thoracic outlet narrowing after VEPTR procedure, although the short- and long-term effects of this is procedure is not known. CLINICAL RELEVANCE: Our model supports an iatrogenic thoracic outlet syndrome caused by expansion thoracoplasty. Based on our data as well as a review of the literature, we recommend intraoperative neurologic monitoring of the ipsilateral upper extremity during the VEPTR procedure.

An adaptive vestibular rehabilitation technique.

OBJECTIVES/HYPOTHESIS: There is a large variation in vestibular rehabilitation (VR) results depending on type of therapy, adherence, and the appropriateness for the patient's level of function. A novel adaptive vestibular rehabilitation (AVR) program was developed and evaluated. STUDY DESIGN: Technology and procedure development, and prospective multicenter trial. METHODS: Those with complete unilateral vestibular hypofunction and symptomatic at least 3 months with a Dizziness Handicap Inventory (DHI) >30 were eligible. Patients were given a device to use with their own computer. They were instructed to use the program daily, with each session lasting about 10 minutes. The task consisted of reporting orientation of the letter C, which appeared when their angular head velocity exceeded a threshold. The letter size and head velocity required were adjusted based on prior performance. Performance on the task was remotely collected by the investigator as well as a weekly DHI score. RESULTS: Four patients aged 31 to 74 years (mean = 51 years) were enrolled in this feasibility study to demonstrate efficacy. Two had treated vestibular schwannomas and two had vestibular neuritis. Starting DHI was 32 to 56 (mean = 42), which was reduced to 0 to 16 (mean = 11.5) after a month of therapy, a clinically and statistically significant (P < .05) improvement. The three who continued therapy an additional month improved to a DHI of 4. CONCLUSIONS: This AVR method has advantages over traditional VR in terms of cost and customization for patient ability and obtained a major improvement in symptoms. This study demonstrated a clinically and statistically significant decrease in symptoms after 4 weeks of therapy. LEVEL OF EVIDENCE: 2b. Laryngoscope, 128:713-718, 2018.

Effect of vibration during visual-inertial integration on human heading perception during eccentric gaze.

Heading direction is determined from visual and inertial cues. Visual headings use retinal coordinates while inertial headings use body coordinates. Thus during eccentric gaze the same heading may be perceived differently by visual and inertial modalities. Stimulus weights depend on the relative reliability of these stimuli, but previous work suggests that the inertial heading may be given more weight than predicted. These experiments only varied the visual stimulus reliability, and it is unclear what occurs with variation in inertial reliability. Five human subjects completed a heading discrimination task using 2s of translation with a peak velocity of 16cm/s. Eye position was ±25° left/right with visual, inertial, or combined motion. The visual motion coherence was 50%. Inertial stimuli included 6 Hz vertical vibration with 0, 0.10, 0.15, or 0.20cm amplitude. Subjects reported perceived heading relative to the midline. With an inertial heading, perception was biased 3.6° towards the gaze direction. Visual headings biased perception 9.6° opposite gaze. The inertial threshold without vibration was 4.8° which increased significantly to 8.8° with vibration but the amplitude of vibration did not influence reliability. With visual-inertial headings, empirical stimulus weights were calculated from the bias and compared with the optimal weight calculated from the threshold. In 2 subjects empirical weights were near optimal while in the remaining 3 subjects the inertial stimuli were weighted greater than optimal predictions. On average the inertial stimulus was weighted greater than predicted. These results indicate multisensory integration may not be a function of stimulus reliability when inertial stimulus reliability is varied.