Rear-end Impact Research Articles

Finite Element Analysis of Head-Neck Kinematics in Rear-End Impact Conditions with Headrest.

A detailed three-dimensional (3D) head-neck (C0-C7) finite element (FE) model was developed and used to dictate the motions of each cervical spinal segment under static physiological loadings of flexion and extension with a magnitude of 1.0 Nm and rear-end impacts. In this dynamic study, a rear-end impact pulse was applied to C7 to create accelerations of 4.5 G and 8.5 G. The predicted segmental motions and displacements of the head were in agreement with published results under physiological loads of 1.0 Nm. Under rear-end impact conditions, the effects of peak pulse acceleration and headrest angles on the kinematic responses of the head-neck complex showed rates of increase/decrease in the rotational motion of various cervical spinal segments that were different in the first 200 ms. The peak flexion rotation of all segments was lower than the combined ROM of flexion and extension. The peak extension rotation of all segments showed variation compared to the combined ROM of flexion and extension depending on G and the headrest angle. A higher acceleration of C7 increased the peak extension angle of lower levels, but the absolute increase was restricted by the distance between the head and the headrest. A change in the headrest angle from 45° to 30° resulted in a change in extension rotation at the lower C5-C6 segments to flexion rotation, which further justified the effectiveness of having distance between the head and the headrest. This study shows that the existing C0-C7 FE model is efficient at defining the gross reactions of the human cervical spine under both physiological static and simulated whiplash circumstances. The fast rate of changes in flexion and extension rotation of various segments may result in associated soft tissues and bony structures experiencing tolerances beyond their material characteristic limits. It is suggested that a proper location and angle of the headrest could effectively prevent the cervical spine from injury in traumatic vehicular accidents.

Rear-End Impacts - Part 2: Sled Pulse Effect on Front-Seat Occupant Responses

<div class="section abstract"><div class="htmlview paragraph">This study was conducted to assess the effects of differing rear impact pulse characteristics on restraint performance, front-seat occupant kinematics, biomechanical responses, and seat yielding. Five rear sled tests were conducted at 40.2 km/h using a modern seat. The sled buck was representative of a generic sport utility vehicle. A 50<sup>th</sup> percentile Hybrid III ATD was used. The peak accelerations, acceleration profiles and durations were varied. Three of the pulses were selected based on published information and two were modeled to assess the effects of peak acceleration occurring early and later within the pulse duration using a front and rear biased trapezoidal characteristic shape.</div><div class="htmlview paragraph">The seatback angle at maximum rearward deformation varied from 46 to 67 degrees. It was lowest in Pulse 1 which simulates an 80 km/h car-to-car rear impact. The seatback plastic deformation was greater in the pulse with the rear biased trapezoidal acceleration profile, Pulse 4, than in the front biased trapezoidal acceleration profile, Pulse 5 (46 degrees v 41 degrees). Coincidingly, the longitudinal head displacement was slightly greater in the Pulse 4. There was limited relative motion between the ATD torsos and the seatbacks. The relative motion between the ATD torso and the seatback was less than 7 cm in all tests. The head, chest and pelvis peak acceleration and timing varied depending on the pulse. All peak head, chest, pelvis and upper and lower-neck moments occurred prior to maximum seatback dynamic deflection. The biomechanical responses were all well below injury assessment reference values. The seatback structural restitution was the highest in Pulse 1 which had the lowest amount of dynamic and plastic seatback deformation and had the highest lap belt load. All peak belt loads occurred in the rebound phase of the ATD.</div><div class="htmlview paragraph">The sled coordinate-based data was used to determine the effective restraint stiffness. The results were used to develop a spring-mass model. The model will help understand the effects of pulse characteristics on predicted chest acceleration for future research.</div><div class="htmlview paragraph">In conclusion, the results from this study show that pulse shape has a measurable effect of seat and ATD kinematics in high-speed rear impacts and should considered for future research and testing.</div></div>

Rear-End Impacts - Part 1: Field and Test Data Analysis of Crash Characteristics

<div class="section abstract"><div class="htmlview paragraph">Prior to developing or modifying the protocol of a performance evaluation test, it is important to identify field relevant conditions. The objective of this study was to assess the distribution of selected crash variables from rear crash field collisions involving modern vehicles. The number of exposed and serious-to-fatally injured non-ejected occupants was determined in 2008+ model year (MY) vehicles using the NASS-CDS and CISS databases. Selected crash variables were assessed for rear crashes, including severity (delta V), impact location, struck vehicle type, and striking objects. In addition, 15 EDRs were collected from 2017 to 2019 CISS cases involving 2008+ MY light vehicles with a rear delta V ranging from 32 to 48 km/h. Ten rear crash tests were also investigated to identify pulse characteristics in rear crashes. The tests included five vehicle-to-vehicle crash tests and five FMVSS 301R barrier tests matching the struck vehicle.</div><div class="htmlview paragraph">The analysis of NASS-CDS and CISS data indicates that more than 50% of exposed (MAIS 0+F) occupants were involved in a rear crash with a distributed impact and with no over-ride or under-ride. More than 93% were with a 6 o’clock PDOF. The average rear delta V was 21.3 ± 1.2 km/h (median 18.2, 90th CI 9.7-33.4) in the exposed (MAIS 0+F) occupant sample. For serious-to-fatally (MAIS 3+F) injured occupants, more than 88% were in a fully distributed rear impact and in 6 o’clock PDOF; 10.7% were in offset impacts and less than 1% were in narrow impacts. The average delta V was 35.9 ± 5.2 km/h (median 24.4, 90th CI 16.2-58.3) for serious-to-fatally (MAIS 3+F) injured occupants.</div><div class="htmlview paragraph">The results from the field data suggest that rear impacts with a delta V of 34-38 km/h and a 6 o’clock PDOF are representative of the average rear-crash scenario causing serious-to-fatal injury. Compared to the exposed occupants in the field data analysis, a 40 km/h rear sled is more than 1.9-times more severe than the average rear impact crash severity in terms of delta V and 4.4-times more severe in terms of crash energy. It is 1.11-times more severe than the average delta V for the serious-to-fatally (MAIS 3+F) injured occupant. It accounts for more than 90% of all occupants with injury (MAIS 1+F).</div><div class="htmlview paragraph">EDR data was helpful in accessing overall delta-V and impact duration information. For example, the average delta V in the EDRs included in the analysis was 38.7 ± 7.6 km/h and the average pulse duration was 129.6 ± 24.3 ms. Instrumentation data from crash tests provided more refined information for a detailed analysis of pulse characteristics.</div><div class="htmlview paragraph">The acceleration data obtained from the five vehicle-to-vehicle crash tests was investigated and compared to matched FMVSS 301 tests with the same struck vehicle. The data was scaled to a 40 km/h delta V pulse for comparison purposes. Bi-modal pulse shape characteristics were observed. The peak acceleration averaged 18.4 g in the vehicle-to-vehicle tests and 21.4 g in the FMVSS 301R tests. The average pulse duration was 147.2 ms and 123.8 respectively.</div><div class="htmlview paragraph">The results from this study suggest that using a 34-40 km/h bimodal-rear pulse with a 130-160 ms duration is representative of a serious real world rear impact.</div></div>

Prediction of neck injury using multiple linear regression and bumper damage: Case study for low-speed rear-end collisions

The most frequent type of traffic accident is a low-speed rear-end collision, which can damage parts of the vehicle, including the bumper, and cause neck injury to the occupants. Even in minor damage accidents, such as scratches on bumper covers, 26.3% of occupants received treatment for bodily injuries whose main symptom was neck injuries through auto insurance. This study was conducted to evaluate the potential for neck injuries in low-speed accidents. Fifty-nine low-speed rear-end impact tests were conducted, and the motion of the struck vehicle and the neck injury criterion (NIC) of the occupant according to the test conditions were predicted using multiple linear regression derived via supervised machine learning. It was confirmed that the NIC can be predicted using vehicle motion values that can be obtained through an event data recorder. The coefficients of determination of the regression equations were 0.67–0.83. Lastly, we investigated whether neck injuries can be predicted through bumper cover damage that can be checked immediately after a vehicle accident. In the case of the vehicle damage type 1/2/3 category applied to auto insurance by the Korean government, an occupant would have a very low possibility of neck injury or symptoms. No symptoms or injuries were reported in the volunteer tests conducted for this study.

An Analysis of Rear-End Impact Crash Characteristics and Injury Pattern in Malaysia


 
 
 Rear-end crashes are one of the most common types of accidents. The characteristics of rear impact crash (based on accident data in Malaysia) have not been well studied. The objective of this study is to investigate the rear impact crash characteristics in Malaysia between 2016 and 2018 using data obtained from Bukit Aman Traffic Investigation and Enforcement (JSPT), Royal Malaysia Police (RMP) Pol 27. The analysis revealed that motorcycles (40.3%) were the largest contributor to rear-end crashes, followed by occupant car (36.3%), lorry (16.3%), four-wheel (3.8%), bus (1.6%) and other vehicles (1.6%). The majority did not suffer any injury (60.8%), while there were fatalities (16.8%), injuries (14.3%), and severe injuries (8.1%). The highest percentage of fatal crashes occurred at the speed limit area 110 km/h (23.6%). The chi-square test showed that speed limit and type of crash were significantly associated (p<0.01). The result also showed a significant association between main vehicle part damage and injury level (p<0.01). The study shows a thorough examination and analysis of rear impact crash characteristics can provide important and useful information to guide transport policy, vehicle design, and driver education. Further research is needed to fully understand the key factors that contribute to rear-end impact crashes in Malaysia.
 
 

Model-Aided Design of a Rear-Impact Collision Testing System for In Vivo Investigations.

A collision testing device used to simulate rear-end impacts on human volunteers was developed and validated. The testing device was designed using impact parameters obtained from real crash-test-derived vehicle-to-vehicle rear-end collisions. Experimental results show the proposed testing device achieves repeatable impact parameters well within the reported ranges of real vehicle-to-vehicle rear-end impact simulations reported in the literature. In particular, the device was able to produce a 7.66 (0.30) km/h delta-v collision with a duration of 111.6 (6.2) ms, and a 4.75 (0.29) g peak acceleration.

Severity of motorcycle crashes in Dar es Salaam, Tanzania

Objective: Motorcycles are a common mode of transportation in low- and middle-income countries. Tanzania, in particular, has experienced an increased use of motorcycles in the last decade. In Dar es Salaam, motorcycles provide door-to-door travel and often operate where more conventional services are uneconomical or physically impossible to maneuver. Although motorcycles play a crucial role in improving mobility in the city, they have several safety issues. This study focuses on identifying factors influencing the severity of motorcycle crashes.Method: A multinomial logit analysis was conducted to identify factors influencing the severity of motorcycle crashes in Dar es Salaam, Tanzania. The severity categories were fatal, severe injury, minor injury, and property damage only (PDO). The analysis was based on a total of 784 motorcycle crashes that occurred from 2013 to 2016.Results: The following factors were found to increase the probability of a fatality: Speeding, driving under the influence, head-on impact, presence of horizontal curves, reckless riding, off-peak hours, violations, and riding without a helmet. The results indicate that crashes occurring on weekdays, during peak hours, at intersections, involving a rear-end impact, in daylight, on street roads, and under clear weather conditions decrease the probability of a fatality. However, minor injury and PDO crashes were found to be associated with crashes occurring during peak hours, at intersections, and on street roads, as well as failure to yield right-of-way.Conclusions: Several countermeasures are recommended based on the study findings. The recommended countermeasures focus on the holistic safety improvement strategies constituting the three Es of highway safety, namely, engineering, education, and enforcement.

Design for Headrest Including Guides Slot to Reduce the Neck Force in Rear End Impact

Whiplash injuries are one of the most common injuries reported in automotive rear end collisions. Automobile seat back and head restraints play a role in reducing neck injuries during low speed rear end collisions. Currently, many studies are being conducted on ways to reduce neck injuries. These deal with the design parameters that cause neck injuries and do not address the design of the head restraint connection structure. In this paper, we analyze the various trajectories of the headrest and propose a new design for a connection structure that can move along the corresponding trajectory. We model the headrest connection mechanism as a virtual link using kinematic modeling and perform trajectory analysis. Using the trajectory of motion, we select an oblong shape for the guide slot by fitting it with the equation of an ellipse and propose a new headrest connection mechanism. To evaluate the design of the proposed mechanism, we model the shape of the mechanism and test it using dynamic simulation under collision conditions. In addition, we design a prototype for the proposed guide, conduct a sled test, and confirm that the neck force is reduced by the proposed connection structure. In the proposed structure, the values of maximum upper neck shear and tension decreased by more than 20 % compared to existing headrest.

Head postures during naturalistic driving

Objective: A rotated head posture at the time of a rear-end impact is associated with a higher risk of acute and chronic whiplash injury. The objective of this study was to quantify the amplitude and duration of rotated head postures observed in drivers during naturalistic driving.Methods: Twenty volunteers (14 males: 36 ± 12 years, 6 females: 27 ± 5 years) drove a 2010 Subaru Impreza on public roads while their 3D head angular position relative to the car was recorded using inertial measurement units. An experimenter rode in the passenger seat (right side) and logged when subjects performed one of 6 head movements: Bilateral shoulder and side mirror checks, looking at the rearview mirror, and looking at the front seat passenger. Video of the subjects was used to confirm the logged head movements and identify movements that the experimenter missed. The duration and amplitude of all 6 head movements were tabulated and then compared between periods when the car was moving and when the car was stationary.Results: During a 68 ± 5-min drive, subjects performed a median (range) of 15 (5–39) left shoulder checks, 82.5 (29–167) left mirror checks, 40.5 (10–168) rearview mirror checks, 27.5 (3–113) right mirror checks, 60 (0–185) passenger looks, and 12.5 (1–28) right shoulder checks. Peak yaw angles of the head relative to the vehicle for these 6 movements averaged −81.5°, −34.3°, 16.2°, 42.1°, 58.2°, and 84.3°, respectively. Drivers spent a larger proportion of time in nonneutral postures when the vehicle was stopped (17.5%) compared to moving (8.2%) (Z = 3.92, P < .0001). Drivers also moved their head further from neutral during the movements when the car was stationary compared to moving (t19 = 5.90, P < .0001).Conclusions: Drivers use larger and longer duration head movements when stationary than when driving. Given an increased risk of whiplash injury for initially rotated head postures, these findings provide a possible explanation for why drivers are more likely to be injured when hit from behind while their vehicle is stationary. Further, the head postures characterized in this study can be used as initial conditions in volunteer and computational studies to improve our understanding of why nonneutral head postures are associated with increased whiplash injury risk.

Investigation of the Effect of Neck Muscle Active Force on Whiplash Injury of the Cervical Spine.

The objective of the present study is to investigate the influence of neck muscle activation on whiplash neck injury of the occupants of a passenger vehicle under different severities of frontal and rear-end impact collisions. The finite element (FE) model has been used as a versatile tool to simulate and understand the whiplash injury mechanism for occupant injury prevention. However, whiplash injuries and injury mechanisms have rarely been investigated in connection with neck active muscle forces, which restricts the complete reappearance and understanding of the injury mechanism. In this manuscript, a mixed FE human model in a sitting posture with an active head-neck was developed. The response of the cervical spine under frontal and rear-end collision conditions was then studied using the FE model with and without neck muscle activation. The effect of the neck muscle activation on the whiplash injury was studied based on the results of the FE simulations. The results indicated that the neck active force influenced the head-neck dynamic response and whiplash injury during a collision, especially in a low-speed collision.

Similarity of the measured NIC of a BioRID II dummy in car-to-car rear end impact and sled experiments

The Japan New Car Assessment Program (J-NCAP) evaluates the performance of cars in terms of protection against whiplash injuries in rear-end collisions. In the test protocol, a simplified triangular acceleration is applied to the sled. This study clarifies whether biofidelic rear-impact dummy II (BioRID II) measurements obtained for simplified triangular acceleration reflect car-to-car rear-end impacts in real-world accidents in Japan. We conducted a car-to-car rear-end impact experiment and a simplified-triangular-acceleration sled test. Our results indicate that the time series of dummy responses were approximately consistent in the two test conditions. The neck injury criterion (NIC) and maximum acceleration of the head and T1 measured using the BioRID II dummy were similar in the car-to-car and sled experiments. This revealed that the J-NCAP test protocol using simplified triangular acceleration reflects the car-to-car rear-end impact experiment using Japanese cars, in terms of the NIC and maximum acceleration of the head and T1.

저속 추돌 시 반발계수에 관한 연구

저속 추돌 시 반발계수에 관한 연구

Dogs in passenger vehicles – crash safety evaluation of travel crates

ABSTRACTMethods for evaluating the crash safety of travel crates for transportation of dogs in the vehicle cargo space have previously been proposed. This study aims to (1) explore how two crate designs, a plastic crate and a metal crate, previously evaluated according to the Center for Pet Safety (CPS) method that only accounts for frontal impact, perform when evaluated according to the Safe Pet Crate Test (SPCT) that accounts for multiple crash modes, and (2) evaluate if the use of standard vehicle cargo hooks for securing the crate and a standard vehicle seatback, as opposed to the ‘strength-rated’ anchor points and rigid seatback structure specified for the CPS method, yields results consistent with published CPS method test results. Frontal and rear-end impact sled tests and drop tests were conducted. The results indicate that the metal crate, which did not comply with the CPS method, offers safety benefits over the plastic crate which complied with the CPS method. The results further indicate that the limited strength of standard vehicle cargo hooks and limited strength and stiffness of vehicle seatbacks may both affect the frontal crash response of crates initially positioned away from the seatback and therefore must be accounted for.

Effect of cervical spine alignment on neck injury risk during rear-end impact – numerical study using neck finite element model

ABSTRACTMany neck safety technologies have been developed in recent years; however, the incidence of whiplash-associated disorders (WAD) in rear-end collision accidents remains high. A lack of consideration of individual differences among vehicle occupants is considered a major factor. Individual differences in the neck can be represented by the differences in cervical spine alignment. In this study, images of typical cervical spine alignments, such as lordotic, straight, kyphotic, s-shaped, and inverse s-shaped alignments, were selected from a hospital database. Shape transformations of a head–neck finite element model were then performed to obtain multiple head–neck finite element models with five different cervical spine alignments. Rear-end impact analysis results showed quantitative differences in relative intervertebral rotation and ligament strain. These differences might be the cause of variability in the neck injury risk and severity among occupants in rear-end impact accidents.

乗車姿勢における脊柱アライメントの男女差が後突事故時の脊柱挙動に及ぼす影響

乗車姿勢における脊柱アライメントの男女差が後突事故時の脊柱挙動に及ぼす影響

Effects of whole spine alignment patterns on neck responses in rear end impact

ABSTRACTObjective: The aim of this study was to investigate the whole spine alignment in automotive seated postures for both genders and the effects of the spinal alignment patterns on cervical vertebral motion in rear impact using a human finite element (FE) model.Methods: Image data for 8 female and 7 male subjects in a seated posture acquired by an upright open magnetic resonance imaging (MRI) system were utilized. Spinal alignment was determined from the centers of the vertebrae and average spinal alignment patterns for both genders were estimated by multidimensional scaling (MDS). An occupant FE model of female average size (162 cm, 62 kg; the AF 50 size model) was developed by scaling THUMS AF 05. The average spinal alignment pattern for females was implemented in the model, and model validation was made with respect to female volunteer sled test data from rear end impacts. Thereafter, the average spinal alignment pattern for males and representative spinal alignments for all subjects were implemented in the validated female model, and additional FE simulations of the sled test were conducted to investigate effects of spinal alignment patterns on cervical vertebral motion.Results: The estimated average spinal alignment pattern was slight kyphotic, or almost straight cervical and less-kyphotic thoracic spine for the females and lordotic cervical and more pronounced kyphotic thoracic spine for the males. The AF 50 size model with the female average spinal alignment exhibited spine straightening from upper thoracic vertebra level and showed larger intervertebral angular displacements in the cervical spine than the one with the male average spinal alignment.Conclusions: The cervical spine alignment is continuous with the thoracic spine, and a trend of the relationship between cervical spine and thoracic spinal alignment was shown in this study. Simulation results suggested that variations in thoracic spinal alignment had a potential impact on cervical spine motion as well as cervical spinal alignment in rear end impact condition.

Investigating the interplay between the attributes of at-fault and not-at-fault drivers and the associated impacts on crash injury occurrence and severity level

ABSTRACTThe article proposes a two-staged modelling approach to identify the association between one vehicle's attributes, as well as roadway engineering, environmental and crash characteristics, and the injury severity of occupants in the partnering vehicle in two-vehicle crashes. The modelling approach uses a bivariate binary probit model, and crash data for Toronto, to first determine the probability of injury and no injury occurring, followed by the use of a bivariate ordered probit model to investigate the conditional probability of the specific severity level. Vehicles in two-vehicle crashes are categorized as “not-at-fault” (NAF) or “at-fault” (AF) and their occupants also categorized as such. The findings demonstrate that the modelling approach used in this study can reveal meaningful insights by improving understanding of how the same attribute could behave differently for NAF and AF vehicles. For example, factors found to be associated with increased probability of more severe injuries of NAF vehicle occupants are inattentive driving, left-turn movement, heavy vehicle type of the AF vehicle, and angle and rear-end impact type; conversely, for AF vehicles, their probability of more severe injury is positively associated with inattentive driving and heavy vehicle type of the NAF vehicle, and angle and approaching impact type.

Comparison of crash rates and rear-end striking crashes among novice teens and experienced adults using the SHRP2 Naturalistic Driving Study

ABSTRACTObjective: Motor vehicle crashes are the leading cause of death for teens. Previous teen and adult crash rates have been based upon fatal crashes, police-reported crashes, and estimated miles driven. Large-scale naturalistic driving studies offer the opportunity to compute crash rates using a reliable methodology to capture crashes and driving exposure. The Strategic Highway Research Program 2 (SHRP2) Naturalistic Driving Study contains extensive real-world data on teen and adult driving. This article presents findings on the crash rates of novice teen and experienced adult drivers in naturalistic crashes.Methods: A subset from the SHRP2 database consisting of 539 crash events for novice teens (16–19 years, n = 549) and experienced adults (35–54 years, n = 591) was used. Onboard instrumentation such as scene cameras, accelerometers, and Global Positioning System logged time series data at 10 Hz. Scene videos were reviewed for all events to identify rear-end striking crashes. Dynamic variables such as acceleration and velocity were analyzed for rear-end striking events. Number of crashes, crash rates, rear-end striking crash severity, and rear-end striking impact velocity were compared between novice teens and experienced adults.Results: Video review of the SHRP2 crashes identified significantly more crashes (P < 0.01) and rear-end striking crashes (P < 0.01) among the teen group than among the adult group. This yielded crash rates of 30.0 crashes per million miles driven for novice teens compared to 5.3 crashes per million miles driven for experienced adults. The crash rate ratio for teens vs. adults was 5.7. The rear-end striking crash rate was 13.5 and 1.8 per million miles driven for novice teens and experienced adults, respectively. The rear-end striking crash rate ratio for teens vs. adults was 7.5. The rear-end striking crash severity measured by the accelerometers was greater (P < 0.05) for the teen group (1.8 ± 0.9 g; median = 1.6 g) than for the adult group (1.1 ± 0.4 g; median = 1.0 g), suggesting that teen crashes tend to be more serious than adult crashes. Increased rear-end striking impact velocity (P < 0.01) was also observed for novice teens (18.8 ± 13.2 mph; median = 18.9 mph) compared to experienced adults (3.3 ± 1.2 mph; median = 2.8 mph).Conclusion: To our knowledge, this is the first study to compare crash rates between teens and adults using a large-scale naturalistic driving database. Unlike previous crash rates, the reported rates reliably control for crash type and driving exposure. These results conform to previous findings that novice teens exhibit increased crash rates compared to experienced adults.

Reduction of whiplash injury in rear-end automotive collision using linear damping seat

Automotive rear-end collisions cause neck injuries. This has become a major problem in traffic safety over the last two decades. The situation calls for more research in the field. The damping seat slide is one area of interest which is used for reducing neck injury. To reduce neck injury (whiplash), based upon new biomechanical research, the motion between head and torso should be reduced. In case of a rear-end impact, a new seat will slide backwards during the impact, which allows the motion to damp. Working Model software was used first to simulate and analyse the behaviour of the new system. Also, a test rig was developed for experimental purposes. The results show occupant protection increases with the new damping seat slide by reducing the neck injury criterion by 35%.

Vestibular evoked myogenic potentials in evaluation of whiplash syndrome disability

Objective: Whiplash is an acceleration-deceleration mechanism of energy transfer to the neck that may result from a rear-end or side impact, predominantly in motor vehicle accidents but also from other mishaps. Vertigo and dizziness after whiplash injury are the most frequent, persistent and disabling symptoms, even in the absence of anatomical and cervical spine damage. Vestibular disturbances in whiplash patients have been widely investigated; nevertheless, physiopathology of vertigo and dizziness still remains an unsolved problem. The aim of our study was to demonstrate that cVEMPs (cervical Vestibular Evoked Myogenic Potentials) represent a valid and non-invasive technique able to investigate vestibular function, in particular the vestibulo-collic reflex and macular function. Study design: We examined 25 patients affected by disabling post-whiplash injury by means of audiovestibular tests: audiometric and impedance tests, nystagmus evaluation, caloric test, dynamic posturography and cervical VEMPs. Data obtained were compared with those of a normal control group. Results: Audiological tests, impedance tests, nystagmus evaluation, and caloric tests were normal in all patients. Comparison of dynamic posturography values obtained in whiplash patients and in the normal control group demonstrated significant differences in the Composite Equilibrium Score and Visual Component. Finally, cVEMPs were bilaterally absent in 72% of patients, unilaterally absent in 16% and present in 12%. Conclusions: Based upon neurophysiological evidence and our results, we can hypothesize that a concussion of the macular receptors takes place and that the maculae are more sensitive than the ampulla or cochlea receptor to this kind of injury. We conclude that cervical VEMPs represent a valid and non-invasive technique to evaluate disability after whiplash injury.