Bunketorp O, Jakobsson L and Norin H. Comparison of frontal and rear-end impacts for car occupants with whiplash-associated disorders: Symptoms and clinical findings. Procedures of the International IRCOBI Conference, Gratz (Austria), Sept 2004: 245 –256

OBJECTIVES/METHODS

Swedish investigators aimed to identify symptom patterns and clinical findings for car occupants injured in frontal and rear-end motor vehicle crashes (MVC). They recruited 131 adult patients who presented to two emergency departments with whiplash injury between 1997 and 2001. Subjects completed questionnaires and received clinical, psychological and radiological evaluations shortly after injury, then at three and twelve months. Complete data were available for 125 subjects (48 males).

RESULTS

(1) The mean delta-V was 13 (<5-20) kph in frontal impacts and 8 (<5-30) kph in rear-end impacts. WAD grade II symptoms predominated in both groups at primary assessment. Head rotation at impact was predictive of more severe initial symptoms. Impact severity, determined by delta-V or property damage, was not predictive of neck pain or cervical range of motion (CROM). Indeed there was a trend towards an inverse relationship between delta-V and symptoms.

(2) Sixty-nine subjects (55%) remained symptomatic at one year. Eighteen patients deteriorated between the first and last assessments, the index crash was thought to be the only possible cause of this deterioration in 15 of these cases.

The prevalence of residual problems was twice as high with rear-end crashes than frontal impacts. Age, weight, stature and prior neck symptoms did not influence outcome at one year. Females were more likely than males to have chronic symptoms. Other factors included high initial pain intensity, brachial radiations, reduced CROM (for women) and psychoneurosis. 

Head rotation at impact was positively associated with chronic symptoms. Of 45 subjects with rotation 16 (36%) had non-minor symptoms after one year compared to13 (18%) of 71 without rotation (p=0.037). This association was less significant for rear impact crashes (p=0.18).

(3) Delta-V was not significantly associated with symptom duration, regardless of vector. Of 39 patients injured in MVC at delta-V less than 5 kph, eight (21%) had problems at one year. There was no difference in the prevalence of chronic symptoms according to  delta-V below 26kph. The authors concluded  ‘we cannot specify a delta-V below which it is impossible to sustain a neck sprain with long term consequences’. Case histories are presented for five previously healthy patients with significant symptoms at one year following low speed crashes.

INTERPRETATION

This recent paper shows a high rate of persistent symptoms in patients injured in MVC. Chronicity did not correlate with measures of impact severity. A number of subjects remained symptomatic at one year following crashes with an estimated delta-V of 5 kph (3mph) or less. The data on crash severity may not be reliable, the authors relied on the subjective accounts of the injured parties. There was no corroboration of delta-V by on-board crash pulse recorder in any of the rear-impact crashes. However, there would be little advantage in subjects underestimating the crash severity or impact speed. The authors conclude that human factors (gender, pain intensity, brachial radiations and psychological distress) and kinematics (crash vector, head position) are more reliable predictors of chronic symptoms that estimates of impact speed. Indeed, in crashes causing speed changes of less than  26kph the relationship may be an inverse one.