Experimental pathologists renowned for their work on severe neck injury have been developing and validating a whiplash-simulation model incorporating a fresh, intact cadaveric neck 1.
In one of their initial experiments, they
showed the primary and most severe distortion of the neck to be S-shaped
2,
with lower hyperextension and upper flexion.
|
PRACTICE POINT Vertebral artery injury less severe than that producing whiplash stroke may cause commoner Whiplash Associated Disorders |
In
another experiment 3,
they replaced a vertebral artery with #3 a nylon-covered wire attached
to a special transducer. Whiplash forces of variable severity caused significant
stretching of the right vertebral artery with left lateral flexion
and particularly left axial rotation, but not in simple flexion
or extension.
|
PRACTICE POINT Reduced regional blood flow (SPECT) and metabolism (PET) in the brain accompany neck pain and cognitive difficulties |
In some regions of the brain, both blood flow (Single Photon Emission Computed Tomography, SPECT) and metabolic activity (Positron Emission Tomography, PET) are significantly reduced after whiplash injury.
A
new study 4
has confirmed the parieto-occipital
(also see Medical Litigation News Volume
2, Issue 2) and abnormalities which distinguish whiplash patients from matched
controls. The authors propose a reflex mechanism arising from pain detectors
in the neck.
|
PRACTICE POINT Velocity-dependent clinical signs developed in whiplash volunteers examined at 24 hours |
Magnetic Resonance Imaging (MRI) and Motor Evoked Potentials (MEP) were not useful for investigating early or late whiplash 5, 6.
However, in 13 late whiplash patients with cognitive abnormalities and psychological problems, metabolic (PET) abnormalities (frontopolar, lateral temporal cortex, putamen) were significant for the group 7, though they were not sufficiently reliable for diagnosis in the individual patient. These abnormalities correlated with scores on the Beck Depression Inventory.
Not only characteristic Whiplash Associated Disorder (WAD) symptoms, but also de novo appearance of objective clinical signs were demonstrable at 24 hours in 42 volunteers subjected to experimental rear-end collision 8. There was a significance difference in presence, severity and duration WAD between 4 km/hour and 8 km/hour velocity change.
Subtle
abnormalities of balance and
posture after whiplash injury have been characterised and further clarified
9
using computer analysis of posturography.
|
PRACTICE POINT Abnormal posture and balance, and deficits of divided attention, may be characteristic of Whiplash Associated Disorder |
Other workers have shown deficits of divided attention in neuropsychological tests of whiplash patients both with 10 and without 11 reduced posture control.
The benefits of high dosage corticosteroid therapy, previously proven in spinal cord injury, were explored in whiplash patients.
Even short-term corticosteroid therapy is not without material risk but it is commonly used with good effect in a variety of noninfective inflammatory conditions.
In
this pilot study 12,
methylprednisolone therapy was initiated within 8 hours of whiplash injury.
At review six months later, there was a significant improvement in disabling symptoms,
total number of sick days and sick leave profile.
|
PRACTICE POINT A course of corticosteroid therapy started within hours of whiplash may significantly reduce disability |
In an elegantly simple Norwegian study 13, matched whiplash patients were randomly allocated to either 14 days’ cervical collar plus sick time or encouragement to return immediately to normal activities. At 6 months, the "ignorers" were significantly better symptomatically.
German research workers similarly compared 3 weeks’
collar immobilisation with immediate physiotherapy and found the health
of actively treated whiplash patients similar to normal controls at 3 months 14.
|
PRACTICE POINT Studies continue to show that cervical collars and immobilisation are ineffectual and counterproductive |
After a year of disabling whiplash-associated headache, 30 days of home traction resulted in dramatic improvement 15. Although single-case studies are of very limited value in Evidence Based Medicine, such innovative therapy may usefully contribute to the debate about the mechanisms of specific late whiplash symptoms.
Belgian psychiatrists 16, using a recently developed test of short term memory concluded that malingering was prevalent among whiplash litigants, twice as common as in nonlitigant patients.
Though they found the performance level of litigants to be comparable with those of head-injured patients, the authors cautioned against attributing cognitive deficits to organic brain damage.
Instead, they frequently found
evidence that chronic pain, chronic fatigue and depression
better explained the poor mental functioning.
|
PRACTICE POINT In Whiplash Litigation, psychiatric assessment should be routine for: 1. Malingering |
The rosy outlook of the much-lauded and unashamedly defence-oriented Report of the Quebec Task Force on Whiplash Associated Disorders is counter-intuitive.
The authors
of a recent paper 17
submitted the Report to methodological critique and found it wanting to such a
degree that the conclusions were meaningless. One of the severest
criticisms is that these conclusions are incongruous with the literature the Task
Force is purported to have reviewed.
1.
selection bias |
In a recent epidemiological paper
18
from Quebec’s McGill University, half of over 3000 whiplash patients had no other
injury. Speed of recovery, as measured by duration of compensation, correlated
with various factors easily determined at the time of the accident.
|
PRACTICE POINT Poorer prognosis - socio-demographic: 1. female
|
Accident
victims with 0-2 factors recovered in an average of 19 days, whereas those with
6 or more had a median compensation period of 71 days.
|
PRACTICE POINT Poorer
prognosis - crash-related: 5.
in a truck or bus |
A
more modest but still substantial Australian study 19
identified three factors which significantly altered the prognosis of whiplash
in drivers. Here occupation was not an independent variable.
|
PRACTICE POINT Poorer prognosis - driver: 1. history of neck
injury |
An English team showed that psychological
abnormalities are largely a result rather than a cause of WAD 20.
By a week after injury, psychological scores were normal in four-fifths, but became
abnormal in four-fifths after 3 months, and remained so for 2 years in 70%.
Neck stiffness and psychological profile at 3 months were powerful
predictors of disability status at 2 years.
|
PRACTICE POINT At least 60% of psychological abnormality is the result, not the cause, of WAD |
Another Australian study 21 came to similar conclusions in sufferers from whiplash-associated headache. Their psychological profiles were closer to those of patients with other types of traumatic headache or whiplash neck pain but no headache, and of normal controls, than to the profiles of non-traumatic headache patients.
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