WHIPLASH STROKE

Both whiplash injury of the neck resulting from a Motor Vehicle Accident (MVA) and Stroke arising from CerebroVascular Accident (CVA) are common causes of disability in affluent societies. When MVA is followed within hours or days by CVA, the potential increase in Quantum often raises the question of Causation.

Usually it is not possible to establish a causal link on a balance of probability, and post hoc ergo propter hoc is fallacious.

Occasionally, however, the stroke can be shown to result from dissecting aneurysm[1], [2] of a vertebral artery - blockage by a false channel in the wall of the artery, of which traumatic tear is a possible cause. If the neurological symptoms arise within minutes or a few hours, probable cause may be established.

PRACTICE POINT

Some strokes following whiplash injury of the neck can be causally related

Less frequently still, the unusual torsional forces of cervical whiplash may fragment a pre-existing atherosclerotic plaque, an aggregation of fatty material and blood platelets which is causing incomplete and symptomless blockage of a vertebral artery. A large enough fragment of plaque may break away and lodge in a smaller but critical artery deep in the brain[3].

Again, a very short delay between MVA and onset of symptoms may combine with circumstantial evidence on diagnostic imaging studies to support a probability of medical causation.

Exceptionally, it has been proposed[4] that a characteristic pattern of traumatic injury to the lining of the vertebral artery has triggered development of a new atherosclerotic plaque that has resulted in a stroke days or even weeks later.