Objectives: To review current knowledge and recent concepts of the causes o
f injuries after minor impact automobile collisions and to acquaint those w
ho treat these types of injuries with possible injury thresholds and mechan
isms that may contribute to symptoms.
Data Sources: A review of literature involving mechanisms of injury, tissue
tensile threshold, and neurologic considerations was undertaken. A hand-se
arch of relevant engineering, medical/chiropractic, and computer Index Medi
cus sources in disciplines that cover the variety of symptoms was gathered.
Results: Soft-tissue injuries are difficult to diagnose or quantify. There
is not one specific injury mechanism or threshold of injury. With physical
variations of tissue tensile strength, anatomic differences, and neurophysi
ologic considerations, such threshold designation is not possible.
Conclusions: To make a competent assessment of injury, it is important to e
valuate each patient individually. The same collision may cause injury to s
ome individuals and leave others unaffected. With the variability of human
postures, tensile strength of the ligaments between individuals, body posit
ions in the vehicle, collagen fibers in the same specimen segment, the amou
nt of muscle activation and inhibition of muscles, the size of the spinal c
anals, and the excitability of the nervous system, one specific threshold i
s not possible. How individuals react to a stimulus varies widely, and it i
s evident peripheral stimulation has effects on the central nervous system.
It is also clear that the somatosensory system of the neck, in addition to
signaling nociception, may influence the control of neck, eyes, limbs, res
piratory muscles, and some preganglionic sympathetic nerves.