Whiplash is caused by the rapid back and forth motion that occurs in the classic rear-end collision, in some sports, and during slip and falls. The initial symptoms associated with whiplash often include muscle tightness and pain. But where is the pain coming from?
First, the mechanism of injury that is involved in a rear-end collision is important to understand. In the first 50-100 milliseconds, the body below the neck is pushed forward in relation to the neck, resulting in straightening of the neck. Between 100-200 msec, the lower half of the neck extends while the upper half flexes, after which the head accelerates backwards, where it is hopefully stopped by the head rest. This is followed by a forward rebound where the head and neck accelerate forward, hopefully limited by the seat belt and/or air bag. This entire event is completed within 300msec, which is faster than what we can voluntarily brace or guard against, even if we see it coming!
Factors that contribute to injury that are more difficult to calculate include the angle and springiness of the seat back, the position of the headrest, the build of the person (tall slender females are at greater risk than a husky male), whether the head was turned at the point of impact, the slipperiness of the road, the size of the two vehicles, etc.
So what’s causing your pain? Is it muscles, ligaments, or something else? There are many symptoms associated with whiplash and hence the term ‘whiplash associated disorders’ or WAD that is applied to these cases. There are four categories of WAD: 1) few symptoms/no exam findings; 2) more symptoms/positive exam findings but no nerve pain; 3) nerve pain—numb/tingling and/or muscle weakness; and 4) fracture/dislocations.
The term “cervical sprain/strain” refers to ligament/muscle injury, respectively. Muscles move bones and joints and are more elastic while ligaments firmly hold two bones together at a joint. The muscles attach to bone by tendons, and a strain refers to a muscle and/or tendon injury. Both sprains (ligaments) and strains (muscle/tendon) are graded as one, two, and three or, mild, moderate, and severe, respectively, depending on how much tearing occurs. The rate of healing is dependent on the amount of tearing and how “nice” you are to it after injury. Pain can last a long time if you keep “picking at the cut” or in other words, not respecting the healing process.
What makes the neck so unique are the many layers of muscles that exist. Like an onion, there are layers upon layers of muscles that do different jobs, but unlike an onion, these muscles run in many different directions. The muscles on the outside tend to be long, large, and strong while the deep ones are short, small, and are important with fine motor control and coordination. The deep muscles are NOT voluntary (the larger/stronger outside muscles are), so to exercise them, we have inhibit the outside muscles to get the deep ones to work. The deep neck flexor muscles are always weak in those of us with neck pain (from any cause) and need to be isolated and strengthened in order to feel and function better.