You’re waiting at a stoplight when it changes from red to green. You hesitate and then, out of the blue, crunch! You feel the impact of a car colliding with yours from behind. Your head jerks back, and then snaps forward. It’s whiplash!
In technical terms, whiplash refers to the sudden transfer of energy that causes the structures of the neck to abruptly straighten and bend beyond their normal range of motion, potentially resulting in an injury. A car accident is the most common scenario, but it’s not the only one. Many kinds of falls, the jerking movement of amusement park rides, and blows to the face can also create the whiplash motion and its related injuries.
Many recover, although it may take awhile — weeks, even months. But about half of those affected continue to have neck pain a year or more later, and about 10 percent may end up with chronic pain that interferes with work and everyday life.
Whiplash injuries invite skepticism. How can a fender bender result in chronic, even debilitating pain? Imaging tests don’t necessarily show anything. And there’s some good evidence that insurance and lawsuit settlements do, in fact, encourage some people to exaggerate and invent whiplash injuries.
Yet, whiplash is a real phenomenon with real effects. Researchers have identified a critical moment during a whiplash accident that may have catastrophic consequences for the neck. This insight may lead to the design of headrests that will prevent more injuries. Meanwhile, whiplash patients continue to seek effective treatments, often trying a variety of remedies in search of relief.
The S-Phase
It was long believed that the initial jolt jerked the head and neck back, and then they snapped forward. Now, high-speed cameras and other instruments have shown that there is a critical moment or two before that back-and-forth motion. When your car is hit from behind, your trunk is pushed forward by the force from the rear impact. As a result, your head moves both back and down. That motion bends the vertebrae in your upper neck back while those in the lower neck move forward. Seen from the side, your neck momentarily looks like an S, as the upper and lower areas of your neck are unnaturally forced in different directions (see illustration). Researchers now believe that this “S phase” of whiplash is when injury is most likely to occur, as the muscles, ligaments, and joints strain to hold the vertebrae together against opposing forces. The S-phase is quickly followed by the classic whip-like action of your head and neck. This entire sequence occurs within the first second after impact.
Headrests Help
Whiplash injuries often occur during low-speed collisions, but low speeds translate to a lot of force. For example, if you are sitting in a stationary car that’s hit from behind by a car moving at just 10 miles per hour, the force from the collision can briefly put 9 Gs of force on your neck (a G is the gravitational “pull” of the earth). It’s not difficult to imagine how one or more structures of your neck could be injured under these circumstances.
Since headrests were first mandated for passenger cars in the United States over 40 years ago, the risk of neck injuries following rear-impact collisions has fallen by almost 20 percent. Studies suggest that proper adjustment of headrests could make even more of a difference.
Improved Imaging Tests
Typical whiplash symptoms include pain in the neck, jaw, shoulder, or arm; headaches; dizziness; ringing of the ears (tinnitus); and sometimes difficulty with memory and concentration.
Sometimes, there is a psychological component. Research suggests that a person’s fear of re-injury may lead to a physical reaction known as muscular bracing, in which the body holds itself in a rigid posture in an effort to protect the injured area from further pain. Unfortunately, muscular bracing only prolongs recovery.
Imaging studies such as x-rays or computed tomography (CT) or magnetic resonance imaging (MRI) scans may not be done right away unless the doctor suspects damage to the nerve roots or spinal cord, which can lead to permanent disability. Acute whiplash neck pain is often caused by strains and sprains of the soft tissues (muscles, tendons, and ligaments). Many strains and sprains don’t show up on most standard imaging tests, and they usually resolve within a few weeks or months with the help of some pain relievers, stretching and strengthening exercises. If symptoms don’t improve, imaging tests may be ordered to see if one of the vertebrae might have been fractured or a nerve compressed. Imaging tests can also show if the disks that separate the vertebrae are protruding and out of place.
What has frustrated doctors and patients alike is that in many whiplash cases, imaging studies cannot identify the source of chronic pain. Some people with persistent pain have perfectly normal imaging test results, while others whose imaging tests show abnormalities are pain-free. So, it’s not as straightforward as one might think to link an imaging abnormality to symptoms, let alone to whiplash trauma.
Improvements in imaging technology are beginning to clear up some of the ambiguity. In a study published in the journal Spine, researchers used high-resolution MRIs to look at the cervical spines of patients with a history of chronic pain whose post-whiplash x-rays were normal. They found significantly more damage to soft tissues, particularly ligaments, in the whiplash patients, compared with patients who had no history of neck injury. Furthermore, the amount of damage correlated with the patient’s self-reported assessments of pain and ability to perform everyday activities.
Doctors have other ways of locating the cause of chronic pain from a whiplash injury. If it is due to damage in the nerve roots, an electromyography (EMG) could prove valuable as a diagnostic tool. If the pain is coming from an injured facet joint — facet joints are where vertebrae connect — the doctor may inject a local anesthetic into the nerve that supplies that joint. If the patient is free of pain after the injection, that’s a good indication that the facet joint is the source of the problem. By some counts, facet joint injuries are the most common source of whiplash-related neck pain.
Less Time In The Collar
In the first couple of days after a whiplash accident, ice packs and over-the-counter pain relievers like ibuprofen or naproxen can help with pain and swelling. Sometimes, doctors will prescribe a short course of a narcotic pain reliever, an antidepressant, which at lower doses provides pain relief, or a muscle relaxant.
The iconic image of the whiplash patient wearing a bulky collar to hold the neck steady is out of date. Studies have shown that cervical collars don’t help recovery and may even interfere with it by causing neck muscles to atrophy. Still, they may be helpful for short periods, relieving pain by taking the weight of the head off the neck and redistributing it to the shoulders. Some patients will wear a neck collar for longer stretches during the night if it helps them get a good night’s rest.
Gentle stretching exercises that involve turning the head from side to side and in other directions are often prescribed. Heat packs used before exercising can help relax joints and muscles. Other sorts of exercises can strengthen muscles, so they take some of the strain off vertebrae and disks, and give damaged tissue an opportunity to heal.
Passive pain-relieving treatments such as ultrasound, transcutaneous nerve stimulation, and low-level laser therapy may also provide short-term relief but should be done as part of a physical therapy program.
Many people swear by chiropractic treatments. However, in well-controlled studies, chiropractic manipulation hasn’t been shown to be any better at relieving neck pain than conventional treatments such as physical therapy and neck exercises. And some doctors advise against chiropractic manipulation for neck pain because of rare but serious complications.
What about massage? Its effectiveness for neck pain is still unclear but results from a review of 19 trials did suggest that massage is safe. It may help promote healing by relieving muscle tension and spasms, loosening stiff joints, and promoting relaxation. And besides, what can feel better than a nice massage — whiplash or no whiplash?
Sources: • “Neck pain,” Mayo Clinic Health Information, Nov. 2009
• “Whiplash: The harm may occur just before the neck jerks back and forward,” Harvard Health Publications, Sept. 2009