You're in stop and go traffic on the freeway. You're doing 40 mph, then see the brake lights ahead. You slow down. Just as you come to a complete stop, you glance in your rear-view mirror. The person behind you is going too fast to stop in time. You hear the screech of brakes, and brace for the impact: You hear a loud crash of metal, and feel a surge of power push your stopped car forward. You feel your neck arc backwards and your torso sink into your seat. A second later, the car stops, but the built- up energy in your neck causes it to flex forward, then back again like a whip, and finally, silence. You have just experienced a cervical acceleration-deceleration injury, or whiplash.

The amount of damage to the spine from a whiplash accident is determined by several variables. First of all, the mechanics of the crash: the velocity of the vehicles involved; their relative masses, the angle of impact, the position of the seat headrest, whether or not the seatbelt was worn, and the type of bumper. Secondly, the physical factors of the person injured: his or her height, the position of his neck at impact (turned, looking down?), the position of his arms; whether or not he was aware of the impending collision (did he brace before impact, or was he relaxed?), and obviously, his state of health at the time of the accident (history of neck problems?).

A surprising finding in whiplash research is that oftentimes, the speed of the colliding car is not always directly proportional to the amount of injury sustained. One would think that, the faster the car was going, the stronger the whiplash force generated, and thus, the more injury. But that is not the case. One possible explanation has to do with energy absorption. You see, a car body will deform (dent) at a certain pounds per square inch force. When a car deforms from a collision, it absorbs some of the kinetic energy. If a car is subject to a force that is not sufficient to cause a deformation but strong enough to generate significant g-forces to the neck, then it's possible for a lower speed collision to cause more injury than a higher speed collision. Think about race cars: they are designed around this concept: upon colliding with another car or the racetrack wall, a race car will disintegrate (sections will fly off, rather than stay with the frame). If race cars were not designed to disintegrate upon collision, the drivers would sustain very serious injury as they would absorb most of the kinetic energy of the crash.

Whiplash injuries result in soft tissue damage (sprains and strains of ligament, fascia, tendons, and muscles) and vertebral misalignments. The more serious variety can result in ligament rupture, nerve damage, vertebral fractures, ruptured discs, spinal cord injury, hematomas (blood pooling at the surface of the brain), concussion, and temporomandibular joint (TMJ) injury. Shortly after a typical low speed rear-ender car collision, the victim will first feel a sense of shock. The neck will typically not hurt immediately. As the injured soft tissues slowly release inflammatory products (swelling), the internal pressure in the neck joints and muscles increases. This will continue for several hours, eventually peaking at 72 hours post-accident. This is why your neck feels very stiff about 2-3 days after the accident. Victims also typically report fuzziness/ cloudiness in thinking, and fatigue. This is probably due to the stress to the nervous system-- brain, nerves-- from the forces of the accident.

Some victims of low speed car collisions will go the emergency room to rule out serious injury. The on-duty physician will check for brain and spinal cord damage by checking the pupillary reflex and asking the victim to perform some dexterity tests. He/she will examine the internal ear for bleeding. X-rays may be taken to rule out vertebral fracture. If all check out, the physician will prescribe pain medications, muscle relaxants, and instructions to ice the painful areas.

Despite emergency room treatment, victims often find persistent symptoms of neck and back pain, headaches, and sometimes numbness and tingling in the upper extremities weeks after the accident. This is most likely due to altered spinal function due to the forces of the accident. This can affect nerve function and delay soft tissue healing. It is at this point that the victim will seek more intervention care, most often at a chiropractic office. A chiropractor will typically have the whiplash victim fill out a questionnaire that will extract the fine details of the accident-- speeds, forces, angle of collision, body positioning at the time of collision, and so-on. This can provide useful information of the nature of the injury. Motion x-rays of the neck may be taken (flexion, extension) not only to rule out fracture, but to identify vertebral dyskinesia, or abnormal joint coupling (movement). An orthopedic and neurological exam will be done to assess soft tissue structures, joint function, and nerve function (cranial nerves, nerve roots, and peripheral nerves). Of course, the patient's medical history will be taken. Of particular interest will be history of previous major trauma, surgical implants, bone disease, soft tissue disease, history of cancer, diabetes, and heart disease. Then, assuming there are no contraindications to chiropractic care, a treatment plan will be prescribed. This will typically consist of spinal manipulation to restore vertebral alignment and movement; modalities to address acute symptoms, and perhaps massage therapy to reduce scar tissue formation and move out swelling and stagnant lymph. Treatment may be done over several weeks to months, depending on the extent of the injuries. The last phase will focus on rehabilitation, or strengthening and coordination exercises to retrain weakened muscles and nerves.

The bottom line: if you were injured in a car accident and have persistent or residual symptoms such as headaches, neck pain, extremity numbness, or back pain, consult with a chiropractor. Chiropractic treatment can be very effective in treating and rehabilitating whiplash injuries.

Dan W. Perez

Dan W. Perez is a San Francisco Chiropractor