This article is part 1 of a 2 part series. For Part 2, click here.
There have been many statements made about whiplash that are either totally or partially false. Let’s take a look at some of the “FACTS.”
1. Pain is NOT the only symptom: Although neck and/or shoulder area pain is the most common symptom associated with a whiplash injury, look for other symptoms such as (but not limited to) headache, numbness/tingling in the arms, nausea, difficulty swallowing, dizziness, poor concentration, jaw pain, blurred vision, ringing in the ears, and more. Many of these symptoms may not manifest until days, weeks, or months after your collision.
2. Cervical spine injury can occur at low speeds: It doesn’t take a lot of force to inflict injury to the neck. In fact, speeds of only 5-10 mph (~8-16 km/h) can generate significant G-forces to injure the soft tissues (muscles, tendons, ligaments, and disks) in the neck. Factors influencing injury include (but are NOT limited to) vehicles size/weight and speed differential, location of impact direction, head restraint location, seat failure, seat back angle and “spring,” seat back height, surface slipperiness, and more.
3. No vehicular damage does NOT mean no injury: As stated in #2, low-speed collisions can generate enough force to cause injury to the neck. It is important to know that an 8 mph (~13 km/h) rear-end collision may result in a 2 g force acceleration of the impacted vehicle and a 5 g force acceleration acting on the occupant’s head, all within 250-300 msec. after impact. (FYI: 1 g = an acceleration of approximately 32 ft/sec or 10 m/sec.). IF the metal of the car crushes (“plastic deformity”), energy is absorbed and LESS is transferred to the occupants and VICE VERSA! So, to avoid injury, it’s BETTER to have vehicular damage (the opposite of what you’d think)! Studies show a 10 mph (~16 km/h) impact can produce a total collapse of only 2.5 inches or 6.35 cm (mostly to the back bumper). Often, you have to crawl underneath the vehicle to see the damage.
4. An unusual S-shaped curve has been identified during the rear-end impact: There are seven cervical or neck vertebrae which form a 35-40° curve called a lordosis, which is “C-shaped.” In the initial 50-75 milliseconds after impact during a rear end collision, the head remains stationary while the seat moves the torso and rest of the body forwards and for an instance, an “S-shaped” curve is created (flexion in the upper half and extension in the lower half). This abnormal curve occurs BEFORE the head hyperextends backwards POSSIBLY hitting the headrest and then springing forwards (like “cracking a whip”).
5. X-ray CAN prove soft tissue damage: X-rays are often used to “rule-out” a fracture and as a result, they are often initially read as “normal” as radiologists (the specialists who read x-rays) don’t often report on the subtle findings found on the x-ray that may support the presence of a soft tissue injury. As chiropractors, we OFTEN take “stress views,” or flexion and extension x-rays, after the initial painful symptoms improve. Stress x-rays can yield a much better image of how well the ligaments are holding the vertebra together. When ligaments are stretched or torn (just like in a sprained ankle), excessive movement and/or angles can form between the bones, which are often only be seen at the extreme end-points of movement. We can measure the angle formed between the vertebrae and the amount of translation or “slip” that occurs to determine if there is a loss of ligament control which results in excessive motion, increasing the likelihood of future problems.
We will have to resume this interesting discussion next month in “Part 2” of this topic.