Role of the startle reflex and cervical multifidus in whiplash injury

Low-speed rear-end collisions can generate whiplash injuries, especially when the victim is unprepared for the collision. Neck pain is the most frequent symptom experienced by victims of a car collision, and up to 30% of people injured in a car collision will develop chronic symptoms. In fact 6% of people who develop chronic whiplash from a collision have not returned to work 12 months after the injury. The precise cause of whiplash is not known, but an overreaction in unprepared individuals — known as a startle response — along with the sudden recoil movement of the head, is thought to damage the joints and muscles of the neck.

As an MSFHR-funded post doctoral fellow, Dr. Jean-Sébastien Blouin conducted research that suggested the presence of a startle response when people are exposed to low-speed rear-end collision. Now he is investigating whether the startle response is linked to stimulation of the deep neck muscles, and if activation of these muscles during a collision may increase the risk of injury. With volunteers acting as “crash test dummies,” Blouin is simulating very low speed (1.8 km/hour) collisions to observe their startle response and measure the corresponding muscle activity. He’s investigating the link between a strong startle response during a low speed collision and the development of whiplash symptoms. He’s also exploring if stimuli delivered immediately prior to the collision can inhibit the startle response, possibly providing protection against injury. Findings could contribute to development of a warning device in cars that will help prevent whiplash injuries.