Shared by: webinfo@chiroviewpresents.com Mandibular Whiplash: The Undiagnosed Injury 4-23-01 James M. Kennedy, DDS, FAGD Facial Pain/TMJ Treatment Centre jmkdds@earthlink.com Mandibular whiplash is a term used to describe the injury to the temporomandibular joints (TMJ) that occurs during accidents that involve cervical whiplash trauma. Often this injury to the TMJ is overlooked in diagnosing and treating the whiplash syndrome. This undiagnosed injury can become the missing component that prevents anticipated patient recovery. When the head is thrown backward during a whiplash trauma, the infrahyoid muscles stabilize the hyoid bone and the suprahyoid muscles restrict the movement of the mandible posteriorly. As the head continues to move backward, the effect of this bracing of the hyoid muscles is to pull the mandibular condyles forward beyond their normal range of motion over the anterior end of the articular eminence. This creates a stretching and injury to the posterior ligaments in the joints causing instability in the relationship of the condyles and the cartilaginous disks within the TMJ's. The head then reverses its movement and moves rapidly forward causing the jaw to be thrown posteriorly into the mandibular fossae. The condyles travel posteriorly faster than the disks resulting in an anterior displacement of the disks relative to the condyles. This further damages the posterior ligaments. The condyles then contact the posterior wall of the fossae injuring the blood vessels, lymphatics and ! other soft tissue structures present there. Hemorrhage and edema occurs within the joint capsule. Mandibular whiplash can occur without the person striking their head or jaw during the accident. Patient symptoms after a mandibular whiplash injury may include: 1. Jaw pain, unilaterally or bilaterally 2. Limited range of motion of the jaw 3. Deviation of jaw on opening to one side 4. Clicking or popping sounds within the TMJ's 5. Masticatory muscle pains 6. Headaches and facial pain 7. Pain behind or around the eyes 8. Ear pain, fullness or hearing changes 9. Vertigo or dizziness 10. Awareness that the bite feels different - the teeth do not fit together properly 11. Tooth pain and sensitivity to hot/cold and chewing The normal measurements for range of motion of the jaw are 48-50 mm on opening, 6-8 mm anteriorly and 10-12 mm laterally right and left. These may vary with the stature of the patient. An easy way to screen for normal jaw opening, is to see if the patient can place the first three fingers of their hand between the upper and lower front teeth when the jaw is fully opened. These fingers should be held parallel to each other in performing this assessment. If the jaw deviates to one side on opening and/or is limited to an opening of two fingers or less than 32 mm then suspect a closed lock of one or both joints. A closed lock is when the disk is out of place and wedged anterior to the condyle preventing it from moving forward during opening. Deviation to one side suggests a closed lock of that side only. Popping or clicking sounds from the TMJ's during movement occurs when the anteriorly displaced disk snaps back on top of the condyle (recaptures) during opening. This can occur on one or both sides. You may also find a closed lock on one side with a recapturing of the disk on the other side. If you suspect that a TMJ injury has occurred the patient should be referred to a dentist who is educated in treating TMJ disorders; not all dentists are competent in handling these problems. A mandibular orthotic appliance (splint) can be placed to separate the teeth and create a new bite relationship. This is done to support the jaw in a position that distracts the condyles from their posteriorized position in the fossae, reducing pain and edema. As healing occurs, adjustments to this orthotic are done to attempt to unlock a restricted joint or to stabilize the disk /condyle relationship in a clicking or popping joint.