Cervical Acceleration/Deceleration Syndrome (CAD Syndrome)Sudden acceleration/deceleration of the cervical spine is not an easy condition to treat. Degeneration and spondylosis are common outcomes of this type of injury, leading to chronic pain. About 40 percent of all patients with CAD syndrome suffer some type of ongoing, chronic pain with 20 percent having pain that interferes with quality of life. People who have pre-existing degenerative syndromes are more likely to suffer from chronic pain than those without previous degenerative cervical pain.
Some pain can come from the facet joints becoming dislodged or fractured. Accidents as low as 6 mph can result in a change in the dynamics of the cervical spine and chronic pain. It is estimated that 60 percent of the pain from a CAD injury comes from damage to the facet joints. Sometimes, there can be severe damage to the facet joints that doesn’t even show up on MRI scan of the cervical spine. Facet nerve injections and radiofrequency rhizotomies are often used as treatment for these types of injuries. Problems can occur with hypertrophy at the level of the facet joints after trauma that can cause narrowing of the intervertebral foramina and nerve damage if not treated promptly.
In an acceleration/deceleration injury to the neck, the intervertebral disk at C5 to C6 can be damaged—shearing and tearing the annular fibers. The nucleus pulposus can fall out of tears in the annulus. MRI cannot always detect these kinds of injuries. Discography may have to be done if there is suspicion of cervical disc injury that doesn’t show up on routine MRI testing.
Ligamentous injury can happen with acceleration/deceleration injuries to the cervical spine. The ligaments can stretch or tear following a CAD injury. Headaches are a common symptom, especially if the upper ligaments are involved. Lower cervical injuries in which the patient has had a disc surgery usually have resolution of pain and disability. Overall, however, headaches are a common complication of a CAD type injury.
Sometimes muscles are the cause of posttraumatic cervical injuries. One muscle in particular, called the rectus capitis posterior minor muscle is involved in posttraumatic headaches. Trigger points are often found that radiate to the back of the head. The usual treatment involves trigger point injections, stretching exercises and massage therapy. Some people get better with chiropractic manipulation and/or acupuncture. Pain comes when the fascia of the muscle is involved and inflamed. The fascia is usually the location of trigger point pain.
Pain can also be because of injury to the dorsal horn of the spinal cord itself. When these areas are damaged, substance P, GABA and N-methyl-D aspartate (NDMA) is released, which become the source of the pain.
The prognosis of long-lasting cervical pain depends on many factors. Injury to the central nervous system appears to predict chronic pain, especially dorsal horn involvement of the spinal cord. Disc injury, joint injury or nerve injury also predicts the presence of impending chronic pain. Older people with degeneration have a greater chance of having chronic pain than younger, healthier patients.
If the chin is elevated or the neck is turned to one side during a cervical injury, the chances of chronic pain are greater. If the person slouches so that there is a greater distance between the back of the head and the headrest, there is likelier to be a greater acceleration/deceleration injury.
The treatment of acceleration/deceleration injuries involves the judicious use of medications to ease pain to the degree that stretching and other exercises can be undertaken. Biofeedback in neck injuries has been found to be helpful. Chiropractic manipulation helps in some people. Manipulation often breaks up interarticular adhesions and frees up fixed joints. The narrowed nerve foramina can be widened with chiropractic manipulation as well.
Trigger point injection is also helpful in CAD injuries and often relieve areas of inflammation associated with chronic pain. Treatment plans for patients who have CAD injuries need to be individualized to the patient and to what part of the cervical spine has been injured. Pain medications, anti-depressants, smoking cessation, dietary modification, vitamin therapy, and exercise all are good therapies to try.