Cervical Disc Disease with Referred Pain to TMJ
For many patients and doctors, issues that may relate to cervical pain are often complex and frustrating. It is not easy to determine why a patient suffers cervical, occipital or temporal pain, determine an accurate diagnosis, or create a successful treatment plan. It is now generally accepted in medicine that back pain accounts for the majority of visits to the physicians’ office on a given day and, second to back pain visits, are visits for painful symptoms associated with the cervical or neck region.
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In this article, I hope to highlight some of the common causes of cervical-related pain and referred pain and present a case report that illustrates the premise of referred TMJ pain from cervical injury.
Bogduk1 and others have stated that approximately half of patients suffering cervical-related pain are as a result of changes with the facet joint. Either hypo- or hypermobility of the facet joint or joints can lead to structural changes that reduce intervertebral joint stability and consequently can cause pain and suffering in some patients. One of the problems associated with the spinal column is that there is not a correlation between imaging findings of anatomical change and clinical pain. Diminished joint space, hypertrophic changes, or osteoarthritic changes do not, in themselves, necessarily indicate the cause of pain in a given patient.
Degenerative change in the spinal column is now recognized as a progressive consequence of normal aging and are common imaging findings in those over sixty five years of age, often without symptoms of pain or limitation. The diagnostic dilemma for the physician then is that he/she cannot rely solely on imaging or other findings alone to confirm or deny a pain generator. Cervical-related painful symptoms may be due to either instability, bony spurs, rupture of the facet capsular ligaments, disc bulging/herniation, or multifidus muscle changes.
Some investigators believe that there may often be the presence of inflammatory mediators responsible for pain at a chemical level when the integrity of the intervertebral disc has been compromised. The leakage of disc contents into the surrounding tissues can cause a chemical inflammatory reaction that is painful.1
If a bulging disc extends to the point that the spinal cord or others tissues are compressed by the disc, then a decision may be made to operate and remove the damaged disc. Such a procedure is an anterior discectomy with a bone graft and fixation with metal plate and screws. While this procedure is commonly performed, about half of the patients operated fail to experience any degree of pain relief. The neurosurgeon is operating to effect spinal stability not to stop the pain of the patient. If pain relief occurs, it is only a side benefit of the stabilization procedure rather than the purpose of the operation. In my community, more than half of all neurosurgical procedures performed by a particular surgical group are anterior cervical discectomy with bone grafting and fixation. The referring doctor and the attending neurosurgeon would certainly like to be able to offer the patient some degree of certainty that a given procedure would offer pain relief but that cannot be stated unequivocally.
Part of the problem encountered in cervical pain diagnosis and treatment is that the cervical spine does not function as separate, individual elements. The facet joints, capsular ligaments, intervetebral discs, vertebrae, and the multifidus muscles2 all work together as an integrated system. So, when one part of the system is negatively affected, the stability of the system is often compromised. For example, a hypo- or hypertrophic facet joint can alter vertebral stability and lead to movement of the cervical disc and result in bulging or herniation of the cervical disc. The loss of joint stability can also lead to bony spurs as a result of uneven pressure, or to osteophytic bars that can form on the anterior or ventral surface of the intervetebral canal wall. The latter is often nature’s way of trying to regain structural stability. An injured interveterbral disc can lead to facet joint changes with more instability. Another scenario could include tearing of the facet capsular ligaments with resulting strain or degenerative change of the multifidus muscle tendons3 that insert on the facet joint capsular ligaments. The result of a cascade of changes in the cervical structures can cause pain that is multifactoral in nature and refer pain to the TMJ and facial structures.
An often unrecognized consequence of intervetebral instability is hypomobility and fatty deposition in the multifidus muscle that does not automatically restore itself after cervical disc surgery.4 Specific exercises designed to restore tone and integrity of the Multifidus muscle can be the key in some cases to help eliminate the symptoms of cervical related pain. It is common to observe pain relief when the exercises have been started, and to see the pain return when the exercise regimen has not been followed to completion. This muscle is very important in the neck and back because it not only acts to bend the spine, but it is primary in maintaining vertebra-to-vertebra orientation and stability. Some researchers believe that the multifidus muscle (see Figures 1 and 2) is the most important muscle of the neck and back due to its core function of maintaining vertebra to vertebra relationship.
An injury in the region of the cervical area presents the examining doctor with a difficult situation. The patient is usually seeking pain relief, but the doctor cannot insure that a procedure will give pain relief if the patient is suffering a bulging cervical disc. The patient, once informed, will often have the procedure with the hope that pain relief might happen even though the surgeon cannot offer hope of pain relief with disc surgery. Fortunately, about half of patients who undergo anterior cervical discectomy with graft and fixation do obtain some degree of pain relief as is evidenced in the case that follows in this article. If the patient’s primary symptoms of cervical and occipital and temporal headache or pain is discogenic in nature, then the discectomy may eliminate or reduce the pain. However, if the pain is facet joint capsule related, then discectomy may not reduce or stop the pain.
A patient may have a C-4 to C-5 and C-5 to C-6 disc bulging with accompanying headache, neck ache and shoulder and hand pain. One may also find that the pain over time (six months or more) may also refer into the TMJ and face area of the affected side. This is not commonly recognized in these cases injured in the C-4 to C-5 and C5 to C-6 areas as the patient’s doctor is often unfamiliar with referral into the spinal nucleus of