Causal Relationship of Bell’s Palsy and Temporomandibular Joint Dysfunction
(Primary Suspected Cause Of Bell’s Palsy)
Mark W. Ericsson D.M.D.
Bell’s Palsy, also called “Idiopathic Facial Paralysis” is a relatively rare affliction (fewer than 200,000 US cases per year). It is a frightening condition of rapid onset which paralyzes half of the face. Many theories of its cause over the years have been purported. In this paper, I will outline my personal theory of what I believe causes most cases of Bell’s Palsy in human populations.
I have been a practicing dentist in Boca Raton, Florida for over 32 years (Ericsson Dental.com) During that time, my practice has focused on Full Mouth Dental Reconstruction. During this tenure, I have restored and re-engineered a great number of these cases which were coincident with Temporomandibular Dysfunction (TMD). This overlap led me to incorporate treatment of Temporomandibular Dysfunction into my restorative practice. Interestingly, some patterns involving Bell’s Palsy began to emerge in our experience. We began to notice a significant coincidence of TMD and Bell’s Palsy. Given the rarity of Bell’s Palsy, I consider this observation to be highly significant, potentially groundbreaking, and important. It is my belief that Bell’s Palsy and TMD share a common link: inflammation.
Temporomandibular Joint Dysfunction is caused by a number of factors. The Temporomandibular Joint (TMJ) is an articulating joint like many others in the body. Simplistically, it is a “ball and socket” type mechanism with a “washer” (cartilaginous disc) in between. This Joint allows us to move the lower jaw in relation to the skull and provides our ability to speak and masticate food. The movements of the TMJ are controlled by a group of muscles. When a single or multiple causative factors cause TMD, inflammation occurs in the TMJ and surrounding muscle groups. Inflammation from these muscle groups can then spread to other surrounding nerves, blood vessels, and muscle groups. It is well documented that TMD causes migraine headaches, neck aches, back aches, ear aches, tinnitus, deafness, restricted opening, deviated opening, and jaw aches. It has been my observation that many of these symptoms are coincident with TMD AND Bell’s Palsy. Consistently, It is also notable that TMD symptoms AND Bell’s Palsy are often predominant unilaterally. When I diagnose a case of TMD, I routinely mention to the patient that I believe they are at increased risk for Bell’s Palsy because of their TMD. Interestingly, In response, I sometimes get a look of disbelief and they notify me that “I already had Bell’s Palsy”. Given the rarity of Bell’s Palsy, I believe the coincidence of Bell’s Palsy and TMD observed in my practice over the last 32 years to be highly significant.
After observing a significant clinical coincidence of TMD and Bell’s Palsy, I sought a physiological rationale for this fascinating finding. I believe I have found the explanation. Multiple factors and characteristics in the human dentition and/or jaw trauma can cause TMD. However, to limit the scope of this discussion, I will focus on TMD as an inflammatory process of the TMJ and surrounding muscle groups. It has been long understood and accepted that inflammation in the body spreads. The nerve that becomes paralyzed in Bell’s Palsy is called the Facial Nerve. Before the Facial Nerve innervates the face, the main motor portion of facial nerve exits the skull through the Stylomastoid Foramen. This foramen is very narrow in diameter and is in close proximity to the TMJ. It is my belief that inflammation originating and spreading from TMD to the neurovascular supply of the facial nerve is the primary cause of Bell’s Palsy. The narrow diameter of the Stylomastoid Foramen is unforgiving of an inflamed Facial Neurovascular Supply and causes a constriction of the nerve and resulting paralysis. Supportively, Bell’s Palsy is widely known to be associated with an “inflammation” and swelling of the facial nerve within the facial canal or at the stylomastoid foramen.
Why has TMD not been widely recognized as a cause of Bell’s Palsy? Because of the rarity of Bell’s Palsy and the wide information disconnect between the medical and dental communities. In addition, diagnosis of TMD is often goes undiagnosed in the dental profession. On multiple occasions, patients in our office that we diagnosed and treated for TMD, had previously undergone tens of thousands of dollars in extensive medical tests only to find out in our office their symptoms were TMD related. The medical community needs to include TMD in their differential diagnoses before needlessly exposing patients to the expense and harmful ionizing radiation from diagnostic scans. In our office, we implement the simplest and most effective treatment solutions first. Most cases of TMD are easily diagnosed and economically treated in our office. Results are often achieved within a few days. When treating TMD, our approach is to address the causative factors promptly. Similarly, our recommendation to Bell’s Palsy sufferers is to address coincident TMD as soon as possible or preferably before Bell’s Palsy is diagnosed. Without treatment of underlying TMD, I believe Bell’s Palsy sufferers are at high risk for recurrence. In my opinion, following any diagnosis of Bell’s Palsy, virtually every patient should be evaluated for Corticosteroid Therapy and TMD Treatment as soon as possible. Simple cold compresses to the back of the neck and TMJ should also be applied as soon as possible. It is notable that Antiviral Medications (such as Acyclovir) are no longer recommended regimen for Bell’s Palsy as they are found to provide no added clinical benefit. Perhaps this lack of efficacy is an indictment of purported Viral Etiology in Bell’s Palsy patients.
I believe effective resolution of underlying causative TMD in Bell’s Palsy serves to resolve Bell’s Palsy dysfunction more completely and more rapidly. In addition, in my opinion, effective TMD treatment aids in reducing the risk of Bell’s Palsy recurrence. Contributing risk factors for Bell’s Palsy are the diameter of the stylomastoid foramen relative to the facial neurovascular supply and the severity of the underlying TMD inflammation.