Lockjaw, or jaw trismus, is a medical condition characterized by the sustained, spasmodic contraction of the jaw muscles, making it difficult or even impossible to open the mouth normally. This can severely compromise one’s ability to eat, speak, yawn, and maintain oral hygiene, significantly affecting daily activities and necessities, including dental care.
Historically, lockjaw was predominantly associated with tetanus, a serious bacterial infection that compromises the nervous system, leading to a critical reduction in the ability to open the jaw. Although tetanus has become rare in the United States, the term “lockjaw” is still widely used to describe the experience of restricted mouth opening.
While the historical association of lockjaw with tetanus provides a backdrop for understanding its severity, there are many more common reasons why an individual may experience profound and lasting limited jaw opening.
The Connection Between Lockjaw & Temporomandibular Disorders (TMD)
As an Orofacial Pain Specialist, one of my goals is to help patients understand that temporomandibular disorders encompass a broad spectrum of conditions affecting the temporomandibular joint (TMJ) and the muscles responsible for jaw movement.
Symptoms commonly associated with TMD include jaw pain or discomfort, jaw muscle soreness and tightness, headaches in the temples, difficulty chewing, audible clicking or popping sounds when moving the jaw, bite changes, tooth pain absent of dental abnormalities, and limited jaw mobility.
Pain, joint noises, and limited jaw motion are the most common symptoms experienced by the patients we see. When limited jaw motion is experienced, there can be multiple origins.
Common Causes of TMD and resultant limited jaw motion
- Traumatic Events:? Incidents such as sports injuries, car accidents, acts of violence, medical or dental procedures requiring extended mouth opening, intimate activities, or unexpected diet-induced injuries can lead to muscle trauma or direct damage to the TMJ structures, including ligaments and the cushioning disc.Such trauma can initiate a cascade of inflammatory responses, protective muscle reflexes by the brain, and structural instability/anatomic restrictions in the joints, all leading to restricted jaw movement.
- Neck Injuries:? It’s critical to recognize that injuries involving the neck muscles and nerves can gradually cause jaw muscle tension, pain, and significant limitation in jaw motion due to the interconnectedness of the jaw and neck nerve networks. Persistent neck pain and inflammation can, at times, lead to jaw movement restriction as?a result of the jaw muscles shortening because of nerve excitation in the neck.
- Repetitive Minor Traumas:? Daily habits and acquired behaviors such as excessive gum chewing, nail, cuticle, lip, and chin biting, as well as tooth clenching and jaw muscle bracing without tooth contact, can overwhelm the jaw muscles’ and TMJs’ ability to adapt.As a result, muscle fatigue, shortening, soreness, and inflammation can result, along with joint inflammation and ligament sprains, all contributing to limited jaw motion.
- Emotional Stressors:? Anxiety and worry alone can cause the muscles of the jaw and neck to shorten, often observed in patients going through difficult life circumstances. As a result, these patients who are already concerned about life challenges now have another problem to worry about: limited jaw motion. The ability to control these emotional stressors is often difficult, leading to stubborn symptoms despite supportive care.
- Medication Side Effects:? Over the past decade, we’ve noted a rise in patients presenting with limited jaw motion linked to jaw muscle tension induced by medications aimed at treating ADD and ADHD. Though these medications are well tolerated by the vast majority of individuals taking them, some patients get into trouble within a few weeks or months of drug use. Common medications in this group include Concerta?, Adderall? Ritalin?, Stratera and Vyvanse?. Although often not solely responsible for the onset of limited jaw motion and pain, this group of medications should be recognized as significant risk factors.
- Sleep Bruxism:? The correlation between nocturnal teeth grinding and the onset of TMDs is a subject of ongoing research. While millions engage in sleep bruxism without developing any jaw-related disorders or jaw motion issues, a subset of individuals do exhibit symptomatic manifestations. Some patients simply wake up with jaw pain and soreness, while others have limited jaw motion. Other patients can wake up with a locked jaw because the protective disc in the joint slips out of place as a result of unstable ligaments giving way to the forces of bruxism activity. The limitation commonly results from the jaw muscles being overworked by bruxism activity with a resultant depletion of the energy source ATP necessary to sustain normal function.Note: As the origin of sleep bruxism appears to be related to arousals in the CNS, controlling the arousals and or dampening the impact of the resultant bruxism remains the focus of treatment at this time.
Medical and Dental Conditions Contributing to TMD
Diverse medical and dental conditions can impact the jaw muscles and temporomandibular joints, leading to pain and limited jaw motion; all forms of arthritis (such as osteoarthritis, rheumatoid arthritis, and psoriatic arthritis), movement disorders (e.g., oromandibular and cervical dystonia), ?various pathologies affecting the head and neck regions (like tumors) or the effects of radiation therapy can prompt the jaw muscles to guard and even scar limiting jaw motion.
Infections, particularly those involving dental structures like wisdom teeth, can lead to restricted jaw motion, and complications following dental anesthesia (post-injection trismus) represent additional factors that lead to restricted jaw motion and the need for a careful evaluation process.
Post-injection trismus, which is most commonly the result of an inferior alveolar nerve block, is a condition that, though rare in its occurrence, leads to the most profound jaw limitations that can last 3-12 weeks before resolving.
Conclusion and Clinical Approach
To summarize, the restricted ability to open the jaw, commonly called lockjaw, can have many origins. A thorough investigation often requires a detailed patient history, comprehensive examination, and appropriate medical imaging or testing to arrive at an accurate diagnosis.
This multidimensional approach underscores the necessity for practitioners to maintain a broad perspective while assessing and managing patients presenting with symptoms indicative of lockjaw or TMDs.
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At New York TMJ & Orofacial Pain, we highly value the insights and experiences of our professional community. Please share your thoughts, clinical experiences, or questions about lockjaw and TMD management in the comments section below—let’s learn and grow together!
