Trismus commonly called as “lock jaw”, is a medical condition in which the normal movement of the mandible (jaw) is reduced as a result of sustained, tetanic spasm of the muscles of mastication (Chewing) hence interfering with the patient’s eating, normal speech, swallowing, oral hygiene and in some cases increased risk of aspiration (sucking food into airway) due to impaired swallowing. Intubation through oropharyngeal route may be impossible in patients with significant Trismus. It typically resolves after twoweeks or can be permanent. When its duration is prolonged, Trismus may lead to fibrosis of the TMJ, necessitating directed therapy.
The normal range of mouth opening varies from one individual to the other, with males having a larger mouth opening compared to females. It is usually between 40-60mm and often corresponds to two-three finger breadths when inserted sideways. There are two primary groups of muscles that determine mandibular (jaw) motion viz Temporalis, Masseter and Medial Pterygoid responsible for mandibular elevation (mouth closure). While the Lateral Pterygoid which inserts into the articular disc as well as the neck of the condyle is primarily responsible for depression (mouth opening) of the mandible. The muscles of closure are approximately 10 times more powerful than the opening muscles and are made up slow twitch fibres. This fact is helpful in treatment planning for trismus patients. The muscles of mastication act in antagonism, as neurogenic stimulation of one group causes reflex neural inhibition of the other. In Trismus, while the inciting insult may be unilateral, the reflex activated is bilateral. This necessitates examination of Jaw joints on both the sides.
The causes of Trismus are congenital disorders, Infections, Trauma, Iatrogenic, Neoplasia, Radiotherapy, Temporomandibular disorders, Drugs, Psychogenic and etc. Some important causes are 3rd molar extraction related inflammation, inaccurate nerve block injection procedure, puncturing Medial Pterygoid muscle or vessels, Radiotherapy for head and neck cancer. Infections causing Trismus could be odontogenic (related to teeth) such as Pulpal infections, periodontal infections and Pericoronal infections. Examples of non-odontogenic infection include Tonsillitis, Tetanus, Meningitis, Parotid Abscess and Brain Abscess. Also, disorders involving the temporomandibular joint (TMJ) can lead to Trismus. These disorders are divided into intra articular or extra articular. Intra articular causes include Fibrous Ankylosis, Anchored Disc Phenomenon, Bilateral Anterior Disc Displacement without reduction, Arthritis and Unilateral Condylar Hypoplasia. The extra articular covers all myofascial related causes.
Common characteristics of Trismus
Restricted mouth opening, preventing the 2-3 fingers positioned side by side from fitting into the intercisal space as seen in normal subject. Inability to perform lateral mandible movements often indicates Trismus due to bony TMJ ankylosis.
- Pain during forced mouth opening. Palpation of the masticatorymuscles affected in the acute phase also elicits pain.
- Deviation of the mandible towards the affected side as a result of muscles not functioning properly because of spasms.
- Sensation of muscle tightness, cramping, or stiffness.
- Diffuse facial swelling and fever when associated with infections.
- Speech impairments often referred to as “Hot Potato Voice”.
- Impaired oral intake, mastication and nutrition leading to weight loss. Weight loss may also be associated with neoplastic cause.
- Poor Oral Hygiene, Aspiration and Difficulty in breathing.
How can a Physiotherapist help?
A Physiotherapist can help restore the natural movement of your jaw and improve daily function. In some patients Trismus progresses so slowly that they might not even notice it until they can open their mouth only halfway. Therefore, the sooner you see a Physiotherapist the better it is. The Physiotherapist will review your medical history, conduct examination of your neck and jaw, evaluate your posture and examine TMJ for movements. He might place hishand in the mouth in order to examine the movement. Following examination the he will select appropriate treatments to improve the Jaw movement and relieve pain. Therefore, evaluation remains crucial in order to manage it.
Thorough history is conducted to ascertain the cause and duration of the Trismus. It is diagnosed when the mouth opening is less than 35mm. Measurements are also taken for lateral movements (normal = 8-12mm), protrusion (normal = 10-11mm) and retraction (normal = 0-1mm). These measurements are determined usingthe 3 finger test.
Neck mobility is screened to rule out neck muscle shortening, especially the flexors.Cervical spine and TMJ are interrelated therefore; problem in one can affect the other. A lot of research reports suggest assessment and treatment of cervical spine in patients with TMJ dysfunctions. The upper cervical spine positioning can impact the position of your jaw when you are sitting and thus can impact your chewing. The Physiotherapist will assess your cervical joints and TMJ mobility, range of motion in your neck and jaw, muscle strength and tenderness to palpation.
Examination of posture from bottom to top in order to ascertain precipitating factors and devise the methods to address them. An abnormality in pelvis can lead to problems in the spine (lumbar and cervical) and eventually the TMJ. Therefore, taking all this into considerationdiagnosis and treatment of Trismus will become easier.
Intervention
Role of Physiotherapy remains crucial particularly when Trismusis of extra-articular origin. The objectives of Physiotherapeutic interventions are to Reduce Edema, Soften the scar tissue, Increase the Range of joint Movement, and Increase the strength of muscle of mastication.This may include joint mobilization to the upper neck and/or TMJ, strengthening exercises for the cervical stabilizers, and stretching to muscles of upper neck and those that attach near the TMJ. In addition to the manual therapeutic proceduresadvantage of electrotherapeutic technology can be taken.
Neuromuscular training using various active, passive and resisted movementsplays an important part in facilitating the muscles around TMJ.Physiotherapy includes performingspecial low load exercises which do not exert the TMJ and at the same time strengthen the muscles of mastication and prevent the further loss of muscle strength. In addition the use of Maitland mobilisation (Grade I and II) helps to alleviate pain in the acute phase.
Kinesiotaping and Dry Needling have been used byPhysiotherapists across the globe for Trismus and other TMJ disorders. Through Kinesiotaping we intend to facilitate a particular muscle or a group of muscles and/or inhibit others. Dry needling includes the insertion of fine needles into myofascial structures to help reduce hypertonicity, pain, and inflammation. The Physiotherapist may insert needles directly into the muscles of mastication which include Pterygoids, masseter as well as the joint capsule. He/She may also insert them into the suboccipital muscles (upper neck). Depending on the level of severity, your physical therapist may hook the needles to an electrical stimulation unit to break down the tissue more. Dry needling is a safe and effective way to treat TMJ dysfunctions.
Therapeutic Ultrasound is commonly used as an adjunct to stretching exercises involving the muscles of mastication. This is to bring about an increase in collagen tissue extensibility, decreased stiffness of joint, and to relieve pain and muscle spasm. Its mechanical energy is transferred in the manner of acoustic compression waves to evoke thermal and mechanical physiological changes in the targeted tissue. The mechanical strains of ultrasound provoke biochemical changes which accelerate the tissue repair. The thermal physiological changes include the increment of local tissue temperature, plenty of blood flow and improvement of the flexibility and extensibility of tissue with diminished fluid viscosity.
Low Level Laser Therapy (LLLT) reduces the inflammatory conditions without adverse consequences by lessening pain and swelling and supporting the repair of the tissue. The force of LLLT in treating pain originating from soft-tissue trauma can be attributed to the indirect reduction of edema, bleeding, neutrophil activity, provocative cytokines and enzymatic action. LLLT reduces swelling and subsequent pain resulting in, enhanced tissue repair since lymphatic vessels regeneration is accelerated and the vascular permeability is minimized.
Transcutaneous Electrical Nerve Stimulation (TENS) is a method of electrical stimulation which primarilyaims to provide pain relief by exciting sensory nerve fibres thereby stimulating pain gate system or endogenous opiodsystem. It could be useful in relieving the pain associated with forced mouth-opening exercises aimed at overcoming Trismus caused by muscle spasm, which is associated with prolonged immobilization of the jaws.
Therefore, Physiotherapy is the essence of Trismus management. I have emphasised in the past through various newspaper publications that Physiotherapy as a Science has diverse roles; it plays crucial role in Neurology and Neurosurgery, Cardiopulmonary Medicine, Critical Care, Sports Medicine, Orthopaedics, Paediatrics, Gynaecologyetc. Likewise Physiotherapy has a role to Play in Dentistry too which warrants understanding between Physiotherapists and Dentists in the interest of patient care. Patients with Trismus and other TMJ dysfunctions suffer a great deal and lose their ability to speak, eat and drink and maintain the oral hygiene due to extreme pain and restriction. Experts from both the sides can come together, develop a healthy mutual understanding, explore areas where they can help each other and make concrete efforts to remediate ailments like Trismus. It will facilitate paving way for the implementation of Multidisciplinary Healthcare wherein experts across professions engage themselves in clinical decision making for welfare of thepatients.
(The Author is Physiotherapist, JK Health Services and Former Assistant Professor, Hamdard University Delhi)
