CC
A 37-year-old female presents to the office reporting a sudden onset of reduction in mouth opening and jaw pain.
Temporomandibular joint dysfunction (TMD) refers to any signs and symptoms that are attributed to pathologies of the temporomandibular joint (TMJ), the masticatory muscles, or associated structures. Internal derangement of the TMJ is a commonly diagnosed disorder under the umbrella term that is TMD, and it is most frequently seen in females.
HPI
The patient reports a sudden lancinating pain in her left jaw followed by an inability to open her mouth that occurred while eating lunch. The pain is 8 of 10 on the visual analog scale. It gets worse with jaw function, including chewing and speaking. She describes a longstanding “click” in her left joint for many years. She also reports feeling generally sore in her jaw when she wakes up in the morning. She denies any history of trauma. There have been no prior episodes of locking. Her mouth opening has significantly decreased since this incident. There are no associated headaches. Her husband has told her she grinds and clenches her teeth at night, but she does not wear an occlusal splint.
PMHX/PDHX/medications/allergies/SH/FH
Her medical history is not significant.
Examination
The patient appears well and is in no apparent distress.
She is orthognathic in appearance and has balanced facial proportions. The ear canals are both patent, and the tympanic membranes are normal. There is considerable pain to palpation of her left TMJ. There is no tenderness to her muscles of mastication on firm palpation. Palpation of her joints reveals no clicking. Her maximum incisal opening is 12 mm. Normally, an opening click occurs when the condyle captures an anteriorly displaced disk, and the reciprocal click happens during closure when the condyle returns behind the anteriorly displaced disk. In the case of a nonreducing disk, the condyle merely rotates and does not translate beyond the articular disk.
The intraoral examination reveals a class I occlusion with a normal overbite and overjet. There are significant wear facets and craze lines on her dentition. These are signs that may point to parafunctional habits such as clenching or bruxism. A Mahan’s test is performed to assess for intraarticular pathology. The test is performed by having the patient bite on a tongue depressor (at the level of the canine), which loads her contralateral joint. Her test result is positive for pain on the left side.
Imaging
The initial radiographic assessment for all patients with TMD should start with a panoramic study. It is a readily obtainable, low-cost, and low-radiation radiograph that can immediately rule out uncommon disorders causing TMD (tumors, fractures, and so on). The panoramic radiograph can provide a good general overview of the bony architecture of the TMJs as well as the entire mandible. In most patients with TMD, the panoramic examination will be unremarkable.
For further assessment of the soft tissues surrounding the TMJ, including the articular disk, a contrast-enhanced magnetic resonance imaging (MRI) is performed. Obtaining this study in open- and closed-mouth views can identify anterior disk displacement (ADD) with or without reduction ( Fig. 67.1 A and B). Areas of inflammation, such as synovial enhancement or joint effusions, can be illustrated on T2-weighted sequences ( Fig. 67.1 C).
Computed tomography scans are often not indicated in patients with internal derangement unless there are suspicions of bony pathology from the initial panoramic study.
In the current patient, the panoramic radiograph revealed grossly normal condyles without any obvious pathologies. MRI revealed left ADD without reduction and limited translation on the open-mouth view. There were also some signs of osseous degeneration and synovitis.
Labs
Routine lab work is not necessary for the workup of internal derangement of the TMJ. If a patient requires surgery, investigations are dictated by underlying comorbidities and often at the discretion of the preoperative clinic after a full history and physical examination.
In the event of a systemic arthritis, a referral to a rheumatologist would be prudent for a thorough laboratory evaluation at time of consultation.
Assessment
The patient was diagnosed with internal derangement of the left TMJ (ADD without reduction), likely from chronic overload caused by nocturnal parafunction.
It is imperative to include the etiology or causative factor as part of the diagnosis because the internal derangement itself is merely a sign and symptom that is attributed to an underlying pathology (nocturnal parafunction). If you get caught in treating only symptoms without addressing underlying causes, then all your interventions will yield less than desirable results.
Many patients have anteriorly displaced disks without any symptoms. It is only when there is a functional impairment that accompanies an abnormally positioned disk that we can diagnose an internal derangement. Functional impairments associated with displaced disks typically include joint pain, limited mouth opening, audible or painful clicks, and locking.
Myofascial pain disorders can often accompany internal derangements and are important to identify because they do not respond to surgical management.
The Wilkes classification of TMJ internal derangements can be used to classify the stage of internal derangement according to their clinical, radiologic, and pathologic findings. In a small number of patients, this staging system can unfortunately represent a natural course of their disease progression. Wilkes Classification System for Internal Derangement of the TMJ is well described and classifies the pathology into five categories. Wilkes I is painless clicking with no locking and no restricted motion. The disc is normal and slightly anteriorly displaced.
Wilkes II has occasional painful clicking and intermittent locking. The disc is slightly anteriorly displaced and reduces on opening. Wilkes III has frequent pain and joint tenderness with headaches and locking causing restricted motion. Wilkes IV has chronic pain, headaches, and restricted motion with crepitus. The disc is anteriorly displaced and does not recapture. Degenerative changes in the condyle and fossa are seen. Finally, Wilkes V has variable pain and joint crepitus. The disc is anteriorly displaced and does not recapture, with significant deformity and degenerative osseous changes.
Treatment
As previously mentioned, internal derangement occurs when there is dysfunction associated with an abnormal disk position. Patients with asymptomatic displaced disks do not have internal derangement and do not require treatment.
It is important to know that most patients with TMD improve with time alone. Therefore, the goal of treatment is to begin with the least invasive therapies with the highest chance of success. First-tier treatment is often referred to as conservative or nonsurgical ( Fig. 67.2 ). It consists of a multimodal approach to target joint load reduction, maintain mouth opening, and reduce the inflammatory process of the TMJ. A soft diet, control of parafunction with occlusal splints, and muscle relaxants can reduce unnecessary load, and home exercises or physiotherapy can prevent reduced mouth opening from intraarticular adhesions. Adding a course of nonsteroidal antiinflammatory drugs targets the joint inflammation and pain. Adjuvant treatments such as massage, warm compresses, and acupuncture have also been reported by patients to relieve symptoms.
