Signs of temporomandibular joint dysfunction in spinal cord injured patients wearing halo braces: a clinical report.

The halo brace is used to rigidly stabilize with minimal discomfort the cervical spine of the spinal cord injured patient.1 The brace consists of an adjustable aluminum halo ring that is secured to the skull by five skull pins. The ring is attached by four posts to a halo vest worn on the trunk of the patient.(2) Recently, physical therapists at Jackson Memorial Hospital (Miami, Fla) and various spinal cord injury (SCI) centers who have been treating spinal cord injured patients with halo braces have observed that these patients frequently complain of nonspecific pain in the face and temporomandibular joint (TMJ) area and that they seem to have discomfort and lack mandibular motions necessary for chewing and swallowing. In previous studies that considered the complications of the halo brace, these complaints were not primary findings. Garfin et al studied 512 patients wearing halo braces and found that 2% of these patients had complications of dysphagia and that 2 patients complained of pain at the anterior pin site of the halo when eating.3 Once the pins were removed from the temporal fossa and relocated more anteriorly, the patients had a resolution of this problem. Garfin et al concluded that penetration of the temporalis muscle by the halo pins might have caused pain during mastication.3 Glaser et al identified one case out of 245 patients wearing halo braces in which a severe mandibular underbite developed after the halo-vest application. This situation was corrected by disconnection of the halo device, which enabled restoration and maintenance of the normal mandibular occlusion when the halo vest was reapplied.4

No attempt has been made in a clinical setting to evaluate the mandibular mobility of halo-braced patients with SCI or to assess other complaints of symptoms indicating TMJ dysfunction. Clinical characteristics of TMJ dysfunction include nonspecific pain in the face and neck areas, facial muscle tenderness, joint clicking, ringing in the ears, spontaneous subluxation of the jaw, loss of equilibrium, discomfort when chewing or swallowing, and decreased mandibular mobility.(5-7) Some investigators have found that the degree of vertical mouth opening is not associated with the signs and symptoms of TMJ dysfunction.(7,8) Balthazar et al found instead that limited lateral excursion of the mandible was associated with the signs and symptoms of potential TMJ dysfunction." Kopp, however, found that vertical mouth opening and protrusion are reliable indicators of TMJ dysfunction and show less intraobserver and interobserver variability in the evaluation of this condition.(9) Agerberg has stated that maximal mandibular mobility must be evaluated when assessing the functional status of the masticatory system.(6) In a longitudinal study of healthy subjects, Agerberg determined differences of at least 4 mm in vertical mouth opening and 2 mm in horizontal displacement from a preexisting reference point may be used to indicate a significant change in mandibular mobility when treating a person with TMJ dysfunction.(6) Because of the controversy in the literature concerning which mandibular movements are important in assessment, active and passive mandibular motions in all directions were assessed in this clinical study.

In an effort to confirm the clinical observations of physical therapists that halo-braced patients with SCI may develop TMJ dysfunction, four halo-braced spinal cord injured subjects were followed to assess the changes in TMJ mobility and to record other related symptoms of TMJ dysfunction. The purpose of this clinical report is to describe the assessment of TMJ mobility and the occurrence of symptoms of TMJ dysfunction in these four subjects.

Assessment

Initial measurements of mandibular mobility were made as soon as possible after halo-brace application. This time frame varied greatly because some subjects were transferred to the rehabilitation center from other locations with the halo brace already applied. Initial measurements included active and passive range of motion of the mandible, forward head position, and anterior pin-site location. An initial estimation of face and neck pain was also made by the subjects at that time. The subjects would indicate to the investigator where to mark a 100-mm linear scale indicating the severity of their pain at that time (O = no pain, 100 = most intense pain imaginable in that area). Subjects also answered single-response questions that focused on the frequency of occurrence of other symptoms indicative of TMJ dysfunction by responding "frequently ... .. occasionally," or "never." This assessment was repeated every two weeks until halo-brace removal, at which time a final set of measurements and questions were completed.

All ROM measurements and the questionnaire administration were completed by the same physical therapist evaluator. Active ROM of the TMJ was measured using a clear plastic millimeter ruler, according to the procedure of Storum and Bell.(10) Each subject was positioned supine or semireclined with the bed angle maintained at less than 45 degrees for ease of the examiner and those subjects who had difficulty sitting. The subject repeated each active movement three times, and the average measurement was rounded off to the nearest whole number and recorded. Passive ROM was also measured with the millimeter ruler and was performed as described by McCarrol et al. (11) Anterior pin-site location was measured with the millimeter ruler as the perpendicular distance from the supraorbital ridge to the base of the pin. The procedure for measuring forward head position was similar to that described by Rocabado for the standing position. (12) It was modified for quadriplegic subjects in the sitting position by using a rod extended cephalad from the apex of the thoracic spine as a reference point for the horizontal distance measurement instead of the wall (Fig. 1).12 Records were kept of any anti-inflammatory medications the subjects were taking that could mask TMJ dysfunction symptoms. Recordings were made of all physical therapy programs the subjects were participating in at the time of the interval assessments and listed on the data sheets to identify any activities in therapy that could affect the TMJ.

Patient Data

Four male subjects wearing halo braces were evaluated at Jackson Memorial Hospital's SCI center within a six-month period. The subjects verbally consented to the evaluation of the TMJ for this report. The participants ranged in age from 21 to 60 years. These patients had no previous significant history of TMJ dysfunction, no trauma to the jaw at the time of the SCI, and intact sensory and motor function of the facial area, as determined by questionnaire during the initial assessment. The Table describes each subject's injury, total days in the halo brace, and number of days passed before initial measurements were taken.

Figure 2 represents the active ROM measurements of mouth opening and of right and left excursions of the TMJ for the four subjects. In mouth opening, Subjects 2, 3, and 4 began with a measurement that was below the minimum normal value (40 mm). All subjects demonstrated a trend of increasing mouth-opening ROM over the intervals measured. At final evaluation, only Subject 2 did not reach a mouth-opening active ROM within the normal range (40-60 mm).

In the lateral excursions, active ROM was initially within the normal limits of 7 to 10 mm for Subjects 1, 3, and 4. Right lateral excursion was decreased in Subject 2 (5 mm). These movements varied minimally during the interval measurements. They remained within normal limits at final measurement for all subjects and displayed no apparent increasing or decreasing trends. Additionally, the final right and left lateral excursion measurements were symmetrical for Subjects 1 and 4 and varied by only 1 mm in Subjects 2 and 3.

Passive ROM measurements of the TMJ were similar to the active ROM measurements for all subjects. All subjects displayed passive ROM within normal limits at final measurement except Subject 2 who had decreased passive ROM on mouth opening (32 mm) and during right and left lateral excursions (6 mm).

Measurements that did not change appreciably throughout the interval assessments were active protrusion, overbite, and forward head position. Active protrusion was below the normal range (7-10 mm) for all subjects at initial and final measurements. it did not vary from values of 2 to 4 mm during the interval assessments. Overbite and forward-head-position measurements were equal at initial and final recordings for each subject. At initial measurement, Subjects 1 and 4 had no complaints of face pain. Subjects 2 and 3 complained of a moderate amount of face pain (25 mm and 45 mm on the linear scale, respectively). By final assessment, Subjects 2 and 3 had a reduction in face pain (1 mm and 35 mm, respectively) and Subject 1 continued to have no complaint. Subject 4 experienced a minimal increase in face pain (15 mm on the linear scale). When assessed for neck pain, Subjects 1, 2, and 3 initially complained of mild to moderate neck pain (1840 mm on the linear scale). Subject 4 had no complaint. By halo-brace removal, neck pain had increased in Subjects I and 3 to a moderate level (47 and 56 mm, respectively). Subject 4 developed a complaint of increased neck pain (14 mm). Only Subject 2 experienced a slight decrease in neck pain at halo-brace removal (ie, from 34 mm to 25 mm). The symptoms of TMJ dysfunction most frequently complained of by the subjects were stress, shoulder and neck pain, and headaches.

Discussion

The intent of this clinical study was to follow spinal cord injured patients wearing halo braces to determine whether mandibular ROM limitations and other symptoms of TMJ dysfunction might develop in this population. Acceptable active ROM values for mandibular mobility have been reported by a number of investigators.6,8,13 in the halo-braced spinal cord injured subjects in this project, initial mouth-opening active ROM was below normal limits in three subjects and active protrusion was below normal limits in all four subjects. Mouth-opening ROM did reach normal limits by the final assessment for all subjects except Subject 2. Protrusion remained below the normal limits. The reason for this finding is unclear; however, it may be related to the extended position of the cervical spine in the halo brace, creating a posterior and caudal pull on the anterior cervical muscles that interplay with the TMJ, the suprahyoids, and the sternocleidomastoids. This pull may decrease anterior glide during protrusive movements. Furthermore, because these muscles become shortened with prolonged positioning in the halo brace, no dramatic change in this movement was noted at the time of halo-brace removal.

The active ROM measurements for right and left lateral excursion were within normal limits for all subjects, both initially and at final assessment, except for the initial right lateral excursion in Subject 2. Subject 2's movement also reached the normal range at halo-brace removal. At no time did any of the subjects receive treatment to the TMJ that might have affected its mobility. The final measurements of active ROM recorded during mouth opening and during the lateral excursions for the subjects in this report suggest that TMJ ROM could reach normal values regardless of the decreased cervical ROM resulting from the halo-brace traction and cervical stabilization. Physical therapists treating these patients need to be aware that assessment of the status of TMJ mobility in halo-braced spinal cord injured patients may be warranted. The findings presented in this clinical report suggest that these patients may initially demonstrate symptoms of TMJ dysfunction or decreased mandibular mobility or may experience mobility changes over variable periods of time. These symptoms or changes could necessitate assessment and treatment to attain optimal or functional ROM for the patient.

Some other clinically meaningful observations are apparent in these four subjects. Agerberg established that vertical displacement changes of 4 mm and horizontal displacement changes of 2 mm should be the minimum amount of variation from previous measurements in order for clinicians to evaluate the response of the TMJ to treatment.6 Although the subjects in this report received no treatment, these same guidelines are helpful when considering the change in active TMJ mobility occurring in spinal cord injured patients wearing halo braces. The subjects did show some remarkable changes in active ROM during mouth opening. Subjects 3 and 4 showed an increase in active ROM during mouth opening of 13 and 12 mm, respectively. On initial measurement, active ROM during mouth opening was below normal limits in three subjects. This lack of ROM could be a sign of TMJ dysfunction. A possible cause of decreased ROM of the mandible during mouth opening in halo-braced subjects might be muscle guarding secondary to face and neck pain. Muscle guarding would not be an uncommon finding following any cervical surgery preceding the application of the halo brace, and it might result from the application procedure itself or from the subject adjusting to the weight of the brace. As subjects became more accustomed to the halo brace, the mandibular mobility might have increased, especially in vertical mouth opening. Mandibular mobility could increase to compensate for the lack of mobility in the cervical area attributable to the halo-brace traction. The observed decrease in face pain for two subjects who gained ROM during mouth opening could contribute to this observed increase in mandibular mobility. Movements of passive mandibular mobility showed variability between the interval measurements. Some observable differences in excess of 2 mm in mouth opening and 4 mm in the lateral excursions were noted at interval assessments. It was a concern of the evaluator, however, that the subjects' true passive ROM was not being assessed. The subjects seemed to resist the passive movement by muscle guarding. This resistance might have been due to the discomfort of having their jaw manipulated during the test. Passive ROM measurements reached normal limits for all subjects at halo-brace removal except for Subject 2. His mandibular mobility was below the normal range for all movements, and his active and passive ROM measurements were comparable.

All subjects displayed symptoms associated with TMJ dysfunction. No symptom, however, was consistently reported by every subject at every interval. The most common symptoms reported were headaches and dizziness. In subjects with SCI, these complaints should not be surprising, and they could be related to the pathology of the injury. Difficulty chewing, which concerned clinicians and facilitated this clinical assessment, was a complaint of two subjects less than half of the time they were in the halo brace. Difficulty swallowing was occasionally a complaint of three subjects. Both of these symptoms were prevalent early after halo-brace application and disappeared over time. This finding may indicate the possibility of TMJ dysfunction occurring in the initial stages after halo-brace application in these subjects.

Postural alterations of the normal craniovertebral and craniomandibular relationship have been suggested by some investigators as a factor in the development of TMJ dysfunction.1 16 This relationship can be altered in the spinal cord injured patient as a result of cervical trauma such as whiplash-type injuries.,,17,18 The surgical fusion procedure and application of the halo brace to immobilize the cervical spine and protect the injured spinal cord can also cause adaptive cervical muscle shortening and spasms. These sequelac can augment the postural alterations that may exist in the patient with SCI and increase the possibility of the development of TMJ dysfunction. Three of the subjects in this report had suffered cervical trauma similar to a whiplash injury and had cervical fusions. This fact presents another reason why clinicians treating this population must be aware of the possibility of TMJ dysfunction developing.

Postural alterations also occur in the spinal cord injured patient as a result of his or her inability to stand and achieve an erect posture. The patient with SCI is forced to assume a kyphotic, forward-head-sitting posture because of the muscle imbalances of the trunk and cervical area. These patients use their head and neck to maintain their center of gravity and sitting balance. When the halo brace is applied, the extensor muscles that maintain balance are responding to the immobility of the cervical spine and the additional weight of the halo brace. Subjects in this report were observed to lean forward a greater degree than normal to keep from falling backward during sitting activities. This position can further exaggerate the postural adjustments of the patient with SCI. Further clinical research should be considered to examine the postural alterations in the spinal cord injured population as they relate to the occurrence of TMJ dysfunction. Additional research is also indicated to assess the occurrence of TMJ dysfunction after halo-brace removal and, in the long term, to determine whether TMJ dysfunction may develop as a result of decreased cervical mobility.

In this clinical report, the changes displayed in TMJ mobility over time and the infrequent occurrence of symptoms associated with TMJ dysfunction do not support the suspected occurrence of TMJ dysfunction in patients with SCI in this rehabilitation setting. The trends displayed by the initially observed limitations in mandibular mobility, especially active ROM during mouth opening and decreased ROM during protrusion, coupled with early symptoms of TMJ dysfunction, however, suggest that TMJ dysfunction might exist in these patients during the early stages of halo bracing. Therefore, physical therapists who treat these individuals should be aware of this possibility and should be prepared to assess and treat the halo-braced spinal cord injured patient for this condition. It is recommended from this clinical report that assessment of TMJ mobility be considered as part of the evaluation of all spinal cord injured patients to further assess TMJ involvement and to intervene if necessary in the early stages of its development.

Summary

In this clinical report, changes in mandibular mobility and symptoms of TMJ dysfunction were followed in four halo-braced spinal cord injured subjects. Some limitations in protrusion and changes in vertical and horizontal displacement were found, along with complaints of other characteristic symptoms of TMJ dysfunction, primarily in the early stages of halo bracing. Physical therapists treating patients with SCI need to be aware of the potential of these individuals to display or develop a TMJ dysfunction. The impact of halo bracing on this population has yet to be resolved. Further clinical research is indicated to evaluate the incidence of TMJ dysfunction in spinal cord injured patients with and without halo braces.

Acknowledgments

I thank Larry Mengelkoch, PT, Jackson Memorial Hospital, Miami, Fla, for his assistance in data collection; Dr Parker Mahan for his assistance in the design of the study; and Dr Martha Clendenin, Dr Daniel Martin, and Dr Janice Derrickson for their constructive critique of the manuscript.

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