Key Words: TMD (temporomandibular disorder); otalgia;, pain.

Temporomandibular disorders (TMD) are defined as a collective term embracing a number of clinical problems that involve the masticatory muscles, the temporomandibular joint (TMJ) and associated structures, or both" [1]. They are considered to be a sub-classification of musculoskeletal disorders, and typically run a recurrent or chronic course, with a substantial fluctuation of TMD signs and symptoms over time. Common signs and symptoms of TMD are clicking or crepitation noises in the TMJ, limited jaw opening capacity, deviations in the movement patterns of the mandible, and masticatory muscle and/or TMJ pain in the face [2,11].

Chronic pain in the TMJ or the pain dysfunction syndrome is common affecting 15-20% of the population at some time in their life [3].

Not only is the TMJ the immediate anterior relation of external auditory meatus, but also its capsule is supplied by an articular branch of the auriculotemporal nerve that also supplies cutaneous sensation to a large portion of the pinna of the ear [4,10]. Not surprisingly, temporomandibular disorders are frequently misinterpreted by the patient as earache.

Goodfriend (1933) [5]; an American dentist, is often credited as the first to report a relation between otalgic symptoms and the temporomandibular articulation.

Costen (1937) [6], described a syndrome consisted of a symptom complex of loss of hearing, otalgia, tinnitus, dizziness, headache, and burning sensation of the throat, tongue; originally ascribed to over closure causing excessive backward movement of the head of the condyle and pressure on the auriculotemporal nerve. Currently, Costen's syndrome, is recognized as not being well founded on anatomic and physiologic principles. Moreover, Brookes, Maw and Coleman (1980) [7], in a series of 45 patients with TMD and aural symptoms were unable to find a direct aetiological basis to link TMJ dysfunction and other aural symptoms apart from otalgia.
Otalgia is a common aural symptom of functional disturbances of the masticatory system; it is surprising that in only less of 50% of the adult patients with otalgia, it is possible to diagnose ear disease [8].

Few studies in the literature focus on the occurrence, prevalence and treatment of otalgia in TMD patients. The reported prevalence of otologic complaints varies in the literature. However, only few complaints are supported by audiometric documentation [14]. Most authors agree that the prevalence of otalgia in TMD patients is in the range of 5-20% [12,13].

The aims of this study are to investigate the prevalence of otalgia in a group of TMD patients and to evaluate the response to conservative TMD treatment.

This prospective, clinical study was carried out with TMD patients attending the dental department at Prince Hashim Bin AL-Hussein Hospital of the Royal Medical Services between February 2002 and January 2003.

A total of 125 patients diagnosed with some form of TMD participated in this study; they were divided into two groups:
Group 1 consisted of 79 patients (63.2%) with no ear complaint, and

Group 2 consisted of 46 patients (36.8%) who presented with otalgia along with TMD symptoms. All patients in this second group were referred to an ENT clinic and were examined by the otolaryngologist before initiating TMD treatment to exclude organic ear cause of otalgia.

The diagnosis of TMD was based on the finding of at least two of the following features: limitation of jaw opening, deviation of mandibular movement, joint sounds (click or crepitation), pain on palpation of the TMJ, and pain on palpation of associated muscles.

Because no apparent ear disorder was found, no specific therapy for otalgia was initiated.

For both groups, a similar treatment protocol was followed which consisted of TMD conservative treatment policy: counseling, physiotherapy, occlusal splint therapy and occasionally, non-steroidal anti-inflammatory drugs (NSAIDs). In severe cases of acute osteoarthroses, intra-articular steroid injections were carried out. In indicated cases, some form of occlusal therapy (occlusal equilibration or restorative treatment) was also performed, but only after pain and most of the dysfunctional symptoms subsided.

Self-administered questionnaires regarding the severity of pain were used to collect the data based on a visual analogue scale. The patients were divided into four groups according to severity of pain: no pain, mild, moderate or severe pain.

The treatment outcome was evaluated by improvement in the pain severity using the same visual analogue scale questionnaires six months after first examination and start of treatment.

Statistical analysis was performed with the chi-square test. Significance levels of p< 0.05 were established.

Of the 125 patients, 86 (68.8%) were female and 39 (31.2%) were male, they were aged 13-68 years (mean 29.8 years).

Table 1 shows the age distribution of study population.
79 patients (63.2%) had no ear complaint, while 46 patients (36.8%) reported otalgia as a presenting symptom along with TMD symptoms.

In the otalgia group, more women (67.4%) than men (32.6%) had otalgia.

More patients in the otalgia group had severe pain (19.6%) than patients without otalgia (13.9%); however, this difference was not statistically significant.

In both groups, most patients complained of moderate pain (75.2% of both groups). Figure 1 demonstrates percentage distribution of patients at initial examination.

There was a statistically significant decrease in overall pain experience in both groups six months after initial examination and start of treatment.

Only 4.0% of the patients were found to still suffering from severe pain as compared with 16.0% of patients at initial examination.

23.2% of patients reported moderate pain, while most of the patients (72.8%) ended with mild or no pain; when compared with 8.8% of patients who had reported mild or no pain at initial examination; in both groups, this was statistically significant (p<0.05).

Figure 2 demonstrates percentage distribution of patients six months of initial examination and start of treatment.

There was no longer any significant difference between the severity of pain experienced by both groups six months after the first examination and the commencement of treatment.

Figure 3 and Figure 4 demonstrate the significant improvement in pain experience in group 1 (without otalgia) and in group 2 (with otalgia) respectively following the six-month conservative treatment.

Finally, by the end of the six-month treatment period, 54.3% of the otalgia-group patients no longer had ear pain, and 30.4% experienced mild or occasional ear pain.

This current study revealed a high prevalence of otalgia in patients with TMD (36.8%). This was higher than the frequency reported in most studies in the literature, which ranges between 5% and 20% [12,13]. This difference can probably be explained by differences in patient material studied and in better estimation of prevalence of otalgia in TMD patients that were carried out by the dentist and the otolaryngologist in close cooperation. Pain is one of the most disturbing of human experience, and it must be remembered that individuals vary widely in their appreciation of, and reaction to it, and the same individual may react in different ways to a similar pain at different times.

A higher pain level was found in TMD patients with otalgia than in TMD patients without otalgia. Most patients suffered from moderate pain.

Women had more incidence of otalgia (67.4%) than men (32.6%). This warrants more investigation; in their study of symptoms and signs of TMD, Kuttila et al [24], concluded that women had more aural symptoms than men. Literature review revealed that women report symptoms of TMD at least twice more often than men, also it has been stated that women are more likely to have multiple TMD symptoms than men [11,20,24].

Six months after the first examination and the start of conservative TMD treatment, the pain score had decreased significantly in both groups. The majority of patients (72.8%) ended with mild or no pain. Earache disappeared completely in 54.3% of patients initially presented with otalgia and TMD; otalgia was mild or very occasional in frequency in 30.4% of patients. In 15.3% of patients, no change in pain intensity or pain frequency could be obtained.
Different theories have been proposed to explain the occurrence of otalgia and other ear symptoms such as stuffiness, tinnitus and hearing loss in association with temporomandibular disorders.
Some investigators have hypothesized that Eustachian tube dysfunction, masticatory muscle dysfunction, or reflex sympathetic vasospasm of labyrinthine vessels occurs secondary to abnormal stimulation of autonomic nerves of the TMJ [7,19,20,22,23].

Some authors considered compression of the external auditory meatus or of the auriculotemporal nerve due to mandibular over-closure and posterior displacement of the condyle a possible cause inducing the aural symptoms in TMD [6,18], whereas others refuted this theory [19].

Moreover, reflex motion disturbances of the tensor tympani and veli palatini muscles, as well as the oto-mandibular tiny ligaments (diskomalleolar and tympanomandibular ligaments); have been suggested by some authors as being responsible for ear symptoms [4], but other investigators could not confirm these anatomic findings [16,17].

Other concepts that pertain to aural symptoms of TMD have focused on the internal derangement of the TMJ as a possible cause [21] and the direct mechanical influence on nerve branches in the TMJ region [8,15].

Current explanation of otalgia occurrence in patients with TMD stems from the complex innervations of all parts of the ear and the phenomenon of referred pain that probably can be explained by a central summation mechanism in relation to gate theory [9].

Definitive conclusions on the direct aetiologic mechanisms cannot be drawn from these studies because the mechanism involved is not identical for all TMD patients with otalgia. However, it should be always remembered that pain is a warning and is always real to the patient, and that if it is not possible to find the cause of pain, this should be regarded as the physician's responsibility rather than being the patient's fault.

1. The prevalence of otalgia in TMD patients is high.
   
2. The conservative treatment is an effective way for managing TMD patients, moreover, otalgia in TMD patients did respond to the treatment protocol instituted for all TMD patients.
   
3. Close cooperation between the dentist and the otolaryngologist is of paramount importance in recognizing and diagnosing the TMD patients with otalgia.