A minireview of the anatomical and pathological factors pertaining to Costen’s syndrome symptoms

ABSTRACT

Objective: Interest in the symptoms pertaining to Costen’s syndrome has revived in recent years. The aim of this work is to address the symptoms of Costen’s syndrome from the basic science perspective

Methods: A minireview of the literature related to Costen’s syndrome symptoms was performed by retrieving relevant articles from the PubMed database from 1980 until 2021.

Results: The validity of Costen’s syndrome symptoms has been confirmed by a multitude of articles.

Conclusion: Maladaptive plasticity in the central nervous system pathways probably accounts for the incidence and severity of Costen’s syndrome symptoms.

KEYWORDS:

• Costen’s syndrome
• temporomandibular disorders
• temporomandibular joint
• masticatory muscles

Introduction

The human masticatory system consists of the mandible, which is able to move with six degrees of freedom in relationship to the skull. The mandibular movements are guided by the two temporomandibular joints (TMJs) through contractions of the muscles of mastication [1]. The articulating surfaces of the TMJ (the mandibular condyle and the glenoid fossa and articular eminence of the temporal bone) are separated by an intra-articular disc, which reduces friction between the highly incongruent articulating surfaces [2]. Excessive or abnormal loading of the TMJ may result in changes in the ligamentous attachments of the disc-condyle complex, leading to disc displacement and instability of the joint [3]. The TMJ disc is especially prone to degenerative disorders associated with abnormal stresses imparted on the joint [4]. TMJ malfunction is clinically manifested as pain over the joint, limited or asymmetric jaw motion, and/or TMJ sounds associated with motion [5]. Additionally, repetitive or excessive masticatory muscle strain may result in regional muscle pain [6]. Collectively, the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) are used to describe the heterogeneous spectrum of musculoskeletal disorders that affect the jaw system [7]. Axis I of the DC/TMD is used to describe the pertinent clinical findings, whereas Axis II addresses psychosocial and behavioral factors commonly associated with TMD [7].

In 1934, James Costen, an otolaryngologist from St. Louis, MO (USA) reported a syndrome of ear and sinus symptoms dependent upon disturbed function of the temporomandibular joint [8]. He later expanded his observations in a series of articles. In his original report, Costen described otolaryngologic symptoms in 11 cases (9 female) with variable degrees of malocclusion; and notably, all had prompt resolution of their symptoms on correction of the dental bite. The constellation of symptoms reported by Costen included headache, otalgia, eye pain, hearing loss/blocked-ear sensation, tinnitus, vertigo, nasal stuffiness, and pain over the sinuses [8]. He concluded that all these symptoms could be attributed to disturbances in the TMJ, its ligaments, and associated muscles.

Materials and methods

The aim of this article is to review anatomical and pathological factors pertaining to Costen’s syndrome symptoms guided by recent studies on the topic. For this purpose, the PubMed database was searched for relevant articles from 1980 until 2021.

Results

Hearing loss/ blocked-ear sensation in patients with TMD

Current research suggests involvement of the middle-ear cleft, inner ear, and possibly certain brain networks in the pathogenesis of hearing loss/ blocked-ear sensation in many patients with TMD.

Evidence for middle-ear cleft affection comes from a study on middle-ear impedance, using multiple frequency tympanometry. That study revealed a subtle increase in stiffness of the middle ear in patients with TMJ disorders [9]. Anatomical factors that are putatively recognized as causing this increase in stiffness are increased tension exerted on the malleus by the discomalleolar and anterior malleolar ligaments, as well as increased tone in the tensor tympani muscle [10,11]. The latter muscle is attached to the tensor veli palatini muscle by a tendon. Brain mapping in patients with TMD has revealed changes in corticostriatal brain pathways, which could lead to mandibular nerve over-activity [12]. Indeed, an electromyographic study has revealed a markedly increased tone of the masseter muscle in patients with TMD and otologic symptoms [13]. Moreover, as originally hypothesized by Costen, the membranocartilaginous portion of the Eustachian tube can be pushed inward by a contracting medial pterygoid muscle, leading to Eustachian tube dysfunction in patients with TMD [14]. These factors may lead to a conductive hearing loss.

Based on tuning fork tests, Costen observed that some cases of hearing loss in his series were of the conductive type, whereas others were of the sensorineural type [8]. Recently, pure-tone audiometry on 104 TMD patients revealed an incidence of documented hearing loss of 25%. The hearing loss was predominantly sensorineural in nature and mild in degree [15]. The author postulated that the sensorineural hearing loss was caused by an altered position of the stapes at the oval window, consequent upon an altered position of the malleus. This would cause a middle-ear to inner-ear pressure dysequilibrium with altered firing patterns of the cochlear hair cells [16].

Tinnitus in patients with TMD

Tinnitus is the conscious perception of sound without a corresponding external acoustic stimulus. If the sound is detected by an examiner, it is termed objective tinnitus. Subjective tinnitus is a (phantom) sound perceived by the patient in the ear(s) or head in the absence of a known internal or external stimulus. Somatic tinnitus is a form of subjective tinnitus that can be evoked or modulated by inputs from the somatosensory or somatomotor systems [17]. The TMJ is the most common tinnitus-modulating region in somatic tinnitus. Notably, Costen described these forms of tinnitus in his original report [8].

Sounds may be elicited from a pathological TMJ during mandibular movement. These sounds can be heard by an examiner with or without a stethoscope. The nature of these sounds (click or crepitus) may allow the examiner to clinically categorize the joint pathology according to the DC/TMD [17]. The commonest pathology in the TMJ is a displaced articular disc, a condition known as internal derangement [18]. During opening and closing of the mouth, replacement and displacement of the disc may elicit an audible click [19]. Degenerative changes in the disc and articular surfaces are associated with a grating sound (crepitus), elicited over the TMJ during mandibular movement [20].

Subjective tinnitus in TMD patients is a special form of tinnitus, where modulation of the tinnitus volume and pitch by movements of the mandible can occur (somatic tinnitus) [21]. In a recent comparative study involving 294 TMD patients, 40% of myogenous TMD patients and 32% of arthrogenous TMD patients reported subjective tinnitus [22]. The author postulated that in both groups of TMD patients, subjective tinnitus could start as a change in mechano-electric transduction at the level of cochlear hair cells resulting from an altered position of the stapes at the oval window [16]. In TMD patients, the dorsal cochlear nucleus in the brain stem may receive abnormal somatosensory input from the trigeminal nucleus in addition to the altered acoustic input from the cochlea, thereby accounting for somatic tinnitus [23]. Moreover, the dorsal cochlear nucleus receives inputs from higher brain centers, especially the limbic system. Maladaptive central neural plasticity seems to underlie the association of chronic subjective tinnitus with other morbidities common in TMD patients, such as pain, anxiety, depression, and lack of sleep, via top-down mechanisms [24].

Vertigo in patients with TMD

In the original series of 11 patients with malocclusion reported by Costen, 5 patients complained of dizziness, which was abolished completely by Eustachian tube inflation [8]. Costen attributed the dizziness to Eustachian tube compression, with the resultant change in intratympanic pressure affecting the labyrinth.

Recent prospective studies on TMD patients with TMJ disorders revealed an incidence of vertigo of 56% [15,22]. On the other hand, the incidence of vertigo in myogenous TMD was higher (80%) (p = 0.001) [22]. The possible reason for the higher incidence of vertigo in myogenous TMD patients, compared with arthrogenous TMD patients, is affection of central nervous system networks in myogenous TMD patients. Myogenous TMD may be a more global issue, with affection of the brain pain neuromatrix and the limbic system responsible for affective disorders [6,25,26]. Human neuroimaging studies have revealed the crucial role of thalamic nuclei in the genesis of vertigo. In addition to their being a relay station from the vestibular nucleus complex to the brain cortex, they play a critical role in integrating sensory, motor, cognitive, and affective functions of the brain [27]. Recurrent vertigo may be a manifestation of a defect in the descending central histaminergic system to the vestibular nuclei via top-down mechanisms [28].

Headache in patients with TMD

In the original paper published by Costen, he stated that patients with malocclusion frequently suffer from headache, even after exclusion of other causes of headache, especially eye and sinus disorders [8]. Headache related to TMD is one of the diagnostic categories in the DC/TMD, and the relationship between the two disorders is bi-directional [29]. Chronic headache in TMD patients is a multi-faceted problem associated with sensitization of peripheral nociceptors as well as a central sensitization process [30,31]. Peripheral sensitization is associated with a low-grade inflammatory process in the jaw structures exposed to stress [32,33]. The trigeminal subnucleus caudalis in the brain stem had been regarded as being crucial in the development of central sensitization in patients with chronic headache and TMD [34]. In addition to its role in integrating nerve impulses from trigeminal and upper cervical nociceptive afferents, the subnucleus caudalis receives inputs from higher centers, especially those concerned with emotions (the corticolimbic circuitry). This may lead to the intensification of headache symptoms in TMD patients with psychological distress and lack of sleep [35,36]. Human brain imaging studies, as well as animal studies related to chronic headache associated with TMD, have verified a degree of neuroinflammation in the relevant brain pathways associated with the peripheral sensitization process [37,38].

Facial pain and associated autonomic symptoms in patients with TMD

In his original report on 11 patients with malocclusion, Costen described 5 patients who had facial pain and nasal stuffiness. These 5 patients had no mucopus in the nose, and sinus radiographs on 2 of these patients were normal. Notably, these patients became asymptomatic after correction of the dental bite [8]. More recently, Jones introduced the term “midfacial segment pain,” which he described as analogous to tension-type headache and that could be related to an exaggerated myofascial afferent nociceptive input [39]. Jones and colleagues stressed that, in patients with this form of facial pain, endoscopy of the nasal cavities and computed tomography (CT) scans of the paranasal sinuses were normal [40,41]. Recently, the current author performed a comparative clinical and CT study on 212 patients with chronic facial pain with and without TMD, noting that, in the cohort of patients with TMD (132 patients), 48 patients had normal nasal endoscopic findings and clear CT scans of the sinuses, and their facial pain was either heterotopic, referred, or radiating pain from the jaw [42]. It was postulated that the facial pain experienced by some TMD patients could be due to facilitatory nociceptive inputs from higher brain centers onto the subnucleus caudalis in the brain stem. The subnucleus caudalis receives convergent nociceptive afferents from the trigeminal system, which could account for the experience of pain in areas remote from the jaw in TMD patients [30]. The same author, in another study on eye pain in 314 TMD patients, noted that TMD-related eye pain was present in 22.8% of arthrogenous TMD patients and in 25.6% of myogenous TMD patients (p = 0.56) [43]. This type of pain was characterized as a deep dull aching pain (regional myofascial pain) [44].

Facial and eye pain attributed to TMD could be associated with autonomic manifestations, including nasal congestion, rhinorrhea, and lacrimation, which might erroneously be diagnosed as chronic rhinosinusitis [45]. The pathophysiological basis for the autonomic symptoms associated with trigeminal pain is that nociceptive neurons from the trigeminal nucleus project directly to the superior salivatory nucleus in the brain stem. The superior salivatory nucleus drives the parasympathetic flow to the nasal and lacrimal glands, thus, causing nasal congestion, rhinorrhea, and lacrimation associated with the trigeminal pain [46,47].

Conclusion

The central nervous system appears to play an essential role in the genesis of otological and alleged sinus symptoms associated with Costen’s syndrome. Maladaptive neuroplasticity in relevant brain pathways stresses the role of affective disorders in the experience of these symptoms associated with temporomandibular disorders.

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