Discomalleolar ligament in the adult human

Is there an association between otologic symptoms and temporomandibular disorders?: An evidence-based review

BACKGROUND

The aim of this article is to discuss the scientific evidence available on the the pathophysiology and management of otologic complaints in patients with temporomandibular disorders (TMDs).

TYPES OF STUDIES REVIEWED

The authors conducted an electronic search in MEDLINE, Web of Science and ScienceDirect and retrieved all the relevant peer-reviewed journal articles available in English on the topic. No time restriction was applied.

RESULTS

No consensus exists on the management of otologic symptoms in patients with concomitant TMD. The scientific evidence suggests that conservative or reversible TMD therapy might provide relief. However, this evidence is scarce and low, thus further studies with larger sample sizes and better designed methodological frameworks are needed. Until such evidence is available, dentists and orofacial pain specialists should treat TMD patients using current guidelines and refer those with otologic symptoms to an otolaryngologist.

PRACTICAL IMPLICATIONS

Given the wide range of potential pathophysiologies and treatments for each otologic symptom described in the TMD patient, close collaboration with otolaryngologists is essential to achieve the best patient care.

Microscopic reconstruction and immunohistochemical analysis of discomalleolar ligament

Discomalleolar ligament represents the vestiges of the primitive lateral pterygoid muscle which penetrates in the caudal end of Meckel's cartilage; during the development of newborn, the petrotympanic fissure close almost completely leaving inside the discomalleolar ligament. After entering in tympanic cavity, some fibers of the discomalleolar ligament insert to walls of cavity, other fibers continue with the lateral margin of the anterior ligament and insert in the neck of malleus; in contrast, other Authors demonstrated that discomalleolar ligament is an independent structure inserted in proximity of the neck of the malleus. Although the discomalleolar ligament can be considered as a structure of clinical importance, it is not described by anatomy textbooks. Moreover, it is likely that important correlations between temporomandibular diseases and otological symptoms exist. We have studied discomalleolar ligament submitting the specimens to the 3D volume rendering technique, light microscopy, reconstructing a wide light microscopic fields to analyze the real connection between retrodiscal connective tissue and middle ear, and immunofluorescence methods in order to analyze the consistence of ligament. We have shown two types of connections between TMJ and ear: first, with external acoustic meatus and, second, with middle ear through discomalleolar ligament. The different insertion represents a strong support in order to demonstrate that the TMJ disorders can determine variations of tension that are transmitted on the tympanic membrane provoking tinnitus in according to clinical features. Then, we propose that it is necessary to mention, also in anatomy textbook, the discomalleolar ligament as ligament distance of TMJ.

The discomallear ligament: anatomical, microscopical, and radiologic analysis

BACKGROUND

Several anatomic relationships between the ear and the temporo-mandibular joint have been proposed to account for the presence of tinnitus during temporo-mandibular disorders. Among the otomandibular structures, the discomallear ligament (DML) is interposed between the malleus and the retrodiscal capsular complex. The aim of present paper was to study through dissection the frequency and morphology of DML, to characterize its type of collagen, and to evaluate the DML on routine computed tomography (CT).

METHODS AND RESULTS

The study has been conducted on five un-embalmed adult cadavers, and in all cases, the DML was present (100%). It was constituted mainly by fibers of collagen I, with abundant elastic fibers. On CT exams of 40 patients with no reported pathology of the ear, on axial images, a dense structure, going from the upper end of the petrotympanic fissure to the neck of the malleus, was present in all the cases. In 90%, it showed a triangular shape, in 5% a rectangular shape, and in 5% a curved course. The mean length of the antero-medial side was 2 ± 0.6 mm and that of the antero-lateral side was 1.63 ± 0.5, and the mean area was 1.29 ± 0.83 mm².

CONCLUSION

The DML could represent an anatomical structure that joining the temporo-mandibular joint and the malleus may play a role in the otologic symptoms during temporo-mandibular disorders.

The Role of Magnetic Resonance Imaging of the Temporomandibular Joint to Investigate Tinnitus in Adults with Temporomandibular Joint Disorder: A Comparative Study

Introduction  The prevalence of tinnitus is higher in individuals with temporomandibular joint disorder (TMD) than in the general population. Magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ) is the method of choice for investigation, and it has been hypothesized that specific MRI findings might be observed in TMD with comorbid tinnitus.

Objective  To comparatively describe MRI findings in patients with TMD with and without tinnitus, identifying the most common TMJ alterations and determining whether a correlation exists between severity of TMD and tinnitus.

Methods  A cross-sectional study of 53 adult patients with bilateral or unilateral TMD (30 with and 23 without tinnitus). The association between tinnitus and morphological aspects of TMD (changes in condylar morphology, articular eminence morphology, and disc morphology), disc displacement (with/without reduction), condylar translation, and intra-articular effusion was analyzed on MRI images.

Results  The mean patient age was 46.12 ± 16.1 years. Disc displacement was the most common finding in both groups (24 patients with tinnitus versus 15 without; p  = 0.043). Only the frequency of disc displacement with reduction was significantly different between groups.

Conclusion  Additional imaging techniques should be explored to detect specific aspects of the relationship between tinnitus and TMD.

Clinical implications of magnetic resonance imaging in temporomandibular disorders patients presenting ear fullness

OBJECTIVES/HYPOTHESIS

The aim of this study was to investigate whether findings detected by temporomandibular joint magnetic resonance imaging (TMJ-MRI) can provide pathognomonic evidence of temporomandibular disorders (TMD) in patients with nonspecific ear fullness (EF). The association of nonspecific EF with clinical characteristics of TMD based on TMJ-MRI findings was examined.

STUDY DESIGN

Retrospective analysis.

METHODS

Thirty-four subjects (42 ears) who had no detectable otologic problems as a cause of EF were enrolled in this study. Each subject underwent TMJ-MRI to identify pathology of the TMJ as a possible cause of nonspecific EF. All subjects participated in the re-evaluation process following TMD treatment.

RESULTS

Anatomical abnormalities in TMJ-MRI, irrespective of TMD signs, were observed in 34 of the 42 ears (80.9%), such as degenerative change of the TMJ (16 ears), articular disc displacement (11 ears), and joint effusion (seven ears). Specific abnormalities of the TMJ were associated with nonspecific EF, and this symptom showed improvement following individualized TMD treatment in those with internal derangement and/or effusion of the TMJ. However, abnormal TMJ-MRI findings were also observed in seven of nine ears with no TMD signs, and there was no significant association between the presence of TMD signs and abnormal TMJ-MRI findings (χ² = 0.075, P = .784).

CONCLUSIONS

Patients presenting with nonspecific EF may have TMD, which can be effectively diagnosed using TMJ-MRI. The present study revealed the causal relationship between nonspecific EF and abnormal TMJ findings based on MRI. Individualized TMD treatments based on TMJ-MRI led to improved treatment outcomes with special regard to nonspecific EF LEVEL OF EVIDENCE: 4. Laryngoscope, 128:1692-1698, 2018.

Painful temporomandibular disorders, self reported tinnitus, and depression are highly associated

OBJECTIVE

The aim of this study was to investigate the association among painful temporomandibular disorders (TMD), self reported tinnitus, and levels of depression.

METHOD

The sample consisted of 224 individuals with ages ranges from 18 to 76 years. The Research Diagnostic Criteria for Temporomandibular Disorders Axis I were used to classify TMD and Axis II were used for self reported tinnitus, and to score the levels of depression. The odds ratio (OR) with 95% confidence interval (CI) was applied.

RESULTS

The presence of painful TMD without tinnitus was significantly associated with moderate/severe levels of depression (OR=9.3, 95%; CI: 3.44-25.11). The concomitant presence of painful TMD and tinnitus self-report increased the magnitude of the association with moderate/severe levels of depression (OR=16.3, 95%; CI, 6.58-40.51).

CONCLUSION

Painful temporomandibular disorders, high levels of depression, and self reported tinnitus are deeply associated. However, this association does not imply a causal relationship.

The canine jaw-ear connection: The malleomandibular and tympanomandibular ligaments

In the human, two ligaments derived from the first embryonic pharyngeal (branchial) arch that unite the mandible and temporomandibular joint (TMJ) with the middle ear have been identified as the discomalleolar ligament (DML) and sphenomandibular ligament (SML), also known as the malleomandibular ligament (MML), anterior ligament of the malleus (AML), and tympanomandibular ligament (TML). Neither of these structures has been previously described in the dog. The homologue of the human sphenomandibular ligament (SML) exists in the dog and is represented as a fibrous remnant of Meckel's cartilage. In the newborn puppy, the ligament is a true malleomandibular ligament (MML), extending from the medial mandible to the rostral process of the malleus with no intermittent attachments. In the adult dog, the ligament is entrapped within a bony passageway, likely due to the development and ossification of the tympanic bulla, making it difficult to grossly view the complete course of the ligament. The majority of the ligamentous fibers attach near the tympanic bulla in the adult dog, thus this portion of the ligament has been named the tympanomandibular ligament (TML). Those fibers of the ligament not attaching near the tympanic bulla appear to continue through a canal, located between the tympanic annulus and the surrounding tympanic bone, to become continuous with a connective tissue sheet within the cavity of the middle ear that has attachments to the malleus and incus. Tension on the adult canine TML did not result in movement of the malleus.

Anatomical study of the human discomallear ligament using cone beam computed tomography imaging and morphological observations

In the present study, the human discomallear ligament (DML) was observed in structures at both macroscopic and cone beam computed tomography levels. Assessments were made regarding the distribution of calcitonin-gene-related peptide (CGRP), protein gene-product (PGP) 9.5, and substance P (SP) of the DML based on immunohistochemical analyses of the anatomical properties of jaw movements using 27 Japanese human cadavers (mean, 79.3 +/- 8.6 years; male, 74.9 +/- 8.0; female, 82.8 +/- 7.5). The DML of the anterior region was connected to the TMJ disc. The DML of the posterior region was attached to both the head and the anterior process of the malleus through the petrotympanic fissure, which formed a narrow channel. The structure of the petrotympanic fissure through the DML was attached to the malleus, and this structure was associated with the mobility of the malleus. In the anterior and posterior parts of the disc-associated connective tissue of the DML, CGRP-, PGP9.5- and SP-positive nerve fibers were located around numerous blood vessels, a condition which may be correlated with chronic pain syndrines disorders and the auditory system.

Histological study of the extratympanic portion of the discomallear ligament in adult humans: a functional hypothesis

This study was carried out on histological aspects of the extratympanic portion of the discomallear ligament (DL) in adult humans. The temporomandibular joint (TMJ) was dissected bilaterally in 20 cadavers; in 15 cases the articular disc (AD) and the retroarticular tissue were extirpated. The extratympanic portion of the DL had the shape of a base-down triangle, in relation to the AD, and an upper vertex, in relation to the petrotympanic fissure. In five cases, the base, measured bilaterally, had an average length of 6.4 mm, while the distance from the base to the upper vertex averaged 9.3 mm in length. The extratypanic portion of the DL is an intrinsic ligament of the TMJ, composed of collagen fibres and abundant elastic fibres. We propose that this ligament could act as a tensor of the synovial membrane in movements of the TMJ.

Prevalence of the types of the petrotympanic fissure in the temporomandibular joint dysfunction

BACKGROUND

Petrotympanic fissure (PTF) is a fissure in the temporal bone that runs from the temporomandibular joint (TMJ) to the tympanic cavity (TC). In PTF, the discomallear ligament (DML) connects the malleus in the tympanic cavity and the articular disc and capsule of the temporomandibular joint. PTF with the DML is a possible cause of aural symptoms related to temporomandibular joint dysfunction (TMD).

PURPOSE

To investigate the prevalence of different types of PTF in TMD using dental volumetric tomography (DVT) and determine whether PTF type correlates with age.

MATERIAL AND METHODS

DVT scans in the sagittal planes of PTFs of 134 patients with TMD were examined for the types of PTF present. Three main PTF types were described: wide, tunnel-shaped structure (type 1); tunnel-shaped structure that is wide open in the PTF entrance to the mandibular fossa and gradually thins out in the tympanic cavity (type 2), tunnel-shaped structure that is wide open in the entrance of the mandibular fossa, with a middle region with a flat-shaped tunnel structure and a narrow exit in the tympanic cavity (type 3).

RESULTS

In DVT scans, PTF types 1, 2 and 3 were seen in 67.2%, 1.5%, and 31.3% of cases, respectively. We found no significant relationship between age or gender and PTF type.

CONCLUSION

The low percentage of type 2 PTF and high percentage of type 1 PTF must be taken into consideration during pre-surgical planning related to TMD. However, future well-designed clinical studies involving larger numbers of subjects will be necessary to confirm the findings of this study.

The vascular relationship between the temporomandibular joint and the middle ear in the human fetus

PURPOSE

The aim of this work was to clarify the vascular relationships between the middle ear and the temporomandibular joint region during human fetal development.

MATERIALS AND METHODS

Light microscopic studies were done on 40 human fetuses from 72 mm crown-rump length (C-R) to 150 mm C-R, which were stained by various methods. Five human fetuses were dissected. Natural latex with industrial coloring was injected through the external carotid artery. All specimens were dissected bilaterally.

RESULTS

The limits of the retroarticular region and the fetal tympanosquamosal fissure are shown. The anterior tympanic artery has a variable origin. In most cases, it originates from the maxillary artery; in other cases it originates from the superficial temporal artery or the bifurcation of the external carotid artery. On its way through the retroarticular region, it gives branches to the posterior part of the temporomandibular joint. It progresses along the most lateral part of the tympanosquamosal fissure, dividing into three branches that extend throughout the middle ear. A number of venous spaces in the retroarticular region that constitute the retrodiscal venous plexus. Small venous vessels along the fetal tympanosquamosal fissure accompany the anterior tympanic artery and drain into the retrodiscal venous plexus.

CONCLUSIONS

During human fetal development, there is a wide connection across the tympanosquamosal fissure between the middle ear and the temporomandibular joint region. The anterior tympanic artery and its branches, as well as small venous vessels that are connected with the retrodiscal venous plexus, extend along the most lateral part of the fissure.

The medial capsule of the human temporomandibular joint

PURPOSE

Attachments of the medial capsule of the temporomandibular joint (TMJ) to structures other than the medial fossa wall are thought to exist and to have functional significance. This study evaluated these relationships.

MATERIALS AND METHODS

The anatomic relationships between the medial capsule and other medial structures, the sphenomandibular ligament, discomalleolar ligament, and auriculotemporal nerve, were examined in 14 cadaver heads.

RESULTS

The results showed that the sphenomandibular ligament attaches separately from the medial capsule of the TMJ and therefore has no functional significance to the biomechanics of the joint. The discomalleolar ligament was found to be a continuation of the retrodiscal tissues and minimally associated with the medial capsule. The auriculotemporal nerve was not found to be in a relationship with the medial aspect of the condyle to the extent that mechanical irritation is possible during TMJ movement or disc displacement.