|Year : 2017 | Volume
| Issue : 1 | Page : 26-28
Multidetector computed tomography depiction of foramen of huschke with reversible herniation of temporomandibular joint soft tissue into external auditory canal
Preeti Garg1, Puneet Mittal2, Ranjana Gupta2, Amit Mittal2
1 Department of Oral Medicine and Radiology, Maharishi Markandeshwar Institute of Dental Sciences and Research, Mullana, Ambala, Haryana, India
2 Department of Radiodiagnosis, Maharishi Markandeshwar Institute of Medical Sciences and Research, Mullana, Ambala, Haryana, India
|Date of Web Publication||14-Mar-2017|
Department of Radiodiagnosis, Maharishi Markandeshwar Institute of Medical Sciences and Research, Mullana, Ambala, Haryana
Source of Support: None, Conflict of Interest: None
We present a case of an adult male who presented with herniation of soft tissues of temporomandibular joint into the external auditory canal (EAC) through a persistent foramen tympanicum. The patient was referred for computed tomography (CT) for suspicious mass in the left EAC. Multidetector CT helped in correctly characterizing the lesion with retraction of the soft tissue mass in open mouth biopsy and thereby avoiding unnecessary biopsy.
Keywords: Herniation, Huschke, multidetector computed tomography, temporomandibular
|How to cite this article:|
Garg P, Mittal P, Gupta R, Mittal A. Multidetector computed tomography depiction of foramen of huschke with reversible herniation of temporomandibular joint soft tissue into external auditory canal. J Mahatma Gandhi Inst Med Sci 2017;22:26-8
|How to cite this URL:|
Garg P, Mittal P, Gupta R, Mittal A. Multidetector computed tomography depiction of foramen of huschke with reversible herniation of temporomandibular joint soft tissue into external auditory canal. J Mahatma Gandhi Inst Med Sci [serial online] 2017 [cited 2021 Sep 23];22:26-8. Available from: https://www.jmgims.co.in/text.asp?2017/22/1/26/202012
| Introduction|| |
Foramen tympanicum is a developmental bony defect due to anomalous development of temporal bone. The temporal bone is complex bone comprising squamous, petrous, mastoid, tympanic parts, and the styloid process. External auditory canal (EAC) and the tympanic cavity develop from tympanic portion of temporal bone. Foramen tympanicum is a developmental defect during ossification process which leaves a bony defect which is anteriorly related to temporomandibular joint (TMJ). In adults, the persistence of foramen of Huschke defines an anatomic variation with clinical and otological significance, and a radiologist should be aware of this entity to avoid unnecessary surgical intervention/biopsy which can be harmful.
| Case Report|| |
A 70-year-old male was referred to us for high-resolution computed tomography (HRCT) of both temporal bones. He presented with clicking sound and otalgia in the left ear. There was associated fullness in the left ear but no discharge and no previous history of trauma, ear surgery, or instrumentation. On clinical examination, a pulsatile polypoidal mass was suspected to be bulging into EAC on the left side. Biopsy was planned and prebiopsy HRCT was performed. HRCT was performed on 128-slice Philips Ingenuity multidetector CT (Philips Medical Systems, The Netherlands) on 120 kV, 200 mA, an ultra-high-resolution filter, 1-mm section thickness, 0.3-mm section increment, 512 × 512 matrix, and 160-mm field of view.
HRCT of the temporal bone demonstrated a bony defect in the anteroinferior part of the EAC posteromedial to the TMJ. Through this defect, soft tissue protrusion was seen into the EAC along with few air specks [Figure 1]. An open mouth view was done which demonstrated that the herniated soft tissue retracted back into the TMJ with few air pockets [Figure 2]. Hence, this mass was diagnosed to be a soft tissue protrusion of TMJ into EAC through foramen tympanicum. Due to typical imaging findings, no contrast study was done. Biopsy was abandoned and no further treatment was given.
|Figure 1: Axial (a) and sagittal (b) multidetector computed tomography images in closed mouth position show defect in anteroinferior part of bony external auditory canal with protrusion of temporomandibular joint soft tissue into external auditory canal (white arrows). Dotted arrow in image b shows mandibular condyle in condylar fossa consistent with closed mouth imaging|
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|Figure 2: Axial (a) and sagittal (b) images multidetector computed tomography images in open mouth position show complete retraction of the soft tissue and air loculi in temporomandibular joint (white arrows). Dotted arrow in image b shows mandibular condyle out of condylar fossa consistent with open mouth imaging|
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| Discussion|| |
Foramen tympanicum was first described by Professor Emil Huschke, a German anatomist, and is therefore also known as foramen of Huschke. The term foramen is a misnomer as no nerves or vessels pass through it. It is rather only a persistent bony defect. Deglutition and respiration are some of the factors affecting its closure in postnatal period. It is a congenital bony defect located in the anteroinferior part of EAC, posteromedial to TMJ. EAC is incompletely formed at birth. After birth, further development occurs by anterior and posterior bony processes growing toward each other with approximation at about 1 year of age with small bony defect medial to it, which is known as foramen tympanicum. This bony defect normally closes by 5 years of age through the process of progressive membranous ossification. Failure of its closure beyond this age results in persistent foramen tympanicum.,
The incidence reported in literature ranges between 7-10%. But one study has reported as high as 30% incidence, while Lacout et al. observed an incidence of 4.3% with bilateral defects in half of them in their anatomical CT study. Recently, Tozoglu et al. found the incidence of unilateral foramen tympanicum in 11.6% and bilateral foramen tympanicum in 6.3% using cone-beam CT. It is now considered a normal developmental variant; however, herniation of TMJ into EAC is also seen in one-fourth of the cases and is directly related to the size of defect. Moreover, even if the defect is small initially with no herniation, the opening can be enlarged with softening of soft tissues over the years due to mastication.,,,
Patients with persistent foramen tympanicum can be asymptomatic or can present with complaints of otalgia, otorrhea (during mastication), and soft tissue mass protruding through EAC. The mass may be visible only on closed mouth and may completely disappear when mouth is open because the soft tissues retract back. The exact nature of this soft tissue is unclear, but it has been suggested to be secondary to TMJ arthritis or otitis externa. In our patient, there were no definite features of otitis externa; therefore, it could be secondary to TMJ arthritis. It can present with ear discharge during mastication, which occurs due to fistula formation of EAC with TMJ or fistula with parotid gland. Movement of the lesion with jaw movement during otoscopy can be falsely interpreted as pulsatile mass on clinical examination as was seen in our case. If unrecognized and inadvertent biopsy is attempted at otoscopy, it can cause TMJ damage and fistula formation. In our patient, due to patient's advanced age and minor symptoms, no surgical intervention was taken. Moreover, during TMJ arthroscopy, inadvertent injury of external and middle ear structures has been reported. Spread of infection can also occur in the infratemporal fossa through foramen tympanicum.
HRCT is an excellent technique to detect foramen tympanicum because of its high spatial resolution, sharp bony algorithm, and thin sections. Both sides should be carefully observed as it can occur bilaterally. Location of the bony defect is considered fairly diagnostic; however, if there is any clinical suspicion, open mouth HRCT can convincingly demonstrate partial or complete retraction of soft tissue
In symptomatic cases, surgical closure of foramen may be required. Two types of surgical approaches have been described: preauricular and endaural. For smaller defects, tragus cartilage and temporal fascia have been used to close defects, while for larger defects, use of synthetic materials such as polypropylene and titanium mesh has been described with good results. In case of fistula formation with parotid gland, simple ligation of tract has been found to be effective technique.
Therefore, it can be concluded that patients presenting with earache and discharge should be evaluated by HRCT as infection or tumor is not the only cause. Foramen tympanicum should be ruled out before planning any surgical procedure or taking a biopsy from a soft tissue mass protruding from the EAC.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2]