|Year : 2014 | Volume
| Issue : 4 | Page : 226-228
Foramen of Huschke (tympanicum) in a Nigerian male with articular soft-tissue herniation into the external auditory meatus
SA Olarinoye-Akorede1, IS Olanrewaju2, AO Suleiman3
1 Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
2 Department of Family Medicine, Rapides Regional Center, Alexandria, Louisiana, USA
3 Department of Orthorhinolaryngology, Federal Medical Center, Katsina, Nigeria
|Date of Web Publication||7-Oct-2014|
S A Olarinoye-Akorede
Department of Radiology, Ahmadu Bello University Teaching Hospital Zaria
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The protrusion of articular soft-tissue from the temporomandibular joint (TMJ) into the external ear in the absence of trauma, neoplasm or inflammation is rare. We present below a Nigerian adult male with retrodiscal herniation of soft-tissues of the TMJ into the external auditory meatus through a persistent foramen of Huschke. We are not aware of any reports of this developmental defect or its prevalence in the Nigerian medical literature. Therefore, this case is presented to heighten the index of suspicion of physicians when managing patients with otorrhea and otalgia; which is often primarily diagnosed or misdiagnosed as otitis externa. This will help avoid complications associated with the anomaly, some of which could be very serious.
| Abstract in French|| |
La saillie de problθmes articulaires des tissus mous dans une couronne temporaire (ATM) dans l'oreille externe en l'absence de traumatisme, nιoplasme ou inflammation est rare. Nous prιsentons ci-dessous un Nigιrian mβle adulte avec retrodiscal hernie discale de soft-tissus de l'ATM dans le conduit auditif externe mιat en persistant foramen de Huschke. Nous ne sommes pas au courant de tous les rapports de ce dιfaut de dιveloppement ou sa prιvalence dans le Nigιrian littιrature mιdicale. Par consιquent, ce cas est prιsentι ΰ aviver l'index de suspicion de mιdecins lors de la gestion des patients avec otorrhιe otalgia; ce qui est souvent principalement diagnostiquιe ou mal diagnostiquιes comme une otite externe. Cela contribuera ΰ ιviter les complications associιes ΰ l'anomalie, dont certains pourraient κtre trθs graves.
Mots clιs: Du conduit auditif externe, hernie discale, Huschke, une couronne temporaire
Keywords: External auditory canal, herniation, Huschke, temporomandibular joint
|How to cite this article:|
Olarinoye-Akorede S A, Olanrewaju I S, Suleiman A O. Foramen of Huschke (tympanicum) in a Nigerian male with articular soft-tissue herniation into the external auditory meatus. Ann Afr Med 2014;13:226-8
|How to cite this URL:|
Olarinoye-Akorede S A, Olanrewaju I S, Suleiman A O. Foramen of Huschke (tympanicum) in a Nigerian male with articular soft-tissue herniation into the external auditory meatus. Ann Afr Med [serial online] 2014 [cited 2019 Jul 23];13:226-8. Available from: http://www.annalsafrmed.org/text.asp?2014/13/4/226/142296
| Introduction|| |
The temporal bone is a composite bone, consisting of the following: Squamous, petrous, mastoid, tympanic portions, and the styloid process. However, just before birth it comprises of only the squamous, petromastoid and the tympanic parts. The tympanic portion of the temporal bone forms part of the external auditory canal and the tympanic cavity. Its ossification process could infrequently leave a bony communication between the structures of the external ear canal and its anteriorly related temporomandibular joint.  In adults, the persistence of foramen of Huschke defines an anatomic variation with clinical significance and this should be sought for in otologic practice.
| Case Report|| |
This was a case report of a 28-year-old man who complained of right sided ear pain and partial hearing loss of 2 weeks duration. The pain was worse in the temporomandibular joint (TMJ) region during mastication. There was associated fullness in the right ear but no discharge and no previous history of trauma, ear surgery nor instrumentation. There were no abnormalities on general physical examination and there were no salivary gland swellings. An initial clinical assessment of otitis externa was made.
On examination of the ear, there was a visible deformity of the right external auditory meatus (EAM) and the tympanic membrane was inflamed. Further examination revealed that the apparent deformity of right external auditory canal was present only on opening the mouth, with normalization of the external auditory canal anatomy on closing the mouth. This prompted a computerized tomographic (CT) Scan to better analyze the abnormal deformity.
CT of the temporal bones [Figure 1] and [Figure 2] showed right sided foramen tympanicum. The defect on the right measured 3 mm in axial diameter and there was also herniation of the soft-tissues of the TMJ into the right EAM. The TMJ on the left side showed a focal reduction in bone thickness (<1.0 mm) at the Huschke location. The patient was managed conservatively on antibiotics and analgesic with resolution of his symptoms. The patient is being considered for surgical closure, should conservative management fail.
|Figure 1: There is a bony defect in the postero medial aspect of the right temporomandibular joint. A bulge is also seen, representing soft-tissue herniation from the right TMJ into the external auditory meatus through the osseous defect (arrow)|
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|Figure 2: There is a focal reduction in the left temporal bone thickness at the same Huschke location as on the right. A thin bar of bone is also displaced posteriorly into the nutrient artery on the left (arrow)|
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| Discussion|| |
The Foramen of Huschke (also known as foramen tympanicum) is a persistent developmental anomaly which represents a defective ossification in the tympanic portion of the temporal bone. By anatomic definition, it is not a true foramen as it does not transmit any neurovascular structures within it. When present, it is located anteroinferior to the external auditory canal and anteromedial to the TMJ. It was first described by Emil Huschke (1889) and prior to 2005, only 16 cases had been reported in the literature world-wide.  In asymptomatic population, its prevalence varies from 4.6% to 20% respectively, , but this has been shown to decrease with age, suggesting that it closes with time.  Embryologically, the tympanic bone develops intramembraneously. The foramen of Huschke represents an opening in the developing tympanic ring which is at the floor of the EAM. Closure begins postnatally and is mostly complete by 5 years of age. This process is influenced by mechanical factors such as mastication, deglutition and respiration. Inadequate closure of the anterior portion of this ring results in persistence of the foramen in adult life. 
Although mostly asymptomatic, awareness of this anatomic variation is important because it could be associated with complications involving the TMJ or EAM. TMJ herniation as was seen in this case was also reported by other authors. ,,] Other complications include ear injury following TMJ arthroscopy,  salivary gland fistula.  Infection and tumoral spread could occur from the ear to the infratemporal fossa and vice versa. Patients may therefore present with pain, ear discharge or hearing loss. In children, it could mimic a branchial cleft anomaly. 
Several imaging studies have been employed to describe this foramen. A study done by Lacout et al.  examined 65 patients (130 ears) using high resolution CT while Tozoglu et al.  did anatomic coned beam CT detection in 207 patients (404 ears). They found mean axial diameter of 4.2 mm and 5 mm respectively; mean sagittal diameters of 3.6 mm and 2 mm respectively; and they documented a female preponderance. Like in this case, Lacout et al., in addition also reported as a separate entity, a focally reduced tympanic bone thickness (<1.0 mm) in the same location as Huschke foramen in 45 (35%) of their patients. Foramen Huschke was more common in the right ear 15.5% than the left 7.2%.  Toyama et al. added that it was more common in females in fifth decade and mostly unilateral.  This is in contrast to the patient presented.
Using plain radiographic techniques (panoramic, submental vertex, TMJ tomography) and contrast agent, Moreno et al. sought to assess and locate the foramen in four dried skulls.  It was most evident by linear tomography. However, being a rather obsolete technique, they recommended CT as the best technique to visualize the foramen. Magnetic resonance imaging (MRI), due to its excellent soft-tissue resolution is considered most useful in visualizing the herniated TMJ soft tissue (closed mouth position) and to differentiate it from salivary fistula caused by ectopic salivary gland. , MRI was not done in this patient because there was no fistula and CT eloquently demonstrated the osseous defect as well as the herniating soft-tissue. CT would therefore be very helpful in the Nigerian setting where MRI is still either not available or not affordable.
Asymptomatic patients are best left untreated. Surgical closure has however yielded good results in symptomatic patients. ,
| Conclusion|| |
Based on the above case study it can be concluded that ear ache and ear discharge may not be primarily due to infection. High resolution CT and/or MRI should be requested to further rule out an underlying developmental defect. We hope this report would also serve as an impetus for further studies to find out the prevalence of foramen tympanicum and racial differences in Africa.
| Acknowledgement|| |
We would like to thank Drs. Paul Lawson and Alfred Mansour of Rapides Regional Medical Center Alexandria, Louisisana for their help and suggestions on this article.
| References|| |
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[Figure 1], [Figure 2]