Persistent foramen of Huschke: a tomographic study

Abstracts

OBJETIVO: Avaliar a persistência do forame de Huschke por meio do exame de tomografia computadorizada da região da orelha, abordando importantes aspectos clínicos da presença desse forame. MATERIAIS E MÉTODOS: Dois examinadores analisaram toda a região timpânica do osso temporal de 150 tomografias da região da orelha, bilateralmente, observando a presença ou a ausência do forame. RESULTADOS: No total, foram encontrados 17 (11,3%) pacientes com a referida anomalia anatômica, sendo que, destes, 13 (76,5%) pertenciam ao sexo feminino e quatro (23,5%), ao sexo masculino, com maior incidência para o sexo feminino, sendo comprovada estatisticamente. CONCLUSÃO: Os profissionais que atuam na região da orelha e/ou da articulação temporomandibular devem estar atentos quanto à persistência do forame de Huschke.

Forame de Huschke; Tomografia computadorizada; Osso temporal

ORIGINAL ARTICLE

Persistent foramen of huschke: a tomographic study^*

Henrique Nogueira Reis^I; Antonio Carlos Pires Carvalho^II; Horácio Faig Leite^III; Rossana Corbo Ramalho de Mello^IV; Sergio Salles Xavier^V

^IDental Surgeon, Doctor in Sciences by Department of Radiology at Faculty of Medicine, Universidade Federal do Rio de Janeiro

^IIMD, Doctor in Radiology, Adjunct Professor of the Discipline of Radiology at Faculty of Medicine, Universidade Federal do Rio de Janeiro

^IIIDoctor in Morphofunctional Sciences by Universidade de São Paulo, Titular Professor at Faculdade de Odontologia de São José dos Campos – Universidade Estadual Paulista "Júlio de Mesquita Filho"

^IVAdjunct Professor at Department of Radiology, Adjunct Coordinator for Program of Post-Graduation in Radiology at Universidade Federal do Rio de Janeiro

^VMD at Service of Cardiology, Hospital Universitário Clementino Fraga Filho, Teacher for Programs of Post-Graduation in Cardiology and Radiology at Universidade Federal do Rio de Janeiro

^{Mailing address}

ABSTRACT

OBJECTIVE: To evaluate the persistency of foramen of Huschke by means of computed tomography study of the ear region and approaching important clinical aspects related to the presence of this anatomical anomaly.

MATERIALS AND METHODS: Two examiners have analyzed the whole tympanic portion of temporal bone in 150 bilateral computed tomography studies of the ear region, searching for foramen of Huschke presence or absence.

RESULTS: The mentioned anatomical anomaly was found in 17 cases (11.3%), 13 patients (76.5%) being female and four (23.5%) male. This higher female incidence is statistically confirmed.

CONCLUSION: Ear and/or temporomandibular joint specialists should turn their attention to the persistency of foramen of Huschke.

Keywords: Foramen of Huschke; Computed tomography; Temporal bone – formation and development.

INTRODUCTION

In the phase of postnatal development of the temporal bones tympanic portion, one can found an osseous communication between the external acoustic meatus and the temporomandibular joint denominated foramen of Huschke^(1–3). This opening was first described by Emil Huschke, and normally is present in the antero-inferior temporal bones tympanic portion of children during the first five years of life, closing like a diaphragm at the end of this period. The persistency in adult subjects is considered as an anatomical anomaly^(1,4).

Foramen of Huschke formation occurs after birth, when the tympanic ring develops into tympanic bone, and is a ring-shaped structure interrupted on its superior extremity. During its development, which occurs circularly and upwards through ossification centers, the tympanic bone fuses with the petrous portion of the temporal bone, forming the outer wall of the tympanic cavity. The next phase of development is the appearance of two tubercles or prominences which grow one for the other, up to fuse in the first year of life. In this phase, the tympanic bone presents an opening denominated foramen of Huschke, as a result of those two tubercula fusion⁽¹⁾.

The clinical relevance of this anomaly has been recognized by several authors who have drawn attention to the fact of this anomaly being a potential route for: dissemination of infections from the external acoustic meatus affecting the temporomandibular joint^(5,6) and the parotid gland^(7,8); tumors originated in the articular fossa which uncommonly reach the external acoustic meatus⁽⁷⁾; cases of spontaneous salivary fistulas in the same acoustic meatus^(9,10); and complications resulting from temporomandibular joint arthroscopy^(10–15).

Considering that the introduction of the technique of CT images acquisition has brought, amongst innumerable advantages, the visualization of the foramen of Huschke^(16–18), this study is aimed at investigating its persistency by means of computed tomography (CT).

MATERIALS AND METHODS

We have performed a retrospective analysis of mastoid process CT studies of 150 adult patients attended in the Service of Otorhinolaryngology at Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. Patients age range was between 11 and 88 years (mean age 47 years) and, from the 150 subjects, 68 were male and 82 female.

All the CT studies have been carefully analyzed by a dental surgeon and a radiologist, aiming at researching the presence of a persistent foramen of Huschke in the region of articular fossa and external acoustic meatus. Once the presence of this anomaly was identified, the images of interest were photographed and data regarding this sample were recorded on an appropriate form as follows: a) patient's name, age and sex; b) presence or absence of foramen; c) uni- or bilateral incidence; d) number of the patient's dossier; e) date of CT examination.

For sampling uniformity purposes, we have excluded CT studies of patients who had undergone surgery and/or trauma in the ear region as well as patients´ control studies once they were evaluated. Intravenous contrast-enhanced CT studies have not been excluded.

In order to visualize the foramen of Huschke tomographic image, we have performed axial and coronal CT scans of two anatomical pieces; the first one with a present foramen of Huschke (Figure 1) and the second, as a control, anatomically without alteration. After evaluation of the images obtained, we can assure that in the axial series from the first anatomical piece, the foramen of Huschke was perfectly visualized (Figure 2); on the other hand, this was not possible with the control piece (Figure 3).

All the tomographic studies of evaluated patients have included increment images of the mastoid process region in axial 1.00-1.5 mm thick slices (distance between cuts = 1.00 mm).

After CT studies analysis, the results underwent statistical treatment by means of Fisher's exact test, aiming at evaluating the female or male prevalence of foramen of Huschke, besides the unilateral/bilateral incidence according to sex.

RESULTS

The foramen of Huschke was present in 17 (11.3%) and absent in 133 (88.7%) patients. From the total of 17 patients presenting the anomaly, 13 (76.5%) were female and four (23.5%) male, with a statistically significant higher incidence in women. Therefore, one can assert that the female incidence of foramen of Huschke is higher. As regards uni- or bilaterality, foramen of Huschke was bilaterally identified in 11 (64.7%) and unilaterally in six (35.3%) patients.

In order to see if, in the region of the foramen of Huschke and external acoustic meatus, the sexes induce equal frequencies of the anomaly, we have elaborated the Table 1. By submitting data included in Table 1 to Fisher's test, we have obtained p = 0.037, lower than the 0.05 significance level. So, statistically, one can assert that the persistency of foramen of Huschke, in our sample, was prevalent in women.

With Table 2, one may analyze the hypothesis that sex has induced equal unilateral and bilateral frequencies of persistent foramen of Huschke.

One may observe, in Table 2, that unilateral and bilateral presence of foramen of Huschke has occurred respectively in 30.8% and 69.2% of CT studies of female patients, and in 50% of male patients' CT studies the presence was unilateral, and in the other 50%, bilateral. By submitting these data to the Fisher's test, we have obtained p = 0.347, higher than the 0.05 significance level, demonstrating that the sex has not influenced the unilaterality/bilaterality of the anomaly.

Some tomographic images recorded during the development of this study can be found. They identify foramen of Huschke on the right and/or on the left side (Figures 4 and 5).

DISCUSSION

The figures related to persistency of foramen of Huschke^(1,8,19) reported by the authors present a quite remarkable variation, as well as the volume of samples studied by each of them. While Ars⁽¹⁾ has found persistency of only two foramina (0.7%) in 300 temporal bone studied without specifying sex and ethnic origin of the sample, Herzog & Fiese⁽²⁰⁾ have found 16 foramina in 100 Indian skulls evaluated (16.0%), similarly to Ars⁽¹⁾, without specifying the sexual identity of the sample, a criterion equally adopted by Wang et al.⁽⁸⁾. These authors, analyzing 377 skulls (300 Asiatic and 77 Caucasoid), have found the foramen in 7.2% of the sample, however, in a separate analysis and taking ethnic origin into consideration, the persistency was of 7.2% and 9.1% respectively. Faig-Leite & Horta Júnior⁽⁴⁾ have found persistent foramen of Huschke in 9.9% of a quite expressive sample including 776 skulls. Amongst these skulls 305 were carefully identified according sex, age range and ethnic group. In a separate analysis of the identified skulls, they observed that foramen of Huschke was more frequent in female skulls (16.2%) than in male skulls (8.3%).

Results collected in anatomical pieces by the previously mentioned researchers confirm that the persistency of foramen of Huschke varies remarkably. However, when compared with results from this imaging study (11.3%) they approach the results found by Faig-Leite & Horta Júnior⁽⁴⁾ (9.9%). Also in consonance with the latest author mentioned, we have observed higher incidence of this anatomical structure in female subjects (8.7%), while in male subjects the incidence was of 2.6%, which had not been observed by the other authors who involved themselves in the study of this anatomical anomaly like Ars⁽¹⁾, Herzog & Fiese⁽²⁰⁾ and Wang et al.⁽⁸⁾.

It is important to bring to one's attention to the fact that, by reviewing the literature and finding reports on severe clinical conditions resulting from the persistency of foramen of Huschke, one can observe that the greatest majority of cases described have affected female individuals^{(2,3,10,13,18,21–24)}.

When the presence of unilateral foramen of Huschke is identified in the CT studies evaluated, one can observe that this anatomical anomaly was unilaterally present in 4.0% of the sample (six patients), a rate similar to that obtained by Wang et al.⁽⁸⁾, who have found unilateral foramen in 3.4% (13 skulls), but distant from rates collected by Faig-Leite & Horta Júnior⁽⁴⁾ (5.3%; 41 skulls) and by Herzog & Fiese⁽²⁰⁾ (9.0%; nine skulls).

Foramen was bilaterally found in 7.3% (11 individuals) of evaluated CT studies, a rate similar to that found by Herzog & Fiese⁽²⁰⁾ (7.0%; seven skulls), but different from those obtained by Wang et al.⁽⁸⁾ (3.7%; 14 skulls) and by Faig-Leite & Horta Júnior⁽⁴⁾ (4.6%; 36 skulls). It is important to note that Ars⁽¹⁾ has not reported these data in his study.

Some authors have observed that plain X-rays failed in detecting the presence of foramen of Huschke^(6,19). For others, it was really impossible to identify it⁽²¹⁾, due overlapping of temporal bones structures, including the tympanic portion where this anatomical anomaly is located^(21,22). In these cases, when it is necessary to visualize the structures that constitute the external acoustic meatus and the middle ear covered by the temporal bone, according to several authors^{(5,9,17,18,21,23–25)}, CT is the study of choice and the most appropriate for visualizing the mentioned anatomical structure. In the present study, CT has shown effectiveness to identify the persistency of foramen in the sample evaluated, although Applebaum et al.⁽¹¹⁾, when describing terrible iatrogenies occurred during TMJ arthroscopy (for example, irreversible deafness) have highlighted the possibility of CT failing in detecting little osseous deficiencies that could allow arthroscope penetration into the external acoustic meatus.

According to Heffez et al.⁽¹⁹⁾, Herzog & Fiese⁽²⁰⁾ and Schickinger et al.⁽¹⁴⁾, the foramen of Huschke could predispose to such lesions as a result of the arthroscope penetration into the external acoustic meatus, subsequently reaching the middle ear structures with significant sequelae for the auditory tract, as a result of the arthroscope diameter (ranging between 1.7 mm and 2.7 mm in its transverse section).

Therefore the data obtained in the present study allow us to suggest that CT is an extremely important examination for visualization of anatomical substructures — for example, foramen of Huschke —, in compliance with information reported by Hawke et al.^(21,23), Herzog & Fiese⁽²⁰⁾, Cecire et al.⁽⁹⁾, Dingle⁽⁵⁾, Schunk et al.⁽²⁶⁾, Rabinov et al.⁽¹⁸⁾, Ali & Rubinstein⁽¹⁶⁾ and Anand et al.⁽¹⁷⁾.

CONCLUSION

Persistent foramen of Huschke was identified in 17 patients (11.3%). The incidence of this anatomic anomaly was statistically higher in female individuals. A possible higher unilateral or bilateral incidence in men or women has not been taken into consideration.

Specialists in ear, temporomandibular joint and adjacent regions should rule out the persistency of foramen of Huschke, as well as being aware of the significant clinical implications of its presence for the patient.

REFERENCES

Received August 17, 2005.

Accepted after revision November 4, 2005.

• 1. Ars B. Le foramen de Huschke. Acta Otorhinolaryngol Belg 1988;42:654658.
• 2. Bento RF. Anatomia do osso temporal. In: Bento RF, editor. Tratado de otologia. São Paulo: Universidade de São Paulo, 1998;1721.
• 3. Bento RF. Embriologia do osso temporal. In: Bento RF, editor. Tratado de otologia. São Paulo: Universidade de São Paulo, 1998;4960.
• 4. Faig-Leite H, Horta Júnior JAC. Persistence of the foramen of Huschke. Dent Res 1999;77:1177.
• 5. Dingle AF. Fistula between the external auditory canal and the temporomandibular joint: a rare complication of otitis externa. J Laryngol Otol 1992;106:994995.
• 6. Thomson HG. Septic arthritis of the temporomandibular joint complicating otitis externa. J Laryngol Otol 1989;103:319321.
• 7. Sharma PD, Dawkins RS. Patent foramen of Huschke and spontaneous salivary fistula. J Laryngol Otol 1984;98:8385.
• 8. Wang RR, Bingham B, Hawke M, Kwok P, Li JG. Persistence of the foramen of Huschke in the adult: an osteological study. J Otolaryngol 1991; 20:251253.
• 9. Cecire AA, Austin BW, Ng PK. Polyp of the external ear canal arising from the temporomandibular joint: a case report. J Otorynolaryngol 1991;20:168170.
• 10. Sanders B. Arthroscopic surgery of the temporomandibular joint: treatment of internal derangement with persistent closed lock. Oral Surg Oral Med Oral Pathol 1986;62:361372.
• 11. Applebaum EL, Berg LF, Kumar A, Mafee MF. Otologic complications following temporomandibular joint arthroscopy. Ann Otol Rhinol Laryngol 1988;97:675679.
• 12. McCain JP, Podrasky AE, Zabiegalski NA. Arthroscopic disc repositioning and suturing: a preliminary report. J Oral Maxillofac Surg 1992; 50:568579.
• 13. McCain JP, Sanders B, Koslin MG, Quinn JL, Peters PB, Irdresano AT. Temporomandibular joint arthroscopy: a 6-year multicenter retrospective study of 4,831 joints. J Oral Maxillofac Surg 1992;50:926930.
• 14. Schickinger B, Gstoettner W, Cerny C, Kornfehl J. Variant petrotympanic fissure as possible cause of an otologic complication during TMJ arthroscopy. A case report. Int J Oral Maxillofac Surg 1998;27:1719.
• 15. Van Sickels JE, Nishioka GJ, Hegewald MD, Neal GD. Middle ear injury resulting from temporomandibular joint arthroscopy. J Oral Maxillofac Surg 1987;45:962965.
• 16. Ali TS, Rubinstein JT. Rheumatoid arthritis of the temporomandibular joint with herniation into the external auditory canal. Ann Otol Rhinol Laryngol 2000;109:177179.
• 17. Anand VT, Latif MA, Smith WP. Defects of the external auditory canal: a new reconstruction technique. J Laryngol Otol 2000;114:279282.
• 18. Rabinov CR, Alavi S, Canalis RF, Lee EJ. Recurrent pleomorphic adenoma of the parotid gland involving the osseous external auditory canal. With a note on the foramen of Huschke. Ann Otol Rhinol Laryngol 1997;106:589593.
• 19. Heffez L, Anderson D, Mafee M. Developmental defects of the tympanic plate: case reports and review of the literature. J Oral Maxillofac Surg 1989;47:13361340.
• 20. Herzog S, Fiese R. Persistent foramen of Huschke: possible risk factor for otologic complications after arthroscopy of the temporomandibular joint. Oral Surg Oral Med Oral Pathol 1989;68:267270.
• 21. Hawke M, Kwok P, Mehta M, Wang RG. Bilateral spontaneous temporomandibular joint herniation into the external auditory canal. J Otolaryngol 1987;16:387389.
• 22. Swartz JD, Harnsberger HR. The external auditory canal. In: Imaging of the temporal bone. 3rd ed. New York: Thieme, 1998;1620.
• 23. Hawke M, Kwok P, Shankar L, Wang RG. Spontaneous temporomandibular joint fistula into the external auditory canal. J Otolaryngol 1988;17: 2931.
• 24. Panda NK, Verma A, Mann SB, Mehra YN. Indeterminate salivary fistula through the external auditory canal. Ear Nose Throat J 1990;69:657659.
• 25. Greene MW, Hackney FL, Van Sickels JE. Arthroscopy of the temporo mandibular joint: an anatomic perspective. J Oral Maxillofac Surg 1989; 47:386389.
• 26. Schunk M, Schultz-Coulon HJ, Köster R, Shadou S. Arthrogener gehörgangstumor. HNO 1996;44: 640643.

*

Study developed at Service of Images Archive, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.

Publication Dates

• Publication in this collection
  26 Sept 2006
• Date of issue
  Aug 2006

History

• Received
  17 Aug 2005
• Accepted
  04 Nov 2005