Research Article

Incidence of foramen of Huschke in V. Sharon Keziah1, K. Yuvaraj Babu2*, Karthik Ganesh Mohanraj2

ABSTRACT

Introduction: The foramen of Huschke (FH) otherwise known as foramen tympanicum represents a developmental defect in the anteroinferior aspect of the bony external auditory meatus and is an uncommon disorder. It is posteromedial to the temporomandibular joint (TMJ) occurs due to a defect in normal ossification in the first 5 years of life. The FH may predispose individuals to TMJ pathology or it may be associated with salivary discharge into the external acoustic during mastication. The aim of this study is to find the incidence of FH in the temporal bone. Materials and Methods: A total of 34 dry adult skulls of unknown sex and age were observed from the Department of Anatomy, Saveetha Dental College and Hospitals, Chennai. Results: FH was observed in two dry human adult crania of the 34 human crania with an occurrence of 5.8%. Both the FHs were present on the left side of the crania and were circular in shape. Conclusion: This case report describes one of the variations of a temporal bone, the FH with its embryological and clinical aspects. This study might enhance the knowledge of temporal bone in the field of osteology.

KEY WORDS: External acoustic canal, External acoustic meatus, Foramen Huschke, Foramen tympanicum, Tympanic plates

INTRODUCTION The temporal bone has four parts, namely the squamous, mastoid, petrous, and tympanic parts, of The foramen of Huschke (FH) also known as foramen which the FH can be seen in the tympanic plate (TP). tympanicum is an anatomic variation due to defective TP lies in between the squamous and mastoid parts of development. It predominantly occurs in the tympanic temporal bone.[8] FH is located on the anteroinferior part of the temporal bone[1] due to a defect in normal wall of the external acoustic meatus (EAM) on the ossification in the first 5 years of life.[2] It is located in TP of the temporal bone, presenting a communication the anteroinferior part of the external auditory canal between the EAM and the mandibular fossa. (EAC) and posteromedial to the temporomandibular joint (TMJ). MATERIALS AND METHODS

Its presence in the tympanic portion of the temporal A total of 40 dry human adult crania of unknown sex bone is extremely rare. There are various shapes and and age were observed from the Anatomy Department, sizes of the foramen. FH can either be asymptomatic Saveetha Dental College and Hospitals. Only those or it may cause a persistent ear discharge after crania were selected in which the TPs remained intact and mastication, in which case it might be connected to the undamaged, so a total of 34 dry adult skulls were observed TMJ or .[3-5] The presence of the foramen in the study. The TPs were observed for the occurrence of FH. Any defect in the TP called FH was observed may make the external and internal part of the ear meticulously. The incidence of FH was noted down. vulnerable to injuries mainly during arthroscopy of the TMJ. It may also lead to inadvertent passage of the endoscope into the TMJ leading to its damage.[6,7] RESULTS FH [Figure 1] was observed in two dry human adult Access this article online crania of the 34 human crania examined with an occurrence of 5.8%. Both the foramina were found on Website: jprsolutions.info ISSN: 0975-7619 the left side of the TPs and both the foramina were

1Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India, 2Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India

*Corresponding author: K. Yuvaraj Babu, Department of Anatomy, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India. Phone: +91 9840210597. E-mail: [email protected]

Received on: 12-05-2018; Revised on: 15-06-2018; Accepted on: 19-07-2018

Drug Invention Today | Vol 10 • Special Issue 3 • 2018 3321 V. Sharon Keziah, et al. circular in shape.

DISCUSSION The FH is a bony defect in the anteroinferior wall of EAC which persists after 5 years of age. Anteroinferior wall of EAC is formed by tympanic bone, which develops from a membranous ossification process.[9,10] The foramen tympanicum can be most probably seen in the TPs of the temporal bone. Therefore, FH is also known as foramen tympanicum. Rushton et al. reported that, in a proportion of the population, ranging from 5% to 46%, the FH may persist through life.[11]

After birth, the tympanic bone is developed incompletely, and if the fusion of the anterior and posterior prominence to the tympanic bone does not happen by the age of 5 years, then this leads to Figure 1: Red arrow indicating foramen of Huschke the persistence of FH. The factors that lead to the formation of this foramen are mastication, deglutition, to previous studies. Soft tissue herniation may occurs and respiration against the tympanic bone.[12] rarely in the EAM and spread of infection or tumor Furthermore, a persistent FH has been associated with occurs between EAM and TMJ. It was reported that fistula formation between the parotid gland and the FH was present in 38% of south Andhra population external auditory meatus.[13] by Bhanu and Sankar.[18] Keerthana and Thenmozhi in their study have reported the presence of this foramen The FH is variable in shape, size, and location. They in 23.33% of the 69 skulls they have examined.[19] It can pinpoint, pinhead, circular, irregular, triangular, was obseved that FH was present in 38% of south and U-shaped foramen. In this study, the common Andhra population by Bhanu and Sankar.[8] Umme foramen seen was the circular foramen. The most reported that this foramen may be present in young probable reason could be the ethnic variation. They children but only occasionally persist after 5th year.[20] could also be observed on the right as well as the left side of the temporal bone. They vary in diameter and CONCLUSION size with regional variation being a possible region.[14] The study revealed that the occurrence of FH in dry Knowledge and information of this anatomical defect human cranium is around 5.8% . Its presence may affect may be useful in evaluating patients with short- the health and cause many different abnormalities of lived otorrhea where no local cause is identified. the EAC and may lead to otological complications. Occasional or frequent ear discharge after mastication Therefore, ENT surgeons should be aware of persistent may be due to this foramen with the possibility of it FH and consider it as one of the possible diagnoses connecting with TMJ or parotid gland. Awareness of while dealing with patients presenting with otological the presence of FH may prevent unintentional passage complications. Furthermore, the surgeons should of the endoscope into the TMJ and ultimately result be careful while performing an endoscopy of TMJ in its damage. If this foramen is persistent, infection so that accidental damage of TMJ can be prevented. may spread from EAC to and vice Its clinical significance should be considered by the versa. Data obtained from this study might benefit health-care system. This study, therefore, describes anatomists, ear, nose, and throat surgeons, dentists, the incidence of FH. and radiologists. Clinicians and the health-care system should be aware of the presence of this defect because REFERENCES it may affect the diagnosis of the problem and the successful treatment and prognosis.[15] 1. Lacout A, Marsot-Dupuch K, Smoker WR, Lasjaunias P. Foramen tympanicum, or foramen of huschkle: Pathologic cases and anatomic CT study. Am J Neuroradiol 2005;26:1317-23. The FH is asymptomatic. Patent FH has been reported 2. Humphrey LT, Scheuer L. Age of closure of the foramen as being the cause of persistent ear discharge following of Huschke: An osteological study. Int J Osteoarchaeol mastication due to the connection with the TMJ. 2006;16:47-60. [16,17] The foramen can be easily detected with high- 3. Rezaian J, Namavar MR, Nasab HV, Nobari ARH, Abedollahi A. Foramen tympanicum or foramen of Huschke: A bioarchaeological resolution spiral computed tomography or magnetic study on human skeletons from an iron age cemetery at Tabriz resonance imaging, and it can demonstrate the soft Kabud Mosque zone. Iran J Med Sci 2015;40:367-7. tissue herniation or parotid fistula into EAC. The FH 4. Sharma PD, Dawkins RS. Patent foramen of Huschke and has been found to be common in females according spontaneous salivary fistula. J Laryngol Otol 1984;98:83-5.

3322 Drug Invention Today | Vol 10 • Special Issue 3 • 2018 V. Sharon Keziah, et al.

5. Sharma PD, Dawkins RS. Patent foramen of Huschke and 2004;125:676-89. spontaneous salivary fistual. The Journal of Laryngology & 13. Rushton VE, Pemberton MN. Salivary otorrhoea: A case Otology 1984;98:83-5. report and a review of the literature. Dentomaxillofac Radiol 6. Applebaum EL, Berg LF, Kumar A, Mafee MF, Otologic 2005;34:376-9. complications following temporo mandibular joint arthroscopy. 14. Srimani P, Mukherjee P, Ghosh E, Roy H. Variant presentations Ann Otol Rhinol Laryngol 1989;97:675-9. of foramen of Huschke in seven adult human crania. Int J Anat 7. Herzog S, Fiese R. Persistent foramen of Huschke: Possible Var 2013;6:120-3. risk factor for otologic complications after arthroscopy of the 15. Langer J, Begall K. Otosialorrhoea-diagnostics and therapy of temporo mandibular joint. Oral Surg Oral Med Oral Pathol a salivary fistula of the external auditory canal. Laryngo Rhino 1989;68:267-70. Otol 2004;83:606-9. 8. Bhanu PS, Sankar KD, Incidence of foramen of Huschke 16. Psillas G, Guyot JP. Spontaneous temporomandibular joint in South Andhra Population of India. J Clin Diagonos Res herniation into the external ear canal. Ann Otolaryngol Chir 2016;10:AC01-3 Cervicofac 2007;124:305-8. 9. Stedman TL. Bone. In: Stedman TL, editors. Stedman’s 17. Chilla R. Otosialorrhoea: A rare case of a spontaneous salivary Medical Dictionary. 26th ed. Baltimore: Lippincott William fistula of the external auditory canal. HNO 2002;50:943-45. and Wilkins; 1995. p. 674. 18. Ars B. Le foramen de Huschke. Acta Otorhinolaryngol Belg 10. Sperber GH. The temporomandibular joint. In: Derrich DD, 1988;42:654-58. editor. Craniofacial Embryology. 2nd ed. Chicago: John Wright 19. Keerthana B, Thenmozhi MS. Occurrence of foramen of and Sons; 1975. p. 121-49. Huschke and its clinical significance, research. J Pharm 11. Tozoğlu U, Caglayan F, Harorlı A. Foramen tympanicum Technol 2016;9:1835-6. 20. Durbar US. Racial variations in different skulls. J Pharm or foramen of Huschke: anatomical cone beam CT study. Technol 2014;6:370-2. Dentomaxillofacial Radiology 2012;41:294-7. 12. Mao JJ, Nah HD. Growth and development: Hereditary Source of support: Nil; Conflict of interest: None Declared and mechanical modulations. Am J Dentofacial Orthop

Drug Invention Today | Vol 10 • Special Issue 3 • 2018 3323