IJAR.2020.142
Type of Article: Original Research
Volume 8; Issue 2.2 (May 2020)
Page No.: 7486-7491
DOI: https://dx.doi.org/10.16965/ijar.2020.142
SURGICAL ANATOMY AND LANDMARKS OF TYMPANOMASTOID SEGMENT OF FACIAL NERVE USING MORPHOMETRY AS A MEASUREMENT TECHNIQUE: CADAVERIC TEMPORAL BONE DISSECTION STUDY
Tripti Shrivastava 1, Renu Rajguru *2, D Baruah 3, Sushil Kumar 4.
1 Professor, Department of Anatomy, AFMC, Pune, Maharashtra, India.
*2 Professor, Department of ENT, INHS Ashwini, Mumbai, Maharashtra, India.
3 Scientist D, Department of Pathology, AFMC, Pune, Maharashtra, India.
4 Professor & HOD, Department of Anatomy, AFMC, Pune, Maharashtra, India.
Corresponding author: Dr Renu Rajguru, Professor, Department of ENT, INHS Ashwini, Mumbai, Maharashtra, India. E-Mail: renurajguru@yahoo.com
ABSTRACT
Introduction: Facial nerve is unique in terms of a long and tortuous course in a bony canal within the temporal bone. The intricate course of the nerve is of vital concern to all otologic surgeons as maximum otological surgeries involve tympanomastoid segment of the nerve. While removing the disease, surgeons need to pay attention to the adjacent reliable landmarks, to ensure complete removal of disease while avoiding injury to the facial nerve.
Aim: To study the tympanomastoid course of facial nerve and to determine its effective surgical landmarks using morphometry
Material and methods: The present study was conducted in the temporal bone dissection laboratory in the Department of Otorhinolaryngology, AFMC, Pune on 20 temporal bones (ten left and ten right) harvested from cadavers from the Department of Anatomy, AFMC Pune. The temporal bones were dissected under Karl Ziess Operating microscope with an inbuilt camera. Images were captured and morphometric analysis of the recorded images was performed with image analysis software.
Observations and Results: Standard surgical approach was commenced with cortical mastoidectomy followed by facial recess approach. The distance between the facial and chorda tympani nerve was measured. Subsequently posterior canal wall was removed to study the relationship of Lateral semicircular canal and ossicles with the facial nerve. Normal surgical landmarks are often distorted in the diseased mastoid. Therefore, the surgeon should use as many of the available anatomical landmarks which act as a frame of reference for the facial nerve location.
Conclusion: Cochleariform process, distance of tympanic segment of facial nerve from the dome of lateral semicircular canal, short process of incus and pyramid were found to be constant landmarks. It is extremely important that surgeons are well versed with the surgical anatomy of facial nerve and various landmarks for its identification.
Key words: Facial nerve, Chorda tympani, Cochleariform process.
REFERENCES
- Glasscock ME, Gulya AJ. Anatomy of the ear and temporal bone. In: Surgery of the Ear 5th Hamilton, Ontario: BC Decker Inc; 2003: 35-36.
- Bibas T, Jiang D, Gleeson MJ. Disorders of the facial nerve. In: Gleeson M, editor. Scott-Brown’s Otolaryngology, Head and Neck Surgery. 7th ed. Great Britain: Hodder Arnold; 2008: 3870-91.
- How to Avoid Facial Nerve Injury in Mastoidectomy? Nam-Gyu Ryu and Jin Kim. J Audiol Otol. 2016 Sep; 20(2): 68–72.
- Wetmore SJ. Surgical landmarks for the facial nerve. Otolaryngol Clin North Am 1991; 24:505-30.
- Chi FL, Wang J, Yuan YS, Liu HJ, Gu J, Huang T, et al. Landmark of facial nerve in middle ear surgery. Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi 2006; 41:5-8
- Green JD Jr., Shelton C, Brackmann DE. Iatrogenic facial nerve injury during otologic surgery. Laryngoscope 1994; 104(8 ):922-26.
- Nager GT, Proctor B. Anatomic variations and anomalies involving the facial canal. Otolaryngol Clin North Am 1991; 24:531-53
- Rulon JT, Hallberg OE. Operative injury to the facial nerve.Explanations for its occurrence during operations on the temporal bone and suggestions for its prevention. Arch Otolaryngol1962; 76:131-9.
- Wilbrand HF. Multidirectional tomography of the facial canal. Acta Radiol Diagn (Stockh) 1975;16:654-72.
- Măru N, Cheiţă AC, Mogoantă CA, Prejoianu B. Intratemporal course of the facial nerve: Morphological, topographic and morphometic features. Rom J Morphol Embryol 2010;51:243-8.
- Kharat RD, Golhar SV, Patil CY. Study of intratemporal course of facial nerve and its variations.25 temporal bones dissection. Indian J Otolaryngol Head Neck Surg 2009; 61:39-42.
- Yadav SP, Ranga A, Sirohiwal BL, Chanda R. Surgical anatomy of tympano-mastoid segment of facial nerve. Indian J Otolaryngol Head Neck Surg 2006; 58:27-30.
- Botros G. The facial nerve in the surgery of congenital atresia of the ear.Ann Otol Rhinol Laryngol 1957; 66:173‑
- Dimopoulos PA, Muren C, Smedby O, Wadin K. Anatomical variations of the tympanic and mastoid portions of the facial nerve canal.A radioanatomical investigation. Acta Radiol Suppl 1996; 403:49-59.
- Kullman GL, Dyck PJ, Cody DT. Anatomy of the mastoid portion of the facial nerve. Arch Otolarygol 1971; 93:29-33
- Şentürk M, Somdaş MK, Ekinci N, Bayram A, Erkorkmaz U, Ünlü Y.Important landmarks for facial canal in the middle ear and mastoid: Human cadaveric temporal bone study. Erciyes Tip Dergisi 2009; 31:201-7.
- Çakýr N. Boyun ilgili konular. In: Çakýr N, editor,Otolaringoloji, Bas ve Boyun Cerrahisi. 2. Baský. Istanbul:Nobel Týp Kitabevleri; 1999. 393-440..
- Kaya S, Sennaroglu L. Iatrogenic facial paralysis in middle ear operations. Türk Otolarengoloji Arsivi. 1998;36:74-76.
- Candan H, Aktaþ D, Kanýmtürk Fasiyal kanal boyutlarý ve dehisanslarý. Türk Otolarengoloji Arsivi 1985; 23: 44-47.
- Wong DLH, Chen JM. Surgical anatomy of the epitympanic space. Am J Otol 1996; 17: 193-196.
- Schaitkin B, May M. Disorders of the facial nerve.Kerr AG, editor. In: Scott Brown.s Otolaryngology. 6th Vol. 3. Oxford: Butterworth- Heinemann International Editions; 1997. 1-38.
- Donaldson JA, Anson BJ. The triple “S” triangle, a topographical guide to the facial nerve in temporal bone surgery. Ann Otol Rhinol Laryngol 1965; 74: 59-62.