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Surface Projection of Internal Acoustic Meatus
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Swayam Jothi. S
Introduction: The cerebellopontine angle tumours account for 8% of all intracranial tumours in infants. Today, the availability of non-invasive imaging procedure such as CT scan and MRI, make it easy to diagnose them and some successful operations have been done by enlarged middle cranial fossa approach (Haider, 1992). When translabyrinthine and middle cranial fossa approaches are contraindicated, the posterior cranial fossa approach could be tried for cerebellopontine angle tumours.
Aim: This study aims to collect adequate gross information which may be of help in various surgical interventions of the facial nerve; for example cerebellopontine angle tumours.
Materials & Methods: 39 fetal craniums were used for measurements to locate the internal acoustic meatus from surface. Two intact fetal heads were used to confirm this method of reaching the Internal Acoustic meatus (IAM) from the entry point.
Cranial index was calculated for all the skulls: For surgical procedures to reach the IAM from surface and for biopsy with a needle, the following measurements were made.
<!--[if !supportLists]-->1. <!--[endif]-->Distance between the entry point and surface point.
<!--[if !supportLists]-->2. The angle between the entry point, internal acoustic meatus, and the surface point.
<!--[if !supportLists]-->3. <!--[endif]-->Depth of IAM from EP.
Observation: Percentage ratio of the entry point to cranial index, IAM to cranial index & depth of IAM to cranial index respectively, the mean value were found to be 3.11, 45.3 & 4.13 respectively. The constants derived were utilized to locate the entry point of the needle, angle of passage and the depth to which it should be passed. The validity of this method was verified in the 39 exposed craniums. Two intact fetal heads were used to confirm this method of reaching the IAM from the entry point.
Keywords: Cerebellopontine angle tumours, Facial nerve, Internal acoustic meatus (IAM)
References
- Glasscock et al.(1985)Lyme disease: A cause of bilateral facial paralysis.Arch.Otolaryngol.,Vol.III.
- Haid C.T and Wigand M.E,(1992).Advantages of the enlarged middle cranial fossa approach in neurinomas surgery- a review. Acta. Otolaryngol. Stockh. 112(3):387-
- Hitselberger, W.E and House, W. F (1966). Acoustic Neuroma. Diagnosis. Arch Otolaryngol, 83:218-221.
- Hughes, G.B.(1982) Electromyograph: Objective prognostic assessment of facial paralysis.Am.J.Otol.,4:73-76.
- Inioue, A., Sekiguchi, K., Sato, S., and Fujita. T. (1994). Neonatal brain tumour. A report of 3 cases. Noshuyo. Byori. 11:77–83.
- Knoblauch: cited by Cushing. H(1917).Tumours of the nervus Acusticus and syndrome of the cerebellopontine angle. Hafner publishing company, New York.
- Lescanne, E; Evelut, S.; Lefrancq, T & Destrieux, Ch. The internal acoustic meatus and its meningeal layers; a micro anatomical study, Neurosurgery, 97(5),
- Moeller, T.B. Normal Findings in Radiology, Thieme, 2000, pp.33.
- Portman. M, Sterkers. J and Charachon. R (1975).The internal auditory meatus. Churchill Livingstone, New York.
- Ravilla, G.A (1948). Differential diagnosis of tumours at the cerebellopontine recess. Bull. Johns. Hopk. Hosp., 83:187.
- Standring. S Gray’s Anatomy: the anatomical bases of clinical practice. 39 th ed. Elsevier, Churchill, Livingstone, 2005: pp. 463,468-71.
- Smith J.D, Cromley R.C and Harker L. A(1981)Facial paralysis in newborn. Otolaryngol. Head Neck surg.,89:1021-1024.
- Takaharshi, M., Okudera, T., Tomanaga, M. And Kitamura K. (1971). Angiographic diagnosis of acoustic neurinomas: analysis of 30 lesions. Neuroradiology 2:191-200.
- Wishart, J. (1822). Cases of tumours of the skull, duramater and brain. Edinburgh Medical Society’s Journal,17:393-397.
How to Cite This Article
Vancouver
S SJ. Surface Projection of Internal Acoustic Meatus [Internet]. IP Indian J Anat Surg Head Neck Brain. 2016 [cited 2025 Oct 08];2(1):1-15. Available from: https://doi.org/
APA
S, S. J. (2016). Surface Projection of Internal Acoustic Meatus. IP Indian J Anat Surg Head Neck Brain, 2(1), 1-15. https://doi.org/
MLA
S, Swayam Jothi.. "Surface Projection of Internal Acoustic Meatus." IP Indian J Anat Surg Head Neck Brain, vol. 2, no. 1, 2016, pp. 1-15. https://doi.org/
Chicago
S, S. J.. "Surface Projection of Internal Acoustic Meatus." IP Indian J Anat Surg Head Neck Brain 2, no. 1 (2016): 1-15. https://doi.org/