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DOI: 10.1055/s-0032-1329621
Microsurgical Localization of the Cochlea in the Extended Middle Fossa Approach
Publikationsverlauf
26. Januar 2012
26. Juni 2012
Publikationsdatum:
07. November 2012 (online)
![](https://www.thieme-connect.de/media/jnlsb/201206/lookinside/thumbnails/10.1055-s-0032-1329621-1.jpg)
Abstract
Objective In the extended middle fossa approach, a portion of the petrous bone known as Kawase's rhomboid can be drilled to expose the posterior fossa through a middle fossa corridor. During this bony resection, the cochlea is placed at risk. The objective of this study was to objectively detail the position of the cochlea in relation to reliable surgical landmarks.
Methods Eleven cadaveric specimens were dissected—including six cadaveric heads and five dry temporal bones by means of an anterior petrosectomy with skeletonization of the cochlea. Three anatomic measurements describing the location of the cochlea in relation to the extrapolated intersection of the greater superficial petrosal nerve (GSPN) and facial nerve were recorded. These measurements were then correlated with thin-cut temporal bone computed tomography scans from 25 patients with morphologically normal inner ears.
Results In the cadaveric specimens, the anterior border of the membranous basal turn of the cochlea was located an average of 7.56 mm (6.4 to 8.9 mm) anterior to the extrapolated junction of the GSPN and facial nerve, as measured along the course of the GSPN. The medial border of the membranous cochlea (medial margin of basal turn) was located an average of 8.2 mm (6.9 to 8.9 mm) medial to the extrapolated junction of the GSPN and facial nerve, as measured along the course of the facial nerve. The average maximum distance from the extrapolated junction of the GSPN and facial nerve to the membranous cochlea was 9.3 mm (8.2 to 10.3 mm). These anatomic measurements correlated well with radiologic measurements of the same parameters.
Conclusion When drilling Kawase's rhomboid, it is useful to locate the extrapolated junction of the GSPN and the facial nerve. Drilling of the anteromedial petrous bone outside of a radius of 12.5 mm from the extrapolated junction of GSPN and facial nerve appears to be associated with a low degree of risk to the cochlear apparatus.
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References
- 1 Day JD, Fukushima T, Giannotta SL. Microanatomical study of the extradural middle fossa approach to the petroclival and posterior cavernous sinus region: description of the rhomboid construct. Neurosurgery 1994; 34: 1009-1016 , discussion 1016
- 2 Miller CG, van Loveren HR, Keller JT, Pensak M, el-Kalliny M, Tew Jr JM. Transpetrosal approach: surgical anatomy and technique. Neurosurgery 1993; 33: 461-469 , discussion 469
- 3 Garcia-Ibanez E, Garcia-Ibanez JL. Middle fossa vestibular neurectomy: a report of 373 cases. Otolaryngol Head Neck Surg 1980; 88: 486-490
- 4 Isolan GR, Krayenbühl N, de Oliveira E, Al-Mefty O. Microsurgical anatomy of the cavernous sinus: measurements of the triangles in and around it. Skull Base 2007; 17: 357-367
- 5 Sameshima T, Mastronardi L, Friedman A, Fukushima T. Middle fossa dissection for extended middle fossa and anterior petrosectomy. In: Sameshima T, Mastronardi L, Friedman A, Fukushima T, , eds. Fukushima's Microanatomy and Dissection of the Temporal Bone for Surgery of Acoustic Neuroma and Petroclival Meningioma. Raleigh: AF NeuroVideo; 2004
- 6 Mastronardi L, Sameshima T, Ducati A, De Waele LF, Ferrante L, Fukushima T. Extradural middle fossa approach. Proposal of a learning method: the “rule of two fans.” Technical note. Skull Base 2006; 16: 181-184
- 7 Dew LA, Shelton C, Harnsberger HR, Thompson Jr BG. Surgical exposure of the petrous internal carotid artery: practical application for skull base surgery. Laryngoscope 1997; 107: 967-976
- 8 Rhoton Jr AL. The temporal bone and transtemporal approaches. Neurosurgery 2000; 47 (3, Suppl) S211-S265
- 9 Jung SM. JSJ, Ahn T.H. Microanatomical study of the extradural middle fossa approach for preventing cochlear damage. J Korean Neurosurg Soc 2004; 36: 353-357
- 10 Sennaroglu L, Slattery III WH. Petrous anatomy for middle fossa approach. Laryngoscope 2003; 113: 332-342
- 11 Laurikainen E, Kanninen P, Aho H, Saukko P. The anatomy of the human promontory for laser Doppler flowmetry. Eur Arch Otorhinolaryngol 1997; 254: 264-268
- 12 Jackler RK , ed. Atlas of Skull Base Surgery and Neurotology. New York, NY: Thieme; 2008