Decompression of the tympanic and labyrinthine segments of the facial nerve by middle cranial fossa approach: an anatomic study.
BACKGROUND
Peripheral facial palsy is characterized by the permanent or temporary interruption of facial muscle function. The middle cranial fossa (MCF) approach has been used to decompress the facial nerve (FN) when hearing needs to be preserved. In this work, we describe a technique for decompressing the FN through the MCF approach, which allows the direct exposure of the labyrinthine and entire tympanic segment of the FN, with preservation of inner ear function.


METHODS
Twenty cadavers heads were used in this study. The reference landmarks used were the middle meningeal artery, greater superficial petrosal nerve, arcuate eminence, inferior petrosal sinus and meatal plane following the petrous apex from its most anterior and medial portion.


RESULTS
The tympanic segment of the FN presented, on average, a total length of 11 ± 0.67 mm to the right and 11.5 ± 0.60 mm to the left. The longitudinal lengths of the bone window in the tegmen tympani were 16.8 ± 1.67 mm to the right and 16.8 ± 1.20 mm to the left. The cross-sectional lengths of the bone window in the tegmen tympani were 5.5 ± 1.20 mm and 5.0 ± 1.75 mm to the right and left sides, respectively. The average value of the elliptical area formed by the longitudinal and transversal lengths of the bone window made in the tegmen tympani was 72.5 ± 22.5 mm(2) to the right and 65.9 ± 30.3 mm(2) to the left.


CONCLUSION
The proposed technique can be used for the surgical decompression of the tympanic, labyrinthine and meatal segments of the FN through the MCF in addition to reducing the surgical time and the risk to patients.
['da Franca Pereira|Marcos Alexandre|MA|', 'Bittencourt|Aline Gomes|AG|', 'de Andrade|Emerson Magno|EM|', 'Bento|Ricardo Ferreira|RF|', 'de Brito|Rubens|R|']
D000328:Adult D002102:Cadaver D035301:Cranial Fossa, Middle D019299:Decompression, Surgical D007758:Ear, Inner D005154:Facial Nerve D005158:Facial Paralysis D005260:Female D006801:Humans D008297:Male
Facial nerve Middle cranial fossa Facial palsy Anatomy