Total Facial Nerve Decompression via Combined Middle Cranial Fossa and Transmastoid approach

- Temporal bone trauma
- Iatrogenic facial nerve injury
- Tumor resection
- Recurrent Bell's palsy

- Inability to tolerate temporal craniotomy / middle cranial fossa approach

- Patient positioned supine with head turned to the side

- Computed Tomography (CT) scan
- Magnetic resonance imaging (MRI) scan
- Electroneuronography (ENoG)
- Facial Electromyography (EMG)

Middle cranial fossa approach:
- A 4cm x 5 cm is created centered on the zygomatic root
- The temporal lobe is retracted to expose the middle cranial fossa floor
- The greater superficial petrosal nerve (GSPN) is identified
- The middle ear space is identified via unroofing of the middle ear space
- The tympanic segment of the facial nerve is identified and decompressed by following GSPN posteriorly
- The superior semicircular canal is identified
- The internal auditory canal is idenified
- The labyrinthine segment of the facial nerve is identified and decompressed of bone
- The internal auditory canal dura is opened and the facial nerve is evaluated proximally to the brainstem

Transmastoid:
- The sigmoid sinus is identified
- The posterior external auditory canal is identified
- The tegmen mastoidium is identified
- The digastric muscle is identified
- The lateral semicircular canal is identified
- The incus is identified
- The mastoid segment of the facial nerve is identified and decompressed
- The facial recess is identified and opened
- The stapes is identified
- The incudostapedial joint is identified and separated
- The tympanic segment of the facial nerve is identified and decompressed of bone

Advantages:
- The surgery allows for total decompression and evaluation of the facial nerve from the brainstem through the mastoid component of the nerve
- The surgery allows for hearing preservation (both conductive and sensorineural) by sparing the ossicular chain and the labyrinth (compared to the translabyrinthine approach for example)

Disadvantage:
- The surgery requires a temporal craniotomy and retraction of the temporal lobe (something that is not required in the translabyrinthine approach)

- Bleeding, pain, infection, cerebrospinal fluid leak, meningitis, facial nerve paralysis or weakness, deafness, dizziness, tinnitus, taste change

Dr. Ravi N. Samy, MD, FACS receives research support from Cochlear Corporation