Intraoperative Electrical Stimulation for Traumatic Facial Nerve Paralysis

We present the case of a 14-year-old male who survived an ATV accident in which he sustained severe blunt head trauma with bilateral temporal bone fractures ([Fig. 1]) and delayed onset right sided facial paralysis. The patient was initially informed that facial function would return to normal after three months. After a lack of improvement in his facial paralysis 45 days after initial injury, the patient presented to us, and was offered intraoperative electrical stimulation of the facial nerve.

Physical examination demonstrated a HB grade VI right-sided facial paralysis and normal left facial function. Microscopic otoscopy showed an anteriorly displaced malleus in the right ear. The audiogram from 6 days after the accident showed bilateral symmetric conductive hearing loss with normal sensorineural function. CT demonstrated injury in the geniculate region on the right ([Figs. 2], [3]) and MRI showed swelling of the facial nerve in the region of the geniculate ganglion on the right.

Fifty-three days after initial trauma, this patient underwent a transmastoid internal middle cranial fossa (MCF) approach with intraoperative electrical stimulation of the perigeniculate portion of the facial nerve with incus interposition ossiculoplasty. Positive findings at time of surgery included a superficial aneurysmal wall of the sigmoid sinus, old blood in the mastoid cavity, disarticulation of the ossicular chain with the malleus being anteriorly dislocated and separated from the incus. The patient also had a hypermobile stapes that was not attached to the ligamentous annulus of the oval window. The facial nerve was exposed near the cochleariform process with a right angle hook. It was edematous and there was blood deep to the perineurium with microscopic fragments of bone embedded in the nerve. The perineum was incised and irrigated. Stimulation was introduced initially at 0.1 mA, increased by 0.2 mA increments, until a definitive response was obtained at 0.9 mA. The intraoperative electrical stimulation was then delivered for 30 seconds. There were no intraoperative complications.

Approximately 7 to 10% of temporal bone fractures result in facial nerve paralysis. Treatment is dependent on the severity of the nerve trauma and can range from conservative medical management to surgical intervention. A study by Hato et al. (2011) showed the rates of recovery of facial nerve function secondary to temporal bone trauma decline the longer surgical intervention is delayed. Additionally, as detailed in the literature, facial nerve decompression alone may result in poor functional recovery. While it has not been specifically studied in the facial nerve in a trauma setting, intraoperative electrical stimulation has been shown to accelerate motor nerve regeneration after peripheral nerve injury requiring surgical intervention.

Despite a 53-day delay between trauma and surgical intervention, the patient's facial function improved from House-Brackmann (HB) grade VI to grade II within 6 months ([Fig. 4]). Intraoperative facial nerve stimulation, which we have previously used for unresolved Bell's palsy, may be useful for patients with posttraumatic, persistent facial paralysis.

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
15 February 2022