Iatrogenic facial nerve paralysis refers to facial paralysis resulting from medical interventions. Procedures involving the cerebellopontine angle region and the lateral cranial base carry a relatively higher risk of iatrogenic facial paralysis. In contrast, the likelihood of iatrogenic facial paralysis during middle ear and mastoid surgeries is lower. However, if facial nerve paralysis occurs during routine middle ear surgery, it is considered a serious complication.
Management Principles and Considerations
Management of Intratemporal Facial Nerve Injuries
If significant facial nerve damage is observed intraoperatively, the bony canal of the facial nerve on both sides of the damaged segment should be unroofed to expose the intact portions of the nerve. The facial nerve sheath should be explored to assess the extent of the nerve injury. Depending on the severity of the damage, surgical interventions may include decompression of the facial nerve, end-to-end anastomosis of the redirected facial nerve, or nerve grafting.
For injuries caused by traction, accidental abrasion, or contusion from the surgical drill, resulting in facial nerve edema, decompression through incision of the nerve sheath is recommended. For cases where more than one-third of the main trunk of the facial nerve is severed, end-to-end anastomosis of the redirected nerve or nerve grafting may be performed based on the situation. Nerve grafting is often performed for midterm facial paralysis (ranging from 3 weeks to 2 years). Studies suggest that nerve grafting yields the best results when performed within 6 months of the injury.
Management of Extratemporal Facial Nerve Injuries
When the main trunk or significant branches of the facial nerve sustain severe injuries, surgical repair is required. Damage caused by traction of the facial nerve may recover spontaneously after surgery. However, in cases of a complete transection, immediate management is necessary. During parotid surgeries, if severe nerve damage or transection of the facial nerve is detected, end-to-end anastomosis or nerve grafting should be performed promptly.
Corrective Surgery for Facial Paralysis
Corrective surgeries for facial paralysis are generally performed during the late stages of the condition and can be categorized into functional (dynamic) and non-functional (static) procedures.
Dynamic corrective surgeries include nerve transfer procedures, cross-facial nerve grafting, pedicled muscle flap transfers, and vascularized neuromuscular transplants.
Static corrective surgeries are primarily cosmetic procedures, such as skin suspension and fascia suspension techniques.