HSC Section 3 - Trauma, Critical Care and Sleep Medicine

Medical Management of Acute Facial Paralysis

TRAUMA

Blunt or penetrating trauma to the head may result in acute FP secondary to intratem- poral or extratemporal bone injury. In blunt force trauma, the area of injury may be investigated with imaging. A fine-cut, noncontrast temporal bone CT may demon- strate a fracture oriented transverse or longitudinal to the petrous segment. Trans- verse fractures are less common but have a higher risk of FN injury. 31 Displaced fractures may result in bony impingement of the nerve, whereas nondisplaced frac- tures may result in perineural inflammation and subsequent neural ischemia. These patients are typically treated with parenteral steroids and antiviral agents. The mode of FN injury and timing of paralysis, as well as the imaging and electrophysiological testing results will determine whether or not the patient will benefit from FN decom- pression 32,33 (see Dr. Daniel Q. Sun and colleagues’ article, “ Surgical Management of Acute Facial Palsy ,” in this issue, for further details.) In cases of penetrating trauma to the soft tissues of the head and neck with acute FP, immediate surgical exploration and debridement are warranted. Depending on the FN deficit, a partial or full FN exploration is performed. Early exploration is impor- tant because within 1 to 3 days after the event, the distal nerve branches are still able to be stimulated with a nerve stimulator. The nerve continuity is checked and any transected segment is repaired. Ideally, a primary coaptation is performed. If neces- sary, an interposition graft is placed. Birth trauma (ie, forceps delivery) can affect 1 or more branches of the facial nerve and is evident with the first cry. The mastoid bone is not fully developed until 2 years of age, thus exposing the FN. Risks of birth trauma include forceps delivery, birthweight more than 3.5 kg, and primiparity. 34 Fortunately, most infants recover fully without intervention. Soft tissue or mandibular surgery distal to the stylomastoid foramen can cause facial nerve injury. This includes surgery of the temporomandibular joint or other orthog- nathic procedures, and parotid, masseter, or other soft tissue excision. Certain oto- logic procedures also carry a risk of facial nerve injury. FP noticed immediately after surgical intervention should be explored. Autoimmune or systemic causes In patients with recurrent FP or bilateral involvement, the likely cause is autoimmune. A medical and family history of autoimmune disease or other symptomatology, such as an unexplained rash or facial swelling should be investigated. Guillain-Barre (GBS) 35,36 is an uncommon cause of FP. GBS is a postinfectious in- flammatory demyelinating polyradiculoneuropathy of motor and sensory nerves. Approximately a third of patients with GBS will present with FP. Typically, patients have a history of a viral prodrome. 37 Therapy includes plasmapheresis and intrave- nous immunoglobulin therapy. Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system and may present with unilateral or recurrent FP. 38 Diagnosis may involve blood tests, lumbar puncture and imaging (MRI). Amyloid disease is associated with the deposition of amyloid proteins that can directly infiltrate the facial nerve. 39,40 An autosomal dominant Finnish type of amyloidosis is also associated with progressive bilateral FP (BFP). 41 Congo red staining and a polarizing microscopic examination of tissue biopsies is diagnostic for amyloidosis. IATROGENIC CAUSES

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