Peripheral facial nerve paralysis: Etiology, diagnosis and management

Peripheral facial nerve palsy is a common clinical entity which requires multidisciplinary management for its successful management. The etiology of peripheral facial nerve palsy varies greatly. The most common cause is idiopathic facial nerve paralysis (Bell's palsy), followed by trauma and infection. Iatrogenic injury to the facial nerve, as a complication of surgical procedures involving the middle ear, the parotid gland and the cerebellopontine angle, also constitutes a significant cause of facial nerve paralysis. Evaluation of the facial nerve and its function is still debated in the relevant literature, with various systems being proposed, but none has displaced the House-Brackmann scale as the main evaluation tool. Electroneuronography and electromyography are electrophysiological tests that are applied in the case of facial nerve paralysis to evaluate the potential for recovery and to guide decisions on surgical intervention. Computed tomography (CT) and magnetic resonance imaging (MRI) also play an important diagnostic role in the investigation in some cases. The management of facial nerve palsy is dictated by the underlying pathology. In Bell's palsy corticosteroid therapy, although not generally accepted, is the mainstay of treatment, while in cases of infectious etiology the therapeutic management is directed towards the resolution of the infection. Permanent damage to the facial nerve necessitates appropriate management of potential corneal exposure, with tarsorrhaphy or upper eyelid loading being viable options. Soft tissue repositioning techniques can be helpful in the management of brow and midface ptosis, while facial reanimation can be achieved by free nerve-muscle grafts or nerve transposition procedures, which most commonly involve the hypoglossal and spinal accessory nerves.