Bell's palsy

Bell’s palsy is the most common cause of unilateral facial paralysis. The cause of damage to the seventh cranial nerve is usually unclear and the majority are considered idiopathic. The condition typically presents acutely with weakness of the muscles on one side of the face. It may be associated with hyperacusis, a decrease in lacrimation, salivation, or dysgeusia, as the facial nerve controls the salivary and lacrimal glands, as well as the upper and lower facial muscles. As a result of partial bilateral cranial nerve innervation of the upper face, the diagnosis of Bell’s palsy requires attention to the forehead muscles. If forehead strength is preserved, a central cause of weakness, such as a cerebrovascular accident should be considered. The diagnosis is usually one of exclusion and often made on the physical examination. Physical protection of the cornea is one of the mainstays of treatment. Most guidelines currently recommend corticosteroids and some suggest the addition of antiviral medication to cover potential herpetic involvement though evidence for benefit of the latter is lacking. Most cases resolve spontaneously without complications, although these can be present in up to 30% of people who are affected. Other alternative treatments, such as physiotherapy, botulinum toxin and acupuncture, and eventually surgery, can help with those cases of incomplete recovery.