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PATHOLOGY PERSPECTIVES BELL'S PALSY Difficult to close the eye, sensitivity to dryness, tears Because this condition involves facial nerve facial muscles Distorted taste, dry mouth Medical Illustration Copyright ©2009. Nucleus Medical Art www.nucleusinc.com And while this is usually a self-limiting condition with full or nearly full recovery, appropriate intervention in early stages can speed healing, improve prognosis, and forestall short- and long-term complications. ANATOMY REVIEW The facial nerve runs a peculiarly convoluted path from its origins on the brainstem to its final destination in the facial muscles and the tongue. It travels through narrow passageways in the cranium, often sharing space with other cranial nerves. It takes at least three sharp turns to get to its destinations. The narrowest tunnel is the temporal facial canal, which allows only about .66 millimeters of clearance. Understandably, any swelling or irritation to the nerve can compress it here, leading to the risk of demyelination and loss of function. The branches of the facial nerve emerge behind the ear, anterior to the mastoid process. Any bone spur, inflammation, or irritation to the soft tissues at this emergence site can also put mechanical pressure on the delicate nerve tissue. SIGNS AND SYMPTOMS Bell's palsy has a classic set of symptoms that set it apart from other cranial nerve disturbances; a sudden onset of unilateral weakness of facial muscles is the key sign. This weakness involves the upper as well as the lower face: a feature that is important to distinguish Bell's palsy from other disorders. Some fibers of the facial nerve also supply the taste buds, salivary glands, and tear ducts, so distorted taste, as well as problems with tears and salivating may also occur. This is especially inconvenient because the muscles of the mouth are weakened, so eating and drinking neatly can become complicated. The muscles that control eyelids are weak with this condition, so it is difficult or impossible to fully close the eye. Bell's phenomenon, where the eye rolls superiorly and medially during the attempt to close the lid, is frequent. Sensitivity to light, dryness, dust, and other irritants can be problematic without a functioning eyelid. 100 massage & bodywork july/august 2009 damage to a nerve that has mostly motor rather than sensory neurons, Bell's palsy tends not to be acutely painful. Many patients report hyperacusis, however. This is the amplification—sometimes painfully so—of sound signals related to the paralysis of the stapedius muscle inside the ear. Chronic headaches and an aching pain at the mastoid process are also common. These pain sensations are quite different from the gripping, seizing, hot-poker-in-the-eye kind of sensations common to trigeminal neuralgia—a different disorder that causes damage to the trigeminal nerve, a mainly sensory nerve that shares some pathways with the facial nerve. POSSIBLE CAUSES AND TREATMENT OPTIONS Bell's palsy is a general term that simply describes irritation and or damage to the facial nerve. Finding the source of that damage is important in discerning the best possible treatment options. Facial nerve irritation is usually brought about by one of two factors: viral infection or bacterial infection. Obviously, these require two quite different treatment strategies, because in addition to taking pressure off the nerve as quickly as possible, it is important to combat whatever pathogens might be attacking the delicate tissue. VIRAL INFECTIONS Herpes Simplex Herpes simplex type 1 is probably the most frequent trigger for Bell's palsy. This viral infection causes the characteristic lesions we sometimes call fever blisters or cold sores, but in this case the concurrent inflammation also irritates the facial nerve.