Bell’s palsy is named after Sir Charles Bell, a 19th century Scottish surgeon who was the first to describe the condition. The disorder, which is not related to stroke, is the most common cause of facial paralysis. Generally, Bell’s palsy affects only one of the paired facial nerves and one side of the face, however, in rare cases, it can affect both sides.
Bell’s palsy accounts for almost three-quarters of all acute facial palsies, with the highest incidence in the 15- to 45-year-old age group (Peitersen E, 2002). Men and women are equally affected, although the incidence is higher in pregnant women.
There is no specific laboratory test for Bell’s palsy, but it can usually be diagnosed based upon clinical presentation, including a distorted facial appearance and the inability to move muscles on the affected side of the face, as well as by ruling out other possible causes of facial paralysis. Bell’s palsy (and other types of facial nerve paralysis) can be distinguished from a stroke because a stroke usually causes weakness in the lower part of the face only. People who have had a stroke can close the eyes tightly and wrinkle the brow. In addition, a stroke typically causes weakness of an arm and a leg.
Patients with facial palsy require careful examination of the other cranial nerve and cerebellar function. The modified House-Brackmann facial grading scale allows consistent documentation of facial palsy (House JW, Brackmann DE, 1985).
Symptoms of Bell’s palsy vary from person to person and range in severity from mild weakness to total paralysis. They may include twitching, weakness or paralysis on one or both sides of the face, drooping of the eyelid and corner of the mouth, drooling, dryness of the eye or mouth, impairment of taste, and excessive tearing in one eye. Most often these symptoms, which usually begin suddenly and reach their peak within 48 hours, lead to significant facial distortion.
The most alarming symptom of Bell’s palsy is paresis; up to three-quarters of affected patients think they have had a stroke or have an intracranial tumour.
Severe pain suggests herpes zoster virus and may precede a vesicular eruption and progression to Ramsay Hunt syndrome. Features may be consistent with a mild polyneuropathy. A slow onset progressive palsy with other cranial nerve deficits or headache raises the possibility of a neoplasm (Holland NJ, Weiner GM, 2004).
Other symptoms may include pain or discomfort around the jaw and behind the ear, ringing in one or both ears, headache, loss of taste, hypersensitivity to sound on the affected side, impaired speech, dizziness, and difficulty eating or drinking.
The cause of idiopathic Bell’s palsy is thought to be a sensory ganglionitis of the central nervous system with a secondary muscle palsy. The muscle paralysis is caused by inflammation and autoimmune demyelination instead of ischemic compression.
Increasing evidence implies that the main cause of Bell’s palsy is latent herpes viruses (herpes simplex virus type 1 and herpes zoster virus), which are reactivated from cranial nerve ganglia (Tani M et al, 1988). Sensitive polymerase chain reaction techniques have isolated herpes virus DNA from the facial nerve during acute palsy (Murakami S et al, 1996). Herpes zoster virus shows more aggressive biological behaviour than herpes simplex virus type 1 because it spreads transversely through the nerve by way of satellite cells.
The prognosis is reported as being typically good, with 86% of patients having a complete recovery. Increasing evidence shows that the way the patient is managed has an important effect on outcome.
Of patients with Bell’s palsy registered by general practitioners between 1992 and 1996, a fifth were referred for specialist opinion, just over a third received oral steroids, and 0.6% received acyclovir (Rowlands S et al, 2002).
Traditionally, Bell’s Palsy has been treated with steroid drugs such as prednisolone or methylprednisolone and/or antiviral drugs such as acyclovir. These powerful agents reduce the inflammation of the nerve and address viral infection.
Two recent systematic reviews concluded that Bell’s palsy could be effectively treated with corticosteroids in the first seven days, providing up to a further 17% of patients with a good outcome in addition to the 80% that spontaneously improve (Grogan PM, Gronseth GS, 2001; Ramsey MJ et al, 2000). Other studies have shown the benefits of treatment with steroids; patients with severe facial palsy showed a significant improvement within 24 hours of treatment (Williamson IG, Whelan TR, 1996; Shafshak TS et al, 1994). Recovery rates in patients treated within 72 hours were enhanced by the addition of acyclovir (Hato N et al, 2003).
Prednisone is a synthetic hormone that mimics the glucocorticoid steroid hormone cortisol. Under stress (injury or illness) cortisol production is increased four-fold as part of the body’s normal response to the stress. Prednisone has approximately five times the potency of cortisol. It is estimated that 20mg of prednisone is equal to normal daily cortisol secretion while under stress.
Prednisone works as an anti-inflammatory via its effect on immune cells. It acts as an immuno-suppressant, inhibiting the secretion of cytokines. The result is that antibody production is suppressed and the inflammatory process is slowed, reducing the inflammation compressing the nerve. As prednisone works through an immuno-suppressant process, it cannot be administered to patients with existing immune system problems.
Treatment with antivirals is beneficial in Bell’s palsy due to the possible involvement of herpes viruses. Acyclovir, a nucleotide analogue, interferes with herpes virus DNA polymerase and inhibits DNA replication. However, it does have relatively poor bioavailability (15% to 30%) (De Miranda P, Blum MR, 1983). Newer drugs in its class are being trialled. Better bioavailability, dosing regimens and clinical effectiveness in treating shingles have been shown with valacyclovir (prodrug of acyclovir), famcyclovir (prodrug of pencyclovir) and sorivudine (Snoeck R et al, 1999).
Acyclovir with prednisone
A recent systematic review found that patients treated with combined acyclovir and prednisone had a better outcome than those treated with prednisone alone (Grogan PM, Gronseth GS, 2001). However, a Cochrane review at that time concluded that more studies were required (Sipe J, Dunn L, 2001). More recently, a study of patients with severe palsies found better recovery with combined acyclovir and prednisone than with prednisone alone. The main determinate of the difference was treatment within three days of the onset of palsy (Hato N et al, 2003).
Vitamins B1, B2 and B6 (in addition to vitamin B12) are particularly effective at boosting other factors that nourish the nerve. They are used in any form of nerve damage or brain failure.
The chemical adenosine triphosphate (ATP) is an essential agent involved in producing energy in the cells. Experiments using this nutrient, together with the vitamins of the B group mentioned above, show that this combination can have a measurable impact on the recovery from Bell’s palsy. The results showed that 100% of those patients who had a partial paralysis of the nerve and up to 87% of those who had full paralysis recovered completely. In contrast, only 67% of patients treated with steroids recovered.
An early study also showed that 74 Bell’s palsy patients treated consecutively with niacin (vitamin B3) at a dose of 100-250mg achieved ‘excellent results’ within two to four weeks (Kime CE, 1958).
Vitamin B12 (cobalamin)
Vitamin B12 has been shown to improve the symptoms of Bell’s palsy. In a recent study, methylcobalamin, a form of vitamin B12, was compared with steroids in a trial involving 60 patients with Bell’s palsy. Three groups of patients were tested: one received methylcobalamin (vitamin B12), one received corticosteroids, and the third received methylcobalamin in combination with corticosteroids The shortest time required for complete recovery of facial nerve function occurred in the group receiving methylcobalamin alone. At the end of the study, the patients in both methylcobalamin groups showed greater improvement in their symptoms than those in the corticosteroid group (Jalaludin MA, 1995).
Methylcobalamin is one of the two coenzyme forms of vitamin B12. Evidence indicates this form of vitamin B12, in addition to having a theoretical advantage over cyanocobalamin, actually has some metabolic and therapeutic applications not shared by the other forms of vitamin B12 (Alternative Medicine Review, 1998). Methylcobalamin is an essential component in the process of building nervous tissue. It is an important contributor to nerve growth, and maintains and repairs the critical, protective myelin sheath. Myelin sheath formation at the site of the damage is enhanced. This may, in part, explain recent findings that ultra-high doses may enhance nerve regeneration. B12 actively protects nerves, reduces nerve inflammation and reduces the amounts of nerve irritants such as the toxic chemical glutamate (Alternative Medicine Review, 1998).
An early study has also shown cyanocobalamin (another B12 derivative) to have worked in two chronic cases at high doses, one of 1.5 years’ duration and the other of four years. Large doses of B12 were given (500-1,000mcg daily) with complete recovery (Mitra M, Nandi AK, 1959). Another more recent study has linked recurrent facial palsy in a 40-year-old woman with primary Sjögren’s syndrome and vitamin B12 deficiency (Rousso E et al, 2005). This suggests further study in this field may be beneficial.
In addition to vitamin B12, another nutrient, acetyl-L-Carnitine (ALC), was found to improve the symptoms of Bell’s palsy (Neurol, 1997).
ALC is an anti-inflammatory compound used in a variety of neurological diseases such as nerve injury, nerve weakness and memory problems. ALC reduces damage due to free radicals, preserves production of energy within the nerve cells and stabilises the membrane of the nerve (Virmani MA et al, 2001).
Low-dose histamine therapy has been prescribed by otolaryngologists primarily to treat Bell’s palsy, vestibular disorders, vascular headache, Ménière’s attacks and urticaria vasculitis (King WP, 1999). The scientific explanations for the usefulness of this once-empiric treatment are becoming more apparent. The author also reports on a 100-patient retrospective clinical study that revealed that the objective, endpoint-titration approach was effective in treating 80% of patients. In light of such success and the ease and economy of this treatment, low-dose histamine therapy appears to be a valuable clinical tool.
Although histamine in large amounts is toxic to the body, causing allergies, small amounts are effective in reducing inflammation in general, and Bell’s palsy in particular (Virmani MA et al, 2001).
Histamine is not generally available in tablet form, but the nutrient carnosine that regulates the production of histamine is available in doses of 100mg a day.
A sixth of patients are left with either moderate to severe weakness, contracture, hemifacial spasm or synkinesis. Patients with a partial palsy fair better, with 94% making a full recovery. The outcome is worse when herpes zoster virus infection is involved in partial palsy. In patients who recover without treatment,for most major improvement occurs within three weeks. If recovery does not occur within this time, then it is unlikely to be seen until four to six months, when nerve regrowth and reinnervation have occurred. By six months it is clear who will have moderate to severe sequelae. Untreated Bell’s palsy leaves some patients with major facial dysfunction and a reduced quality of life.
Disorders of the facial nerve, including paralysis, are not rare and have a variety of causes. The appropriate diagnosis and treatment are very important to achieving the best possible recovery of facial nerve function. Improving outcomes requires co-ordination between specialists and general practitioners so that patients are treated during the critical first 72 hours.