What is Facial Nerve Paralysis?
The skin sensation and the muscle responsible for much of the mouth movement and facial expression are controlled by the facial nerves (or the seventh cranial nerves) that originated from the brain; one on each side. Facial nerve paralysis is the condition when the facial nerves loss their functions either wholly or partially. The resulting muscle paralysis and loss of sensation occur when the facial nerve is variably damaged by inflammation.
What causes Facial Nerve Paralysis?
When facial nerve paralysis was first described by Sir Charles Bell in 1830, the cause of it was essentially unknown. In this 21st century, 70% of the facial nerve paralysis is still of unknown origin. Some facial nerve paralysis however may be caused by viral infection, toxic drugs, trauma at the base of skull, tumour and blood cancer.
Pregnancy appears to increase the chance of having facial nerve paralysis; estimated to be 3.3 times more likely than the age-matched individuals. The risk of suffering from it during pregnancy is about 41-45 per 100000 deliveries; which is still relatively uncommon. The increased tendency may be due to fluid retention, reactivation of HSV infection, gestational immunosuppression, unknown effect induced by pregnancy hormones, or blood vessel spasm and blockage. Some early studies suggested an association between facial nerve paralysis in pregnancy and hypertensive disease in pregnancy.
What Is the Prognosis?
In the early days, surgical depression of the facial nerve canal to alleviate the pressure-damage on the nerve had to be performed early to avoid incomplete return of the nerve function. Modern day management is the early use of steroids and anti-viral therapy. The natural untreated progress of the nerve paralysis depends on the severity and rapidity of the affliction. Some cases run the course quickly and the nerve recovers in a few weeks. Others may improve over months with residual weakness of the facial nerve.
The recent prospective, randomised, double blind, placebo-controlled multi-centre study (conducted in Scandinavia, published in 2012) concluded that early steroid use resulted in higher complete recovery rates regardless of severity at baseline. The additional use of anti-viral therapy however was not as conclusive; with some studies supporting its usefulness in severe disease.
TCM perspective of Facial Nerve Paralysis
In traditional Chinese medicine, this condition is also called “deviation of the mouth and eyes”. It can occur in patients of any ages and through any season. Commonly occur in people whose defensive qi is insufficient (as from over exertion) or healthy qi is weakened. It is caused by the pathogenic wind-cold attacking the Shaoyang (Liver, Gall Bladder) and Yangming (Stomach, Large Intestine) channels supplying the face; which affects the related tendons and muscles. The environmental pathogen enters the body when the person is exposed to wind (e.g. sleeping near an open window, driving with the windows down, going on a boat when the winds are strong).
Acupuncture is the first line treatment in TCM. It aims to dredge and regulate qi and blood of the local tendons and collaterals, and to promote blood circulation so as to purge the obstructed channels. Anecdotal reports suggested good outcomes with acupuncture therapy, although in view of the natural course of the disorder, only a randomised controlled study in a large sample population will be able to objectively demonstrate the contribution of acupuncture in the management facial nerve paralysis.