Bell's Palsy is a nerve issue.  Nerves keep muscles of the face in a balance of tension and relaxation.  When the facial nerve that controls these muscles is damaged, the muscles will drop.  This usually occurs on one side but can be bilateral.  It is thought that Bell's Palsy is likely a virus (like herpes/shingles) and this virus is responsible for inflammation of facial nerves.

Bell's Palsy comes on suddenly with un-noticeable warning signs.  Sometimes it is confused with stroke and doctors may insist on ruling that out.  
Those more often at risk are:  diabetics, a person with the flu or respiratory illness, or a severe ear, nose, or gum infection.  These persons may likely be under great physical or emotional stress and/or may have a lowered immune system. Exacerbating those risks are improper diet or rest, or exposure to chemicals or drugs.

Whether the diagnosis is a stroke or Bell's Palsy, having an Acupuncture treatment as soon as possible helps the patient recover faster.  The Acupuncture Physician will advise to eat (or juice) lots of organic fruits and vegetables to flood the body with nourishing elements from which to recover faster.  In addition, eating nuts, legumes, wild-caught cold-water fish, a little grass-fed red meat or pasture-raised chicken could be helpful.  Finding creative outlets for any emotional stress is important.  And rest!

If you are an Acupuncture Physician looking to treat your patient, here is a treatment option:

Treat wind/cold attacking Shao yang (liver & Gb) and Yangming (ST&LI) and tendons & muscles.  This may be a matter of "too much wind" from somewhere.  It could be from a boat, a window, a fan at night while sleeping, etc.

If exposure to toxins, treat as such.  Same for physical or emotional stress.

Acupuncture Points:  
Liver 3   moves qi
K3, Sp6, St36   tonifies qi
GB 34   moves qi & eliminates wind
LI 4   eliminates wind from face channels
SJ5   moves qi and eliminates wind
SJ 17 stimulates the ends of the 7th cranial nerve which controls the facial nerve
Local points include BL 1,2    GB 1,2,14    ST 2,4,5    LI 19,20    SI 18   Bitong    Ren 2     Du 26,   Yuyao    
In the hours after the attack do acupuncture on bilateral sides.  If chronic then only the affected side.  If it has "not been long", do some points bilateral.  After the needles are out, cupping on Du 14 or GB 20 would activate blood.