Bell's palsy

Bell's palsy (idiopathic facial nerve palsy) produces one-sided paralysis of the lower and upper face. The mechanism is swelling of the facial nerve due to a viral or immune disorder. The most common cause is thought to be herpes simplex. Typically, full recovery occurs within a few months.

CASES/YEAR
40,500 (US); 810,000 (Global)
CATEGORY
Localized Infections
AGENT TYPE
Viruses
OTHER NAMES
ACUITY
Acute-Moderate
INCUBATION
Estimated: days to weeks:
INITIAL SYMPTOMS
Unilateral facial weakness often preceded by pain behind the ear; Maximum paralysis usually develops within 48 hours; [Harrison]
PRECAUTIONS
COMMENTS
Idiopathic facial paralysis is a common disorder affecting 1 in 60 persons over a lifetime. It is associated with reactivation of herpes simplex virus type 1 and varicella zoster virus. Patients have maximal weakness by 48 h, sometimes preceded by retroaural pain. Hyperacusis may be present. 80% of patients have full recovery within several weeks or months. The most favorable prognostic sign is incomplete paralysis in first week. Ramsay Hunt syndrome is distinguished from Bell's palsy by a vesicular eruption in the pharynx and external auditory canal caused by a herpes zoster infection of the geniculate ganglion. Guillain-Barre syndrome, sarcoidosis, Lyme disease, and leprosy can cause bilateral facial weakness. [Harrisons, p. 538, 1030] Lyme disease can cause Bell's palsy and should be considered the likely cause in endemic areas. [5MCC-2020]
DIAGNOSTIC
Clinical diagnosis if typical with no risk factors & otherwise normal neuro exam; In atypical cases, consider: MRI; Chest x-ray & angiotensin-converting enzyme to rule out sarcoidosis; Fasting blood glucose; Lyme titer; CSF analysis; [Harrisons, p. 1030]
SCOPE
Global
SIGNS & SYMPTOMS
  • N muscle weakness
  • *cranial neuropathy
  • *paralysis
ANTIMICROBIC

Yes

VACCINE

No

ENTRY
RESERVOIR
RISK FACTORS
TREATMENT
Patch eye at night to prevent drying of cornea. Prednisone 60-80 mg/d for 5 days and tapered over next 5 days; No added benefit from antiviral drugs (acyclovir or valacyclovir) in two large randomized trials; [Harrisons, p. 1030]
DRUG LINK
REFERENCES FOR CASES/YEAR
1. (US) 13-14 cases/100,000; [Gorbach, p. 92] Calculate: 13.5 x 3000 = 40,500 (US);
2. (Global) 20 X US cases/yr;;