General Examination

Erythema migrans in a woman with Lyme disease (Reproduced with permission from CDC)

General examination of the patient should be normal in Bells palsy. Derangement of vital signs, fever, rash or other abnormality on examination all point to an alternative cause for facial weakness.
Causes of LMN facial nerve palsy with systemic upset include:

• Lyme disease
• Sarcoidosis
• HIV infection

In addition, acute peripheral facial weakness may either be found in known diabetics or be a presenting feature of previously undiagnosed diabetes [8].

Mononeuropathy in diabetes is most commonly caused by vascular occlusion and therefore has a poorer prognosis than facial weakness from other causes.