Disease	Cause	Distinguishing factors
Nuclear (peripheral)
Lyme disease	SpirocheteBorrelia burgdorferi	History of tick exposure, rash, or arthralgias; exposure to areas where Lyme disease is endemic
Otitis media	Bacterial pathogens	Gradual onset; ear pain, fever, and conductive hearing loss
Ramsay Hunt syndrome	Herpes zoster virus	Pronounced prodrome of pain; vesicular eruption in ear canal or pharynx
Sarcoidosis or Guillain-Barré syndrome	Autoimmune response	More often bilateral
Tumor	Cholesteatoma, parotid gland	Gradual onset
Supranuclear (central)		Forehead spared
Multiple sclerosis	Demyelination	Additional neurologic symptoms
Stroke	Ischemia, hemorrhage	Extremities on affected side often involved
Tumor	Metastases, primary brain	Gradual onset; mental status changes; history of cancer