Around 10% to 15% of untreated or undertreated people will develop neuroborreliosis, a neurological manifestation of Lyme disease. Symptoms vary from person to person and may include: Meningitis (typically mild with headache, stiff neck, and light sensitivity) Facial palsy (impairing muscles on one side of the face) Radiculopathy (causing nerve pain with weakness and abnormal sensations) Encephalitis (causing impaired movement, speech, or tremors)