Lyme Disease Complications: Neurologic, Cardiac, and Arthritic Risks If Untreated

Lyme disease (Borrelia burgdorferi) is rarely fatal, but untreated or inadequately treated infection can disseminate causing serious complications:

Neurologic (Neuroborreliosis) — 10–15% Untreated

• Meningitis (lymphocytic), cranial neuritis (VII palsy common), radiculoneuritis (pain, sensory/motor deficits)
• Encephalitis, myelitis—rare but severe
• Can persist months-years → cognitive, mood, fatigue syndromes (controversial: PTLDS)

Cardiac (Lyme Carditis) — 1–5%

• AV block (1st to complete), myopericarditis
• Syncope, palpitations, dyspnea
• Requires hospitalization, monitoring, IV ceftriaxone if high-grade block

Arthritic (Lyme Arthritis) — 60% Untreated

• Mono/oligoarticular, large joints (knee >90%)
• Can become chronic (antibiotic-refractory) → synovial immune dysregulation

Critical Window

Early localized (EM rash) → oral doxycycline/amoxicillin/cefuroxime × 10–21 days = cure in >95%. Delayed treatment ↑ complication risk. Post-treatment symptoms ≠ active infection—don't retreat indefinitely.