Which insect bite causes facial nerve palsy
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insect bite causes facial nerve palsy Lyme disease tick
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Here is a complete, textbook-sourced answer:
Insect/Arthropod Bite Causing Facial Nerve Palsy
The Answer: Ixodes Tick Bite (Lyme Disease)
The bite of the Ixodes tick (a hard-bodied arachnid) transmits Borrelia burgdorferi, the spirochete causing Lyme disease - the most important arthropod-associated cause of facial nerve palsy.
Note: Technically, ticks are arachnids, not true insects. However, in clinical MCQ/exam context, "insect bite causing facial palsy" invariably refers to the tick bite transmitting Lyme disease.
Key Facts
| Feature | Detail |
|---|---|
| Vector | Ixodes scapularis (deer tick) / Ixodes pacificus |
| Pathogen | Borrelia burgdorferi (spirochete) |
| Stage | Early disseminated (secondary) Lyme disease |
| Palsy onset | Within 4 weeks of erythema migrans (EM) rash |
| Laterality | Can be unilateral or bilateral |
Why Facial Palsy is Unique to Lyme Disease
- Facial palsy is the most characteristic neuropathy of early Lyme disease in the US, occurring in 40-50% of patients with borrelial neurologic involvement - Fitzpatrick's Dermatology
- Bilateral facial palsy should immediately raise suspicion for Lyme disease, as it is uncommon in virtually all other causes of facial palsy - Fitzpatrick's Dermatology
- The classic triad of lymphocytic meningitis + cranial palsy (often facial) + radiculoneuritis = Bannwarth syndrome, pathognomonic for Lyme disease - Fitzpatrick's Dermatology
- Consider Lyme disease in any patient with facial palsy plus erythema migrans, tick bite history, or arthritis - Tintinalli's Emergency Medicine
Clinical Context
- The palsy results from early disseminated Lyme disease (spirochetal hematogenous spread)
- Other neurologic features: meningitis, radiculopathy, mononeuropathies
- Facial nerve palsy without EM can be the presenting manifestation of Lyme disease - Harrison's Internal Medicine
- In such cases, both IgM and IgG serologic responses to the spirochete are usually positive
Treatment (Facial Palsy in Lyme Disease)
- Doxycycline 100 mg twice daily for 14-21 days (first-line in adults)
- Alternatives: amoxicillin, cefuroxime, ceftriaxone, azithromycin
- Facial nerve palsies represent secondary-stage disease and require 1 month of treatment
- Delayed antibiotic treatment is associated with longer-lived neurologic symptoms - Shambaugh Surgery of the Ear
Summary for exams: Tick bite (Ixodes) → Lyme disease (B. burgdorferi) → facial nerve palsy (the most common cranial neuropathy of Lyme disease; bilateral palsy is nearly pathognomonic).
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