In many patients with early Lyme disease, the only finding of erythema migrans on physical examination is sufficient to establish a working diagnosis of Lyme disease. Careful attention to details often makes the difference between the need to proceed with further confirmatory tests and an empiric course of antibiotics. In particular, the examination findings must be interpreted in the epidemiologic context; this cannot be overemphasized. The location, time of year, and patient's activities can be important diagnostic clues.
Regional lymphadenopathy may be seen, and a low-grade fever is not uncommon. High-grade fever suggests another co-infecting tick-borne organism such as Ehrlichia or Babesia species or some other diagnosis altogether, such as streptococcal cellulitis.
Rash location is another important diagnostic clue. Unlike spider and other arthropod bites, erythema migrans is rarely found on the hands or feet. Rather, ticks tend to bite where natural barriers impede their forward motion (eg, popliteal fossa, axillary or gluteal folds, hairline, areas near elastic bands in bra straps or underwear).
Frank arthritis associated with Lyme disease (most often affecting the knee) can occur after weeks, months, or years and may lead to erythema, edema, synovial effusion, and tenderness of the affected joints. Usually, this is a monoarthritis or oligoarthritis involving large joints. Swelling is often disproportional to the tenderness.
Patients with Lyme disease who do not receive treatment may have signs of cranial neuropathies, and up to 60% of patients with early neuroborreliosis develop cranial neuritis. Seventh nerve palsy is by far the most common. Bilateral facial palsy can be seen and is a unique characteristic that is useful for distinguishing Lyme disease from idiopathic Bell palsy and other disorders.
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Cite this: Herbert S. Diamond. Fast Five Quiz: Lyme Disease Practice Essentials - Medscape - Feb 25, 2021.