-IBIS-1.5.0-
tx
immune system
Lyme disease
diagnoses
definition and etiology
definition: A zoonotic inflammatory disorder recognized clinically by an early skin lesion, erythema chronicum migrans (ECM), that may be followed weeks to months later by neurologic, cardiac, or joint abnormalities. Cryoprecipitates (resulting from cooling), and immune complexes may occur in the serum early in the condition, as well as in the synovial fluid.
Lyme disease appears to be a systemic, immune mediated inflammatory disorder that becomes localized to the joints.
Patients tend to have increased IgM levels in the prearthritis phase.
By the time arthritis appears, immune complexes are no longer found in most serum samples but are found in the synovial fluid.
etiology:
Tick-borne infection of spirochete Borrelia burgdorferai. The disease was first recognized by mapping close geographic clustering of cases in the small community of Lyme, Connecticut. Endemic foci exist in other areas.
signs and symptoms
The distinctive skin lesion (ECM) has an indurated central area with heavy infiltration of all layers of the epidermis with mononuclear cells. It begins as a red macule or papule that expands to as large as 50 cm. Most patients report being bitten by a tick 3-12 weeks before. The lesion is usually hot to the touch. Soon after onset many patients develop multiple, smaller lesions without indurated centers. ECM usually lasts for several weeks.
The most common symptoms accompanying ECM are:
malaise and fatigue
chills
fever
headache
stiff neck
Other less common symptoms include myalgia, nausea, sore throat, lymphadenopathy, and spleen enlargement.
Arthritis may occur 2 weeks to months after ECM, in various joints but with the knees being very susceptible.
Neurologic abnormalities may occur in about a quarter of the patients with ECM and before onset of arthritis. These may last for months but resolve completely. They include lymphocytic meningitis, chorea, meningoencephalitis, cerebellar ataxia, cranial neuritis, bilateral Bell's palsy, motor and sensory radiculoneuritis, myelitis.
Myocardial abnormalities may occur in one in ten patients. They include varying degrees of atrioventricular blocks, myopericarditis, and cardiomegaly.
ESR may be elevated.
Synovial membranes in affected joints appear similar to those seen in RA.
lab findings:
specific antigen/antibody studies available for spirochete
course and prognosis
The condition usually persists for some weeks or months, with transition from ECM to neurologic or cardiac symptoms then arthritis. The arthritic stage may remit and exacerbate for years; and may lead to chronic arthritic conditions. Conventional sources suggest that administration of tetracycline during the ECM stage may reduce the severity of later stages.
differential diagnosis
Lyme disease must be differentiated from juvenile RA. Lyme disease does not usually have morning stiffness, subcutaneous nodules, iridocyclitis, mucosal lesions, rheumatoid factor, antinuclear antibodies.
Rheumatic fever
Spondyloarthropathies are differentiated by the lack of axial skeletal involvement in Lyme disease.
footnotes