Cause:Clostridium tetani, via wound contamination with dirt
Pathophys: Exotoxin production and transported both via circulation to CNS (probably most significant in humans) and along motor nerves to CNS (but can't correlate wound distance from CNS with morbidity and mortality in humans)
Present in most soils; 535 cases in 1965 in US; ~4 cases/100 million, mainly in southern states; Texas had 56% of cases; highest incidence in very young and very old (inadequate immunization); <3% of patients have hx of ever having had tetanus toxoid; increased incidence in "skin popping" drug addicts. Females > males
Sx:
Puncture wound or laceration (58%), or postpartum, postsurgery, skin ulcers
1- to 54-d incubation period, median = 8 d, 88% within 14 d; short incubation period in patients under age 50 yr is poor prognostic sign
Si:Spastic paralysis; tonic convulsive contractions precipitated by intrinsic or extrinsic muscle movement; no or rarely fever
r/o "STIFF MAN SYNDROME," autoimmune antibodies against GABA neurons (Ann IM 1999;131:522; Nejm 1990;322:1555) that induce muscle spasms over years, seen with hypopituitarism, IDDM, Graves' disease, and other endocrinopathies (Nejm 1988;318:1012, 1060), occasionally is an autoimmune paraneoplastic syndrome in breast cancer (Nejm 1993;328:546); rx w iv immunoglobulin (Nejm 2001;345:1870) and diazepam
r/o malignant neuroleptic syndrome (Neuroleptic Malignant Syndrome)
Lab:Bact:Smears show gram-pos bacilli; culture shows fastidious anaerobe, pos in 32% of proven cases
Rx:
Prevent w toxoid vaccine im, primary series of 3 over 1 yr, then q 10 yr, more frequently increases risk of reaction without increasing protection (Nejm 1969;280:575); booster of dT is enough even for dirty wounds if last dT was less than 5 yr ago (Nejm 1983;309:636)
Tetanus human immune globulin 250 U im, for dirty wounds with vaccine if not sure has had primary series; give coincident with vaccine in different im area
of disease: metronidazole 500 mg iv q 6 h (Nejm 1995;332:812); human immune globulin; respirator