The diagnosis is made on clinicalngrounds. There may be a mild polymorphonuclear leukocytosis. The CSF is normal with the exception of mild elevation of opening pressure. Serum muscle ensymes may be elevated. Transient electrocardiographic and electroencephalographic abnormalities may occur. Anaerobic culture and microscopic examination of pus from the wound can be helpful, but C tetani is difficult to grow, and the drumstick-shaped gram-positive bacilli often cannot be found.