A febrile seizure may be as mild as the child's eyes rolling or limbs stiffening. Quite often a fever triggers a full-blown convulsion that involves the whole body.

Febrile seizures may begin with the sudden sustained contraction of muscles on both sides of a child's body -- usually the muscles of the face, trunk, arms, and legs. A haunting, involuntary cry or moan often emerges from the child, from the force of the muscle contraction. The contraction continues for seemingly endless seconds, or tens of seconds. The child will fall, if standing, and may pass urine. He may vomit. He may bite his tongue. The child will not be breathing, and may begin to turn blue. Finally, the sustained contraction is broken by repeated brief moments of relaxation -- the child's body begins to jerk rhythmically. The child is unresponsive to the parent's screams.

A febrile seizure may be diagnosed by the health care provider when a grand mal seizure occurs in a child with a fever and no prior history of seizure disorders (epilepsy). In infants and young children, it is important to rule out other causes for a first-time seizure, especially meningitis.

In a typical febrile seizure, the examination usually shows no abnormalities other than the illness causing the fever. Typically, a full seizure workup including an EEG, head CT, and lumbar puncture (spinal tap) is not warranted.

However, the child's condition must meet strict medical criteria if these tests are to be avoided:

• The child must be developmentally normal
• The seizure must be generalized (not focal), meaning more than one part of the body is involved.
• The seizure may not last longer than 15 minutes.
• The child cannot have had more than one febrile seizure in 24 hours.
• The child's neurologic exam performed by a physician must be normal to be called a simple febrile seizure.

If all of these criteria are met, no further studies are likely to be required.