Workshop on neurologic complications of pertussis and pertussis vaccination.

A multidisciplinary workshop held from September 29 to October 1, 1989, at Airlie House, Warrenton, Virginia, considered the neurologic complications of whooping cough and pertussis vaccine. Pertussis mortality in the U.S. in 2-3/1000 cases. Seizures occur in 1.9% of cases, and encephalopathy in 0.3%. Reviewing all data, it appears likely that a combination of one or more bacterial toxins, asphyxia, CO2 retention and loss of cerebral vascular autoregulation is responsible for neurologic symptoms. The timing of the encephalopathy suggests that it results from increased lysis of bacteria, and release of endotoxin. The encephalopathy is not confined to the paroxysmal phase. In evaluating side-reactions to the vaccine, the following must be kept in mind: 1. Vaccines are not standardized between manufacturers. 2. For a given manufacturer, vaccines are not standard from one batch to the next. 3. Unless the vaccine is properly prepared and refrigerated, its potency and reactivity varies with shelf life. In fact, the whole question of vaccine detoxification has never been systematically investigated. Listed in order of increasing severity, observed adverse reactions include irritability, persistent, unusually high pitched crying, somnolence, seizures, a shock-like "hypotensive, hyporesponsive" state, and an encephalopathy. Since the neurologic picture is not specific for pertussis vaccination, its temporal relationship to the vaccination is the critical variable for determining causation. Although the majority of seizures following pertussis vaccination are associated with fever, it was the consensus of the neurologists attending the workshop, that these do not represent febrile convulsions, but are non-benign convulsions. The incidence of post-vaccine encephalopathy is difficult to ascertain.(ABSTRACT TRUNCATED AT 250 WORDS)