Cerebellar ataxia following whooping cough

Bordetella pertussis (BP), the agent of whooping cough, has not been recognized so far as a cause of permanent cerebellar ataxia in human. We describe three patients who developed a disabling and permanent cerebellar syndrome soon after whooping cough. In two patients, diagnosis of BP infection was confirmed by culture of nasopharyngeal secretions. The infection occurred between the age of 13 and 15 years, with neurological symptoms beginning after a delay varying from 3 weeks to 3 months. In our three patients, the cerebellar syndrome was characterized by dysmetria of ocular saccades, scanning speech and ataxic gait. Brain MRI demonstrated a pancerebellar atrophy. The pathogenesis of this cerebellar degeneration is not established. Experimental studies have demonstrated that the cerebellum is particularly vulnerable to lymphocytosis-promoting factor (LPF), one of the exotoxins from BP. The mechanism of this toxicity might be a marked increase in the cellular levels of 3',5'cyclic guanosine monophosphate (cGMP). Since whooping cough is a bacterial exotoxin-mediated disease, this is the first report of a cerebellar syndrome triggered by a bacterial exotoxin.