Reviewing the evidence on nodding syndrome, a mysterious tropical disorder.

Objectives: To review the literature on the prevalence, clinical manifestations, pathogenesis, treatment, and implications of nodding syndrome (NS).

Methods: This is a narrative review.

Results: NS is a mysterious tropical disorder that is emerging in South Sudan, southern Tanzania, and northern Uganda. Over the past decade, thousands of children have become affected, but the prevalence is unknown. NS is characterized by an occasional nodding of the head, which is considered as a form of epilepsy. After symptoms appear, the patient's health rapidly deteriorates. Seizures, stunted growth, and mental retardation may appear. In endemic areas, NS is increasingly becoming a public health problem with high morbidity and mortality, and severe social, psychological, and economic implications. However, the pathogenesis is unknown. Evidence suggests a role for Onchocerca volvulus, the parasitic filarial worm responsible for river blindness, which is highly endemic in these areas. There is no cure for NS, and treatment is symptomatic with common anticonvulsants to improve the quality of life.

Conclusions: NS seems to be a rapidly growing problem in several eastern African countries. Although it is starting to receive more and more attention in the scientific literature, little is known about NS. A better understanding of the pathogenesis may lead to prevention and treatment opportunities.