The head nodding syndrome--clinical classification and possible causes.

Area of Science:

• Neurology
• Tropical Medicine
• Epileptology

Background:

• A seizure disorder characterized by head nodding (HN) was observed in Tanzania in the 1960s.
• A similar condition, termed "nodding disease," later emerged in Sudan.
• The classification and etiology of this seizure disorder remain unclear.

Purpose of the Study:

• To comprehensively describe the clinical features of the "HN syndrome" in southern Tanzania.
• To investigate potential causes and associated pathologies of this epilepsy disorder.
• To explore possible links to infectious agents and genetic factors.

Main Methods:

• A prospective study evaluated 62 patients with head nodding.
• Diagnostic procedures included blood and cerebrospinal fluid (CSF) analysis, electroencephalography (EEG), and magnetic resonance imaging (MRI).
• Skin and CSF polymerase chain reaction (PCR) for Onchocerca volvulus was performed.

Main Results:

• Seizures were classified as "head nodding only" or "head nodding plus."
• MRI revealed hippocampus pathologies and gliotic changes in some patients.
• Skin PCR positivity for Onchocerca volvulus correlated significantly with MRI lesions, while CSF PCR was negative.

Conclusions:

• The "HN syndrome" may represent a novel epilepsy disorder prevalent in sub-Saharan Africa.
• The association between MRI lesions and Onchocerca volvulus (detected via skin PCR) is noteworthy.
• High rates of hippocampus sclerosis and familial epilepsy suggest complex pathogenetic mechanisms requiring further study.