A longitudinal study on nodding syndrome--a new African epilepsy disorder

Abstract

Objectives: Nodding syndrome (NS), a new epilepsy disorder of sub-Saharan Africa, has only recently been classified. In a study conducted in southern Tanzania in 2005, 62 patients with NS were analyzed in great detail. The present study, a follow-up investigation, was conducted to evaluate the progression of NS over time and to obtain serial electroencephalography (EEG) data.

Methods: Of the 62 NS patients, 53 (85.5%), the majority of whom were currently on some form of antiepileptic treatment, could be reevaluated in 2009 with a standardized questionnaire. A subset of these patients (25/53) underwent EEG investigation.

Results: In patients with "head nodding (HN) only" in 2005, 10 (43.5%) of 23 remained with the same diagnosis, whereas 5 (21.7%) of 23 had developed "HN plus" (i.e., HN and generalized tonic-clonic seizures). Six patients (26.1%) had seizures other than HN only, and two patients (8.7%) had fully recovered. In the "HN plus" group of 2005, 9 (30.0%) of 30 patients remained "HN plus," and 15 patients (50.0%) had seizures other than HN only. Four patients (13.3%) reverted to "HN only," and two patients (6.7%) stopped all seizures. In 11 (44.0%) of 25 patients, electroencephalography (EEG) showed generalized slowing. Six (54.6%) of these 11 abnormal EEG studies further showed generalized epileptiform discharges: (1) ictal electroencephalographic pattern with generalized 2.5 Hz spike and waves in two patients and (2) interictal bursts of 1.5-2 Hz spike and waves in four patients.

Significance: This follow-up study confirms that HN represents an epilepsy disorder, possibly of the atypical absence type with dynamic development over time.

Keywords: Epilepsy; Nodding syndrome; Sub-Saharan Africa; Tanzania.