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Purpose: Epilepsy is common in sub-Saharan Africa but is poorly characterized. Most studies are hospital-based, and may not reflect the situation in rural areas with limited access to medical care. We examined people with active convulsive epilepsy (ACE), to determine if the clinical features could help elucidate the causes.
Methods: We conducted a detailed descriptive analysis of 445 people with ACE identified through a community-based survey of 151,408 people in rural Kenya, including the examination of electroencephalograms.
Results: Approximately half of the 445 people with ACE were children aged 6 to 18 years. Seizures began in childhood in 78% of those diagnosed. An episode of status epilepticus was recalled by 36% cases, with an episode of status epilepticus precipitated by fever in 26%. Overall 169 had an abnormal electroencephalogram, 29% had focal features, and 34% had epileptiform activity. In the 146 individuals who reported generalized tonic–clonic seizures only, 22% had focal features on their electroencephalogram. Overall 71% of patients with ACE had evidence of focal abnormality, documented by partial onset seizures, focal neurologic deficits, or focal abnormalities on the electroencephalogram. Increased seizure frequency was strongly associated with age and cognitive impairment in all ages and nonattendance at school in children (p < 0.01).
Discussion: Children and adolescents bear the brunt of epilepsy in a rural population in Africa. The predominance of focal features and the high proportion of patients with status epilepticus, suggests that much of the epilepsy in this region has identifiable causes, many of which could be prevented.
Epilepsy is common in sub-Saharan Africa (SSA) but is poorly characterized (Belhocine et al., 2004; Preux & Druet-Cabanac, 2005). It is thought that the major causes differ from those in the resource-rich countries; in particular infections of the central nervous system may be more common. Recently, exposure to severe malaria was associated with epilepsy (Carter et al., 2004; Ngoungou et al., 2006). Underlying causes may manifest as focal features, but in SSA these features are often difficult to elicit in the semiology because of the difficulties in language and cultural perception of the symptoms. Many people with epilepsy do not use antiepileptic drugs (AEDs) (Meinardi et al., 2001; Scott et al., 2001; Coleman et al., 2002; Belhocine et al., 2004), thus the considerable treatment gap increases the likelihood of a poor outcome. In addition, the common comorbidities of epilepsy—cognitive, behavioral, and motor impairments—are poorly described in studies from SSA, and these may have a profound influence on social functioning and society’s acceptance of people with epilepsy.
Many studies that characterize epilepsy in SSA are hospital-based (Belhocine et al., 2004; Preux & Druet-Cabanac, 2005), but most people with epilepsy in SSA do not appear to use such facilities (Belhocine et al., 2004), for reasons of availability, cost, or trust in the service (Mbuba et al., 2008). Therefore, the data based on hospital studies may not reflect the situation that many people with epilepsy encounter in SSA, particularly in rural areas. The studies that have been conducted in rural areas either do not describe the features of epilepsy (Birbeck & Kalichi, 2004) or have not been conducted in malarious areas (Tekle-Haimanot et al., 1990). In recent studies of epilepsy in areas of Africa with malaria transmission, most seizures were reported as generalized (Dent et al., 2005; Ndoye et al., 2005; Winkler et al., 2009), but electroencephalography could have identified partial seizures (Kaiser et al., 2000), suggesting focal damage.
This study provides a detailed descriptive analysis of the demographic and clinical characteristics of people with active convulsive epilepsy (ACE) aged 6 years and older, identified during a large community-based survey in a rural malaria endemic area of Kenya (Edwards et al., 2008). In particular, we wanted to determine the prevalence of focal features with the use of electroencephalographic facilities.
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This study has been performed on data from people with ACE, identified through the largest door-to-door prevalence survey carried out in sub-Saharan Africa to date (Edwards et al., 2008). It demonstrates that the burden of epilepsy in this rural area lies with the adolescents and young adults, despite excluding children <6 years of age. A high proportion had a history of status epilepticus, often occurring in childhood, associated with a febrile illness. The high proportion of focal features in the semiology, physical examination, and EEG suggests that an underlying cause may be identifiable by the use of magnetic resonance imaging (MRI). The high prevalence of status epilepticus and those with focal seizures suggests that many cases of epilepsy may be preventable. In addition, these patients have substantial comorbidity in terms of neurologic deficits and cognitive impairment, with reduced schooling, employment, and marriage. Furthermore, they considerably underutilize AEDs, the use of which may improve their outcome in terms of functioning within society.
Half of the patients were <18 years of age, with onset of seizures before the age of 18 years in two-thirds. More than half of the patients had seizures starting before 6 years of age, but it was difficult to differentiate between febrile seizures, seizures as part of acute infections, and unprovoked seizures in this context. The recall for febrile status epilepticus was much better in children than adults, because the parents provided the information. The finding that more than one-fourth of all patients had an episode of status epilepticus associated with febrile illness, suggests that infections may be an important cause of epilepsy, particularly malaria. In other contexts febrile status epilepticus is associated with a very high rate of subsequent epilepsy (Annegers et al., 1988). We have documented a high incidence of acute symptomatic seizures (Idro et al., 2008) and convulsive status epilepticus (Sadarangani et al., 2008) in this area and found that malaria was the most common cause. Severe falciparum malaria is associated with the subsequent development of epilepsy (Carter et al., 2004; Ngoungou et al., 2006).
The proportion of patients with abnormal interictal EEG findings using a 30-min sample without sleep in this rural population, is higher than that reported from Ethiopia (Tekle-Haimanot et al., 1990), but lower than in an area with a high prevalence of epilepsy and onchocerciasis (Kaiser et al., 2000). The EEG indicated that more than one-fifth of patients with GTCS only, had focal abnormalities. suggesting that these seizures are likely to be partial in origin. This supports data from other parts of Africa (Tekle-Haimanot et al., 1990; Kaiser et al., 2000). The overall high prevalence of focal abnormalities would suggest insults to the brain, and this is supported by the identification of adverse perinatal events (Mung’Ala-Odera et al., 2008; Sadarangani et al., 2008) and head injury as significant risk factors.
More than one-half of children and adults had seizures more frequently than once per month, with frequency associated with cognitive impairment on clinical examination. In previous studies, cognitive impairment was found to be associated with behavioral difficulties and poor control of the seizures (Sillanpaa et al., 1998). The cognitive impairment may also explain the lower attendance and lack of progression in school in the children. It may also explain the difficulties in obtaining a job and reduce the prospects of marriage in the adults and possibly predict a higher mortality.
In these patients there was considerable evidence for the detrimental effects of epilepsy, in terms of physical manifestations, that is, burns, impaired schooling, and reduced chances of marriage. The increased frequency of burns in female patients is probably related to their domestic duties of cooking over open fires. The severity of burns suggests a hidden mortality. The severe underutilization of AEDs is likely to contribute to social functioning difficulties.
The causes of epilepsy could not be determined in most patients because documentation of antenatal, perinatal, and postnatal events was missing and because of the lack of facilities for investigation. In a multivariate case–control analysis of this group of patients, family history of febrile convulsions and unprovoked seizures and adverse perinatal events were identified as independent risk factors (Edwards et al., 2008). The associations with adverse perinatal events has emerged in other studies of children in this area (Mung’Ala-Odera et al., 2008) and elsewhere (Banu et al., 2003) and needs further investigation to understand the pathogenetic relationship. In the analysis of individual cases, head injury appeared to precede the onset of epilepsy in 8%. Because nearly three-fourths of the patients had focal features from the semiology of their seizures, on the EEG and/or focal neurologic deficits, this would suggest that many other causes may be found with neuroimaging, particularly MRI.
The epidemiologic study screened only for convulsive seizures in order to identify those at highest risk in terms of mortality and comorbidity, and, therefore, those in greatest need of diagnosis and treatment. Hence, this study underestimated nonconvulsive epilepsies, for example, absences, which were only recognized in addition to convulsive seizures. Undetected cases of all ages, due to stigma related nonresponse in early screening phases of the prevalence survey, may mean that the prevalence of certain characteristics within cases of ACE has been underestimated here. Recall bias is likely, particularly in adults who did not have a guardian available to provide additional information. The classification of seizure types and the determination of the onset of unprovoked seizures may also have been influenced by a lack of additional information. The cultural perceptions of symptoms may have influenced the diagnosis and classification of epilepsy. The clinical assessment of cognition is likely to have underestimated the prevalence of cognitive impairment. Finally we examined children 6 years and older only, since there are difficulties in differentiating febrile seizures from epilepsy.
Despite these limitations, it is clear that epilepsy affects mainly children and young adults in this part of Africa, and that it has a profound impact on their functioning in society, reducing their chances for attending school, obtaining a job, and getting married. There is considerable comorbidity in terms of cognitive impairment and physical manifestations such as burns. The lack of evidence of an association between AED use and seizure frequency further highlights the need for increased awareness of epilepsy as a treatable condition. The high proportion of focal features in these patients suggests that a cause of the epilepsy could be identified with further investigation, particularly neuroimaging. These findings together with the high prevalence of febrile status epilepticus suggest that much epilepsy could be prevented in this area.