Neurological disorders in rural Africa: a systematic approach

Introduction

There is very little data on neurological disorders in developing countries. A study carried out in Mnero, southern Tanzania, showed that 10% of all the inpatients of a rural hospital suffered from neurological diseases. ¹ In studies from Nigeria and Zambia, the most frequent neurological disorders were found to be infections of the nervous system and seizures of different origin. ^2,3 Although the above studies clearly point out the areas where the burden of neurological disease lies, a systematic approach to neurological disorders in resource-poor settings so far has not been suggested.

Patients and methods

This study was conducted at the Haydom Lutheran Hospital in the Manyara region of northern Tanzania. Of 8676 admissions all the patients with neurological signs and/or symptoms were seen prospectively in consecutive order by a specialist neurologist (ASW) over a period of eight months in 2003. Basic laboratory examinations, microbiology, cerebrospinal fluid (CSF) analysis and conventional X-ray were available, but there was no access to either neuroimaging or electrophysiology. Also, HIV testing was not available at the time of the study.

The approach to grouping the observed neurological disorders was different from the usual classification of neurological disorders in northern/western countries where diagnostic tools are easily available. Based on the experience gained during the study, we opted for a pragmatic way and chose a three-pronged approach.

Group 1 (Table 1): disorders without diagnostic uncertainties based on (a) medical history and clinical examination only (e.g. epilepsy, febrile seizures, rabies) or (b) medical history and clinical examination together with confirmatory laboratory tests (e.g. cerebral malaria, meningitis);

Ethical clearance and data analysis

Ethical approval was obtained from the National Institute of Medical Research and the study was cleared by the Tanzania Commission for Science and Technology. Free and informed consent from the patients or, in case of children, their respective parents, was also obtained.

The data of all patients was put into a data bank using Microsoft Excel. The same programme was used for calculations (e.g. mean age with standard deviation).

Results

Classification of neurological disorders

The leading diagnostic group was group 1 (n = 340) with disorders that were either diagnosed on clinical grounds alone or needed simple but widely available tests to confirm diagnosis (Table 1). This was closely followed by group 2 (n = 318). Although syndromic description of cases was possible, a satisfactory diagnosis in most cases could not be reached. The available tools were not appropriate to achieve diagnostic certainty (Table 1). Eighty-two patients were allocated to group 3 which contained syndromic cases, mainly impairment of consciousness and obscure encephalopathies, which did not fit any of the established neurological disorders. Clinical implications derived from the above classification have been summarized in Figure 1.

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Figure 1

Clinical algorithm of how to approach a patient with a neurological disorder in a resource-poor setting. Patients are grouped according to diagnostic uncertainties with the ensuing clinical implications. Details of diagnostic groups are given in the text

Discussion

The present study supports our experience that neurological disorders are frequent in developing countries. Of all the 8676 admissions 8.5% were suffering from neurological disorders. Other African studies showed similar results. Osuntokun (1971) analysed neurological illnesses from 1957–1969 at the University College Hospital, Ibadan, Nigeria, and calculated a minimum prevalence of neurological diseases in the hospital population of 4.2%, not including patients with acute head injury, traumatic paraplegia and febrile convulsions. ² Schmutzhard and Aichner (1982) found that 10% of all patients attending the Voluntary Agency Hospital in Mnero, southern Tanzania, suffered from neurological diseases. ¹ A retrospective study from Kwasa (1992) carried out in Kenya showed that neurological disorders made up for 7.5% of all medical conditions at the Kenyatta National Hospital. ⁴ In a Zambian hospital, Birbeck (2001) observed that 10% (186 patients) of the 1886 hospital admissions during a 13-week period were due to neurological diseases. ³ Conversely, a recent study from two hospital sites in Ethiopia showed much higher hospital-based prevalences of 18% and 24.7%. Patients' data were collected retrospectively, which may account for the difference in prevalence rates compared to the above studies. ⁵

Based on our working experience of many years within the African neurological services, we have identified three major diagnostic groups according to the degree of diagnostic uncertainty (definitions see methods). Interestingly, a very similar approach was chosen by Bower et al. in Ethiopia. ⁵ Reassuringly, many patients (46%) could be diagnosed on clinical grounds alone or with the help of simple diagnostic tools, be it laboratory tests or X-ray examination. This is in accordance with findings from Addis Ababa where 42.9% of cases could be diagnosed with high certainty. ⁵ In 43% and 11% of our 740 patients minor and major diagnostic uncertainties remained, respectively. However, patients could be categorized according to syndromes, pointing the way to tentative neurological diagnoses in group 2. Cases of group 3 could only be summarized on a syndromic basis, the underlying neurological disorder remaining obscure. HIV testing was not available at the time of the study; thus it may be possible that some of these patients suffered from HIV-related encephalopathies.

In summary, our study shows that neurological disorders are frequent within a hospital population of rural Tanzania. Emphasis is put on a systematic approach suitable for a resource-poor setting by grouping neurological disorders according to their diagnostic uncertainties.