NEUROEPIDEMIOLOGY / NEUROEPIDEMIOLOGIE
HOSPITAL BASED STUDY ON NEUROLOGICAL DISORDERS IN MADAGASCAR. DATA FROM THE NORTHWESTERN PART OF THE ISLAND
Hospital-based data on neurological disorders from Mahajanga, the Northwestern province of Madagascar are reported.
Les auteurs rapportent les donnees hospitalieres sur les troubles neurologiques rencontres a Mahajanga, province occupant la partie Nord-ouest de Madagascar. Les epilepsies (28,75% des cas), les cephalees chroniques (20,95%), les neuropathies peripheriques (11,30%) constituent les affections les plus frequentes. Contrairement aux statistiques occidentales, les maladies degeneratives et la sclerose en plaques sont rares. Les principaux facteurs de risque (maladies transmissibles, manultrition, stress provoques par la pauvrete) et quelques aspects des realites sanitaires (manque d’equipments de diagnostic et de medicaments fondamentaux) sont partages avec d’autres pays tropicaux en voie de developpement.
Keywords : Epidemiology, Neurological diseases, Madagascar
Tropical countries share common climatic and biologic characteristics. They are thus expected to disclose similar patterns of diseases. However, the prevalence of these diseases vary because of the development and of the sociocultural peculiarities of each country. Population-based studies, the most appropriate ones to assess the magnitude of each health problem are unavailable in Madagascar. We report hospital data from Mahajanga, a Northwestern region of the island.
STUDY POPULATION AND METHOD
The study population was expected to be that of the whole province (1,379,000 inhabitants), but in fact, only the population of the city of Mahajanga and its nearest surroundings (up to 200,000 inhabitants) had access to the University hospital.
The population was young (44<15 years-old, only 3,2°/o>65 years-old), with an isosexual repartition expectancy (52 years vs 69 years for Mauritius) . A considerable proportion of Mahajanga city dwellers have an Islamic influence, expressed in prohibitory eating behaviours (pork, alcoholic, drinks). The region has a hot and dry climate where malaria, schistosomiasis tuberculosis and syphilis are endemic.
The study itself consisted in a retrospective exam of registered inpatients and outpatients’ files in the department of Neuropsychiatry (University Hospital) between June 1, 1993 and December 31, 1995. Patients of both sexes, aged more than one year-old were included.
Electrical devices (EEG.EMG), cerebral imageries (CT scan, MRI), and sophisticated biological investigations were unavailable, so the diagnosis was built up on sole clinical and routine laboratory data. In fact, the most conclusive argument was the radical cure or alleviation of symptoms. The classification of the diseases was made according to internationally.recognised definitions (NINDS, IHS, ILAE, ICD 10).
1161 patients were registered during the study period: 741 had neurological disorders, 334 had psychiatric disorders, 86 had non neuropsychiatric diseases (table 1).
Table 1: Repartition of the diseases registered at the Departement of Neuropsychiatry during the study period.
Outpatients represented 68,42% of cases (n=507) and inpatients 31,58% of cases (n=234). Epilepsie were followed by chronic headaches, which were selectively recruited among outpatients, cerebrovascular diseases occupied the second place among inpatients; the real magnitude of this affection might be underevaluated, because of parallel recruitment in other wards. Unlike series from industrialised countries, degenerative diseases were rare. Peripheral neuropathies were common, whereas spastic paraparesis were of a minor concern. Two per cent (2%) of neuropathies (15/741) were inclassifiable because of tlie lack of specific investigations.
Table 2: Aetiological repartition of the neurological disease (in percentage) among all the patients, outpatients and inpatients.
Epileptic seizures were listed in table 3: their classification, according to the 1981 ICE version was possible in spite of EEC data unavailability. Some authorities have admitted the validity of such classification (2,3). Like in most of tropical reports (3,4,5), partial seizures were predominant wheras absence seizures were underrated (1% vs 10% for GASTAUT’s . Among the epilepsies which were deemed as secondary (56%=l 19/213), a putative aetiology was found in only 54% of them (64/119). Neurocystcercosis was the commonest pathology involved (42% of the aetiologies, i.e. 27/64). Phenobarbital was the drug of first choice (94% of the prescriptions). The other antiepileptic drugs were either unavailable, or too expensive.
Table 3: Distribution of the epileptic seizures according to the international Classification (ICES), 1981 version.
Chronic headaches were dominated by migraine (table 4); tension headaches were unexpectedly rare. Many physicians were still unfamiliar with migraine, as judged by the non negligible rate of diagnosis wanderings (spasmophilia, ocular dsyfunctions, sinusitis), and maladjusted prescriptions (preventive treatment prescribed for one month.). Long term management of migraine suffered from the same bad compliance than that encountered in epilepsies; the main reasons were unavailability or cost inaccessibility (in percentage).
Table 4: Aetiological repartition of the chronic headaches (in percentage).
The aetiology investigations and the classification ofneuropathies (table 5) were limited by the lack of diagnosis facilities (EMG, nerve conduction studies, specific biologic dosages). The main putative cause asserted was polyvitamins deficiency (26% of cases, ie 27/102) within the frame of global malnutrition or alcoholism.
Heavy deficiency sufferers (e.g prisoners) sometimes disclosed aproximal hindlimbs involvement. Three cases were associated with heart failure (wet beriberi). Radicular compressions (mainly of the sciatic type) were surprisingly overrepresented in our series, whereas facial nerve palsy was unfrequent (8,82% of cases). Unlike some African countries (7), no HIV-related palsies were encountered. Mahajanga has a leprosarium, so only a typical manifestations of this infectious disease were addressed in our department (2,94% of cases).
Table 5: Repartition of the different anatomoclinical forms of neuropathies (in percentage).
Like in the majority of Caucasian (8) and African studies (9,10), strokes were dominated by the ischemic type (table 6).
Hypertensive encephalopathy was screened with accuracy because of its better therapeutic issue. Hypertension and syphilis were the main risk factors identified. The global fatality rate was high (58% of cases, i.e. 48/83). Neurosisticercosis was at the head of CNS infections (table 7), although the anatomical specimen prevalence of this Parasitosis (II) was among the lowest in Mahajanga.(6°/o vs 40% for Antananarivo, 32% for Tulear, 15% for Fianarantsoa). Diagnosis was made on sole clinical and serological basis (12); in fact, the therapeutic trial remained the most conclusive argument. Bacterial infections of the cerebrum and its coverings were surely underestimated because of parallel recruitments.
Table 7: Frequency of CNS infections (in percentage).
Intrathecal antibiotics were often useful to palliate the dose inadequacy of parenteral drugs. Cerebral malaria, like in the other underdeveloped countries (13), provided a high fatality-rate (26% of case, ie 4/15), because of delayed chemotherapy. Neither HIV carriers nor proved quinine resistance was encountered among our fatal cases. Among degenerative affections. Parkinson’s disease was the most frequent. Parkinsonism related to chronic use of neuroleptics was far commoner. Alzheimer-type dementia was not yet a public health problem.
The data from Mahajanga, globally display the same patterns of neurological diseases as those found in the majority of tropical regions. In spite of the lack of population-based studies, the leading position of epilepsies among our hospital-registered cases confirm their importance in public health. The predominance of partial seizure parallels the high rate of secondary epilepsies. However, their pattern is not homogenous in different tropical countries: Nigerian studies (4) emphasize the causative role of febrile convulsions to explain the higher rate of complex partial seizures; on the contrary, Indian studies (5) yield a higher rate of partial simple seizures (58% of cases) and credit the prominent role of CNS infections, amongst which neurocysticercosis is paramount. Our pattern is of the Indian type (table 3) and this parasitosis, really plays an important role. Additional studies on risk factors, appropriate drug supply (14/15) and pertinent education of the population, are the most adapted means to fight against epilepsies.
Concerning chronic headaches, post graduate training is needed to improve the diagnosis and the management of the main aetiologic forms, viz migraine and headaches of psychological origin. Drugs availability and cost must be taken into account in case of long term treatment; patients compliance depend on these extramedical factors. Traditional pharmacopoeia (16) and alternative medicine (17) are optional or complementary issues for developing countries, but their use must be regulated. Peripheral neuropathies are probably underrated, for a bulk of patients to the hospital recruitment; the reasons may be a self management with vitamin and plants, geographical isolation and so on. The endowment of essential facilities (EMG, nerve conduction measurement, biological dosages) will enrich the knowledge about these diseases, common in tropical countries; certain aetiologies are likely different from those encountered in Western regions.
Massive polyvitamins deficiency is frequent among prisoners. Associated with a major protein calorie malnutrition it can provoke both axonal and segmental demyelination (18); this latter may explain the involvement of proximal hind-limbs in many patients. It is surprising to detect HTL V1 among Malagasy patients, for the Seychelles, which share the same climatic, ecological, and even cultural characteristics with Madagascar, are considered as endemic areas
The surprising high rate of nerve sciatic compression results likely on local inadequacy in professional training: indeed, Mahajanga is a port, and naive load handlers are recruited without any technical skill learning. However, lumbar disk prolapse is considered as a rather rare condition in Africans (20). Although the proportion of our stroke cases represent only one-third of those reported in the majority of African hospital-based studies (9,10,21,22), they constitute a real human and economic burden; the lack of appropriate diagnosis and therapeutic supplies may explain the high mortality rate, and the worse functional prognosis.
Global campaign against hypertension, the main risk factor, has proved to be an efficient method to decrease the secular trend of strokes (23,24). The infection of the CNS are by far the most important causes of mortality and mobidity in many African countries (25). Our data, probably underestimate their real importance, because of parallel recruitments. The prognosis is often worsened by the delayed management and by the incapacity in identifying and treating adequately the infectious agent. Like in other African series, degenerative diseases are rare, independently of the low life expectancy (26). Before concluding on a case of AIzheimer’s disease, tertiary syphilis and major depression must be ruled out.
The patterns ofneurological diseases in Mahajanga (Madagascar) are globally similar to that of the majority of tropical countries. A descriptive epidemiological survey on general population and epidemiological research on risk factors are basic to build up an appropriate preventive policy. Without an endowment of essential diagnosis facilities (EEG, EMG, Echography) and drugs, curative care would be inefficatious; this failure will reinforce the negative attitude of the population towards Western medicine and favour the action of quacks.