Experience with Guillain-Barré syndrome in a neurological Intensive Care Unit. / Experiencia del síndrome de Guillain-Barré en una Unidad de Cuidados Intensivos neurológicos.

INTRODUCTION: Guillain-Barré syndrome, an acute polyradiculoneuropathy that presents with weakness and areflexia, is the most common cause of acute flaccid paralysis. In certain patients, respiratory failure is secondary to this disorder, eventually causing patients to require mechanical ventilation and experience additional complications due to diminished respiratory support and related mobility limitations. Prognoses for most of these cases are positive; treatment consists of basic support combined with plasmapheresis or administration of immunoglobulins. OBJECTIVE: This study sought to describe the socio-demographic, clinical, laboratory and neurophysiological characteristics of patients with Guillain-Barré syndrome who were hospitalised in the Intensive Care Unit of the Neurological Institute of Colombia between 2006 and 2012. METHODOLOGY: This study presents a case series. RESULTS: We surveyed 25 patients (32% female and 68% male) with Guillain-Barré syndrome and an average age of 54 years. Sixty per cent of these patients were admitted between days 3 and 7 after symptom onset; 64% had a history of respiratory infection and 20% had a history of intestinal infection. In addition, 84% of the patients presented with albuminocytological dissociation. We observed the following clinical subtypes of Guillain-Barré syndrome: inflammatory demyelinating polyneuropathy in 32%, acute motor-sensory axonal neuropathy in 28%, acute motor axonal neuropathy in 28%, and Miller Fisher syndrome in 12%. CONCLUSIONS: In this descriptive study of a group of critical care patients with GBS, results depended on patients' clinical severity at time of admission. Our findings are similar to results published in the international literature.

Lesser-known myelin-related disorders: focal tumour-like demyelinating lesions.

INTRODUCTION: Focal tumour-like demyelinating lesions are defined as solitary demyelinating lesions with a diameter greater than 2 cm. In imaging studies, these lesions may mimic a neoplasm or brain abscess; as a result, invasive diagnostic and therapeutic measures may be performed that will in some cases increase morbidity. Our aim was to analyse and characterise these lesions according to their clinical, radiological, and pathological characteristics, and this data in addition to our literature review will contribute to a better understanding of these lesions. METHODS: This descriptive study includes 5 cases with pathological diagnoses. We provide subject characteristics gathered through reviewing their clinical, radiology, and pathology reports. RESULTS: Patients' ages ranged from 12 to 60 years; 3 patients were female. The time delay between symptom onset and hospital admission was 3 to 120 days. Clinical manifestations were diverse and dependent on the location of the lesion, pyramidal signs were found in 80% of patients, there were no clinical or radiological signs of spinal cord involvement, and follow-up times ranged from 1 to 15 years. CONCLUSION: Brain biopsy is the gold standard for the diagnosis of demyelinating tumour-like lesions; however, their clinical features, along with several magnetic resonance imaging features such as open ring enhancement, venular enhancement, the presence of glutamate in spectroscopy, and others, may be sufficient to differentiate neoplastic lesions from focal tumour-like demyelinating lesions.

Primary angiitis of the central nervous system: report of five biopsy-confirmed cases from Colombia.

INTRODUCTION: Primary (isolated) angiitis of the central nervous system (PACNS) is a rare cause of cerebrovascular disease (CVD), and few leptomeningeal and brain biopsy (LBB)-confirmed cases have been reported from South America. METHODS: We retrospectively reviewed charts of patients with diagnosis of cerebral angiitis admitted between March 1991 and July 2001 to a single university hospital in Medellin, Colombia. Patients with definitive diagnosis of PACNS by Alrawi et al.'s LBB criteria were selected. We excluded other causes of cerebral angiitis as well as cases without LBB confirmation. RESULTS: We report five patients, four men and one woman, with a mean age at onset of 24.4 years, and an average disease progression of 12.4 days. Four presented with headache and motor weakness, three had seizures, and two had alterations of consciousness. Cerebral MRI was abnormal in all five cases; brain CT in four, and cerebral angiography in two. The cerebrospinal fluid (CSF) was abnormal in two patients. Leptomeningeal and brain biopsies revealed mononuclear infiltration in the wall of small blood vessels in all. Three had concurrent meningeal and cerebral involvement, two had necrotizing angiitis, and one had vascular and encephalitic lesions. All received only steroid treatment; the 1-year follow-up revealed good prognosis without relapses. CONCLUSION: We report five biopsy-proven cases of PACNS from Colombia associated with neurological and neuroimaging abnormalities; these patients presented a mild inflammatory disease that was correlated with few CSF abnormalities and good response to single steroid treatment without relapses. Leptomeningeal and brain biopsy is mandatory for a definitive diagnosis.

Short course albendazole treatment for neurocysticercosis in Columbia.

The efficacy of albendazole was evaluated in 20 Colombian patients with neurocysticercosis showing neurological symptoms. All had parenchymal non-enhancing cystic images by computerized tomography and a positive enzyme-linked immunosorbent assay for cysticercus antibodies in serum or cerebrospinal fluid. They stayed in hospital for 8 d during treatment with albendazole, 15 mg/kg/d in 2 divided doses, and were then followed for at least 6 months after treatment. The number of cysts was reduced by 50% after 6 months. In 7 (35%) all cysts disappeared, in 7 (35%) the number was reduced, and in the remaining 6 (30%) the number was unchanged. In the 13 patients who still had cysts at 6 months, 11 showed a moderate decrease in average cyst size and in 2 the size was unchanged. Side effects during treatment were observed in 60% of the cases, but only 3 required corticosteroids.

[Headaches in idiopathic intracranial hypertension. A review of ten years in a Columbian hospital]. / Cefaleas en hipertensión intracraneal idiopática. Revisión de diez años en un hospital colombiano.

INTRODUCTION: Different patterns of headache have been reported in idiopathic intracranial hypertension. PATIENTS AND METHODS: We conducted a retrospective study to evaluate patients in a Columbian hospital who satisfied Friedman and Jacobson criteria for idiopathic intracranial hypertension. Two groups of patients, with throbbing headaches (TH) and heaviness/oppressive headaches (HOH), were correlated with International Headache Society classification criteria. RESULTS: We found 16 patients, 14 of whom were females (87.5%), with a mean age of 27 years. Patients had a history of two months or more (43.7%), 1-2 months (25%) and 2 weeks (18.7%). Six patients were found to be suffering from TH and nine had HOH. In the TH group, headaches were hemicranial (50%), frontal (33.3%), moderate (33.3%), severe (66.6%), got worse with activity (100%), with sickness/vomiting (83.3%), and photophobia (33.3%). All of them had clinical parameters similar to those of migraine. In the HOH group headaches were global (33.3%), hemicranial (22.2%), frontal and occipital (22.2%), moderate (66.6%), severe (33.3%), and with sickness/vomiting (55.5%). 66.6% of them had clinical parameters similar to those of de novo chronic daily headache (NCDH). On carrying out a physical examination in all the patients, paresis of the abducent nerve was found in 31.2% and papilloedema in 93.7%. The average opening pressure was 27 cmH2O. Computerised axial tomography scanning revealed unspecific anomalies in 18.7% and they were also observed with magnetic resonance imaging in 31.2%. Associated pathologies were found in six patients (37%). Pharmacological treatment was effective in 93.8%. There were no relapses or sequelae. CONCLUSIONS: Idiopathic intracranial hypertension is a malady affecting young people, mainly females, with subacute headaches and symptoms similar to those of migraine and NCDH. A neurological abnormality suggestive of intracranial hypertension was found in 31.2-93.7% of patients.

[Neurosyphilis and the prozone effect]. / Neurosífilis y efecto prozona.

INTRODUCTION: Neurosyphilis (NS) is an entity which still frequently presents to our Neurology Department. The prozone phenomenon occurs in approximately 2% of all cases of late primary syphilis or secondary syphilis; we have found no cases described of prozone and neurosyphilis occurring together. CLINICAL CASE: We present the unusual case of a 44 year old patient with NS and dementia PGP (progressive general paralysis). Initially serum VDRL was negative, but in CSF reacted at dilutions of 1:32. When serum VDRL was repeated using dilutions, it was reactive 1:128 and serum FTA was also reactive. The patient was treated with i.v. crystalline penicillin, after which his condition improved. CONCLUSIONS: We wish to draw attention to the possibility that patients with a dementia syndrome and negative serum VDRL may have the prozone phenomenon, and the laboratory should therefore be asked to do serial dilutions.

[Parkinsonian syndromes in Medellin (Colombia)]. / Síndromes parkinsonianos en Medellín (Colombia).

INTRODUCTION: The definition of parkinsonian syndromes is based on clinical criteria. OBJECTIVE: To determine the frequency and management of parkinsonism, using criteria of inclusion and exclusion. PATIENTS AND METHODS: We selected 302 consecutive patients, 147 females and 155 males, with parkinsonism, age 66.8 (11.4) (range: 13-90), grades of education 7.5 (4.3) (range: 0-20). A structured and quantitative protocol was applied to the sample. RESULTS: The most frequent parkinsonian syndrome was the defined idiopathic Parkinson's disease with 132 participants (43.7%). Probably idiopathic Parkinson's disease was found in 60 cases (19.9%), and possible idiopathic Parkinson's disease in eight cases (2.6%); early onset Parkinson's disease in 10 cases (3.3%), juvenile Parkinson's disease in one case (0.3%), familial Parkinson's disease in five cases (1.7%); cortical Lewy body disease in 16 cases (5.4%), progressive supranuclear palsy in nine cases (3.3%), multiple systemic atrophy in eight cases (2.6%). Secondary Parkinson's disease was distributed as follow: vascular disease in 24 cases (8%), local lesion in 11 cases (3%), medications in 16 cases (5.3%), meningoencephalitis in one case (0.3%) and syphilis in one case (0.3%). Without medication was found 1.5% of sample, which was in Hoehn & Yarh's state I to II. In monotherapy was found 23.2%, with two medications 46.7%, with three 23.5% and with four drugs 5.1%. Levodopa was prescript to 70.9%, anticholinergic to 51.3%, MAO-B-I to 33.4%, amantadine to 33.1%, D2 stimulants to 18.5%, and COMT-I to 2.6%. CONCLUSION: Structured protocol for assessment of parkinsonian syndromes allows reliable diagnoses for clinical and epidemiological purposes.

[Prevalence of myasthenia gravis in Antioquia, Colombia]. / Prevalencia de miastenia grave en Antioquia, Colombia.

INTRODUCTION: Myasthenia gravis (MG), considered the commonest of all the illnesses that affect neuromuscular transmission, is a disorder in which the autoimmune system attacks the post synaptic acetylcholine receptor proteins in the end plate terminal; it is characterised by weakness and skeletal muscle fatigue, with no anomalies in reflexes, sensitivity or coordination. Epidemiological indicators, such as incidence and prevalence, are not known in Colombia. AIMS. To determine the prevalence of MG among the inhabitants of Antioquia, through the use of the capture recapture method. PATIENTS AND METHODS: The capture recapture method was used for two sources, the Instituto Neurológico de Antioquia and the Hospital Universitario San Vicente de Pa l, which are the most important institutions for the diagnosis of neurological diseases in Antioquia. MG prevalence was calculated using the following formula: p= n/N 105. We examined the data from the period between 1 July 1995 and 30 June 2000 with the aim of identifying subjects who fitted the profile of MG sufferers. RESULTS: General MG prevalence in Antioquia was 27.7 cases per million inhabitants (CI 95%= 23.2 32.2). The male/female ratio was 1:3.77. CONCLUSIONS: The estimated prevalence of MG is lower than that reported in United States and other temperate regions, where it varies between 60 and 150 cases per million. The prevalence of MG is low in Antioquia, as in other tropical areas

[Genetic anticipation in idiopathic epilepsies]. / Anticipación genética en epilepsia idiopática.

INTRODUCTION: In extended and multigenerational pedigrees, the idiopathic epilepsy phenotype shows an extreme variability. OBJECTIVE: The range of idiopathic epilepsy onset age in multigenerational pedigrees was studied in order to determine if genetic anticipation play a role in the heredity of Idiopathic Epilepsies. PATIENTS AND METHODS: We compare the seizures onset age among relative-pairs of (parents-children, grandfathers-grandsons and nephew uncles). The mean onset age was compared using the Wilcoxon sign-rank paired-sample non-parametrical test to determine whether or not significant differences over > 0 exist, which refutes the null hypothesis of not anticipation. 84 pairs of relatives were taken from 72 extended multigenerational pedigrees. RESULTS: The onset age of idiopathic epilepsy of the pairs showed a difference significantly > 0, which confirm the existence of intergenerational differences. This difference has a tendency to decrease in age which each successive generation. This difference occur in all relative pairs and therefore contradicts the ascertainment bias described by Penrose. CONCLUSIONS: The results outline the existence of unstable mutations (those produced by a nucleotidic variable number of tandem repeats) as a probable explanation of the susceptibility to develop some forms of idiopathic epilepsy.

[Mode of inheritance of idiopathic generalized non-myoclonic epilepsy in families investigated by studying members with idiopathic epilepsy with tonic-clonic crises on waking. Antioquia, Colombia]. / Modo de herencia de epilepsia idiopática generalizada no mioclónica en familias pesquisadas a través de probandos afectados de epilepsia idiopática con crisis tonicoclónicas del despertar en Antioquia, Colombia.

In attempt to identify the possible role of mayor genes, multifactorial inheritance, and cohort effects in the susceptibility to idiopathic epilepsy with generalized tonic clonic seizures of the awakening type (GTCS), complex segregation analysis was performed in 196 nuclear families ascertained through affected with probands with idiopathic epilepsy with GTCS belonging to the Paisa community of Antioquia (Colombia). Models postulating no transmission, single mayor locus (dominant and recessive) only, and multifactorial component only, were rejected. The models postulating no polygenic component to transmission, and no transmission of the major effect were also rejected. Thus far, complex segregation analysis suggested that a major autosomal codominant allele together with a multifactorial component (mixed model) best explains clustering of idiopathic epilepsy with GTCS in families of the Paisa community. The deficit of transmission of heterozygotes (0.17) is compatible with the existence of epistasis acting on a major gene whose frequency was estimated to be 0.0211. Its transmission variance accounts for 81% of the susceptibility to idiopathic epilepsy with GTCS. The complementary variance (19%) is due to polygenic component.

[Thrombosis of the cerebral venous sinuses: a description of its clinical features, risk factors and treatment in a hospital of Colombia]. / Trombosis de senos venosos cerebrales: descripción de las características clínicas, factores de riesgo y tratamiento en un hospital de Colombia.

INTRODUCTION: Thrombosis of the cerebral venous sinuses (TCVS) is an infrequent entity that still represents a challenge in health care. PATIENTS AND METHODS: A descriptive study involving the evaluation of the medical records of patients that met the following criteria: over 18 years of age with a diagnosis of TCVS confirmed by CAT scan or cranial MRI, the absence of a history of intracranial surgery in the previous six months and absence of a history of intracranial infection. RESULTS: A total of 15 patients (14 females and one male) were found with an average age of 28.6 years. The time required for the development of the most frequent symptoms was 1 10 days (60%). The usual presentation was a syndrome of intracranial hypertension with focalisation and encephalopathy. Risk factors were identified in 13 patients (87%). TCVS was diagnosed by cranial MRI in the case of 14 patients (93%), by CAT scanning in one (7%) and this was also used to orient diagnosis in 12 cases (80%). The most frequently affected sinuses were the superior longitudinal and transverse, in 10 cases each (66%), and venous infarctions were also detected in 10 patients (66%). In the patients in whom we were able to evaluate clotting disorders, it was found that the only individual who displayed activated protein C resistance was positive, three out of four patients had a protein C deficiency and four out of six had an antithrombin III deficiency. CONCLUSION: TCVS presents as an intracranial hypertension syndrome and it is possible to find risk factors in as many as 85% of the cases.

[Prevalence of multiple sclerosis in Colombia]. / Prevalencia de la esclerosis múltiple en Colombia.

INTRODUCTION: Multiple sclerosis (MS) is the commonest demyelinating condition of the nervous system. It is characterized by numerous demyelinating areas or plaques of demyelination which are found dispersed throughout the nervous system. It has been shown that MS is less frequent in tropical regions than in subtropical regions. In Latin America particularly, there are some studies which show this phenomenon. However, in Colombia no studies of prevalence of MS have been done. OBJECTIVE: To determine the prevalence of multiple sclerosis in five provinces of Colombia (Antioquia, Caldas, Santander, Risaralda and Bolivar). PATIENTS AND METHODS: The capture-recapture method was used for two sources to determine the number of cases defined on the criteria of Poser et al seen between July 1995 and June 2000. RESULTS: The prevalence (cases of MS per 100,000 inhabitants) varied between 1.48 in Antioquia (95% CI 1.12; 1.78) and 4.98 in Risaralda (95% CI 3.52; 6.43). Seventy two percent were women. The regions included in this study represented 25% of the population of Colombia. CONCLUSIONS: There is a low prevalence of MS which is as expected in tropical areas. Persons with MS in these regions may be very useful in the study of other factors involved in the aetiology of MS (genetic). The capture-recapture method is an excellent tool for carrying out prevalence studies since it is cheap and requires little time.

[Epidemiology of cerebrovascular diseases in Sabaneta, Colombia (1992-1993)]. / Epidemiología de las enfermedades cerebrovasculares en Sabaneta, Colombia (1992-1993).

INTRODUCTION AND OBJECTIVES: In Columbia the epidemiology of cerebrovascular illness (ECV) is unknown. For this reason a study was made to determine the prevalence, incidence and annual mortality, and to identify the different types of ECV and the demographic characteristics of the population. MATERIAL AND METHODS: In the urban area of Sabaneta, Columbia 13,588 door to door interviews were carried out among the inhabitants. A cutoff study carried out between April and June 1992 showed the prevalence of ECV. One year follow-up of persons without ECV between June 1992 and June 1993, enabled the incidence and annual mortality to be evaluated. A structured interview was used to identify the demographic characteristics of the population and classify people as healthy or as possibly having ECV. The latter were examined by neurologists to confirm or rule out the presence of ECV and to determine the type of ECV involved. Of the total urban population, 76.9% agreed to participate in the study. During the follow-up year, 8.4% were lost trace of. RESULTS AND CONCLUSIONS: The prevalence of ECV was 559.3/ 100,000 inhabitants, increasing with age (15). In the 15-40 year old group, the incidence of ECV was 44 times higher in women than in men. The annual incidence rate was 88.9/100,000 inhabitants: thromboembolic disease was the most frequent. Of a total of 87 cases of ECV, 12 (13.98%) died of various causes during the year in which they were being observed. The annual mortality rate for ECV was 16.2/100,000 inhabitants, all being primary cases.

[Comparison of the multifactorial model as a hereditary mechanism of non-myoclonic generalized idiopathic epilepsy and partial idiopathic epilepsy]. / Contraste del modelo multifactorial como mecanismo hereditario de epilepsia idiopática generalizada no mioclónica y de epilepsia idiopática parcial.

OBJECTIVE AND METHODS: An experimental study about the predictions from the multifactorial threshold model created by Falconer is presented, assuming that this model may explain the genetic mechanisms underlying the family aggregation of idiopathic epilepsies. RESULTS: We failed to confirm the following predictions from the falconer model: decreased prevalence of disease in relatives, proportional to decreased family links, and the order of birth effect. An heredity greater than 100% was calculated which is concordant with the presence of at least a locus with a major gen affect. CONCLUSION: Our results reject the multifactorial threshold effect and suggest the presence of a major gen or Mendelian effect. An analysis of complex segregation is suggested for future studies.

[Multiple sclerosis: epidemiological-genetic studies in the population of Antioquia, Colombia. Disequilibrium of HLA DQ alpha]. / Esclerosis múltiple: aproximación epidemiológico-genética en habitantes de Antioquia, Colombia. Desequilibrio de ligamiento al HLA DQ alpha.

INTRODUCTION AND OBJECTIVE: Discrimination and quantification of the environmental and genetic components involved in developing multiple sclerosis (MS) have not been made. In order to discriminate these components we have ascertained affected individuals by MS belonging to the Paisa community from Antioquia, Colombia, a state localized in the tropical area of South America, to detect eventual linkage disequilibrium to HLA, locus DQ alpha, which could demonstrate the relevance of the genetic component. DEVELOPMENT: A contingence analysis among case-control HLA DQ alpha genotype distributions, by using Monte Carlo resampling method to solve small number sample, showed that there are significant differences between the two groups. We observe that HLA DQ alpha 1.1, 1.2 allele frequencies were higher in the cases than in the controls. Also, there was significant HLA DQ alpha 3 allele lower frequency (p < 0.05) in the cases than in the controls. CONCLUSIONS: Similar results have been described in other Caucasian populations living in non tropical areas. Before results could indicate that the Caucasoid populations genetic component implied in the susceptibility to MS have remained in Paisa community, whether the environmental component, being meaningful to develop MS.

[Prevalence of neurocysticercosis in individuals affected by epilepsy]. / Prevalencia de neurocisticercosis en individuos afectados de epilepsia.

INTRODUCTION: In this investigations, was carried out a neurocysticercosis (NC) prevalence study during seven months in the Instituto Neurológico de Antioquia with the purpose of known neurocysticercosis frequency as cause of epilepsy in patients older than ten years that we attended in our institute. MATERIAL AND METHODS: Computerized tomographies (CT) were made to 503 patients, with epilepsy, 24.7% of them were CT positive for NC. Cysticercosis enzyme linked immunoelectrotransfer blot (EITB) and enzyme linked immunoabsorbent assay (ELISA) test were made to 178 patients, 19.6% were EITB positive for NC and 5% ELISA positive for NC. Results. From this result it is possible to infer that about 8% of the 503 patients with epilepsy had cysticercosis, according to EITB that is the golden assay for NC. The CT and ELISA test had 94.3% and 27.7% sensitivity, respectively, according to EITB. The specificity of the CT for NC was 49.2% and specificity for ELISA test was 100% as compared to EITB. The multivariate analysis with logistic regression allowed to establish association of positive EITB with factors such as male sex, eating pork, headaches and multiple lesions in CT. CONCLUSIONS: Prevention and education actions are necessary for the interruption of the neurocysticercosis transmission chain in order to diminish the high prevalence of epilepsy in the country and its complication and consequences.

Complex segregation analysis of non-myoclonic idiopathic generalized epilepsy in families ascertained from probands affected with idiopathic epilepsy with tonic-clonic seizures in Antioquia, Colombia.

In an attempt to identify the possible role of major genes, multifactorial inheritance, and cohort effects in the susceptibility to idiopathic epilepsy with generalized tonic-clonic seizures of the awakening type (GTCS), complex segregation analysis was performed in 196 nuclear families ascertained through affected probands with idiopathic epilepsy with GTCS belonging to the Paisa community of Antioquia (Colombia). Models postulating no transmission, single major locus (dominant and recessive) only, and multifactorial component only, were rejected. Since the codominant single major locus model could not be rejected and models that assign no major locus to transmission, no polygenic component to transmission, and no transmission of the major effect were rejected, complex segregation analysis suggested that a major autosomal codominant allele together with a multifactorial component (mixed model) best explained clustering of idiopathic epilepsy with GTCS in families of the Paisa community. The deficit of transmission of heterozygotes (0.17) is compatible with the existence of epistasis acting on a major gene whose frequency was estimated to be 0.0211. Its transmission variance accounts for 81% of the susceptibility to idiopathic epilepsy with GTCS. The complementary variance (19%) is due to the polygenic component.

Clinical features of multiple sclerosis in a genetically homogeneous tropical population.

Individuals affected with multiple sclerosis (MS) from a genetically homogeneous Caucasian population in Antioquia, a tropical region of Colombia, were evaluated in order to observe the clinical behavior of the disease. The frequency of clinical manifestations in 65 patients with definite MS from Antioquia was compared with those reported from temperate regions. The most common manifestations were optic neuritis and motor symptoms with absence of cerebellar symptoms. This presentation is significantly different from the frequency distribution at onset in series from temperate regions. These differences suggest that environmental factors could modify the clinical expression of MS in this population.

Idiopathic epilepsy with generalized tonic clonic seizures in Antioquia, Colombia: is the joint Amerindian and Negroid racial admixture the cause of its high prevalence?

Most Colombian populations stem from the admixture of Caucasians, Amerindians and Negroids. In the world, these two latter ethnical groups show a significantly higher prevalence of epilepsy than the former one. We tested the hypothesis that the high prevalence of idiopathic epilepsy with generalized tonic clonic seizures found in the Antioquian population (Paisas), from Colombia, is due to their possible joint Negroid and Amerindian ethnic components. We have previously demonstrated that inheritance is the principal factor for developing epilepsy in this community. Analyses of racial admixture, heterogeneity between populations, genetic distance, and phyletic relationships were performed among epileptic and non epileptic samples from the Antioquian community. Also Caucasians, Spaniards, Basques, Jews, Chileans, Negroids, Amerindians and Mongoloids were included in the analysis. Four highly polymorphic blood systems were used as genetic markers: RH, MNS, ABO and FY. They were chosen because of their high discriminant power in these ethnic groups. In the population affected with idiopathic epilepsy, the estimated Negroid and Amerindian rates of admixture were low (3% and 14%, respectively). Although, these degrees of admixture can be explained due to common ancestral origins, the estimated proportion of Amerindian admixture in the epileptic affected population, was significantly higher than the estimated for the Non affected Antioquian population. The latter finding is consistent with the analysis of heterogeneity between populations that discriminated epileptic population from non epileptic Antioquian population (p < 0.05). Epileptic and non epileptic Paisas clustered in topology with Caucasians, very close to Spaniards and Basques and highly distant from Negroids and Amerindians. Thus, far, the origin of the high prevalence of idiopathic epilepsy in the Antioquian (Paisa) population cannot be explained by the hypothetical joint Negroid and Amerindian ethnical admixture, but using additional genetic markers and other methods of racial estimation of admixture it is necessary to corroborate if the Amerindian admixture component is significantly higher in the epileptic population than in the non epileptic Paisa population.