[Etiology of mental retardation in children: experience in two third level centers]

One to three per cent of the world population has mental retardation. This is a frequently consulted and diagnosed disorder in neuropediatric services. Causes are heterogeneous and only a proportion of these patients achieve an accurate etiologic diagnosis.

To determine the etiology of patients with mental retardation who go to the neuropediatric services in two third level hospitals.

We included pediatric patients diagnosed with mental retardation, and used the diagnostic algorithm proposed by the committee of medical genetics and the Academy of Pediatrics for the evaluation of these patients. The data were entered into an Excel database and subsequently analyzed in SPSS 1.5. The etiology of cognitive impairment was classified into five categories.

We included 239 patients: 60.3% were male; according to the severity, 39% of the patients had mild mental retardation, 37.7% had moderate mental retardation, 13.4% had severe mental retardation, and 9.6% had profound mental retardation. In the clinical findings, we found the presence of minor anomalies in 70.3% of patients; these findings in more than two patients suggested a genetic etiology. Definitive etiology of mental retardation was determined in 64.4% of the patients. Environmental causes accounted for 36.4% of this disability in which perinatal hypoxia is the most frequent cause. Genetic causes accounted for 23.8% of the etiology. Finally, 23.8% continued to have no specific diagnosis.

Perinatal hypoxia is the most common cause of cognitive impairment in our population. Early treatment of comorbidities of premature infants can impact the bottom line by decreasing motor and cognitive impairment in these patients. Patients with genetic etiology are the second cause. The proportion of undiagnosed patients could decrease if patient access to genetic studies were better and if these studies were covered by the social security regime in our country, regardless of affiliation.