RESUMO
INTRODUCTION: Pelizaeus-Merzbacher disease is an infrequent hypomyelinating disorder caused by alterations in the PLP1 gene, which leads to a fault in the axonal myelination of the oligodendrocytes in the central nervous system. Two forms have been reported, according to the severity of the presentation: connatal and classic. It is characterised by neonatal hypotonia, delayed psychomotor development, progressive spasticity predominantly in the lower limbs and nystagmus, with pyramidal and extrapyramidal signs and symptoms; the connatal form is far more severe. Magnetic resonance imaging shows diffuse hypomyelinating leukoencephalopathy, evoked potentials are usually altered and confirmation is obtained through a molecular study of the PLP1 gene. CASE REPORTS: We present the cases of five paediatric patients, four of whom had the classic form and one with the connatal form. The clinical characteristics and complementary studies are described, and a concise review of the literature is carried out. CONCLUSION: This disease has a progressive and almost unvarying course, which is the clinical key to be able to differentiate it from other entities such as infantile cerebral palsy, peripheral neuropathies or multiple sclerosis, among others, in addition to the characteristic neuroimaging findings. It is necessary to suspect this diagnosis and confirm alterations in the PLP1 gene with the aim of obtaining a real incidence of this entity, which is probably underestimated, like other leukodystrophies.
TITLE: Clinica y diagnostico de la enfermedad de Pelizaeus-Merzbacher: descripcion de cinco casos.Introduccion. La enfermedad de Pelizaeus-Merzbacher es un trastorno hipomielinizante raro debido a alteraciones en el gen PLP1, que lleva a un fallo de la mielinizacion axonal de los oligodendrocitos en el sistema nervioso central. Existen dos formas descritas segun la gravedad de su presentacion: connatal y clasica. Se caracteriza por hipotonia neonatal, retraso del desarrollo psicomotor, espasticidad progresiva de predominio en los miembros inferiores y nistagmo, con signos y sintomas piramidales y extrapiramidales, y la forma connatal es mucho mas grave. La resonancia magnetica muestra leucoencefalopatia hipomielinizante difusa, los potenciales evocados usualmente se alteran y la confirmacion se realiza mediante estudio molecular del gen PLP1. Casos clinicos. Se presentan cinco pacientes pediatricos afectados, cuatro con la forma clasica y uno con la forma connatal; se describen las caracteristicas clinicas, los estudios complementarios y se realiza una revision concisa de la bibliografia. Conclusion. Esta enfermedad tiene una evolucion progresiva y casi invariable, lo cual es la clave clinica para diferenciarla de otras entidades como la paralisis cerebral infantil, neuropatias perifericas, esclerosis multiple, entre otras, ademas de los hallazgos caracteristicos en las neuroimagenes. Es necesario sospechar este diagnostico y confirmar alteraciones en el gen PLP1 con el fin de obtener una incidencia real de esta entidad, probablemente subestimada, como otras leucodistrofias.
