RESUMEN
Recurrent sixth nerve palsies are usually idiopathic, although they have been postulated to be caused by a postinflammatory insult or abnormal cerebral circulation. We report the case a 9-month-old boy who had 2 episodes of a left abduction deficit that resolved spontaneously. A 3-dimensional high-resolution T2-weighted sequence magnetic resonance imaging scan of the head revealed a hypoplastic left 6th nerve and a small left Dorello's canal.
Asunto(s)
Enfermedades del Nervio Abducens/etiología , Enfermedades del Nervio Abducens/patología , Nervio Abducens/patología , Fosa Craneal Posterior/anomalías , Humanos , Lactante , Imagen por Resonancia Magnética , Masculino , Músculos Oculomotores/patología , RecurrenciaRESUMEN
OBJECTIVE: To test the hypothesis that function of the rod photoreceptors is abnormal in pediatric patients with mitochondrial disorders. METHODS: Patients (n = 22; median age, 5 years) with a deficiency of 1 or more of the mitochondrial enzyme complexes, or a mutation in mitochondrial DNA, were studied by means of scotopic, full-field electroretinography (ERG). The conditions of ERG testing allowed derivation of the parameters of the activation of rod phototransduction from the ERG a-wave, and postreceptoral function from b-wave and P(2) stimulus-response functions. The deactivation of phototransduction was studied in 5 patients. The patients' ERG responses were compared with those of healthy control subjects (n = 25). RESULTS: Responses from 19 patients were sufficient for analysis of rod photoreceptor and postreceptoral function. Saturated amplitudes of the rod photoresponse and b-wave sensitivity were significantly depressed in the patients. Saturated amplitudes of rod cell and P(2) responses were correlated. The kinetics of deactivation of phototransduction were slowed even if the kinetics of activation were normal. CONCLUSIONS: In patients with mitochondrial disorders, some abnormalities of the scotopic ERG responses originate in the rod photoreceptors, but postreceptoral processes may also be abnormal. From a practical perspective, ERG testing can contribute to diagnosis of mitochondrial disorders.