RESUMO
Nearly 51,000 Cubans were afflicted during an outbreak of an optic neuropathy (ON) and peripheral neuropathy (PN) between 1991 and 1993. We re-examined 14 of 20 affected individuals 16 months after an initial evaluation. The optic features were painless symmetric vision loss with poor visual acuity, color vision loss, central or cecocentral scotoma, optic disc pallor, and nerve fiber layer drop-out. The neurologic symptoms included stocking-glove sensory changes, hearing loss, leg cramps, sensory ataxia, hyperactive or absent reflexes, and complaints of memory loss. Two of 11 ON probands tested harbored Leber's hereditary optic neuropathy (LHON)-associated mitochondrial DNA mutations. All patients had received multivitamin therapy. We performed comparisons using the paired two-tailed t test. On re-examination, 12 of 14 patients demonstrated improvement. One patient remained unchanged. One woman with the nt-3460 mtDNA mutation showed a decline in vision. In patients not harboring mtDNA mutations, overall visual acuity, color vision, and peripheral neuropathy manifestations improved significantly (p < 0.001 for each manifestation). Most of the patients with Cuban ON and PN improved on multivitamin therapy. The significance of the mtDNA mutations is unclear. In the 2 LHON patients, manifestation of the disease may have been precipitated by nutritional deficiency. Patients with poor recovery or further deterioration should be evaluated for other factors, including poor vitamin therapy compliance and alternative diagnoses.
Assuntos
Surtos de Doenças , Doenças do Nervo Óptico/epidemiologia , Doenças do Sistema Nervoso Periférico/epidemiologia , Adulto , Estudos de Coortes , Percepção de Cores/efeitos dos fármacos , Cuba , DNA Mitocondrial/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Exame Neurológico , Atrofias Ópticas Hereditárias/tratamento farmacológico , Atrofias Ópticas Hereditárias/genética , Atrofias Ópticas Hereditárias/fisiopatologia , Doenças do Nervo Óptico/complicações , Doenças do Nervo Óptico/tratamento farmacológico , Doenças do Sistema Nervoso Periférico/complicações , Doenças do Sistema Nervoso Periférico/tratamento farmacológico , Resultado do Tratamento , Acuidade Visual/efeitos dos fármacos , Vitaminas/uso terapêuticoRESUMO
Since October 1991, nearly 51,000 Cubans have been afflicted in an outbreak of optic and peripheral neuropathies. To begin an investigation of the possible role of mitochondrial DNA (mtDNA) mutations in the outbreak, we studied mtDNA from 14 affected and two unaffected Cubans for the 12 mutations associated with Leber's hereditary optic neuropathy. Eleven probands (12 patients) had optic neuropathy and two had peripheral neuropathy only. We also studied two unaffected relatives of one proband. We identified two mtDNA mutations, at nucleotides 11778 and 3460, in two of the 11 probands with optic neuropathy. Although this data set is too small to reach statistically valid conclusions, it does suggest that mtDNA mutations might be contributing to the outbreak of optic neuropathy in Cuba.