Chronic ophthalmoplegia is characterized by progressive weakness of ocular muscles and levator muscle of the upper eyelid. The condition is mainly manifested in adults. It may be totally and permanently isolated. However in a minority of cases it is associated with skeletal myopathy, which involves predominantly axial or proximal muscles and which causes abnormal fatigability and even permanent muscle weakness. In this case the affection is still termed isolated progressive external ophthalmoplegia. A large proportion of chronic ophthalmoplegias are associated with other symptoms, leading to the multisystemic pattern of this disease. Associated symptoms are very diverse: neurological signs (hearing loss, retinopathy, cerebellar disorders, peripheral neuropathy, etc.), endocrine (diabetes, hypogonadism, hypoparathyroidism, etc.), kidney (kidney failure, tubulopathy, etc.), and heart disorders (conduction disorders, myocardiopathy, etc.). Some symptom associations enable identification of syndromes featuring ophthalmoplegia, such as Kearns-Sayre or myoneurogastrointestinal encephalopathy (MNGIE). The causes of chronic ophthalmoplegia are multiple. Most of the affections are due to a mitochondrial disease but the cause of mitochondrial dysfunction is variable (point mutations, deletions of mitochondrial DNA, altered nuclear gene with effects on the mitochondrial DNA such as the thymidime phosphorylase in MNGIE). Other suggested etiologies are classical myastheny, oculopharyngeal dystrophy, and congenital myasthenic syndromes. All three affections result in isolated muscular manifestations without multisystemic defects, whereas mitochondrial disorders lead to both strictly muscular forms and generalized and multisystemic forms.
Last update: March 2004