Chronic progressive external ophthalmoplegia Bilateral ptosis without diplopia is seen in chronic progressive external ophthalmoplegia (CPEO). Ptosis & diplopia are presenting symptoms in approx 50% of patients of Myasthenia gravis, & subsequently develop in 96% of patient during the course of the disorder. In thyroid-associated ophthalmopathy, proptosis & lid retraction is found. Pseudoptosis may be observed if contralateral lid retraction is present. Ptosis may occur if levator dehiscence is present b/o inflammation. Diplopia can occur in 5-10% of patients b/o severe muscle swelling . Multiple cranial nerve palsies as in cavernous sinus syndrome & orbital apex syndrome, present with diplopia along with ophthalmoplegia & other symptoms. Chronic progressive external ophthalmoplegia (CPEO): CPEO is the most common feature of mitochondrial myopathy. It occurs in > 50% cases of all mitochondrial myopathies. Typical presentation is B/L ptosis without diplopia in early adulthood Ophthalmoplegia is usually symmetrical & slowly progressive so diplopia is not often a complaint because all eye movements are reduced equally. The progressive ophthalmoplegia is unnoticed till decreased ocular motility limits peripheral vision. Ciliary muscles & iris muscles are often unaffected by CPEO Other variable symptoms are: - Exercise intolerance - Cataract - Hearing loss - Sensory axonal neuropathy - Ataxia - Clinical depression - Hypogonadism - Parkinsonism Diagnosis is made by muscle biopsy. Muscle fibres stained with "Gomori trichrome stain" give rise to dark red staining of muscle fibres k/a "ragged red fibers" This is b/o accumulation of enlarged mitochondria. PCR of blood or muscle tissue can determine a mutation of the mt DNA. There is no definitive treatment for CPEO. Ptosis may be corrected with lid surgery. Experimental treatment with tetracycline & coenzyme Q10 has been used. Also know Kearns - Sayre Syndrome (KSS): Is mutiorgan system, mitochondrial disorder with a triad of - Onset before age 20 - CPEO - Pigmentary retinopathy plus one or more of the following - Cardiac conduction defects - CSF protein > 1.0 gm/1 or - Cerebellar ataxia