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Kearns-Sayre Syndrome — SCE Neurology MCQ

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HardNeurogeneticsKearns-Sayre SyndromeSCE Neurology

A 70-year-old man presents with bilateral ptosis that is not fatigable. He has bilateral symmetric limitation of eye movements in all directions. Pupils are normal. He has a proximal myopathy. Muscle biopsy shows ragged red fibres. He is found to have bilateral pigmentary retinopathy and cardiac conduction defects (complete heart block requiring a pacemaker). Serum lactate is elevated. What syndrome does he have?

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Correct answer: C — Kearns-Sayre syndrome

Kearns-Sayre syndrome (KSS) is a mitochondrial disorder defined by the triad of: (1) onset before age 20 (though can present later), (2) progressive external ophthalmoplegia (PEO), and (3) pigmentary retinopathy, PLUS at least one of: cardiac conduction defect, CSF protein >100 mg/dL, or cerebellar ataxia. Ragged red fibres on biopsy and elevated lactate confirm mitochondrial myopathy. Cardiac monitoring is essential as heart block can be fatal. A: MG has fatigable weakness and normal biopsy. C: OPMD has PABPN1 mutations without retinopathy. D: DM1 has myotonia. E: Miller Fisher has areflexia and ataxia.

Reference: ABN Mitochondrial Disease Guidelines; EFNS Mitochondrial Myopathy Guidelines