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Kearns-Sayre Syndrome (KSS) is a mitochondrial encephalomyopathy characterized
by progressive external ophthalmoplegia, atypical retinitis pigmentosa, and
cardiomyopathy.
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Chronic Progressive External Ophthalmoplegia (CPEO) with
Myopathy; CPEO with Ragged-Red Fibers; Progressive
External Ophthalmoplegia with Ragged-Red Fibers; Kearns Syndrome; Kearns-Sayre
Mitochondrial Cytopathy; Kearns-Sayre-Shy-Daroff Syndrome; Ophthalmoplegia
Pigmentary Degeneration of Retina and Cardiomyopathy Syndrome;
Oculo-Cranio-Somatic Syndrome; Ophthalmoplegia Plus Syndrome; Barnard-Scholz Syndrome.
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The combination of ophthalmoplegia and retinal degeneration was first described by the
two American ophthalmologists R.I. Barnard and R.O. Scholz in 1944; however, the
syndrome now bears the names of the two Americans Thomas P. Kearns, a neuroophthalmologist, and George P.
Sayre, an ophthalmologist, who published their findings in two patients in 1958.
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Approximately 300 cases have been reported. No sex or race
predilection.
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Mitochondrial (deletions in mitochondrial DNA). Incidence of affected children
is dependent upon maternal mutant load. Mitochondrial DNA encodes proteins that
are part of the respiratory chain complexes.
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In vitro studies of mitochondrial metabolism have
identified defects in the respiratory chain and in the oxidative
phosphorylation system. These defects are responsible for the elevated
levels of serum lactate found during and after exercise.
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Clinical and laboratory confirmation of elevated
pyruvate and lactate. Light microscopy reveals “ragged-red muscle fibers,”
which are caused by the presence of abnormal mitochondria. Electron
microscopy demonstrates clusters of cells filled with abnormally enlarged
mitochondria (paracrystalline inclusions). The biochemical defect often appears
segmental on histochemistry.
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KSS is a multiorgan disease characterized by the clinical triad of a chronic,
progressive, external ophthalmoplegia, retinal pigment degeneration (with progressive
loss of vision), and onset before the age of 20 years. Significant other clinical findings
may include increased levels of protein in the cerebrospinal fluid, dementia,
encephalopathy, cerebellar ataxia, bulbar weakness (dysphagia, which may also be related
to cricopharyngeal achalasia), electroencephalographic anomalies (including seizures),
sensorineural hearing loss, corneal anomalies (with increased risk of spontaneous
perforation), but also cardiac anomalies (e.g., high-degree atrioventricular heart blocks,
QT prolongation with the risk of sudden death, dilated cardiomyopathy, mitral valve
prolapse, congestive heart failure), endocrine anomalies (hypogonadism, short stature due
to growth hormone deficiency, hyperaldosteronism, diabetes mellitus, hypoparathyroidism,
hypothyroidism), renal tubular acidosis, and myopathy with weakness. The clinical spectrum
is related to the proportion of normal and mutant DNA.
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Due to the fact that KSS may affect many organ systems, a thorough review of the patient
history and the actual clinical findings is necessary. Special attention has to focus on
the cardiac, endocrine, and renal issues (check electrolytes and acid-base balance). Also
assess the degree of muscle weakness to decide if postoperative mechanical ventilation may
be required.
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Mental retardation, loss of vision and hearing may affect patient
cooperation. Sedative premedication and/or the presence of the primary caregiver for
induction of anesthesia may be helpful.
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The major anesthetic complication is sudden third-degree atrioventricular block. The
patient should therefore be closely monitored at all times ...