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POLIP is an acronym that stands for: Polyneuropathy, Ophthalmoplegia, Leukoencephalopathy, and Chronic Intestinal Pseudoobstruction and consider a mitochondrial myopathy characterized by a tetrad of progressive sensorimotor peripheral nerve disease. Other clinical features include myopathy, diffuse leukoencephalopathy, and ptosis.

Myoneuro-Gastrointestinal Encephalopathy Syndrome; MNGIE Syndrome.

Very rare; 33 patients up to 1997.

There were suggestions that this disorder is an autosomal recessive trait with pathology of the nuclear genome, probably involving the control of the mitochondrial DNA replication (multiple deletions of mitochondrial DNA). Sporadic cases were also reported. Recent report of the MNGIE (mitochondrial neurogastrointestinal encephalomyopathy) locus at 22q13.32qter.

The precise etiology and pathophysiologic significance of the mitochondrial DNA (mtDNA) deletions and the heterogeneity of the modifications of the mtDNA remain unknown. A mutation in the gene encoding thymidine phosphorylase possibly results in a defect of cytochrome c oxidase in liver and muscle.

MRI and CT scans are consistent with leukodystrophy involving the cerebral and cerebellar white matter. Histology shows widespread endoneurial fibrosis and demyelination in the peripheral nervous system. Muscle biopsy with histologic features of mitochondrial myopathy (ragged red fibers, muscle fibers with increased succinate dehydrogenase stain or ultrastructurally abnormal mitochondria). Biochemical examination of the liver and muscle tissues reveals defect of cytochrome c oxidase (complex IV of the respiratory chain). Nerve conduction and electromyographic (EMG) studies are compatible with a sensorimotor neuropathy; quantitative EMG may show a myogenic process. Southern blot analysis reveals multiple deletions of mtDNA.

Symptoms begin before age of 20 years. The first signs are gastrointestinal symptoms (recurrent nausea, vomiting, or diarrhea with intestinal dysmotility) in the majority of cases, or an ophthalmoparesis in some cases. The neurologic manifestations are predominantly outside the central nervous system (CNS); gastrointestinal (GI) dysmotility is a result of severe visceral neuropathy. Gastrostomy or jejunostomy tube feeding may fail because of dysmotility. Malabsorption with intermittent diarrhea and chronic malnutrition ensues. Parenteral alimentation is often necessary. Lactic acidosis after moderate glucose loads may occur. Prokinetic agents, including erythromycin and cisapride, are unsuccessful in improving intestinal motility. Visual disturbances may manifest as blepharoptosis and ophthalmoparesis. Proximal muscle weakness and mild ataxia is common. Neurosensory hearing loss, proximal myopathy with marked muscle atrophy, polyneuropathy, and encephalopathy (with hypodense areas in the white matter on MRI examination) are present. In addition, there also may be an autonomic neuropathy. Electrocardiography may show cardiac conduction abnormalities. Respiratory function may be severely affected. The prognosis is poor because of a severe weight loss bordering on cachexia, with a mean survival age of 28.5 years. The prognosis seems to be worsened by a young age of onset.

The diagnosis of mitochondrial disease should be considered in any child with a multisystem neurological disorder or who is being investigated for hypotonia. Anesthesia-related morbidity and mortality risk is essentially linked to the preoperative status of the child, that is, the number and extent ...

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