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Neurology India, Vol. 53, No. 2, April-June, 2005, pp. 219-220 Case Report Parkinsonism and recovery in central and extrapontine myelinolysis Panagariya Ashok, Sureka R.K., Udainiya D.K. Department of Neurology, SMS Medical College and Hospital, Jaipur Correspondence Address: ‘Raj Niketan’, 7, Moti Doongri Road, Jaipur Date of Acceptance: 18-Feb-2005 Code Number: ni05068 ABSTRACT Central pontine myelinolysis is a demyelinating affection of central pons diagnosed on the basis of characteristic MRI finding in an appropriate clinical setting. The condition has been described as universally fatal; however, recent reports of recovery have been documented. We report a case of central pontine and extra pontine myelinolysis, which presented with parkinsonian features apart from bulbar symptoms and made a remarkable recovery. A short review of the literature follows.Keywords: Hyponatremia, central pontine myelinolysis, magnetic resonance imaging Central Pontine Myelinolysis (CPM) is a demyelinating disease that usually develops following rapid correction of hyponatremia from any cause. It was originally described in chronic alcoholics.[1] Other reported associations include malnourished status, renal failure, diabetes mellitus, and post-orthotopic liver transplantation.[2],[3] However, it can also occur in healthy persons with hyponatremia caused by gastroenteritis or diuretic therapy.[4],[5] Young children and adults of all ages can be affected.[6] The usual presentation is acute onset pseudobulbar palsy with spastic quadriparesis (′locked in′ syndrome). The condition was earlier described as fatal but recent reports have shown better outcomes. The prognosis is not influenced by the degree of hyponatremia, the size of lesion on MRI or the severity of neurological deficit at presentation. Patients have been reported to survive if the non-specific secondary complications of transient illness are avoided. Case Report DISCUSSION The clinical course of affected patients may be biphasic. Following clinical improvement from hyponatremic encephalopathy, a neurological syndrome caused by myelinolysis typically ensues 2 to 3 days after the correction of hyponatremia. This was the pattern in our case as well. Initial symptoms include mutism, dysarthria, lethargy and affective changes. Later, the classical symptoms of spastic quadriparesis and pseudobulbar palsy develop, reflecting damage to the corticospinal and corticobulbar tracts in the basis pontis. These symptoms may be observed in more than 90% of patients.[6] In our case, the patient had mutism and dysphagia, but had no quadriparesis or pseudobulbar features.Extrapontine involvement can present with various movement disorders such as ataxia, dystonia and parkinsonism.[3],[6] The reported patient also had EPM involving basal ganglia and the mid-brain which was responsible for masked facies, extra-pyramidal rigidity and rest tremors. Pathogenesis of myelinolysis and the reasons for vulnerability and predilection of particular brain regions to develop myelinolysis are not fully understood. Pathologically, myelin is destroyed but neurons and axons are typically spared. Classically, the central pons is involved, hence the original name of CPM. This entity is known to affect other areas, notably the thalami, basal ganglia, and cerebral or cerebellar gray-white junctions. The latter condition is termed EPM.[1] In both CPM and EPM, bilateral and symmetrical involvement is usually the rule.[1], [7], [8] MRI brain is superior to CT scan for the diagnosis of CPM and EPM. MRI brain shows characteristic T2 hyperintense signals in the central pons and basal ganglia bilaterally.[8] The initial images may be normal. The characteristic lesion on MRI appears up to 2 weeks after clinical presentation and involves the entire pons except for a rim of periphery. Radiological differentials include stroke, multiple sclerosis and brainstem glioma. There is no consistent correlation between the persistence of radiographic abnormalities and that of symptoms in surviving patients.[9] Treatment of myelinolysis is essentially supportive. Although CPM was once believed to be fatal with a survival rate of only 5-10% beyond 6 months, it is now clear that many patients indeed survive much longer.[4],[6] Myelinolysis itself cannot be specifically treated once it develops. The recovery might be due to increased synaptic plasticity leading to compensation or partly due to reversal of neurotransmitter block at the pontine level after resolution of vasogenic edema caused by osmotic endothelial injury and myelinotoxic factors. A number of treatments have been suggested over the years, for example plasmapharesis, IVIG, steroids, TRH, and reinstitution of hyponatremia but none have undergone clinical trials. A recent large case series documented that outcome does not depend upon the severity of neurological deficit at presentation or on concomitant internal disease including the degree of hyponatremia.[10] MRI findings did not have any prognostic significance. The survival depends upon the proper management and prevention of non-specific secondary complications of transient illness such as aspiration pneumonia, urinary tract infection, septicemia, deep vein thrombosis and pulmonary embolism. CONCLUSION CPM is a distinct condition with unique clinical presentations. Physicians should be aware of this entity while dealing with hyponatremic patients. MR imaging is the radiological modality of choice for the diagnosis. CPM is not a universally fatal disease now and long-term survival with proper supportive management has been recently reported.REFERENCES
Copyright 2005 - Neurology India The following images related to this document are available:Photo images[ni05068f1.jpg] |
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