Clinical and neuroimaging features of osmotic demyelination syndrome

Objective To investigate the clinical features and neuroimaging features of patients with osmotic demyelination syndrome (ODS).Methods The clinical features and examination results ,including the clinical manifestations,the data of cranial MRI/CT,changes of EEG,treatment and prognosis,were analyzed in 4 patients with ODS.Results All the 4 patients had the history of hyponatraemia.The common clinical manifestations included psychiatric disorder,altered consciousness,dysphasia,dysphagia,quadriplegia and dystonia.Severe transient abnormal EEG was found in these patients,and all the brain CT scanning and CSF were negative.MRI features could only be noted 10 d after the appearing of clinical manifestations and all the first time MRI was negative in these 4 patients.Four patients were diagnosed as having extrapontine myelinolysis,showing symmetrical low T1-weighted signal and high T2-weighted signal within the pons,the basal ganglia,the thalami,the insular cortex and the hippocampal head.Three patients were also diagnosed as having central pontine myelinolysis,showing symmetrical T1 low signal and T2 high signal in the basilar part of pons; much clear imaging could be noted with the help of weighing the abnormal signals.Three patients got improvement with 1 having dystonia sequel.Conclusion ODS is correlated with chronic hyponatraemia,and both hypokalaemia and hypochloremia may be the 2 possible triggers; when they appear,quick correction is not needed.MRI features may be significantly delayed,thus,repeated imaging study is necessary. Key words: Osmotic demyelination syndrome; Central pontine myelinolysis; Extrapontine myelinolysis;  Hyponatraemia;  Magnetic resonance imaging