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Table 1 Clinical signs of hyponatremic encephalopathy and osmotic demyelination

From: Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremic encephalopathya Central pontine myelinolysis Extra-pontine myelinolysis
Mild hyponatremia Suggestive features Movement disorders
 Mild neurocognitive impairment  Quadriparesis/plegia  Extra-pyramidal syndrome
 Gait impairment  Ataxia  Dystonia
Moderate hyponatremia  Nystagmus  Choreoathetosis
 Headaches  Dysarthria  Myoclonus
 Nausea  Ophthalmoplegia  Opsoclonus
 Emesis  Dysphagia  Akinetic-rigid state
 Abdominal cramps  Pseudobulbar palsy  Akinetic mutism
Severe hyponatremia  “Locked-in” syndrome Other symptoms
 Restlessness Associated neurological features  Emotional lability
 Lethargy  Impaired consciousness  Depression
 Confusion  Wernicke’s encephalopathy  Paranoia
 Coma    Disinhibition
 Seizure   
  1. aNeurological manifestations according to the severity of hyponatremia which is itself correlated to the magnitude and the rapidity of the fall in PNa