Introduction:Rhabdomyolysis results from many causes including hypernatremia. Postpartum hypernatremia with osmotic cerebral demyelination is a rare cause of reversible rhabdomyolysis. Electromyographic studies in postpartum hypernatremia have not been reported.Materials and Methods:Electromyography (EMG) was performed in five women with postpartum hypernatremia and muscle biopsy was performed in one of them.Results:Among the five women presenting with postpartum hypernatremia associated with marked elevation of serum creatine kinase, four had quadriparesis. All had varying degrees of encephalopathy at admission and recovered without residual deficits after gradual correction of hypernatremia. Needle EMG revealed fibrillations with positive sharp waves in five patients and myotonic discharges in three patients. Serial EMG in one patient revealed the occurrence of transient fibrillations, positive sharp waves and myotonic discharges. Muscle biopsy revealed extensive rhabdomyolysis in one patient.Conclusion:EMG in hypernatremic rhabdomyolysis revealed spontaneous activity including fibrillations, positive sharp waves and myotonic discharges along with myopathic potentials. Electromyographic findings depend on the interval from the onset and the degree of rhabdomyolysis.

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