What EEG findings are characteristic of hyponatremic encephalopathy?

Updated: Oct 09, 2019
  • Author: Eli S Neiman, DO, FACN; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Hyponatremic encephalopathy

Usually, nonspecific slowing is observed in hyponatremic encephalopathy. A variety of other patterns have been described: triphasic waves (TWs); burst of high-voltage rhythmic delta; central, high-voltage, 5- to 7-Hz rhythm; and sensory stimulation-induced, high-voltage delta activity. Epileptic activity is very rare, even in cases of clinical seizure.

Kameda et al reported a case of frontal intermittent delta activity (FIRDA) in the EEG of a patient with pituitary adenoma, hyponatremic encephalopathy, and major depression. The pituitary adenoma is thought to be a major factor for FIRDA in this case. Complicating factors included diffuse encephalopathy and use of antipsychotic drugs; FIRDA remained in the EEG after these factors diminished. The size of the pituitary adenoma that was proposed to be associated with FIRDA in the EEG recording was not noted. FIRDA may be associated with a small pituitary adenoma less than 10 mm in size. [63]


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