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. Author manuscript; available in PMC: 2021 Nov 15.
Published in final edited form as: Epileptic Disord. 2021 Apr 1;23(2):435–436. doi: 10.1684/epd.2021.1272

Generalized periodic discharges with triphasic morphology: to treat or not to treat?

Fábio A Nascimento 1, Patrick M Chen 1, Joseph Cohen 1, Brandon M Westover 1
PMCID: PMC8592021  NIHMSID: NIHMS1753254  PMID: 33926861

We report an 82-year-old woman with recurring episodes of confusion, a left posterior fossa meningioma, and chronic hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion (SIADH). She presented with a habitual episode of confusion. Basic laboratory workup was unremarkable except for hyponatremia (132 mEq/L sodium); head imaging was unrevealing. Continuous EEG showed 2-Hz generalized periodic discharges (GPDs) with triphasic morphology, or “triphasic waves” (figure 1A). Her EEG and mental status improved following 1 mg of lorazepam suggesting non-convulsive status epilepticus (NCSE).

Figure 1.

Figure 1.

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EEG: pre-lorazepam trial (A), and 10 minutes following the lorazepam trial (B). Sensitivity: 10 mV/mm; LF: 1 Hz; HF: 70 Hz; notch: 60 Hz; timebase: 15 mm/second. (A) Bipolar montage showing 100 mV 2 Hz generalized periodic discharges with triphasic morphology. (B) Bipolar montage showing diffuse irregular 50 mV delta slowing of the background, excessive beta frequency activity, and resolution of generalized periodic discharges.

Although traditionally associated with toxic metabolic infectious encephalopathies, GPDs with triphasic morphology may be associated with NCSE. Select patients should therefore undergo a trial with antiseizure medication to assess for electroclinical improvement [1, 2]. Importantly, electrographic improvement alone does not imply a diagnosis of NCSE [3].

Footnotes

Supplementary data.

Summary didactic slides are available on the www.epilepticdisorders.com website.

Disclosures.

F. Nascimento is a member of the Epileptic Disorders Editorial Board. P. Chen, J. Cohen, and B. Westover report no disclosures relevant to the manuscript.

References

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