Secondary Logo

Journal Logo

Institutional members access full text with Ovid®

Stimulus-Induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDs)

Johnson, Emily L.; Kaplan, Peter W.; Ritzl, Eva K.

Journal of Clinical Neurophysiology: May 2018 - Volume 35 - Issue 3 - p 229–233
doi: 10.1097/WNP.0000000000000434
Invited Review

Summary: Stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) are a relatively common phenomenon found on prolonged electroencephalogram (EEG) monitoring that captures state changes and stimulation of critically ill patients. Common causes include hypoxic injury, traumatic brain injury, and hemorrhage, as well as toxic-metabolic disturbances. Some studies have shown an association between SIRPIDs and the presence of spontaneous electrographic seizures. Although the degree to which SIRPIDs should be treated with antiepileptic medications is unknown, the rare cases of functional imaging obtained in patients with SIRPIDs have not shown an increase in cerebral blood flow to suggest an active ictal process. Stimulus-induced rhythmic, periodic, or ictal discharges may reflect dysregulation of thalamo-cortical projections into abnormal or hyperexcitable cortex.

Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland.

Address correspondence and reprint requests to Emily L. Johnson, MD, Department of Neurology, Johns Hopkins School of Medicine, Johns Hopkins Bayview 301 Mason Lord Drive, 2nd floor Baltimore, MD 21224; e-mail:

The authors have no funding or conflicts of interest to disclose.

© 2018 by the American Clinical Neurophysiology Society