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Patient: This 62 year old male suffered a left frontal-parietal Intracerebral Hemorrhage (ICH).

Monitored Data: The CNS Monitor was configured to display multiple channels of processed EEG, specifically Density Spectral Array (DSA).

Clinical Scenario:

  • The nurse caring for the patient noticed "spikes" in the DSA pattern, appearing consistently in the FP1 and F3 areas.
  • The patient was obtunded but not showing clinical signs of seizure activity.
  • Prompted by the nurse to check the patient's EEG, providers confirmed episodes of subclinical seizure consistent with the territory of the patient's injury.
  • Detection of the subclinical seizures allowed prompt treatment of the patient.

FIGURE 1: Using the CNS Monitor, providers detected subclinical seizures and promptly administered treatment to the patient.

Subclinical seizures


Displaying processed EEG, such as DSA, and correlated clinical data at the bedside facilitates timely interpretation, diagnosis, and treatment of patients with subclinical seizures.

A computer algorithm analyzes the frequency content of successive segments of multichannel EEG in real time, resulting in spectra/histograms of the power at each frequency present in the EEG segment. The DSA uses a color map to indicate the amount of power in a particular frequency band. DSA displays produce recognizable patterns that correlate with certain events, such as ischemia or seizures.1

DSA and other processed EEG trends may enable clinicians with varying levels of expertise to identify events that suggest seizure activity. A study conducted in 2015 demonstrated that ICU nurses, fellows, and residents could identify seizures with an acceptable level of accuracy by using digital EEG trend analysis after brief training. As a result, these clinicians could provide earlier notification to electrophysiologists, who may not be present in the ICU.2 While not definitive for seizures, bedside displays with DSA and correlated physiology alert caregivers to events that warrant further investigation.

In addition, pre-screening with compressed EEG data trends, such as DSA or CSA (Compressed Spectral Array), may accelerate review by experienced electroencephalographers.3 For instance, CSA-guided review can reduce cEEG review time by 78% with minimal loss of sensitivity compared to conventional review.4

Reference: Michelle Hill, RN. Ohio Health Riverside Methodist Hospital.

  1. Matta, B.F., Menon, D.K., Smith, M. (Eds). 2011. Core Topics in Neuroanaesthesia and Neurointensive Care, Cambridge University Press, New York.
  2. Dericioglu, N., et al. 2015. Non-expert use of quantitative EEG displays for seizure identification in the adult neuro-intensive care unit. Epilepsy Res 109: 48-56.
  3. Williamson, C. A., et al. (2014). "Sensitivity of compressed spectral arrays for detecting seizures in acutely ill adults." Neurocrit Care 20(1): 32-39.
  4. Moura LM, Shafi MM, Ng M, Pati S, Cash SS, Cole AJ, Hoch DB, Rosenthal ES, Westover MB. Spectrogram screening of adult EEGs is sensitive and efficient. Neurology. 2014 Jul 1;83(1):56-64. Epub 2014 May 23.