Vol. 2Case report

The practice of EEG monitoring in
Neurointensive CareIntroduction
With the rapid spread of the concept of Neurointensive Care in recent years, intensivists and emergency
physicians around the world have become more conscious of the importance of EEG monitoring. In order toprovide information about EEG monitoring that will be useful in clinical practice, we will introduce reports fromdoctors representing each field on the practical implementation and challenges of EEG monitoring at facilities
practicing Neurointensive Care.

The significance of EEG monitoring in ICU
Yasuhiro Norisue, M.D.

Director of Department of Emergency Medicine and Critical Care Medicine,Tokyo Bay Urayasu Ichikawa Medical Center

The purposes and applications of EEG monitoring in Neurointensive Care
The patient conditions for which EEG monitoring is used in our intensive care unit (ICU), listed in descending order,
are altered mental status with unknown cause, neurological prognostication of post-cardiac arrest syndrome (PCAS),
new-onset refractory resistant status epilepticus (NORSE) with suspected encephalitis, seizure after traumatic brain
injury (TBI) and cerebrovascular accidents, status epilepticus in patients with known history of epilepsy, and myoclonus
with unknown causes. The main purposes we use EEG monitoring for are detection of non-convulsive status epilepticus(NCSE), evaluation of response to anticonvulsive treatments and neurological prognostication. The most common reason
to start EEG monitoring for possible NCSE in our hospital is a “Discrepancy between neurological findings and images
such as CT / MRI or clinical history”. In such cases, EEG provides the most important diagnostic information, and may
also prevent unfavorable neurological outcomes resulting from untreated NCSE. Although our ICU does not specialize
only in Neurointensive Care, the use of EEG monitoring is increasing year by year with a current average of 5 to 10 cases
per month in our 14-bed ICU.

The actual practice, workflow and challenges of EEG monitoring
Previously, we had to call the physiology lab and order EEG with a full montage, which was not designed for monitoring of ICU patients. As a result, there were many practical problems such as unavailability at night and interferingwith nursing care due to the large number of electrodes. Therefore, we tried a simple form of EEG monitoring with 2 channels in which waveforms could be seen at bedside monitors. However, the clinical significance of this simple EEG
monitoring was limited because it was not possible to exclude NCSE, as a result of low sensitivity due to too few
electrodes. After the new 6 to 8-channel headband and wireless type headsets became commercially available, conducting
EEG monitoring with decent enough sensitivity to rule out clinically significant NCSE has become much easier in ourICU (*1). In order to display and record EEG waveforms obtained by the headband and wireless type headsets, we have
two choices; either a video-EEG device which is designed for full EEG monitoring, or a device to connect the bedsidemonitors (the EEG waveforms can be seen along with the other routine parameters and waveforms such as EKG, heart
rate and arterial blood pressure) in case the only video-EEG device is being used somewhere else in the ICU. Althoughdisplaying and recording EEG waveforms on bedside monitors has disadvantages, such as the low waveform resolutionand impossibility of completely distinguishing artifacts, especially those caused by nursing care, from true epileptic
discharges simply by reviewing the recorded waveforms without use of a video camera, it is still useful for patients who“may be having NCSE right now”. Because it is not uncommon to have multiple patients with possible NCSE at the sametime, the patients with higher probability of NCSE have priority on the full video-EEG monitoring in our ICU.
Continue to the backThe significance of EEG monitoring in ICU

The duration of EEG monitoring to rule out NCSE is around 24 hours, depending on the case. In order to detect
NCSE, we pay attention not only to EEG waveforms but also to changes in heart rate, blood pressure, respiratory rate,and subtle movements of the facial muscles and limbs. The EEG monitoring may be continued for several days oreven several weeks to monitor therapeutic responses to treatments and recurrence of NCSE, especially when sedatives
are titrated down.
We do not expect nurses or junior residents to learn terminology for EEG-specialists to describe EEG waveforms.
Instead, they are expected to use our simple algorithm sheet in which one of the instructions is “Call attending
physicians or fellows if EEG waveforms look like sinus tachycardia” for example.
Because of the nature of an ICU, false epileptic EEG waveforms are very common due to frequent noise fromvarious devices such as ventilators as well as from the provision of nursing care. The only way to solve the problem isusing EEG-video monitoring to retrospectively conf irm the patient environment synchronously. In addition to theexpensive full video-EEG, EEG monitoring in Neurointensive Care would be further enhanced if the EEG waveforms
recorded in the bedside monitors could be reviewed with a simultaneous video image.
(*1) : The headbands and headsets can be easily applied by nurses or physicians.

Case reports<Case 1>62 yo male was brought to the emergency room with altered mental status after sudden onset of headache. Head CTand MRA confirmed subarachnoid hemorrhage (SAH) of Fisher grade II and an aneurysm at anterior communicatingartery. The patient underwent clipping of the aneurysm and was transferred to our ICU. However, he remained comatosewith GCS of E1 VT M2 even on the next morning without any sedation. The “Discrepancy between the CT image andneurological findings” triggered us to start continuous EEG monitoring, which showed rhythmic delta activities
interrupted by rhythmic sharp waves at 4 / sec in all the 6 channels. He was deeply sedated with propofol and was started
on levetiracetam as NCSE. His mental status improved by gradually titrating down propofol while confirming that there
were no significant epileptic discharges using EEG monitoring.
<Case 2>67 yo male with a PMH of post-stroke epilepsy was hospitalized with fluctuating mental status and muscle jerks in
the left upper extremity. The head CT was normal. He continued to have intermittent altered mental status even withincreased antiepileptic medications for probable epilepsy in the general ward. He finally became comatose and was transferred to our ICU. We immediately started EEG monitoring and did not find any epileptic waves. Chart review revealed
that he had anisocoria with dilated right pupil and relatively low blood pressure whenever he had an impaired level ofconsciousness as recorded by the ward nurses. MRI and MRA of the brain was obtained for possible “hemodynamic-dependent midbrain ischemia”, which showed significant narrowing of right vertebral artery in MRA and mild
ischemia of the right cerebellum and midbrain in DWI. The patient underwent emergency endovascular treatment for theright vertebral artery. Unfortunately, the patient died because reperfusion of the right vertebral artery could not beobtained and the brain stem ischemia progressed.

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SP67-0028 ’17. 10. SE. a.