A 60-year-old man presents to the emergency department with progressive dysarthria and confusion over the prior 24 hours. His wife states that in the past month her husband complained of episodic headaches that occasionally were associated with nausea. On examination, he is obtunded and moaning to painful stimulation. He has a left gaze preference, but localizes equally with his arms and legs. The tone in his legs is increased with bilateral upgoing toes. His noncontrast head computed tomography (CT) reveals a left frontal lesion with mass effect and midline shift (Figure 15-1). He is admitted to the neurologic intensive care unit (NeuroICU) for further evaluation and management.
Noncontrast head CT with left frontal lesion with mass effect and midline shift.
Does his head CT explain the mental status?
There is a mismatch between the neurologic examination and imaging findings; therefore, alternate causes for altered mental status must be explored. The frontal left hypodensity with a surrounding hyperdensity should not account for such a degree of obtundation. Depending on the clinical scenario, this may take the form of obtaining further history or diagnostic tests.
Upon further questioning, his wife states that over the last 2 weeks he has been more forgetful, with fluctuating irritability that lasts anywhere from minutes to hours. She denies any rhythmic jerking of his arms or legs or loss of consciousness, incontinence, or tongue biting. Upon arrival to the NeuroICU, magnetic resonance imaging (MRI) with and without gadolinium is performed, and he is subsequently connected to continuous electroencephalographic (cEEG) monitoring (Figure 15-2).
A. MRI showing a heterogeneously enhancing lesion in the left frontal lobe with mass effect. The diagnosis of high-grade glioma is suspected, steroids are started, and neurosurgery is consulted. B. Continuous EEG monitoring was initiated, and a representative page is shown.
When can cEEG monitoring be helpful in the ICU setting?
The goal of neuromonitoring is to identify secondary brain injury as early as possible and prevent permanent injury by triggering timely interventions. Ideally, such monitoring should be highly sensitive and specific, noninvasive, widely available, and relatively inexpensive; pose no risks to patients; have high inter- and intrarater reliability; and have good temporal and spatial resolution. Limitations of cEEG monitoring include high cost, vulnerability to artifact and medications, poor spatial resolution, and poor inter- and intra-rater reliability. On the other hand, it is noninvasive (as long as limited to surface EEG monitoring), has great temporal resolution, and allows assessment of neuronal activity.
Applications of cEEG in the ICU
To rule out subclinical or nonconvulsive ...