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A 60-year-old man presented to the emergency department (ED) with progressive dysarthria and confusion over the prior 24 hours. In the last month, his wife states that her husband complained of episodic headaches that occasionally were associated with nausea. On examination, he was obtunded and moaning to painful stimulation. He had a left gaze preference, but localized equally with his arms and legs. The tone in his legs was increased with bilateral upgoing toes. His noncontrast head computed tomographic (CT) scan (Figure 13-1) performed in the ED revealed a left frontal lesion with mass effect and midline shift. He was admitted to the neurologic intensive care unit (NeuroICU, NICU) for further evaluation and management.

Figure 13-1.

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, this patient's wife states that over the last 2 weeks he had been more forgetful, with fluctuating irritability that would last anywhere from minutes to hours. She denies any rhythmic jerking of his arms or legs or loss of consciousness. There had been no evidence of incontinence or tongue biting. Upon arrival in the NICU, a magnetic resonance image (MRI) with and without gadolinium was performed, and he was subsequently connected to continuous electroencephalographic (cEEG) monitoring (Figure 13-2).

Figure 13-2.

Magnetic resonance imaging showed a heterogeneously enhancing lesion in the left frontal lobe with mass effect. The diagnosis of high-grade glioma was suspected, steroids were started, and neurosurgery was consulted. Continued electroencephalographic monitoring was initiated, and a representative page is shown below.

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 intra-rater 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 it is limited to surface EEG monitoring), has great temporal resolution, and allows assessment of neuronal activity.

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