Question of the Week

For October 11, 2016

An 81-year-old woman with a history of Alzheimer disease is admitted for an exacerbation of chronic obstructive pulmonary disease and is treated with levofloxacin and intravenous methylprednisolone.

She is fully oriented at admission, but the following day, she is only intermittently lucid, with periods where she suddenly stares into space, does not respond to verbal or tactile stimuli, and exhibits lip-smacking behaviors. These episodes appear stereotyped and are followed by lethargy. They continue to persist despite frequent reorientation and other efforts to prevent delirium, including minimizing the use of restraints, discontinuing the use of a Foley catheter, ensuring adequate sleep hygiene, and minimizing psychoactive medications. Outside of these episodes, the patient is talkative and at her baseline level of orientation. No tonic-clonic movements have been noted.

The patient has a heart rate of 90 beats per minute, a blood pressure of 126/82 mm Hg, a temperature of 36.9°C, and an oxygen saturation of 95% on 3 liters of oxygen per minute via nasal cannula.

Which one of the following tests would be most helpful in confirming the specific cause of this patient's episodic alteration in mental status?

Urine culture
Complete blood count
Folstein Mini–Mental State Examination
Electroencephalogram
Examination of cerebrospinal fluid

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