A 76-year-old woman is brought to the emergency department by her son with 2 days of intermittent confusion, daytime somnolence, and decreased oral intake. Her medical conditions include mild dementia, hypertension, and type 2 diabetes mellitus. The son says that the patient has been talking to people who are not there and wandering around the house in the middle of the night. She has no history of recent falls. Medications include valsartan and metformin. Temperature is 37.2 C (99 F), blood pressure is 100/60 mm Hg, and pulse is 100/min and regular. The patient is easily distracted and disoriented to time and place. Neck is supple. She can move all 4 extremities. Cardiopulmonary examination is normal. Abdomen is soft and nontender. Fingerstick glucose level is 155 mg/dL. Which of the following is the most appropriate next step in management?
Show Explanatory Sources
Mental status changes are commonly due to delirium; however, delirium is frequently under-recognized. The Confusion Assessment Method (CAM) improves delirium identification and differentiates it from other cognitive disturbances (eg, dementia, depression). The CAM assesses 4 fundamental features of delirium:
This patient has all 4 features (delirium diagnosis formally requires both features 1 and 2 plus either feature 3 or 4). Notably, in patients with preexisting cognitive deficits (eg, advanced age, dementia), delirium may be the only sign of acute illness (eg, afebrile, no dysuria). This patient also has hallucinations and sleep-wake reversal, which are common with delirium but not essential for diagnosis.
Delirium indicates acute brain failure and should be considered a medical emergency. Common causes of delirium include infection (eg, cystitis, pneumonia), adverse drug effects, dehydration, and electrolyte/metabolic disturbances. Initial evaluation includes a history and physical examination, medication review, complete blood count, metabolic panel, and urinalysis. This will identify most causes of delirium; however, advanced workup should follow any abnormal clinical findings or negative initial evaluation.
(Choices A and C) CT scan of the head is indicated in patients with altered mental status when history (eg, trauma, anticoagulation) or physical examination (eg, focal weakness, papilledema) suggests intracranial pathology. Lumbar puncture is typically used to diagnose meningitis or encephalitis. However, this patient has no concerning history, focal neurologic findings, fever, or meningismus, so more common delirium causes should be ruled out first. If initial workup is negative or treatment response is inadequate, neuroimaging and lumbar puncture should be considered.
(Choice B) Electroencephalogram (EEG) can identify occult seizures as the cause of altered mental status. Patients with a concerning history (eg, stroke, trauma, critical illness) or inadequate response to delirium treatment require EEG to rule out nonconvulsive seizures as a cause of delirium.
(Choice D) Ammonia is neurotoxic and elevated levels can cause delirium. Hyperammonemia most commonly results from acute or chronic liver failure (eg, cirrhosis), which would be evident on initial evaluation (eg, jaundice, aminotransferase elevation).
Educational objective:
Delirium is common but under-recognized. The Confusion Assessment Method improves delirium identification using its fundamental features of acute-onset, fluctuation, inattention, disorganized thinking, and altered consciousness. Initial evaluation is directed at the most common causes, but further assessment should follow any abnormal findings or negative initial evaluation.