Delirium, Dementia, and Amnesia in Emergency Medicine Workup

  • Author: Paul S Gerstein, MD; Chief Editor: Pamela L Dyne, MD   more...
 
Updated: Apr 22, 2011
 

Laboratory Studies

Laboratory studies may be helpful for ruling in or ruling out specific diagnoses that cause delirium or a dementialike presentation. Many of these tests may not be immediately available to the ED physician, such as vitamin B-12 levels, Venereal Disease Research Laboratory (VDRL) test, and thyroid function studies.

Oxygen saturation and, in some cases, ABG with a carbon monoxide level are helpful. CBC count, electrolytes level, blood glucose level, BUN level, and creatinine level should be checked. In older patients, consider vitamin B-12 and folate levels. Consider calcium level, magnesium level, and liver function tests (LFTs), including serum ammonia, prothrombin time (PT), and activated partial thromboplastin time (aPTT). Consider VDRL and/or fluorescent treponemal antibody absorption (FTA-ABS) test to help rule out neurosyphilis (see cerebrospinal fluid [CSF] studies below). Urinalysis is also indicated.

When alcohol, drugs, and/or toxins are suspected, consider the following:

  • Serum ethanol, salicylate, acetaminophen, carbon monoxide, and other specific drug or toxin levels as indicated
  • Comprehensive drug analyses of blood and urine
  • Such toxic screens are generally not helpful in the acute setting unless turnaround time is rapid.

In a suspected endocrine emergency, the following are required:

  • A bedside fingerstick blood glucose determination followed by serum glucose and serum acetone
  • Thyroid-stimulation hormone (TSH), possibly thyroid panel
  • Serum cortisol
  • Serum calcium, phosphorus, and parathyroid levels

In suspected CNS infection, the following may be ordered:

  • Lumbar puncture may be done for CSF studies, including cryptococcal antigen or India ink prep, and VDRL.
  • CT scan of head should be done before lumbar puncture to rule out toxoplasmosis or abscess, especially in patients with HIV who present with headache.
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Imaging Studies

A head CT scan without intravenous (IV) contrast should be obtained if CNS infection, trauma, or a cerebral vascular accident (CVA) is suspected. A CT scan is excellent for detecting acute hematomas and most subarachnoid hemorrhages (SAH) but is most accurate early in the course. Follow-up lumbar puncture may be needed to rule out SAH.

One study found a high prevalence (41%) of abnormal CT scan findings in patients with AMS in the ED. Eight clinical predictors were significantly associated with an abnormal scan, including diastolic blood pressure of more than 80 mm Hg, focal weakness, a Glasgow Coma Score of less than 15, antiplatelet use, upgoing plantar response, headache, anticoagulant use, and dilated pupils.[6]

Although not typically part of the workup in the ED, a brain MRI may be considered if readily available and the need confirmed by neurologist and/or radiologist. MRI helps distinguish between Alzheimer disease and vascular causes of dementia. The MRI may show subtle signs of stroke missed on CT and is the imaging modality of choice for multiple sclerosis. An example of MRI in a patient with moderate Alzheimer disease is shown in the image below.

Coronal T1-weighted MRI scan in a patient with modCoronal T1-weighted MRI scan in a patient with moderate Alzheimer disease. Brain image reveals hippocampal atrophy, especially on the right side.

Plain abdominal radiographs may reveal swallowed bags that contain drugs of abuse ("body packing") or radiodense substances such as iron tablets.

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Other Tests

An ECG may be performed to search for myocardial infarction or atrial fibrillation with rapid ventricular response. Low voltages, as seen in hypothyroidism and pericardial effusion, may give a clue to the etiology. Look for tachycardia, widened QRS, or prolonged QT interval, which suggest tricyclic overdose.

A postmortem examination of the brain is currently the only way to positively diagnose the various dementing illnesses.

A blood test for apolipoprotein E (ApoE) subtype e4 is still under study, but it promises to greatly enhance diagnostic accuracy for AD.

Researchers at the Stanford University School of Medicine have recently developed a blood test that may be a step toward predicting AD 2-6 years in advance of onset. The test identifies changes in certain blood proteins that cells use to convey messages to one another and has a 90% positive predictive value.[7]

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Procedures

Lumbar puncture to obtain CSF for analysis should be considered in certain circumstances, including the following:

  • To rule out SAH not seen on CT scan
  • To diagnose CNS infections such as encephalitis or meningitis
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Contributor Information and Disclosures
Author

Paul S Gerstein, MD  Attending Physician, Emergency Department, Baystate Mary Lane Hospital

Paul S Gerstein, MD is a member of the following medical societies: American Academy of Emergency Medicine and Massachusetts Medical Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Eric M Kardon, MD, FACEP  Attending Emergency Physician, Georgia Emergency Medicine Specialists; Physician, Division of Emergency Medicine, Athens Regional Medical Center

Eric M Kardon, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

J Stephen Huff, MD  Associate Professor of Emergency Medicine and Neurology, Department of Emergency Medicine, University of Virginia School of Medicine

J Stephen Huff, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Neurology, American College of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

John D Halamka, MD, MS  Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center

John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Pamela L Dyne, MD  Professor of Clinical Medicine/Emergency Medicine, University of California, Los Angeles, David Geffen School of Medicine; Attending Physician, Department of Emergency Medicine, Olive View-UCLA Medical Center

Pamela L Dyne, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

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Coronal T1-weighted MRI scan in a patient with moderate Alzheimer disease. Brain image reveals hippocampal atrophy, especially on the right side.
 
 
 
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