eMedicine Specialties > Emergency Medicine > Neurology
Delirium, Dementia, and Amnesia: Differential Diagnoses & Workup
Updated: Dec 15, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
Workup
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
- 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.
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.
- 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 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.
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.5
Procedures
- CSF evaluation is indicated to rule out SAH not seen on a CT scan. Approximately 5% are missed on CT scan, particularly 12 hours or more from the time of symptom onset.
- CSF evaluation is essential when bacterial or viral encephalitis or meningitis is a consideration.
More on Delirium, Dementia, and Amnesia |
| Overview: Delirium, Dementia, and Amnesia |
 Differential Diagnoses & Workup: Delirium, Dementia, and Amnesia |
| Treatment & Medication: Delirium, Dementia, and Amnesia |
| Follow-up: Delirium, Dementia, and Amnesia |
| Multimedia: Delirium, Dementia, and Amnesia |
| References |
| « Previous Page | Next Page » |
References
Han JH, Morandi A, Ely W, et al. Delirium in the nursing home patients seen in the emergency department. J Am Geriatr Soc. May 2009;57(5):889-94. [Medline].
Mitchell SL, Teno JM, Kiely DK, et al. The clinical course of advanced dementia. N Engl J Med. Oct 15 2009;361(16):1529-38. [Medline].
[Guideline] Folstein MF, Folstein SE, McHugh PR. "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. Nov 1975;12(3):189-98. [Medline].
Berli R, Hutter A, Waespe W, Bachli EB. Transient global amnesia - not so rare after all. Swiss Med Wkly. May 16 2009;139(19-20):288-92. [Medline].
Blood Test Takes Step Toward Predicting Alzheimer's Risk. October 15, 2007. Science Daily. Available at http://www.sciencedaily.com/releases/2007/10/071014163700.htm.
Bennett DA, Whitmer RA. NSAID exposure and risk of Alzheimer disease: is timing everything?. Neurology. Jun 2 2009;72(22):1884-5. [Medline].
Breitner JC, Haneuse SJ, Walker R, et al. Risk of dementia and AD with prior exposure to NSAIDs in an elderly community-based cohort. Neurology. Jun 2 2009;72(22):1899-905. [Medline].
Filson S. 12th international conference on Alzheimer's disease. Part 1. 11-16 July 2009, Vienna, Austria. IDrugs. Sep 2009;12(9):535-6. [Medline].
American College of Emergency Physicians. Clinical policy for the initial approach to patients presenting with altered mental status. Ann Emerg Med. Feb 1999;33(2):251-81. [Medline].
American Psychiatric Association. Mental disorders due to a general medical condition. In: Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), Fourth Edition. Washington, DC: American Psychiatric Association; 1994:165-74.
American Psychiatric Association. Delirium, dementia, and amnestic and other cognitive disorders. In: Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), Fourth Edition. Washington, DC: American Psychiatric Association; 1994:123-63.
Bair BD. Frequently missed diagnosis in geriatric psychiatry. Psychiatr Clin North Am. Dec 1998;21(4):941-71, viii. [Medline].
Cassem EH. Behavioral and emotional disturbances. In: Wilson J, Braunwald E, Isselbacher KJ, eds. Harrison's Principles of Internal Medicine. 12th ed. New York, NY: McGraw-Hill; 1991:183-93.
de la Torre JC. Is Alzheimer's disease a neurodegenerative or a vascular disorder? Data, dogma, and dialectics. Lancet Neurol. Mar 2004;3(3):184-90. [Medline].
Dziedzic L, Brady WJ, Lindsay R, Huff JS. The use of the mini-mental status examination in the ED evaluation of the elderly. Am J Emerg Med. Nov 1998;16(7):686-9. [Medline].
Esteban-Santillan C, Praditsuwan R, Ueda H, Geldmacher DS. Clock drawing test in very mild Alzheimer's disease. J Am Geriatr Soc. Oct 1998;46(10):1266-9. [Medline].
Geldmacher DS, Whitehouse PJ. Evaluation of dementia. N Engl J Med. Aug 1 1996;335(5):330-6. [Medline].
Hebert LE, Scherr PA, McCann JJ, et al. Is the risk of developing Alzheimer's disease greater for women than for men?. Am J Epidemiol. Jan 15 2001;153(2):132-6. [Medline].
Howarth DF, Heath JM, Snope FC. Beyond the Folstein: dementia in primary care. Prim Care. Jun 1999;26(2):299-314. [Medline].
Jick H, Zornberg GL, Jick SS, et al. Statins and the risk of dementia. Lancet. Nov 11 2000;356(9242):1627-31. [Medline].
Kumar. Pick disease. In: Robbins and Cotran: Pathologic Basis of Disease. 7th ed. 2005:1390.
Lagomasino I, Daly R, Stoudemire A. Medical assessment of patients presenting with psychiatric symptoms in the emergency setting. Psychiatr Clin North Am. Dec 1999;22(4):819-50, viii-ix. [Medline].
Locke WC. Thought and affective disorders. In: Rosen P, Barkin R, eds. Emergency Medicine: Concepts and Clinical Practice. 3rd ed. St Louis, Mo: Mosby; 1998:2074-6.
Luchsinger JA, Mayeux R. Dietary factors and Alzheimer's disease. Lancet Neurol. Oct 2004;3(10):579-87. [Medline].
McDowell I. Alzheimer's disease: insights from epidemiology. Aging (Milano). Jun 2001;13(3):143-62. [Medline].
Olson SC, Rund DA. Behavioral disorders: clinical features. In: Tintinalli JE, Krome RL, Ruiz E, eds. Emergency Medicine: A Comprehensive Study Guide. 3rd ed. New York, NY: McGraw-Hill; 1992:1068-9.
Palmer RM. Common clinical disorders in geriatric patients: intellectual failure. In: Dale DC, Federman DD, eds. Scientific American Medicine. New York, NY: Scientific American Inc; 1992.
Roses AD. Alzheimer's disease and the dementias. In: Dale DC, Federman DD, eds. Scientific American Medicine. New York, NY: Scientific American Inc; 1997.
Smith J. Organic brain syndrome. In: Rosen P, Barkin R, eds. Emergency Medicine: Concepts and Clinical Practice. 3rd ed. St Louis, Mo: Mosby; 1992:1766-86.
Sullivan SC, Richards KC. Predictors of circadian sleep-wake rhythm maintenance in elders with dementia. Aging Ment Health. Mar 2004;8(2):143-52. [Medline].
Tong DC, Grossman M. What causes transient global amnesia? New insights from DWI. Neurology. Jun 22 2004;62(12):2154-5. [Medline].
Yee B, Chang F. Altered mental status: is that good or bad. Resid Staff Physician. 1997;43(7):64-6.
Further Reading
Keywords
delirium, dementia, amnesia, acute confusional state, mental status change, organic brain syndrome, OBS, altered mental status, confusion, Alzheimer's disease, Alzheimer disease, treatment, diagnosis, symptoms
