The Massachusetts General Hospital Handbook of Neurology

Authors: Flaherty, Alice W.; Rost, Natalia S.

Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition

Copyright 2007 Lippincott Williams & Wilkins

> Table of Contents > Adult Neurology > Encephalopathy, Delirium, and Dementia

Encephalopathy, Delirium, and Dementia

A. See also

Metabolic, Toxic, and Deficiency Disorders, p. 69.

B. Management of agitation

• 1. Acute: See Psychiatric emergencies, p. 97.

• 2. Chronic: Risperidone (less sedating) or quetiapine (less risk of movement disorder). Although both have black box warnings in the elderly, there are few humane alternatives. Orally disintegrating or depo formulations for pts who cheek pills.

C. Delirium

Agitated confusion, usually with the implication of acute metabolic cause. Usually slurred speech, often frank hallucinations, motor signs (tremor, myoclonus, asterixis), rarely seizures.

• 1. DDx: Hypoxia, hypercapnia, electrolytes, glucose, drug overdose or withdrawal, sepsis, meningitis, encephalitis, high ammonia, uremia, Wernicke's syndrome. Consider also depression, psychosis, thyroid storm, transient global amnesia, nonconvulsive status epilepticus, posterior leukoencephalopathy.

• 2. Tests: Consider head CT, ABG, EKG, electrolytes, BUN, Cr, Ca, ammonia, toxin screen, CBC, ESR, U/A and other infectious workup, LP, EEG.

D. Encephalopathy

Nonspecific term for diffuse brain dysfunction, often from systemic process, that is not a classic dementia.

• 1. Reversible causes of subacute or chronic encephalopathy:

  • a. The big two: Addiction (p. 102), pseudodementia of depression/anxiety (p. 104). Ask family members as well as pt. if their mouth says no but their eyes say yes; contact them in private later.

  • b. Others: Bilateral SDH, NPH, vasculitis, lymphoma, metabolic, tumor (especially falx meningioma), thyroid, B₁₂, thiamine, infection (especially HIV, syphilis, fungal).

• 2. Creutzfeldt-Jakob dz (CJD): Sporadic, acquired (e.g., bovine spongiform encephalopathy, BSE), or familial buildup of prion protein particles.

  • a. H&P: Variable combinations of myoclonus, dementia, and ataxia; progresses to death in weeks to 2 yrs. BSE more often begins with psychiatric symptoms.

  • b. Incidence: Peaks in late 60s for sporadic form, about age 30 for BSE.

  • c. Tests: Brain biopsy shows spongiform encephalopathy. EEG shows diffuse periodic sharps. MRI shows characteristic DWI changes in the caudate, putamen, and cortical ribbon. CSF has 14-3-3 protein (also high in encephalitis and some gliomas). Brain biopsy shows spongiform encephalopathy.

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  • d. Precautions: CJD is transmissible only when infected neural tissue contacts an open wound. However, the agent is not inactivated by standard sterilization techniques.

E. Dementia

Chronic selective loss of 2 higher cortical functions, especially memory and naming. Pt. may be disoriented acutely at night, but frank hallucinations are rare.

• 1. H&P: Education, baseline personality, ADLs, falls, incontinence, drug changes, h/o depression. Check primitive reflexes. See also Mini-Mental Status Exam, p. 98.

• 2. Tests: Head CT, CHEM10, CBC, VDRL, ESR, TSH, B₁₂. Consider HIV test, LP, EEG, heavy metal screen, brain biopsy.

• 3. Potentially reversible causes: See Encephalopathy, above.

• 4. Normal pressure hydrocephalus (NPH):

  • a. H&P: Frontal gait, incontinence (from abulia or not being able to get to bathroom), dementia (frontal, abulic, vs. Alzheimer's type). No headache or papilledema

  • b. Tests: Serial large-volume LPs (not perfectly sensitive, pt can need up to 3 mo of VP shunt before improving). Consider ICP monitor 48 h to look for plateau waves (V or A). Consider trial of levodopa to rule out Parkinson's dz.

  • c. Rx of NPH: Ventriculoperitoneal shunt. Gait apraxia responds best; dementia worst, especially if longstanding. Risk of SDH (vessels already stretched by atrophy).

• 5. Irreversible causes:

  • a. Alzheimer's dz (AD): Usually with triad of aphasia, apraxia, agnosia.

  • b. Lewy body dz: More episodic delirium, psychiatric features (visual hallucinations, depression), and extrapyramidal features than AD. May benefit from low-dose levodopa or a dopamine agonist in combination with an atypical neuroleptic (e.g., quetiapine). Avoid typical neuroleptics.

  • c. Frontotemporal dementia (A tauopathy, formerly Pick's disease): More personality change, less aphasia or amnesia than AD.

  • d. Cortical vs. subcortical dementia: Latter is more manageable because pt has insight, can use cueing and to-do lists. Often associated with executive dysfunction.

    Table 8. Cortical vs. subcortical dementia.
    Subcortical Cortical Examples Basal ganglia dz Alzheimer's dz Language Normal Impaired Memory Bad retrieval Bad encoding Memory cues Cues help Cues do not help Processing speed Slow Normal Insight Normal Impaired Basic motor skills Slow, clumsy Normal Ideomotor skills Normal Impaired

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  • e. Mixed: Lewy body disease, Multi-infarct dementia, CJD, MS.

  • f. Rx: Social services, treat depression (avoid TCAs), neuroleptics such as haloperidol (see Delirium above re black box warnings), or short-acting benzodiazepines for agitation. Consider donepezil (a cholinergic agonist) or memantine (an NMDA antagonist).