Anesthesia for Geriatric Patients - Anesthesia Care for Patients with Aging-Related Diseases

Disorders of the Central Nervous System

Disorders of the Central Nervous System

  1. Delirium is a transient disorder of cognition and consciousness characterized by an acute onset and fluctuating course.
    1. Symptoms may include agitation, somnolence, social withdrawal, and psychosis.
    2. The Confusion Assessment Method (CAM) algorithm, developed in 1990, is widely utilized to determine the presence of delirium in human patients. CAM consists of four clinical criteria: (1) acute onset and fluctuating course, (2) inattention, (3) disorganized thinking, and (4) altered level of consciousness. For delirium to be defined by this algorithm, both the first and the second criteria have to be present, plus either the third and/or the fourth criterion.
    3. Risk factors include advanced age, underlying dementia, use of psychoactive drugs, and perioperative hypoxia, hypercarbia, and sepsis.
    4. Common precipitants include psychoactive drugs (anticholinergics, benzodiazepines, and barbiturates), infection, stroke, MI, electrolyte abnormalities, drug withdrawal, and urinary retention.
    5. The focus is on treating any underlying disorder, encouraging interaction with family members, encouraging normal sleep–wake cycles, and avoiding restraints, if possible. Haloperidol (PO or IM) may be used for control of acute agitation.
  2. Dementia is a persistent and progressive impairment of cognition that interferes with activities of daily living.
    1. Alzheimer disease is the most common cause of dementia in the elderly and affects 30% to 50% of people by age 85.
      1. Pathogenesis is thought to be related to the aberrant production and deposition of A β peptide, the dominant component of neuritic plaques. The pathologic hallmarks of the disease include neurofibrillary tangles, neuritic plaques, neuronal thread protein, and marked cortical atrophy with ventricular enlargement.
      2. Current treatment includes cholinesterase inhibitors such as donepezil, tacrine, and rivastigmine and the NMDA antagonist memantine.
      3. Anesthetic considerations include avoiding preoperative sedation and centrally acting anticholinergic agents. Hypoxia and hypercapnia should also be avoided.
    2. Other causes of dementia include Pick disease, vascular dementia, Parkinson disease, normal pressure hydrocephalus, and Creutzfeldt-Jakob disease.
  3. Parkinson disease is a degenerative neurologic disorder characterized by tremor, bradykinesia, rigidity, and postural instability.
    1. Pathogenesis is due to the degeneration of dopaminergic neurons of the substantia nigra and a reduction in striatal dopamine content.
    2. About 10% to 15% of patients with Parkinson disease develop dementia.
    3. Treatment is directed at controlling symptoms and includes levodopa, anticholinergics, dopamine agonists, amantadine, and type B monoamine oxidase inhibitors.
    4. Anesthetic considerations
      1. Antiparkinsonian medications should be continued perioperatively because of the short half-life of levodopa.
      2. Phenothiazines, butyrophenones, and metoclopramide should be avoided as they may exacerbate symptoms as a consequence of their antidopaminergic activity.
      3. Anticholinergics and antihistamines may be used for acute exacerbations.
      4. Patients may have pharyngeal and laryngeal muscle dysfunction putting them at higher risk for airway obstruction, laryngospasm, and aspiration. One should consider a rapid sequence induction with cricoid pressure in these. Response to depolarizing and nondepolarizing muscle relaxants is normal.
      5. Hemodynamic instability may occur with induction of anesthesia, especially in patients receiving long-term levodopa therapy. Invasive arterial blood pressure monitoring may be warranted.
      6. Cardiac irritability may increase the risk for dysrhythmias. Ketamine and local anesthetics with epinephrine should be used cautiously.

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