General Medical Information

Cognitive Impairment

David M. Barrs

Cognitive function or general mental status may decrease after surgery. Patients aged over 60 years or who have addictions to alcohol or drugs, major organ system disease, preexisting or family histories of psychosis, or even auditory or visual impairment are predisposed to perioperative cognitive impairment. Even a simple otologic procedure with a mastoid head dressing may prevent the use of hearing aids and glasses and add to disorientation. The entire hospital environment of sensory overload, sleep deprivation, anxiety, and pain contribute to disorientation and decreased cognitive function. Underlying medical conditions should be treated promptly, routine medications continued, excessive use of long-acting benzodiazepines (e.g., diazepam) avoided, and a comfortable hospital routine established.

An attempt should be made to classify the type of cognitive impairment. Delirium should be differentiated from dementia, depression, mania, and other organic brain disorders. Dementia is a clinical syndrome that has a protracted course and is characterized by loss of cognitive abilities, personality disorganization, and decreased ability to perform daily activities without disturbance of consciousness. It is usually present in the elderly (e.g., Alzheimer disease) with a presumed organic cause. Depression, mania, and other functional disorders (e.g., schizophrenia) are true psychiatric disorders. The otolaryngologist is more likely to see delirium, a transient organic mental disorder characterized by global impairment of cognitive functions and resulting from diffuse brain cell metabolic dysfunction. It is usually preceded by a lucid period of several days after surgery before the onset of symptoms. Restlessness, insomnia, irritability, frightening dreams, difficulty in thinking, disturbed consciousness, urinary incontinence, focal neurological signs, nystagmus, and loss of motor coordination all are seen in delirium. Causes of delirium can include drug intoxication, drug withdrawal, metabolic disturbances, acute cerebral disorders (e.g., stroke, transient ischemic attack), infections, hemodynamic disturbances (e.g., hypovolemia, congestive heart failure), respiratory disorders, nutritional and vitamin deficiencies, and trauma. Psychiatric consultation may be necessary to help differentiate the type of cognitive impairment and guide the discovery of underlying causes.

Communication with and management of the patient in delirium is difficult. Agitation is pronounced. Conservative therapy can include removal of known precipitating factors, orientation to the environment with special attention to the use of a hearing aid and glasses, and pain control. If reassurance is not sufficient, medications may be necessary.

A continuing search for an underlying cause or management of a known cause of delirium or agitation should be accomplished. The patient should be reassured constantly because the experience is terrifying for patients who fear “losing their mind.” The physician should watch for impending suicide and dangerous behavior, such as wandering.