Examination of the Patient With Altered Mental Status
GOAL
The main goal of the history and examination of the patient with an alteration in mental status is to look for evidence of whether the patient’s symptoms represent a diffuse encephalopathic process, a dementing illness, or a symptom of focal brain dysfunction.
PATHOPHYSIOLOGY OF ALTERED MENTAL STATUS
Mental status can be affected by disorders that affect the level of consciousness (alertness) or disorders that affect cognitive function (see Chapter 5, Approach to the Mental Status Examination).
Disorders of Level of Consciousness
The pathophysiology of changes in consciousness severe enough to cause coma are discussed in Chapter 42, Examination of the Comatose Patient. All of the same processes and mechanisms, either focal or diffuse, that can cause coma can also present as lesser degrees of altered consciousness. One common cause of disordered consciousness, manifested as an acute confusional state, is a toxic-metabolic encephalopathy, the neurologists’ term for delirium; this represents the severe altered mental status that can occur in the setting of a systemic illness or as a result of many metabolic or toxic disorders.
Disorders of Cognition
Dementias are neurologic illnesses that impair function in memory and at least one other aspect of cognitive function, such as judgment, personality, visualspatial ability, language, and abstract thinking. Causes of dementia include, among others, degenerative illnesses (e.g., Alzheimer’s disease, frontotemporal dementia, and Lewy body dementia), multiinfarct dementia, and Creutzfeldt-Jakob disease. Dementing illnesses, for the most part, affect cognitive function without impairing the level of consciousness. Cognitive function can also be affected by any focal neurologic process affecting cognitively important cortical regions.
TAKING THE HISTORY OF A PATIENT WITH AN ALTERED MENTAL STATUS
Depending on the severity of the illness, patients with an alteration in consciousness or cognition may or may not be able to provide much history or have insight into their dysfunction. In most cases, details of the history need to be obtained from family members (see Chapter 42, Examination of the Comatose Patient).
Ask about the time course of the change in mental status. An acute onset of altered mental status over seconds suggests an acute focal process, such as stroke affecting cognitive regions. A subacute onset over hours or days would be expected in most toxic-metabolic encephalopathies or many
structural processes. A chronic and progressive course over months or years would be expected in dementing illnesses (although Creutzfeldt-Jakob disease would be more rapid, and vascular dementia should have a step-wise course).
Ask about the details of the dysfunction. Lethargy or agitation (or both) would be expected in delirium; hallucinations (especially visual) may also be present. Patients with dementias usually present with recent memory impairment as their most prominent symptom or may have personality and behavioral changes, but they rarely have impairment in their level of consciousness, at least not early in their course.Related posts:
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