E. Lee Murray, MD
OVERVIEW
Disorders of mental status are among the most common reasons for neurologic consultation, second only to stroke in most institutions. Mental status change may be the reason for admission, or it may develop during hospitalization. The terminology used to describe these states varies, and there is some overlap in terms:
•Confusional state is a disturbance of memory and other cognitive functions. Whereas dementia is characterized by confusion, the term confusional state generally refers to a more acute or subacute state.
•Dementia is progressive disturbance of cognitive function that can include memory, reasoning, language, and/or personality.
•Delirium is acute to subacute cognitive disturbance with neuropsychiatric manifestations, which may be hyperactive or hypoactive. This can be predisposed by advanced age, dementia, or sensory deprivation.
•Encephalopathy is cognitive disturbance that is usually acute to subacute. This term presumes an organic cause. Delirium can be a manifestation.
•Amnesia is loss of memory, which can be isolated or a component of a broader cognitive disturbance.
•Lethargy is decrease in response, drowsiness, and apathy.
•Persistent vegetative state is unawareness of self or the environment with relative preservation of brainstem function.
•Coma is unresponsiveness with no voluntary movement or behavior.
•Brain death is irreversible cessation of all brain functions. There are established clinical criteria for diagnosis (see Chapter 15).
Concerning hospitalized patients, studies have shown:
•Patients who develop altered mental status in the hospital have an increased likelihood of poor outcome and post-discharge dependence.1
•Patients who have cognitive deficits prior to hospitalization have a higher likelihood of complications.
•Patients with advanced age have a high incidence of cognitive impairment not recognized by providers.2
•Patients with cognitive deterioration are much more likely to die or be placed in a nursing home.
The distinction between delirium and encephalopathy is blurred. Many of us consider delirium to be a state of confusion with hyperactivity and perceptual difficulty, whereas encephalopathy refers to the disordered cognitive state with an organic basis, although it has broader range of semantic use.
DEMENTIA
Dementia is progressive cognitive decline that affects up to 10% of patients over the age of 65. Dementia is discussed in more depth in Chapter 18.
Most patients with dementia have a degenerative cause, with the largest proportion having Alzheimer’s disease (AD). Other important degenerative dementias include Parkinson disease with dementia (PDD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). Nondegenerative dementias include vascular dementia (VaD), normal pressure hydrocephalus (NPH), and chronic infections.
DLB and PDD are sometimes considered as a single entity since there are similarities in presentation, evaluation, and management.
Degenerative Dementias
Alzheimer’s disease (AD): This presents as progressive dementia with relative sparing of other functions early in the course. Diagnosis is suspected by absence of focal signs, behavior, language, or movement deficits. Neuropsych testing can show a specific pattern of deficit. Genetic testing and brain positron emission tomography (PET) are not very useful for nonresearch practice.
Frontotemporal dementia (FTD): This is a group of disorders with dementia associated with behavioral and/or language deficits early in the course. Magnetic resonance imaging (MRI) and computed tomography (CT) may show atrophy, particularly in frontal and temporal regions. Neuropsych testing is supportive. Genetic analysis may be helpful in cases with suspected family history.
Pick disease: This is essentially frontotemporal dementia with pathological findings of Pick bodies. FTD is the preferred term.
Corticobasal degeneration: This presents with Parkinson-like symptoms associated with corticospinal signs. Unilateral arm clumsiness; apraxia, often with rigidity; and bradykinesia are common. Alien-hand syndrome suggests this disorder. Dementia can occur but does not in all patients.
Parkinson’s disease with dementia: This is defined as Parkinsonism with dementia developing late in the course. Classically, for this diagnosis, the movement disorder precedes the dementia by at least a year.
Lewy body dementia: This is dementia and behavioral abnormalities with Parkinsonism, where the dementia develops either before or within 1 year of onset of motor symptoms.
Progressive supranuclear palsy (PSP): This is a combination of supranuclear ophthalmoplegia, pseudobulbar palsy, and axial dystonia. Stiffness and slowness can suggest parkinsonism initially. Dementia develops in many but is overshadowed by the motor symptoms.
Huntington disease: This presents with psychiatric symptoms, chorea, and ultimately dementia. Inheritance is autosomal dominant. Diagnosis is suspected by family history and early psychiatric symptoms before motor symptoms develop
Nondegenerative Dementias
Vascular dementia: Presents with dementia with history or signs of stroke or significant vascular risk factors. Cognitive disturbance has an onset which is often abrupt or stepwise. May develop with one or more multiple vascular events, ischemic or hemorrhagic (e.g., amyloid angiopathy).
Normal pressure hydrocephalus (NPH): The triad of dementia, ataxia, and urinary incontinence is often incomplete. Diagnosis is suspected when CT or MRI shows ventricles larger than expected from cortical atrophy.
B12 deficiency: Dementia may develop with associated signs of neuropathy or myelopathy.
Hypothyroidism: Confusion is common but usually subacute in onset and seldom confused with degenerative dementia.
Korsakoff psychosis: This presents with marked memory deficit with behavioral change. Occurrence is usually in the setting of previous Wernicke encephalopathy from ethanol.
Infectious Dementias
Creutzfeldt-Jakob disease (CJD): Diagnosis is suspected with dementia that progresses rapidly, often with psychotic features, and especially with motor manifestations of myoclonus, rigidity, and/or cerebellar ataxia. Familial or sporadic.
Neurosyphilis: Presents with dementia, myoclonus, psychiatric disturbance, and often Argyll-Robertson pupils.
HIV–AIDS dementia: Presentation is with subacute or chronic progression of dementia with motor manifestations including ataxia, tremor, corticospinal tract signs, and/or signs of myelopathy.
Differential Diagnosis
The most common causes of dementia, in order, are: Alzheimer’s disease, vascular dementia, and frontotemporal dementia. The other most common causes seen in practice are Parkinson disease with dementia and Lewy body dementia. Corticobasal degeneration is difficult to diagnose early in the course. The diagnosis is suspected when the patient presents later with parkinsonism and corticospinal signs (see Figure 5.1).
FIGURE 5.1 Flowchart for confusion
Frontotemporal dementia has subtypes, summarized as follows:
•Behavioral form of frontotemporal dementia: Early behavioral issues are often evident before a dementia, including disinhibition, apathy, and difficulty with interpersonal skills.
•Primary progressive aphasia: Language defect with expression affected out of proportion to reception. Dementia is evident later.
•Semantic dementia: Fluent aphasia, but the semantic defect gives prominent anomia. Reception is preserved initially.
CONFUSIONAL STATE
Confusional state often presents with a clinical picture of delirium and often with a history of pre-existing cognitive disturbance. Some of these patients have dementia, either diagnosed or undiagnosed. Delirium is distinct from dementia but is frequently coexistent. Delirium is associated with a disturbance of cognition and perception. Delirium can be hyperactive or hypoactive.3 Most cases are multifactorial.
Risk factors for hospital delirium include:
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