Encephalopathy and Delirium

1 Encephalopathy and Delirium


Catriona M. Harrop


Abstract


Encephalopathy is characterized by the National Institute of Neurological Disorders and Stroke as “any diffuse disease of the brain that alters brain function or structure,”1 and can be classified as acute or chronic. The definition, diagnosis, and treatment of encephalopathy is reviewed here, along with one of its most common symptoms, delirium.


Keywords: encephalopathy, delirium, confusion, agitation, arousability, Ramsay score, Riker score


1.1 Encephalopathy


1.1.1 Definition


The National Institute of Neurological Disorders and Stroke (NINDS) defines encephalopathy as “a term for any diffuse disease of the brain that alters brain function or structure”1 with the hallmark of encephalopathy being an altered mental state. Encephalopathy can be categorized by chronicity2:


Acute


Toxic: due to medications, illicit substances, or toxins


Metabolic: due to a metabolic disturbance


Toxic-metabolic: due to a combination of both


Chronic: characterized by a slowly progressive alteration in mental status resulting from permanent structural changes within the brain2


1.1.2 Causes of Encephalopathy3


See Table 1.1.


1.1.3 Diagnosis of Encephalopathy


Diagnosis is guided by the history and physical examination of the patient. It is considered on a case-by-case basis.


Laboratory testing


Serum electrolytes


Renal function


Glucose


Calcium


Complete blood count


Urinalysis


Hepatic function


Thyroid function


Drug levels (if applicable), i.e., phenytoin


Drugs of abuse screen


Vitamin levels—B-12, folate


Arterial blood gas


Imaging


Computed tomography (CT) of brain


Magnetic resonance imaging (MRI) of brain


Table 1.1 Common causes of encephalopathy
























Drugs and toxins


Idiopathic


Withdrawal states


Medication side effects


Poisons


Infections


Sepsis


Systemic infections


Fever


Metabolic derangements


Electrolytes


Endocrine disturbance


Hypercarbia


Hyperglycemia and hypoglycemia


Hyperosmolar and hypo-osmolar states


Hypoxemia


Inborn errors of metabolism


Nutritional


Brain disorders


CNS infection


Seizures


Head injury


Hypertensive encephalopathy


Psychiatric disorders


Systemic organ failure


Cardiac failure


Hematologic


Hepatic encephalopathy


Pulmonary disease


Renal failure


Abbreviation: CNS, central nervous system.


Evaluation for infections


Lumbar puncture


Blood cultures


Seizure evaluation


Electroencephalography (EEG)


1.1.4 Treatment of Encephalopathy


Acute encephalopathy


Based on treatment of the underlying pathophysiology, i.e., treatment of sepsis and hypothyroidism with the potential for reversal of encephalopathy.


Chronic encephalopathy


Often not amenable to treatment as the inciting insult has caused permanent brain changes, i.e., anoxic encephalopathy.


1.1.5 Relationship to Delirium


Delirium can be characterized as the symptom of the underlying abnormal brain function, i.e., encephalopathy.2


1.2 Delirium


Delirium is a common disorder in hospitalized patients that has significant societal and economic impact.4 In-hospital mortality rates reportedly associated with delirium range from 22 to 33%.5,6 Currently patients aged 65 years and older account for more than 48% of hospital care; therefore, the impact of delirium on hospitalized patients will continue to grow as our population ages.4


1.2.1 Definition


The Diagnostic and Statistical Manual of Mental Disorders (DSM) 5 defines delirium under Neurocognitive Disorders7 which encompasses “the group of disorders in which the primary clinical deficit is in cognitive function, and that are acquired rather than developmental.” The diagnostic criteria are as follows:


A disturbance in attention (i.e., reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment).


The disturbance develops over a short period of time (usually from hours to a few days), represents a change from baseline attention and awareness, and tends to fluctuate in severity during the course of a day.


An additional disturbance in cognition (e.g., memory deficit, disorientation, language, visuospatial ability, or perception).


The disturbances are not explained by another pre-existing, established, or evolving neurocognitive disorder and do not occur in the context of a severely reduced level of arousal, such as coma.


There is evidence from the history, physical examination, or laboratory findings that the disturbance is a direct physiologic consequence of another medical condition, substance intoxication or withdrawal (i.e., due to a drug of abuse or a medication), or exposure to a toxin, or is due to multiple etiologies.


As outlined in the DSM 5, Delirium can be further subdivided into:


Substance intoxication


Substance withdrawal


Medication induced


Another medical condition


Multiple etiologies


1.2.2 Duration of Symptoms


Acute: Lasting for a few hours or days


Persistent: Lasting for weeks or months


1.2.3 Level of Activity ( Table 1.2)


Hyperactive: The individual has a hyperactive level of psychomotor activity that may be accompanied by mood lability, agitation, and/or refusal to cooperate with medical care.


Hypoactive: The individual has a hypoactive level of psychomotor activity that may be accompanied by sluggishness and lethargy that approaches stupor.


Mixed level of activity: The individual has a normal level of psychomotor activity even though attention and awareness are disturbed. Also includes individuals whose activity level rapidly fluctuates.


Aug 7, 2022 | Posted by in NEUROSURGERY | Comments Off on Encephalopathy and Delirium

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