Metabolic Encephalopathy in Intensive Care Unit

Abstract

Encephalopathy literally means disorder or disease of the brain. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of global brain dysfunction; this syndrome can be caused by many different illnesses. Metabolic encephalopathy can be defined as diffuse, multifocal and functional cerebral disturbances, which are not caused by inflammation, in other words, it is not encephalitis, and, at least in the beginning, is not combined with morphologic changes.

Metabolic encephalopathy is the most common cause of altered mental status in the intensive care unit (ICU) setting, either medical or surgical, (it isthe most common complication of many diseases in patients treated at (ICU) and their clinical manifestation can be taken as a warning of deterioration or beginning of organ dysfunction), and is also one of the most treatable, so; early recognition of it is critical to management of the ICU patient.

Metabolic encephalopathy is always suspected when there is an altered cognitive status in the absence of focal neurologic signs or an obvious anatomic lesion such as an acute cerebrovascular accident or head injury. A patient may progress over days from intermittent agitation into depressed consciousness or quickly into coma without any antecedent signs (e.g., hypoglycemia). In mild cases, it is easily mistaken for fatigue or psychogenic depression, whereas more severe cases may develop into coma and are life threatening

Metabolic encephalopathy is one of the most diverse in its clinical presentations and requires a systematic approach to define the etiology and to institute effective treatment. The features that distinguish most metabolic encephalopathies from structural lesions are (a) a nonfocal neurologic examination, (b) increased motor activity, (c) intact ocular and pupillary reflexes, and (d) laboratory abnormalities that support the clinical picture. Additional tests such as an EEG, head CT, or toxicology screen are useful in ruling out other possible causes.

One should keep in mind that many patients in the ICU have an underlying chronic encephalopathy due to long-standing illness. Therefore, they are more susceptible to minor metabolic perturbations induced by small doses of drugs, slight shifts of fluid balance, or worsening organ failure. Early recognition and correction of such factors improve the patient's prognosis for a full neurologic recovery. Toward this end, it is prudent to consult the neurologist before the complications of multiple treatments and further changes confound the clinical course.