Septic encephalopathy
Reviewed and revised 3 January 2016
OVERVIEW
- Septic encephalopathy is brain dysfunction mediated by the septic inflammatory response, independent of other co-existent causes such as liver or renal dysfunction
- up to 70% of patients with sepsis have some degree of encephalopathy
- sometimes known as sepsis-induced or sepsis-associated delirium
- a degree of long-lasting cognitive impairment is common following recovery from sepsis
DIAGNOSIS
- requires recognition of brain dysfunction in the setting of sepsis, through clinical, biochemical or electrophysiological methods
- no universally agreed diagnostic criteria
- in practice the detection of delirium using tools such as CAM-ICU in patients with sepsis is a pragmatic approach
- EEG is more sensitive that clinical criteria alone
- Brain imaging (MRI/CT) may show non-specific findings such as cerebral infarction, leukoencephalopathy, and vascular edema
- Biochemical markers (e.g. S100 beta and neuron-specific enolase or NSE) have not been shown to be reliable and have clinical role at present
PATHOPHYSIOLOGY
The mechanisms underlying septic encephalopathy are poorly understood.
Proposed mechanisms involve:
- oxidative stress
- cytokines and pro-inflammatory factors
- altered blood brain barrier permeability
- altered levels of CSF and serum amino acids
- endothelial dysfunction
- changes in cerebral circulation
- emboli of microvessels
Leading to:
- altered synthesis and secretion of neurotransmitters
- degeneration of neurons in various areas of the nervous system
CLINICAL FEATURES
- hyperactive or hypoactive delirium
- often manifests before the onset of other organ dysfunction
- this can be clinically important, sub-clinical encephalopathy may be identified by family members as the patient being “not quite right” even thought abnormalities are not obvious to the bedside clinician
- may progress to coma
- other features such as anorexia, malaise, myoclonus and asterixis may be present
- seizures (general or focal) uncommonly occur
MANAGEMENT
- no specific therapy exists
- manage delirium, seizure and coma
- seek and treat underlying cause and complications of sepsis
PROGNOSIS
- 45% of sepsis survivors have cognitive impairment at 1 year
- cognitive impairment may persist for years
- up to 58% of sepsis survivors have long-term symptoms of depression and/or anxiety
- delirium is associated with increased mortality in ICU patients
References and links
LITFL
Journal articles
- Ebersoldt M, Sharshar T, Annane D. Sepsis-associated delirium. Intensive care medicine. 33(6):941-50. 2007. [pubmed]
- Flierl MA, Rittirsch D, Huber-Lang MS, Stahel PF. Pathophysiology of septic encephalopathy–an unsolved puzzle. Critical care. 14(3):165. 2010. [pubmed] [free full text]
- Ziaja M. Septic encephalopathy. Current neurology and neuroscience reports. 13(10):383. 2013. [pubmed] [free full text]
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
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