Acute kidney injury after brain injury: does it exist?

Area of Science:

• Nephrology
• Neurology
• Critical Care Medicine

Background:

• Acute kidney injury (AKI) is a common complication following neurological insults, affecting approximately 10% of patients with traumatic brain injury (TBI) or cerebrovascular disease.
• AKI in this setting is associated with increased mortality and poorer neurological outcomes.
• The interplay between brain injury and kidney function is complex, with several contributing factors identified.

Purpose of the Study:

• To review the epidemiology of AKI after brain injury.
• To examine the potential mechanisms underlying the causal relationship between brain and kidney injury.
• To elucidate the brain-kidney crosstalk in the context of neurological insults.

Main Methods:

• Literature review of studies on AKI following TBI and stroke.
• Analysis of epidemiological data on AKI incidence in brain-injured patients.
• Examination of proposed neuro-endocrine, inflammatory, and direct neural pathways involved in brain-kidney interactions.

Main Results:

• AKI incidence approaches 10% in TBI and stroke patients.
• Potential contributing factors include intravascular volume depletion, increased intra-abdominal pressure, rhabdomyolysis, sepsis, age, and cardiovascular comorbidities.
• Neuro-endocrine pathways (sympathetic system, RAAS, glucocorticoids) and systemic inflammation are implicated in AKI development post-brain injury.

Conclusions:

• A strong rationale supports a causal link between brain injury and AKI.
• Cerebral lesions can trigger neuro-endocrine dysregulation and systemic inflammation, impairing renal autoregulation and leading to AKI.
• Understanding these mechanisms is crucial for improving outcomes in patients with concurrent brain and kidney injury.