What is the medical term for septic embolism to the brain?

Cerebral Septic Embolism: Medical Terminology and Clinical Implications

The medical term for septic embolism to the brain is "cerebral septic embolism" or "septic cerebral embolism." This condition occurs when infected material travels through the bloodstream and lodges in cerebral blood vessels, causing both ischemic damage and infectious complications.

Pathophysiology and Causes

• Cerebral septic emboli most commonly result from hematogenous spread, typically originating from infective endocarditis (IE), where septic microemboli travel to the vasa vasorum or lodge at distal branching points in cerebral vessels 1
• The predominant cerebral insult from septic emboli is ischemic stroke, but may also include intracerebral hemorrhage (either subarachnoid or subdural), infectious aneurysm, brain abscess, and rarely meningitis 1
• Most common causative organisms are Staphylococcus aureus and viridans group streptococci, though other pathogens like enterococci, coagulase-negative staphylococci, and HACEK group organisms can also cause cerebral septic emboli 1

Clinical Presentation

• Up to 40% of patients with infective endocarditis present with clinically evident neurological sequelae, but brain MRI studies have identified embolic lesions in as many as 60-80% of IE patients 1
• Patients may initially present with symptoms of ischemic stroke in the territory of the occluded vessel, though such strokes can be clinically silent depending on the brain region affected 1
• Other clinical manifestations include:
  • Focal neurological deficits 1
  • Altered mental status 2
  • Headache, especially severe and unremitting 1
  • Seizures 1
  • Meningeal signs if rupture into the meninges occurs 1

Complications of Cerebral Septic Emboli

• Mycotic (infectious) aneurysms occur in 2-4% of IE cases but may be more common due to asymptomatic presentations 1
• These aneurysms are typically thin-walled and friable with a high tendency to rupture and hemorrhage 1
• Unlike congenital berry aneurysms, the size of infectious cerebral mycotic aneurysms is not a reliable predictor of rupture risk 1
• Cerebral septic emboli represent two simultaneous insults: the early embolic/ischemic damage due to vascular occlusion and the infectious insult from a deep-seated infection 3

Diagnosis

• Brain imaging is mandatory for any suspicion of neurological complications in patients with IE or other risk factors for septic emboli 1
• MRI with gadolinium contrast offers higher sensitivity than CT in detecting cerebral lesions and may influence clinical management 1, 4
• In patients with sepsis who develop altered mental status with normal coagulation profiles, positive blood cultures, and absent signs of multiorgan failure, cerebral septic emboli should be considered 2
• Vascular imaging (CT angiography or conventional angiography) should be performed to identify potential mycotic aneurysms in patients with neurological symptoms 1

Management

• Prompt diagnosis and initiation of appropriate antimicrobial therapy are crucial for preventing first or recurrent neurological complications 1
• For patients with IE and silent cerebral embolism or transient ischemic attack, cardiac surgery (if indicated) should be performed without delay 1
• After an intracerebral hemorrhage, cardiac surgery should generally be postponed for at least one month 1
• Neurosurgical or endovascular treatment is recommended for large, expanding, or ruptured intracranial infectious aneurysms 1
• In patients with mechanical heart valves and embolic stroke, anticoagulation should be discontinued for at least two weeks of antibiotic treatment to prevent hemorrhagic transformation 4

Prognosis

• Cerebral embolic events pose an independent risk factor for mortality in IE, even when subclinical 1
• Early diagnosis and intensive therapy can facilitate significant regression of neurologic deficits in some cases 5
• Patients with neurological complications tend to have higher morbidity and mortality compared to those without such complications 4

Clinical Pearls and Pitfalls

• Always consider cerebral septic emboli in patients with known ongoing infectious processes who develop altered mental status or focal neurological deficits 2
• While CT can reveal macrobleeds, MRI is more sensitive in confirming cerebral microbleeds and should be considered in septic patients with unexplained altered sensorium 2
• The risk of embolism in IE is highest during the first 2 weeks of antibiotic therapy and is clearly related to the size and mobility of the vegetation 1
• Cerebral septic emboli can occur in the absence of infective endocarditis, such as in cases of bacteremia without valvular involvement 6