What are unusual locations for arterial hemorrhage?

Unusual Locations of Arterial Hemorrhage

Arterial hemorrhage can occur in several unusual locations beyond the common sites, including intranidal aneurysms, flow-related aneurysms, and various locations associated with arteriovenous malformations (AVMs), which require prompt recognition for effective management. 1

Classification of Unusual Arterial Hemorrhage Locations

Aneurysm-Related Unusual Locations

• Nidal aneurysms: Contiguous with the vascular mass of brain arteriovenous malformations (BAVMs), these aneurysms may extend past the margin of the measured BAVM mass 1

• Flow-related aneurysms: Located on pathways carrying nonnutritive blood flow supplying the BAVM shunt 1

  • Proximal flow-related aneurysms: Located on vessels or branch points of the circle of Willis or proximal to it (internal carotid arteries, anterior and posterior communicating arteries, first portions of anterior or posterior cerebral arteries, basilar arteries, or vertebral arteries) 1
  • Distal flow-related aneurysms: Located beyond the circle of Willis 1

• Non-flow-related aneurysms: Aneurysms not exposed to higher flow rates 1

Anatomical Unusual Locations

• Corpus callosum hemorrhages: Rare in subarachnoid hemorrhage, occurring in 67% of pericallosal artery aneurysm ruptures and only 2.5% of anterior communicating artery aneurysm ruptures 2

  • Supracallosal pattern: Blood extends into the anterodorsal aspect of the callosum and spreads posteriorly along its dorsal border 2

• Septum pellucidum hemorrhages: Confined to patients with anterior communicating artery aneurysms (30% of cases) 2

• Arterial pseudoaneurysms: Can occur in any anatomical zone following trauma, particularly in hemophilic patients after surgical procedures like arthroscopy or joint replacement 3

High-Risk Features of Unusual Arterial Hemorrhages

Concerning Imaging Features

• Heterogeneous densities within the hematoma 4
• Irregular margins of the hematoma 4
• Rapid expansion of the hematoma 4
• Signs of mass effect or neurological deterioration 4

Specific Risk Factors for Hemorrhage from AVMs

• Prior hemorrhage: Strong predictor of recurrent hemorrhage 1
• Small AVM size: May predict higher risk of hemorrhage 1
• Periventricular or intraventricular location: May be associated with increased risk 1
• Deep venous drainage: Predictor of presentation with hemorrhage 1
• Intranidal aneurysms: Important finding associated with hemorrhage risk 1
• Single draining vein: May contribute to higher hemorrhage risk 1
• Diffuse AVM morphology: Associated with increased hemorrhage risk 1

Diagnostic Approach for Unusual Arterial Hemorrhages

• CT/CT angiography: Essential for immediate detection of hemorrhage location and extent 1

  • Fisher Grading Scale can be used to assess subarachnoid hemorrhage severity 1

• MRI/MR angiography: Helpful for detecting subacute (1-6 weeks) or chronic (>6 weeks) hemorrhage 1

• Diagnostic catheter cerebral arteriography: Gold standard for detailed vascular assessment 1

• Duplex ultrasonography: Useful for diagnosing pseudoaneurysms 3

Management Considerations

• Serial imaging: Crucial for detecting hematoma expansion, particularly within the first 24 hours 4

• Blood pressure management: Aggressive crystalloid resuscitation with high blood pressure targets (MAP 80 mmHg) may increase hemorrhage volume and mortality in cases with vascular injury 5

• Endovascular techniques: Transcatheter embolization using coils is effective for treating life-threatening arterial hemorrhage in selected cases 6

• Surgical intervention: May be indicated for large hematomas with mass effect, particularly cerebellar hemorrhages >3 cm 7

Pitfalls to Avoid

• Delayed imaging: Can miss critical expansion periods, as most expansion occurs within the first few hours (38% of intracranial hemorrhages show ≥33% volume increase when scanned within 3 hours of onset) 4

• Overlooking anticoagulation status: Anticoagulation therapy significantly increases risk of hematoma expansion and prolongs the expansion period 4

• Underestimating small hematomas: Can lead to significant morbidity if they expand or are located in critical areas 4

• Missing associated aneurysms: Intranidal or saccular aneurysms are important findings that may increase hemorrhage risk 1