Can bridging veins be torn in subarachnoid hemorrhage and subdural hematoma?

Can Bridging Veins Be Torn in Subarachnoid Hemorrhage and Subdural Hematoma?

Bridging veins can be torn in both conditions, but the mechanism and clinical significance differ fundamentally: in subdural hematoma, bridging vein rupture is the primary cause of bleeding, while in subarachnoid hemorrhage, bridging vein injury is an iatrogenic surgical complication rather than part of the disease pathophysiology.

Bridging Veins in Subdural Hematoma

Bridging vein rupture is the defining pathophysiologic mechanism of subdural hematoma. 1

• Bridging veins run as short, straight bridges between the brain surface and the superior sagittal sinus in the subdural compartment 1
• Subdural bleeding occurs when acceleration/deceleration, rotational, and shearing forces cause rupture of these bridging veins 1
• Demonstration of bridging vein rupture at autopsy allows unequivocal diagnosis of a traumatic mechanism 1
• In spontaneous intracranial hypotension (SIH), brain sag from CSF leakage can cause tearing of bridging veins, producing subdural hematomas 2
• The American College of Radiology recommends non-contrast CT as the primary imaging modality for acute subdural hematomas 3

Bridging Veins in Subarachnoid Hemorrhage

In aneurysmal subarachnoid hemorrhage, bridging veins are NOT torn as part of the primary hemorrhage—they are at risk only during surgical intervention. 4, 5

Iatrogenic Surgical Risk

• When operating on anterior communicating artery aneurysms through the interhemispheric approach during acute SAH, sacrifice of bridging veins during surgery causes venous infarction in 47.8% of cases 6
• In contrast, only 5.9% of patients whose bridging veins were preserved during surgery developed cerebral edema 6
• The correlation between sacrifice of bridging veins and venous infarction is statistically significant (p < 0.025) 6
• This complication occurs more frequently when surgery is performed in the acute stage (within 11 days of SAH) 6

Primary SAH Pathophysiology

• The American Heart Association guidelines for aneurysmal SAH management make no mention of bridging vein rupture as part of the primary hemorrhage mechanism 4
• Aneurysmal SAH results from rupture of saccular aneurysms, with blood entering the subarachnoid space directly 4, 5
• The recommended treatment is securing the ruptured aneurysm via endovascular coiling or neurosurgical clipping 4, 5

Critical Clinical Distinction

The key pitfall is confusing the mechanism: subdural hematoma FROM bridging vein rupture versus subarachnoid hemorrhage WITH potential bridging vein injury during surgery. 1, 6

• If both subdural and subarachnoid hemorrhage coexist from trauma, this represents combined injury patterns with bridging vein rupture causing the subdural component 7
• Rare cases of cavernous sinus dural arteriovenous shunts can present with both SAH and subdural hematoma from rupture of engorged cortical veins, not bridging veins 8
• For combined acute subdural and subarachnoid hemorrhage from trauma, early VTE prophylaxis (≤48 hours) reduces thromboembolic complications without increasing need for delayed craniectomy 7

Surgical Implications

When performing surgery for aneurysmal SAH, preservation of bridging veins is essential to prevent venous infarction. 6

• Select alternative surgical approaches based on the pattern of venous drainage in the frontal lobe 6
• Consider delaying surgery beyond Day 11 post-SAH when bridging vein sacrifice may be necessary, as no venous infarction occurred in delayed cases despite vein sacrifice 6
• For patients with large intraparenchymal hematomas requiring emergency evacuation, surgical clipping may be preferred over coiling 4, 5