The Biffl scale or grade illustrates the spectrum of blunt cerebrovascular injury (BCVI) seen on angiography (both CTA and DSA). Some authors refer to the grading scale as the Denver scale, which is not to be confused with the Denver criteria, a series of clinical indications to screen for blunt cerebrovascular injury in trauma patients. 

Classification

• grade I: minimal luminal irregularity or intramural haematoma/dissection with <25% luminal narrowing

• grade II: intramural haematoma/dissection with ≥25% luminal narrowing, intraluminal thrombus, or raised intimal flap

• grade III: pseudoaneurysm

• grade IV: occlusion

• grade V: transection with free extravasation

Arteriovenous fistula is often included with transections (grade V) ^4,5. However, Biffl et al. initially described fistulae as grade I if small and grade III if large ¹, and later revised this description to grade II if small and grade V if hemodynamically significant ⁶. Other authors have proposed classifying these lesions as grade III ⁷.

Treatment and prognosis

This grading system has prognostic and therapeutic implications.

The risk of stroke increases with increasing grade of carotid artery injury ¹:

• grade I: 8%

• grade II: 14%

• grade III: 26%

• grade IV: 50%

• grade V: 100%

The risk of stroke does not correlate with increasing grade of vertebral artery injury ³:

• grade I: 6%

• grade II: 38%

• grade III: 27%

• grade IV: 28%

• grade V: no clear data, but generally accepted to have poor outcomes