title: MRI evidence for altered venous drainage and intracranial compliance in mild traumatic brain injury.
abstract: OBJECTIVE
  To compare venous drainage patterns and associated intracranial hydrodynamics between subjects who experienced mild traumatic brain injury (mTBI) and age- and gender-matched controls.
  
  
  METHODS
  Thirty adult subjects (15 with mTBI and 15 age- and gender-matched controls) were investigated using a 3T MR scanner. Time since trauma was 0.5 to 29 years (mean 11.4 years). A 2D-time-of-flight MR-venography of the upper neck was performed to visualize the cervical venous vasculature. Cerebral venous drainage through primary and secondary channels, and intracranial compliance index and pressure were derived using cine-phase contrast imaging of the cerebral arterial inflow, venous outflow, and the craniospinal CSF flow. The intracranial compliance index is the defined as the ratio of maximal intracranial volume and pressure changes during the cardiac cycle. MR estimated ICP was then obtained through the inverse relationship between compliance and ICP.
  
  
  RESULTS
  Compared to the controls, subjects with mTBI demonstrated a significantly smaller percentage of venous outflow through internal jugular veins (60.9±21% vs. controls: 76.8±10%; p = 0.01) compensated by an increased drainage through secondary veins (12.3±10.9% vs. 5.5±3.3%; p<0.03). Mean intracranial compliance index was significantly lower in the mTBI cohort (5.8±1.4 vs. controls 8.4±1.9; p<0.0007). Consequently, MR estimate of intracranial pressure was significantly higher in the mTBI cohort (12.5±2.9 mmHg vs. 8.8±2.0 mmHg; p<0.0007).
  
  
  CONCLUSIONS
  mTBI is associated with increased venous drainage through secondary pathways. This reflects higher outflow impedance, which may explain the finding of reduced intracranial compliance. These results suggest that hemodynamic and hydrodynamic changes following mTBI persist even in the absence of clinical symptoms and abnormal findings in conventional MR imaging.
authors: Institute of Clinical Radiology, University of Munich - Grosshadern Campus, Ludwig-Maximilians-University Munich, Munich, Germany.
authors: Andreas
authors: A
authors: Pomschar
authors: Inga
authors: I
authors: Koerte
authors: Sang
authors: S
authors: Lee
authors: Ruediger P
authors: RP
authors: Laubender
authors: Andreas
authors: A
authors: Straube
authors: Florian
authors: F
authors: Heinen
authors: Birgit
authors: B
authors: Ertl-Wagner
authors: Noam
authors: N
authors: Alperin
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001930:Brain Injuries / Q000503:physiopathology*; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004322:Drainage / Q000379:methods; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male