Mechanisms of coup and contrecoup injury during trauma to ...starklab.slu.edu/neuro/InjuryDuringTrauma.pdf · Mechanisms of coup and contrecoup injury during trauma to the brain Andrew

Mechanisms of coup and contrecoup injury during trauma to the brain

Andrew McLaughlin

Whiplash

• https://www.youtube.com/watch?v=Vqlkpt9d89g

• Brain is seen to make contact with skull, leading to injury

• Sudden acceleration or deceleration responsible

• Different than if skull contacts an object

Definition of Terms

Coup Injury

• Occurs during blow to the head

• Site of initial impact

• Likely caused by skull inbending or fracture

Contrecoup Injury

• Occurs during blow to the head

• Site opposite the initial impact

• Many theories for mechanism

Review of Skull/Brain Interface

• Skull is a relatively hard, bony interface

• Meninges protect the brain from direct contact

• Dura Mater

• Arachnoid – subarachnoid space contains CSF, blood vessels

• Pia Mater

Coup Injury

• Depression of the skull impacts brain (clear mechanism)

• Typically seen when stationary skull is struck by a moving object

• Focal injuries usually resulting in cerebral contusion/hemorrhage

Contrecoup Injury

• Mechanism is far less easily understood

• Widely recognized as having greater severity

• Often seen when moving skull impacts an immovable/external object

• Similarly results in focal injury and cerebral contusion/hemorrhage

Theories for Contrecoup Injury

• Positive Pressure Theory

• Rotational Shear Stress Theory

• Angular Acceleration Theory

• CSF Displacement Theory

• Negative Pressure (Cavitation) Theory

Positive Pressure Theory

• During movement, the brain lags at the back of the skull while the CSF pools near the front (lessening coup injury)

• Upon impact, compressive waves transmit across the brain and cause it to press against the back of the skull

• Problems: CSF is more dense than brain, meninges would stop brain from migrating towards the back

Rotational Shear Stress Theory

• Takes into account non-linear forces, significant rotational movement during traumatic injury

• Combination of rotational and linear movements cause stress to tear wherever it is greatest

• Problems: does not explain contrecoup, injuries likely from irregular bone

Angular Acceleration Theory

• During angular acceleration, objects attached to another accelerate more slowly

• Similar to positive pressure theory, specifically explains injury to frontal lobe when falling backwards

• Brain accelerates more slowly than skull and is pushed up against frontal portion

• Problems: does not explain linear contrecoup injuries, meninges would counter most differences in acceleration, CSF is more dense

CSF Displacement Theory

• One of the most recent theories, based on fact that CSF is more dense than the brain

• Upon sudden deceleration, the CSF displaces the brain backwards so initial contact will be with contrecoup surface

• In falling backwards, the initial contact will be with narrow, irregular surface and involve a small surface area of the brain

• Problems: CSF composes only 150mL of volume, does not take lateral/angular movement into account

2004 CSF Displacement

• Paper by Drew and Drew, Neurocritical Care

• Modeled brain and CSF off balloon in water

• First picture immediately before impact, second 1 sec. after

• Shows initial movement is in the backwards direction

Negative Pressure Theory

• Also known as the cavitation theory, generally most popular in nature

• Upon sudden deceleration, the brain moves forward creating tensile stress through negative pressure at the contrecoup site

• The cavitation of the brain pulls apart the contrecoup area

• Problems: CSF is more dense and would move forwards first

2012 Cavitation Study

• Goeller et al, Journal of Neurotrauma

• Modeled brain using sophisticated polycarbonate ellipsoid

• Filled ellipsoid with degassed water for CSF and Sylard gel for brain tissue

• Recorded pressure in the CSF and skull deformation

• Results indicated cavitation as a likely cause of damage

Best Candidate?

• Positive pressure, rotational shear stress, and angular acceleration theories seem either inaccurate or incomplete

• 2004 study suggests rudimentary evidence for CSF displacement theory

• 2012 study implies cavitation theory most likely

Occurrence of Contrecoup Injury

• 2012 study used as a model of the effect of a blast wave from an improvised explosive device (IED)

• 2014 Case Study (Sato et al., Legal Medicine)

• 54 y.o. alcoholic woman found dead from traumatic basal subarachnoid hemorrhage (TBSAH)

• Fell and bruised left posterior parietal region, but the hemorrhage appears to have been most serious in right cerebellum

• Cerebellum usually tightly packed into posterior fossa, alcoholism led to atrophy (assessed by Purkinje cell loss and stumbling gait) allowing for increased movement and resulting contrecoup injury

• Proposed as the first recorded instance of contrecoup TBSAH

Subarachnoid Hematoma (notice arteries still intact)

(A) Right cerebellar contusion (arrows) (B) Histological exam shows tissue damage

References • Images

• Types of Neurologic Damage http://www.northeastern.edu/nutraumaticbraininjury/what-is-tbi/types-of-damage/ (accessed Apr 17, 2015).

• medicallegalart. Coup-Contrecoup Injury. YouTube, 2011. • Brain Anatomy http://www.mayfieldclinic.com/PE-AnatBrain.htm#.VTEFXvnF-PU

(accessed Apr 17, 2015). • Meninges Catalog

http://vanat.cvm.umn.edu/neurHistAtls/cataPages/cataMen.html (accessed Apr 17, 2015).

• Ways the Brain is Injured http://www.braininjury.com/injured.shtml (accessed Apr 17, 2015).

• Journal Articles • Bhateja, A.; Shukla, D.; Devi, I. B.; Kolluri, V. S. The Indian Journal of Neurotrauma

2009, 6 (2), 115–118. • Drew, L. B.; Drew, W. E. Neurocritical Care 2004, 1 (3), 385–390. • Goeller, J.; Wardlaw, A.; Treichler, D.; O’Bruba, J.; Weiss, G. Journal of

Neurotrauma 2012, 29 (10), 1970–1981. • Jin, X.; Mao, H.; Yang, K. H.; King, A. I. Annals of Biomedical Engineering 2014, 42

(4), 812–821. • Goggio, A. F. Journal of Neurology, Neurosurgery & Psychiatry 1941, 4 (1), 11–22. • Sato, T.; Tsuboi, K.; Nomura, M.; Iwata, M.; Abe, S.; Tamura, A.; Tsuchihashi, H.;

Nishio, H.; Suzuki, K. Legal Medicine 2014, 16 (2), 92–94.

Questions? Comments?