Enhancement of Experimental Cerebral Edema after Decompressive Craniectomy

Abstract

Decompressive craniectomy has been advocated as a treatment for the cerebral edema associated with massive head injury. Although craniectomy has been successful in lowering intracranial pressure after head injury, a comparison of computerized tomographic scans of comparable patients with traumatic brain edema treated by medical means or decompressive craniectomy showed that bony decompression resulted in apparent exacerbation of edema. To investigate the possibility of enhancement of brain edema by craniectomy, we produced standardized cold lesions in the brains of 10 dogs. Five animals served as controls. In the other 5 animals we performed large decompressive craniectomies after lesioning. Physiological parameters were comparable in both groups. The dogs were killed 8 hours after lesioning. After fixation, their brains were cut into 1-mm-thick slices. We used an image analysis facility built around a PDP 11/105 computer to measure the volume of edema as outlined by Evans blue staining. The mean volume of the brain edema in the control animals was 0.27 +/- 0.19 ml. Mean edema volume was over 7 times greater in craniectomized animals (1.96 +/- 1.89 ml). This difference is statistically significant (p less than 0.05). The driving force for the formation of edema fluid is the difference between intravascular and interstitial presssure. Decompression of the brain by bone removal probably results in a reduction of interstitial fluid pressure and edema enhancement. The clinical literature contains no evidence that craniectomy decreases the morbidity or mortality of human head injury. In view of our experimental findings, this is not surprising. Indeed, pathological evidence indicates that severe edema (such as that accentuated by craniectomy) may produce permanent changes in the neuropil.

Effect of early bilateral decompressive craniectomy on outcome for severe traumatic brain injury

“…Different types of bone decompression have been attempted with variations in the location and size of bone removal depending on the cause of the elevated ICP (1,3,4,5,11,16,17). In a study of 37 STBI patients aged under 40 years, Gaab prospectively performed bilateral DC on 19, and hemicraniectomy on 18 patients.…”

Complications of decompressive craniectomy for traumatic brain injury

“…59 Brain edema following decompressive craniectomy has been modeled in animal studies of injury using Evans blue dye extravasation. 15,25,69 Cooper et al 15 found a 7-fold increase in edema formation as determined by Evans blue dye extravasation following craniectomy. Evidence of increased brain edema following craniectomy has not been verified in humans.…”

Brain oedema in focal ischaemia: molecular pathophysiology and theoretical implications

“…By contrast, if decompressive craniectomy is done later-ie, during the stage of vasogenic oedema-it will decrease tissue pressure, drive formation of vasogenic oedema, and thus may have an unintended deleterious effect. 68 Brain imaging may guide the timing of treatment by detecting these stages. Diffusion restriction on MRI correlates with the cytotoxic stage, 10 whereas early hypodensity before mass effect on computed tomography scans may be useful to assess ionic versus vasogenic oedema before decompressive craniectomy.…”