Decompressive Hemicraniectomy With Duraplasty

Decompressive hemicraniectomy with duraplasty (DHWD) is a surgical procedure designed to decrease ICP. More room becomes available after removal of part of the skull and release of the dura, thereby reducing ICP. Smith, Carter, and Ogilvy (2002) report a 15% decrease in ICP with craniectomy and a 70% decrease in ICP after release of the dura. Thus, opening both the skull and dura affords the greatest benefit.

The concept of removing part of the skull to alleviate increased ICP is not new. It dates back to 1901, when Kocher reported the first surgical decompression for posttraumatic brain swelling (Smith et al., 2002). Decompressive hemicraniectomy has not been widely used because of the lack of evidence of benefit in functional outcomes (Gupta et al., 2004; Schwab & Hack, 2003). Decompressive hemicraniectomy for severe ischemic stroke currently is being investigated in major clinical trials, such as the Hemicraniectomy after MCA Infarction with Life-threatening Edema Trial (HAMLET), Hemicraniectomy and Durotomy for Deterioration from Infarction Related Swelling Trial (HeaDDFIRST), Hemicraniectomy and Moderate Hypothermia in Patients with Severe Ischemic Stroke and Hemicraniectomy for Malignant Cerebral Artery Infarcts (HeMMI) (Internet Stroke Center, 2004). Inclusion and exclusion criteria differ by study and outcome measures generally include mortality and functional status. Decompressive hemicraniectomy is not used more widely in the head trauma population because the ischemic process is more global. In ischemic stroke, however, the process is more focal and theoretically would be of more benefit in this population.

Hemicraniectomy involves removal of a substantial portion of the skull on one side of the head over the area of cerebral infarction. The landmarks for the portion of bone removed are anterior—frontal to the midpupillary line; posterior—posterior to the external auditory meatus; superior—to the lateral edge of the superior sagittal sinus; and inferior—to the floor of the middle cranial fossa at the origin of the zygomatic arch (Fig 1). Surgeons avoid the sigmoid and superior sagittal sinuses to prevent the possibility of sinus thrombosis or hemorrhage (Coplin, 2001).

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Proposed use of prophylactic decompressive craniectomy in poor-grade aneurismal subarachnoid hemorrhage patients presenting with associated large sylvian hematomas. (Reprinted with permission from Smith et al., (2002). Neurosurgery 51, 117–124.)

A DHWD involves performing a cruciate opening of the dura and attaching the pericranium or a dural substitute (Ziai et al., 2003). Examples of dural substitutes include Lyoplant™, produced from bovine pericardium and Neuro-Patch™, created from polyesterurethane. The duraplasty leaves a "bag" for the intracranial volume to fill while ICP is elevated. The skin is closed in the usual manner. The bone flap is preserved in one of two ways. It can be placed in an abdominal wall surgical pouch or frozen in an antibiotic solution. The bone flap is left out of the patient's head for 6 weeks to 5 months, depending on the patient's speed of recovery (Iwama et al., 2003; Flannery & McConnell, 2001). It is generally agreed that it is best to save and use the patient's own bone flap for replacement instead of using synthetic cranioplasty materials because the flaps are safe, efficient, and cost-effective (Iwana et al., 2003; Flannery & McConnell, 2001; Bruce & Bruce, 2003).