Elevated intracranial pressure (ICP), or intracranial hypertension, is a common occurrence in critically ill neurologic patients and is associated with poor outcome. While much disagreement remains about the optimal treatment of elevated ICP, there is recognition of the most commonly employed techniques for lowering critically elevated ICP; hyperventilation followed by osmotherapy (administration of an osmotic diuretic, most commonly mannitol). Recent research supports the use of hypertonic saline (e.g., 3% saline solution) as an alternative or adjunctive agent to mannitol. These medical measures will hopefully temporize the elevated ICP while investigations as to the particular cause ensue. Of course, depending upon the cause, surgery may be necessary to definitively treat the elevated ICP.

If these medical measures are not successful and a definitive surgical procedure is not an option, then for many practitioners the next step is usually general anesthesia. For many years barbiturate-induced coma was the accepted approach. Currently, propofol is recommended because of its short half-life, rapid washout time, and ability to allow for more rapid assessment of neurologic function. Keeping patients under generalized anesthesia for several days reduces cerebral metabolism and consequently reduces cerebral blood flow. It is through this mechanism that generalized anesthesia is thought to reduce the ICP. One important caveat to general anesthesia is the development of clinically significant hypotension. The latter can occur in up to 25% of patients treated with barbiturates and is certainly seen with propofol. Hypotension is associated with poor outcome in patients with neurologic injury.

Should metabolic coma not work, two more drastic measures have been advocated—hemicraniectomy and decompressive laparotomy. A substantial amount of evidence over the past 30 years has lent support to the use of decompressive hemicraniectomy for the treatment of intractably elevated ICP. In the case of unilateral cerebral edema (as determined by head computed tomography scanning),
unilateral decompressive hemicraniectomy can be performed. In the case of bilateral cerebral edema, bilateral hemicraniectomy is often necessary (frontotemporal-parietal). An alternative surgical approach for the treatment of diffuse bilateral edema is bifrontal decompressive craniectomy. Case series and case reports document success with performance of early craniectomy (within 24 to 48 hours) as well as late craniectomy (after 24 to 48 hours). Some patients may have had unilateral mass lesions that were resected surgically and then developed localized reactive edema, which became refractory to standard treatments for intracranial hypertension. In some of these cases (where ipsilateral surgical resection had already been performed), success has been reported with a decompressive hemicraniectomy. Data from randomized, controlled trials are lacking. As a result, patient-selection protocols do not exist and the identification of risk factors predicting poor outcome remains uncertain. Nevertheless, the approach has become widespread, especially in certain specific circumstances, such as malignant cerebral edema due to middle cerebral artery occlusion. Of interest, the management of the bone flap varies between institutions. Some surgeons place the bone flap in the patient’s abdomen for several weeks prior to reattachment, whereas others place the bone flap in (external) sterile environments at subzero temperatures for several weeks to months.