Hypertonic Saline Found to Reverse Transtentorial Herniation

Neurology Today
5 June 2008; Volume 8(11); pp 1,9

CAJIGAL, STEPHANIE

The administration of 23.4 percent saline was associated with reversed transtentorial herniation (TTH) of the brain and reduced intracranial pressure, investigators at Johns Hopkins University reported in a retrospective study published in the March 25 Neurology.

Study author Robert D. Stevens, MD, said the results suggest that hypertonic solutions can buy time for patients with TTH so that other, more definitive therapies can be used.

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A new study suggests that 23.4 percent saline may eventually have a role in standardized care of patients with transtentorial herniation.

Figure. Cross section of a normal brain (left) and a brain with intracranial shifts from supratentorial lesions (right). (1) Herniation of the cingulate gyrus under the falx. (2) Herniation of the temporal lobe into the tentorial notch. (3) Downward displacement of the brain stem through the notch.

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The analogy would be defibrillating someone who suffered a cardiac arrest - it's not fixing the underlying problem, you're modifying brain volumes so you can have enough time to identify the primary process and treat it, he said. Dr. Stevens is assistant professor of anesthesiology critical care medicine, neurology, and neurosurgery at Johns Hopkins University School of Medicine.

The study included 68 men and women admitted with intracranial hemorrhage (29), subarachnoid hemorrhage (16), stroke (8), brain tumor (8), subdural hematoma (5), epidural hematoma (1), and meningitis (1) from April 2002 to June 2006. There were a total of 76 transtentorial herniations among these patients, and 57 had a clinical reversal of TTH.

This reversal was defined by a reduction in pupillary diameter with return of light responsiveness - the patient could open his or her eyes in response to stimuli, make verbal sounds, and move in response to painful stimuli. The reversal occurred within one hour of saline administration.

Twenty-two patients survived to discharge, but 17 had severe disability (defined as having a modified Rankin scale score of 1 to 3) and five had mild to moderate disability (mRS score of 4 to 5). Side effects included transient hypotension in 13 events.

In addition to the 23.4 percent hypertonic saline administered within 24 hours of TTH, 53 patients were also treated with hyperventilation, 43 with mannitol, 25 with continuous infusion of hypertonic saline, 47 with propofol, and 11 with pentobarbital. Surgical interventions included ventriculostomy catheter placement (21 patients) and decompressive hemicraniectomy (14 patients).

Figure. Dr. Robert D. Stevens said the results suggest that hypertonic solutions can buy time for patients with transtentorial herniation so that other, more definitive therapies can be used.

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These data suggest that 23.4 percent saline may eventually have a role in standardized care of patients with transtentorial herniation, Adnan I. Qureshi, MD, and Jose I. Suarez, MD, wrote in an editorial accompanying the study.

Dr. Stevens concurred, adding that future studies will need to compare 23.4 percent saline with another commonly used treatment - mannitol. If we did a trial of that type and proved that 23.4 percent saline was just as or more effective than mannitol, then it could become standard of care, he said.

The beneficial effect of 23.4 percent saline, Drs. Qureshi and Suarez wrote, is probably related to osmotic gradient driven movement of fluid from the interstitial spaces in the intact or even injured areas of the brain. This effect, however, may vary depending on the underlying cause of the herniation, they stated.

Shortcomings of the study, they added, include a small sample size; the possibility that patients who underwent rapid reversal of herniation with other treatments, not including saline, may not have been included; a population with various underlying neurologic injuries; and the possibility that other hypertonic saline solutions may lead to similar results. Drs. Qureshi and Suarez also said they would have liked to know the magnitude of disability and quality of life among survivors after hospital discharge.

Although patients improved, this study didn't prove that saline injection reversed herniation, said Eelco F.M. Wijdicks, professor of neurology and chair of the Division of Critical Care Neurology at the Mayo Clinic College of Medicine in Rochester, MN.

Figure. In a letter to Neurology, Drs. Alexander Y. Zubkov (left) and Eelco F.M. Wijdicks wrote: Although patients improved, this study didn't prove that saline injection reversed herniation… we are not certain that the clinical improvement is due to decompression or dislodging of tissue squeezed through the tentorium.

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In a letter that was published in Neurology, Dr. Wijdicks and colleague Alexander Y. Zubkov, MD, PhD, stated that although the study authors relied on dilated pupils and extensor responses as evidence of a reversal of herniation, we are not certain that the clinical improvement is due to decompression or dislodging of tissue squeezed through the tentorium.

One explanation, they said, is that injection of saline causes an improved blood flow and oxygenation to the displaced ischemic upper brainstem.

To be honest I think hypertonic saline is a very good agent, Dr. Wijdicks said in an interview with Neurology Today. It is a seven times bigger sponge than mannitol, although its effect is short-lived.

He also said the injection of saline will not be a first-line treatment because it requires that the patient have a central line, which usually isn't the case for patients who are transferred from the emergency room or worsen during transfer.

William M. Coplin, MD, chief of neurology and medical director of neurotrauma and critical care at Detroit Receiving Hospital, is also studying the use of saline in patients with intracranial hypertension. His study, which is funded by the Society of Critical Care Medicine, is randomizing patients to receive either normal saline or hypertonic saline. What we have preliminarily found is that patients who are given hypertonic saline need fewer interventions down the line, he said.

As for the injection of saline for people with brain herniation, anecdotal reports until now have suggested that we can turn people around by doing this, Dr. Coplin said.

Dr. Stevens said his study is one step toward his goal of creating a care protocol that his team hopes to promote nationally. I think we need to develop a consensus on how to treat brain herniation and intracranial hypertension using an algorithm that can be used by clinicians everywhere, he said. •

• Koenig MA, Bryan M, Stevens RD, et al. Reversal of transtentorial herniation with hypertonic saline. 2008;70:1023-1029.

• Qureshi AI, Suarez JI. More evidence supporting a brain code protocol for reversal of transtentorial herniation. 2008;70: