SCCM: Concentrated Saline Reverses Brain Herniation

ORLANDO, Feb. 20 -- A bolus of highly concentrated saline can reverse transtentorial brain herniation in about 75% of cases, a Johns Hopkins researcher said here.

In a retrospective cohort study, administering 30 mL of 23.4% hypertonic saline successfully reversed the clinical signs of the herniation in 57 of 76 events over four years, according to Robert Stevens, M.D.

"In our experience, herniation is a reversible event," Dr. Stevens told the Critical Care Congress of the Society for Critical Care Medicine, adding the "effect is to gain time to think about instituting other therapy."

Transtentorial herniation -- usually caused by stroke, tumor, trauma, or abscess -- is "one of the most dramatic and devastating events" in neurology, Dr. Steven said. It's one of five major types of brain herniation and occurs when the brain is displaced up or down past the level of the tentorium.

Although 23.4% saline -- the highest concentration that is commercially available -- has been successfully used to lower intracranial pressure in several studies, its value in treating transtentorial herniation had not been demonstrated, he added.

He noted that the link between intracranial pressure and transtentorial herniation "not always clear and linear." Some patients may have a serious herniation with only a small change in pressure and vice-versa.

Options for treating transtentorial herniation include surgery and a range of medical choices, including using osmotic fluids such as saline or mannitol (Osmitrol).

The researchers examined medical records of patients at Johns Hopkins Hospital from 2002 to 2006 and found 68 with a clinical diagnosis of transtentorial herniation who had been given 23.4% saline. The 68 patients had 76 events, Dr. Stevens said.

The diagnosis required one or both pupils to have dilated and lost reactivity to light, a decrease in the Glasgow Coma Scale of at least two points, and a space-occupying lesion in the skull.

The primary endpoint of the therapy was reversal of those signs within an hour of delivering the saline, Dr. Stevens said.

In fact, the study showed, physicians achieved a reversal in 57 of the 76 events. Also, for the 22 patients with intracranial pressure monitors already in place, the treatment reduced the mean pressure from 23.3 to 13.8 mm Hg within an hour, which was significant at P<0.001.

Multivariate analysis showed that only two factors were independently associated with a reversal of the herniation, Dr. Stevens said:

• Patients were 12 times as likely to have a reversal if their serum sodium concentration increased by five or more mmol/L within the first hour. The odds ratio was 12.0, with a 95% confidence interval from 1.6 to 90.5, which was significant at P=0.015.
• Patients were about 27 times as likely to have a reversal if their serum sodium concentration was above 145 mmol/L within the first hour. The odds ratio was 26.7, with a 95% confidence interval from 3.6 to 200.0, which was significant at P=0.001.

There were no serious adverse events associated with the therapy, Dr. Stevens said, but outcomes were poor in general.

Hypotension was noted in 13/76 (17%) events. There was no evidence of central pontine myelinolysis on MRI at 17 to 27 days after herniation.

Forty-six of the patients eventually died, 17 were left with severe disability, and five had mild disability.

He noted that the herniations arose in patients with serious neurological deterioration from a "wide variety of causes," including stroke and tumor.