Introduction -- Brain swelling is the most feared complication of malignant stroke with massive brain infarction.  Hypertonic saline has been favorably used as a hyperosmolar agent for the past decades in various intracranial pathological conditions. In this study, we evaluated hypertonic saline in the treatment of such conditions in rat model of malignant stroke.      
Methods – A total of 45 adult male rats were studied with embolic stroke model. The rats were divided into three groups to receive normal saline (Group 1 control) or 36  mOsm/kg solution of either 10% hypertonic saline (50-50 chloride-acetate; Group 2) or 30% hypertonic saline (Group 3).  Treatment consisted of a 60-min loading beginning 5 min after embolization and followed 300 mins later by a 34 mOsm/hr infusion of the same solution for 22 hrs.  Twenty-four hours after embolization, blood was sampled for measurement of sodium and osmolality. Rats brain was harvested for measurement of water content after sacrifice.  Brain water contents were derived by wet/dry weight ratio. 
Measurements and results – Twenty-four-hour mortality was significantly reduced in both hypertonic saline treated groups (NS = 58 %; 10% HS = 30 %; 30% HS = 25 %, p<0.05).  Twenty-four hours after embolization, the water content on the infarcted hemisphere was unchanged for those that survived in NS or HS treated rats (NS = 83.1 ± 1.1 %; 10% HS = 83.0 ± 1.1 %; 30% HS = 83.8 ± 0.7 %), whereas the HS-treated contralateral hemisphere was significantly decreased (NS = 79.1 ± 0.6 %; 10% HS = 77.4 ± 0.8 %; 30% HS = 77.4 ± 0.6 %; p<0.05).  
Conclusions – HS reduced contralateral hemispheric water content but did not affect ipsilateral brain water content when compared to NS. This difference was most likely due to a higher sodium permeability across a leaky blood-brain barrier in the ischemic hemisphere. Nevertheless, the reduced contralateral brain water content was associated with decreased mortality.

Effect of hypertonic saline on survival in an experimental embolic model of massive cerebral infarction with severe brain swelling