Hypertonic saline attenuates cord swelling and edema in experimental spinal cord injury: a study utilizing magnetic resonance imaging.
OBJECTIVE
To use magnetic resonance imaging (MRI) to characterize secondary injury immediately after spinal cord injury (SCI), and to show the effect of hypertonic saline on MRI indices of swelling, edema, and hemorrhage within the cord.


METHODS
A prospective, randomized, placebo-controlled study.


METHODS
Research laboratory.


METHODS
Twelve adult Long-Evans female rats.


METHODS
Rats underwent a unilateral 12.5 mm SCI at vertebral level C5. Animals were administered 0.9% NaCl (n = 6) or 5% NaCl (n = 6) at 1.4 mL/kg intravenously every hour starting 30 minutes after SCI. Immediately after SCI, rats were placed in a 4.7T Bruker MRI system and images were obtained continuously for 8 hours using a home-built transmitter/receiver 3 cm Helmholtz coil. Rats were killed 8 hours after SCI.


RESULTS
Quantification of cord swelling and volumes of hypointense and hyperintense signal within the lesion were determined from MRI. At 36 minutes after SCI, significant swelling of the spinal cord at the lesion center and extending rostrally and caudally was demonstrated by MRI. Also, at this time point, a hypointense core was identified on T1, PD, and T2 weighted images. Over time this hypointense core reduced in size and in some animals was no longer visible by 8 hours after SCI, although histopathology demonstrated presence of red blood cells. A prominent ring of T2-weighted image hyperintensity, characteristic of edema, surrounded the hypointense core. At the lesion center, this rim of edema occupied the entire unilateral injured cord and in all animals extended to the contralateral side. Administration of HS resulted in increased serum [Na], attenuation of cord swelling, and decreased volume of hypointense core and edema at the last time points.


CONCLUSIONS
We were able to use MRI to detect rapid and acute changes in the evolution of tissue pathophysiology, and show potentially beneficial effects of hypertonic saline in acute cervical SCI.
Nout
Yvette S
YS
Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, CA, USA.
Mihai
Georgeta
G
Tovar
C Amy
CA
Schmalbrock
Petra
P
Bresnahan
Jacqueline C
JC
Beattie
Michael S
MS
D000818:Animals; D002574:Cervical Vertebrae; D004334:Drug Administration Schedule; D004487:Edema / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D005260:Female; D006470:Hemorrhage / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D008279:Magnetic Resonance Imaging; D009187:Myelitis / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D011237:Predictive Value of Tests; D051381:Rats; D020318:Rats, Long-Evans; D012462:Saline Solution, Hypertonic / Q000627:therapeutic use*; D013119:Spinal Cord Injuries / Q000150:complications / Q000188:drug therapy* / Q000473:pathology*; D013997:Time Factors
D012462:Saline Solution, Hypertonic