Purpose: To assess, by MR spectroscopy (MRS) and diffusion weighted imaging (DWI), the ability of electrical stimulation of the sphenopalatine ganglion (SPG) to augment stroke recovery in transient middle cerebral artery occluded (t-MCAO) rats, when treatment is started 18 +/- 2 h post-occlusion.
Materials and methods: (1)H-MRS imaging ((1)H-MRSI) and DWI were used to evaluate ischemic brain tissue after SPG stimulation in rats subjected to 2 h of t-MCAO. Rats were examined by (1)H-MRSI, DWI, and behavioral tests at 16 +/- 2 h, 8 days, and 28 days post-MCAO.
Results: N-Acetyl-aspartate (NAA) levels of the stimulated and control rats were the same 16 +/- 2 h post-MCAO (0.52 +/- 0.03, 0.54 +/- 0.03). At 28 days post-occlusion, NAA levels were significantly higher in the treated group (0.60 +/- 0.04) compared with those of the untreated animals (0.50 +/- 0.04; P < 0.05). This effect was more pronounced for regions with low NAA values (0.16 +/- 0.03) that changed to 0.32 +/- 0.03 (P = 0.04) for the treated group and to 0.10 +/- 0.03 (P = 0.20) for the controls. DWI data showed better ischemic tissue condition for the treated rats, but the measured parameters showed only a trend of improvement. The MR results were corroborated by behavioral examinations.
Conclusion: Our findings suggest that SPG stimulation may ameliorate MR tissue characteristics following t-MCAO even if treatment is started 18 h post-occlusion.