Effects of cranioplasty in cerebral blood perfusion using quantification with 99m-Tc HMPAO SPECT-CT

Background and Purpose Syndrome of the trephined or sinking skin flap syndrome is an underdiagnosed condition of craniectomized patients that usually improves after cranioplasty. Among the pathophysiological theories proposed, the changes of cerebral blood perfusion (CBP) caused by cranial defects might have a role in the neurological deficiencies observed. We aim to assess the regional cortex changes in CBP after cranioplasty with Technetium 99m hexamethylpropylene-amine oxime (99mTc-HMPAO) SPECT-CT. Methods Twenty-eight craniectomized patients subject to cranioplasty were studied with 99mTc-HMPAO SPECT-CT in three different times, before cranioplasty, a week, and 3 months after. The images were processed with quantification software comparing CBP of 24 cortical areas with a reference area, and with a database of controls. A mixed effects model and T-Student were used. Results CBP increased significantly in both hemispheres after cranioplasty, either using ratio (beta = .019, p-value = .030 first postsurgical SPECT-CT and beta = .021, p-value = .015 in the second study, vs. presurgical) or Z-score (beta = .220, p-value = .026 and beta = .279, p-value = .005, respectively). Nine areas of the damaged side had a significant lower CBP ratio and Z-score than the undamaged. Posterior cingulate showed an increased CBP ratio (p-value = .034) and Z-score (p-value = .028) in the first postsurgical SPECT-CT. These posterior cingulate changes represent a 4.83% increase in ratio and 91.04% in Z-Score (p-value = .035 and .040, respectively). Conclusion CBP changes significantly in specific cortical areas after cranioplasty. Posterior cingulate changes might explain some improvements in attention impairments. SPECT-CT could be a useful tool to assess CBP changes in these patients and might be helpful in their clinical management.