Peng Xu, Wei-Ming Gong, Yao Li, Tao Zhang, Kai Zhang, De-Zhen Yin and Tang-Hong Jia
Chronic mechanical compression of the spinal cord, which is commonly caused by degeneration of the spine, impairs motor and sensory functions insidiously and progressively. Yet the exact mechanisms of chronic spinal cord compression (SCC) remain to be elucidated. To study the pathophysiology of this condition, the authors developed a simple animal experimental model that reproduced the clinical course of mechanical compression of the spinal cord.
A custom-designed compression device was implanted on the exposed spinal cord of female Wistar rats between the T-7 and T-9 vertebrae. A root canal screw attached to a plastic plate was tightened 1 complete turn (1 pitch) every 7 days for 6 weeks. The placement of the compression device and the degree of compression were validated every week using radiography. Furthermore, a motor sensory deficit index was also calculated every week. After 3, 6, 9, or 12 weeks, the compressed T7–9 spinal cords were harvested and examined histologically.
Lateral projection of the thoracic spine showed a progressively increasing rate of mean spinal cord narrowing in the compression group. Motor and sensory deficiencies were observed from Week 3 onward; paralysis was observed in 2 rats at Week 12. Motor deficiency appeared earlier than sensory deficiency. Obvious pathological changes were observed starting at Week 6. The number of neurons in the gray matter of rats with chronic compression of the spinal cord decreased progressively in the 6- and 9-week compression groups. In the white matter, myelin destruction and loss of axons and glia were noted. The number of terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling (TUNEL)–positive neurons increased in the ventral-to-dorsal direction. The number of TUNEL-positive cells increased from Week 6 onward and peaked at Week 9.
This practical model accurately reproduces characteristic features of clinical chronic SCC, including progressive motor and sensory disturbances after a latency and insidious neuronal loss.
Xin-Yi Gao, Qiao Li, Jing-Run Li, Qian Zhou, Jian-Xun Qu and Zhen-Wei Yao
The authors conducted a study to noninvasively and nonradioactively reveal moyamoya disease (MMD) intracerebral perfusion and perfusion territory supplied by the unilateral internal carotid artery (ICA) and external carotid artery (ECA) and bilateral vertebral arteries (VAs) before surgery and to further identify risk factors for preoperative hemorrhage in adult MMD.
Forty-three consecutive adult patients with bilateral MMD underwent unenhanced T1-weighted MRI, territorial arterial spin labeling (t-ASL), and unenhanced 3D time-of-flight MRA (3D-TOF-MRA). Clinical factors, including age, sex, hypertension, diabetes mellitus, hyperlipidemia, current smoking status, and history of taking aspirin, were gathered and stratified. Univariate logistic regression analyses were used to examine the relationship between various risk factors and the occurrence of preoperative hemorrhage. Stepwise multivariate logistic regression analyses were used to determine independent risk factors of preoperative hemorrhage in MMD.
Among the 86 MMD hemispheres, t-ASL revealed 137 perfusion territory shifts in 79 hemispheres. Five distinct categories of perfusion territory shifts were observed on t-ASL maps. The subtypes of perfusion territory shift on t-ASL maps were further subdivided into 2 different categories, group A and group B, in combination with findings on 3D-TOF-MRA. A perfusion territory shift attributable solely to the secondary collaterals was a potential independent risk factor for preoperative hemorrhage (p = 0.026; 95% CI 1.201–18.615; OR 4.729). After eliminating the influence of the secondary collaterals, the primary collaterals had no significant effect on the risk of preoperative hemorrhage (p = 0.182).
t-ASL could reveal comprehensive MMD cerebral blood perfusion and the vivid perfusion territory shifts fed by the unilateral ICA and ECA and bilateral VAs in a noninvasive, straightforward, nonradioactive, and nonenhanced manner. 3D-TOF-MRA could subdivide t-ASL perfusion territory shifts according to their shunt arteries. A perfusion territory shift attributable to the secondary collaterals is a potential independent risk factor for preoperative hemorrhage in MMD patients. A perfusion territory shift fed by the primary collaterals may not have a strong effect on preoperative hemorrhage in MMD patients. These findings make the combined modalities of t-ASL and 3D-TOF-MRA a feasible tool for MMD disease assessment, management, and surgical strategy planning.