Postoperative MRI Evaluation of a Radiofrequency Cordotomy Lesion for Intractable Cancer Pain.

BACKGROUND AND PURPOSE: There are limited data on the use of postoperative imaging to evaluate the cordotomy lesion. We aimed to describe the cordotomy lesion by using postoperative MR imaging in patients after percutaneous cordotomy for intractable cancer pain. MATERIALS AND METHODS: Postoperative MR imaging and clinical outcomes were prospectively obtained for 10 patients after percutaneous cordotomy for intractable cancer pain. Area, signal intensity, and location of the lesion were recorded. Clinical outcomes were measured by using the Visual Analog Scale and the Brief Pain Inventory-Short Form, and correlations with MR imaging metrics were evaluated. RESULTS: Ten patients (5 men, 5 women; mean age, 58.5 ± 9.6 years) were included in this study. The cordotomy lesion was hyperintense with central hypointense foci on T2-weighted MR imaging, and it was centered in the anterolateral quadrant at the C1-C2 level. The mean percentage of total cord area lesioned was 24.9% ± 7.9%, and most lesions were centered in the dorsolateral region of the anterolateral quadrant (66% of the anterolateral quadrant). The number of pial penetrations correlated with the percentage of total cord area that was lesioned (r = 0.78; 95% CI, 0.44-0.89; P = .008) and the length of T2-weighted hyperintensity (r = 0.85; 95% CI, 0.54-0.89; P = .002). No significant correlations were found between early clinical outcomes and quantitative MR imaging metrics. CONCLUSIONS: We describe qualitative and quantitative characteristics of a cordotomy lesion on early postoperative MR imaging. The size and length of the lesion on MR imaging correlate with the number of pial penetrations. Larger studies are needed to further investigate the clinical correlates of MR imaging metrics after percutaneous cordotomy.

Visualization of rat pial microcirculation using the novel orthogonal polarized spectral (OPS) imaging after brain injury.

Recently, the novel optical system, orthogonal polarized spectral (OPS) imaging was developed to visualize microcirculation. Investigation of changes in microcirculation is essential for physiological, pathophysiological, and pharmacological studies. In the present study applicability of OPS imaging was assessed to study pial microcirculation in normal and traumatized rat brain. High quality images of rat pial microcirculation in normal and traumatized rats were generated with the OPS imaging, allowing to easily differentiate arterioles and venules with the dura remaining intact. In non-traumatized rats, mean vessel diameter of arterioles and venules of five different cortical regions was 19.1+/-2.7 and 22.2+/-1.4 microm, respectively. In the early phase following focal cortical contusion vessel diameter was significantly decreased in arterioles by 28% while diameter in venules was significantly increased by 27%. For technical reasons velocity in arterioles was not measurable. In venules, mean flow velocity of 0.68+/-0.08 mm/s was significantly decreased by 50% at 30 min after trauma. OPS imaging is an easy to use optical system allowing to generate high quality images and to reliably investigate pial microcirculation without having to remove the dura. This technique opens the possibility to perform longitudinal studies investigating changes in pial microcirculation.

Vicryl (polyglactin 910) mesh as a dural substitute in the presence of pia arachnoid injury.

Previously presented data showed that Vicryl mesh was a potentially effective dural grafting material. It is easily handled, relatively inexpensive, absorbed over time, and elicits a minimal inflammatory response. The present experimental project was conducted to investigate the effectiveness of a tightly woven version of the material as a watertight seal and to evaluate its performance in the presence of pia arachnoid injury. The mesh formed a seal promptly and adhesion formation was slight. Tightly woven Vicryl mesh appears to have a significant potential as an absorbable dural substitute.

Inhibition by free radical scavengers and by cyclooxygenase inhibitors of pial arteriolar abnormalities from concussive brain injury in cats.

We studied the role of prostaglandins and free radicals in the induction of the functional and morphological pial arteriolar abnormalities produced by concussive brain injury. Anesthetized cats equipped with a cranial window for the observation of the pial microcirculation were subjected to concussive brain injury using a fluid-percussion device following administration of cyclooxygenase inhibitors (indomethacin or AHR-5850) or the vehicle for the solution of these agents (NaCl or Na2CO3 solution). Pial arterioles from vehicle-treated animals displayed sustained dilation, reduced responsiveness to the vasoconstrictor effect of arterial hypocapnia, and a high density of endothelial lesions. Animals pretreated with cyclooxygenase inhibitors showed less pronounced vasodilation, normal responsiveness to hypocapnia, and a significantly reduced number of lesions. The vasodilation and reduced responsiveness to the vasoconstrictor effects of hypocapnia after brain injury also were inhibited by topical application of free radical scavengers (nitroblue tetrazolium, superoxide dismutase, or mannitol). The vessels from cats pretreated with free radical scavengers also had a lower density of endothelial lesions than controls. The results support the view that the immediate cause of cerebral arteriolar damage in concussive brain injury is the generation of free oxygen radicals associated with increased prostaglandin synthesis.

Cerebral prothrombotic state in spontaneously hypertensive rats of different breeds.

The thrombotic tendency in two breeds of spontaneously hypertensive rats (SHRs) was assessed by inducing occlusive thrombosis in pial blood vessels using a helium-neon laser method. A prothrombotic state was observed in the SHR of one breed as compared to the corresponding control WKY, but not in the other. Circulating platelet and erythrocyte counts and haematocrit values were significantly negatively correlated in arterioles with the number of laser pulses, which is an index of the thrombotic tendency, suggesting that the prothrombotic state was partly dependent on the counts of blood components. However, there was no correlation between the measured blood parameters and prothrombotic state in venules. The difference observed in arterioles and venules might be due to their differential haemodynamics and endothelial properties. Prothrombotic state in the SHR of one breed would be partly due to the much higher difference in blood components from its corresponding control compared to the comparatively less difference in the other breed.

Leptomeningeal cyst: nonenhanced and enhanced computed tomography findings.

Leptomeningeal cyst (a growing fracture of childhood) is well recognized as a rare complication of traumatic skull injuries. The clinical and plain roentgenogram findings have been described previously in the literature. These fractures are commonly associated with encephalomalacic changes of the underlying herniated brain tissue that occurs as part of the pathophysiology of leptomeningeal cyst formation. This is a case report of a leptomeningeal cyst with peripheral enhancement of the herniated issue most likely representing the pia mater, and/or development of a highly vascularized pseudodura. The computed tomography findings pre and postcontrast of a growing fracture of childhood have not been previously reported.

Antithrombotic effect of argatroban on the pial vessels of the rat: a study with He-Ne laser-induced thrombus formation.

The antithrombotic effect of the synthetic thrombin inhibitor (2R,4R)-4-methyl-1-[N2-(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfon yl)-L-arginyl]-2-piperidinecarboxylic acid monohydrate (argatroban) was investigated in cerebral vessels of the rat. An occlusive thrombus was formed in pial vessels using a He-Ne laser in a closed cranial window technique. Argatroban retarded the formation of thrombi in a dose-dependent manner. The antithrombotic effect of a single intravenous dose of argatroban at 0.5 mg/kg was diminished after 30 min in arterioles and after 50 min in venules, respectively. The antithrombotic activity was maintained, however, by continuous intravenous infusion (2 mg/kg/h).

Nerve growth factor induces process formation in meningeal cells: implications for scar formation in the injured CNS.

Nerve growth factor (NGF) induces the differentiation and supports the survival of subpopulations of neurons in the PNS and CNS. Here we report that meningeal cells in the pia mater express immunoreactivity and mRNA for both known NGF receptors, the low-affinity receptor p75 and the tyrosine kinase receptor trkA. NGF induces rapid tyrosine phosphorylation of trkA in meningeal cells in vitro. NGF does not stimulate proliferation of primary meningeal cells but induces process outgrowth. p75- and trkA-immunoreactive meningeal cells with long processes, resembling NGF-treated cells in vitro, are abundant in the scar tissue that forms at spinal cord lesions in rat and cat. These data suggest that NGF, which is expressed at increased levels in the brain and spinal cord after lesions, may be involved in scar formation in the injured CNS.