Posterior spinal artery infarct.

Posterior spinal artery syndrome has a variable presentation and often poses a clinical challenge. We describe an acute posterior spinal artery syndrome in a man in his 60s with vascular risk factors, who presented with altered sensation in the left arm and left side of his torso but with normal tone, strength and deep tendon reflexes. MR imaging showed a left paracentral T2 hyperintense area affecting the posterior spinal cord at the level of C1. Diffusion-weighted MRI (DWI) showed high signal intensity in the same location. He was medically managed as having ischaemic stroke and made a good recovery. Three-month MRI follow-up showed a persisting T2 lesion but the DWI changes had resolved, consistent with the time course for infarction. Posterior spinal artery stroke has a variable presentation and is probably under-recognised clinically, requiring careful attention to MR imaging for its diagnosis.

Inferior vena cava calcification, a possible link with recurrent deep venous thrombosis and pulmonary embolism: a case study and review of literature.

Inferior vena cava (IVC) anomalies have been reported to have an association with deep venous thrombosis of the lower limbs. It is, therefore, necessary to study the IVC in recurrent cases of unprovoked deep venous thrombosis (DVT) and/or pulmonary embolism (PE), where all other causes have been excluded. We report a case of a 65-year-old male, who had recurrent episodes of DVT in the past 5 years; some of which associated with PE of unknown cause. CT thorax abdomen and pelvis did not find an obvious cause for the DVT and/or PE, however, it did highlight a diffuse calcification of the IVC. Only a few cases of calcification of the IVC have been reported in literature, and a number of them have been associated with clot formation and PE. We speculate that, as in other anomalies of the IVC, calcification of the IVC might slow the blood flow, and thus predispose to DVT and/or PE. Our opinion is that in all cases of unexplained DVT and/or PE, a careful examination of the IVC should be performed. Furthermore, when this condition is present, other risk factors for hypercoagulability should be avoided and anticoagulant therapy should be considered.

Long term evaluation of brain perfusion with magnetic resonance in high flow extracranial-intracranial saphenous graft bypass.

Assessment was made of the cerebral vascular haemodynamic parameters in patients with a high-flow extra-intracranial (EC-IC) bypass performed for therapeutic occlusion of the internal carotid artery (ICA). Sixteen patients with ICA occlusion and EC-IC bypass (time interval from surgery 1-6 years) underwent MRI. Perfusion-weighted magnetic resonance imaging (PW-MRI) sequences were performed without the use of an arterial input function. The relative cerebral blood volume (rCBV), mean transit time (MTT) and relative cerebral blood flow (rCBF) were evaluated in all patients at the level of the basal ganglia, centrum semiovale and cortex in both hemispheres. Statistically significant differences (P<0.005) were observed in the haemodynamic parameters, indicating increased rCBV in the basal ganglia and decreased rCBF and rCBV in the cortex of the hemisphere supplied by the graft with respect to the contralateral. Patients with occlusion of the ICA and high flow EC-IC bypass do have altered vascular haemodynamic status between the hemispheres. In particular, rCBF is impaired in the surgical hemisphere at the level of the cortex. These patients should be followed-up to rule out chronic ischemia.

Role of contrast-enhanced MR venography in the preoperative evaluation of parasagittal meningiomas.

Parasagittal meningiomas (PSM) may pose a difficult surgical challenge since venous patency and collateral anastomoses have to be clearly defined for correct surgical planning. The aim of this study was to assess the diagnostic value of contrast-enhanced (CE) magnetic resonance venography (MRV) in the preoperative evaluation of venous infiltration and collateral venous anastomoses in patients with PSM. CE-MRV was compared with phase-contrast (PC) magnetic resonance (MR) angiography, conventional angiography (when available), and surgery as a reference. Twenty-three patients undergoing surgery for meningiomas located adjacent to the superior sagittal sinus were prospectively evaluated. All the patients underwent both conventional MR examination and MRV. This was performed by means of PC and CE techniques. Both sets of angiograms (CE and PC) were evaluated by two expert neuroradiologists to assess (1) patency of the sinus (patent/occluded), (2) the extent of occlusion (in centimeters), and (3) the number of collateral anastomoses close to the insertion of the meningioma. Eight patients underwent digital subtraction angiography (DSA). All patients were operated on, and intraoperative findings were taken as the gold standard to evaluate the diagnostic value of MRA techniques. PC-MRV showed a flow void inside the sinus compatible with its occlusion in 15 cases, whereas CE-MRV showed the sinus to be occluded in five cases. CE-MRV data were confirmed by surgery, showing five patients to have an occlusion of the superior sagittal sinus. The PC-MRV sensitivity was thus 100% with a specificity of 50%. In those cases in which both MRV techniques documented occlusion of the sinus, the extent of occlusion was overestimated by PC compared with CE and surgery. CE-MRV depicted 87% of collateral venous anastomoses close to the meningioma as subsequently confirmed by surgery, while PC showed 58%. In the preoperative planning for patients with meningiomas located close to a venous sinus, CE-MRV provides additional and more reliable information concerning venous infiltration and the presence of collateral anastomoses compared with PC sequences.

Magnetic resonance imaging in Posterior Reversible Encephalopathy Syndrome: report of three cases and review of literature.

INTRODUCTION: Eclampsia is one of the main causes of Posterior Reversible Encephalopathy Syndrome (PRES) a recent clinico-neuroradiological entity represented by characteristic MR findings of a symmetric bilateral subcortical/cortical hyperintensity in T2-weighted images, more often in parieto-occipital lobes, accompanied by clinical neurological alterations. Neuroradiological and clinical alterations are commonly completely reversible although ischemic evolution has been described. The pathophysiology is still a matter of debate. Specific magnetic resonance (MR) techniques, such as FLAIR (fluid attenuated inversion recovery) and DWI (diffusion weighted images) sequences, have improved the ability to detect subcortical/cortical lesions and helped to clarify the underlying pathophysiological mechanism of cerebrovascular involvement, which results important for an appropriate therapeutic decision. CASE REPORT AND DISCUSSION: We report the MR imaging findings of three patients with eclampsia and PRES as well as a careful review of literature.

Hemodynamic modifications in patients with symptomatic unilateral stenosis of the internal carotid artery: evaluation with MR imaging perfusion sequences.

BACKGROUND AND PURPOSE: Risk of developing ischemia is higher in patients with reduced cerebrovascular reactivity than in those with preserved cerebrovascular reactivity. Therefore, we assessed cerebral hemodynamic modifications in patients with unilateral stenosis of the internal carotid artery by using perfusion-weighted MR imaging to determine if these modifications underlie or anticipate ischemic signs and symptoms. METHODS: Fifteen patients with unilateral 70-90% carotid artery stenosis were studied with digital subtraction angiography and perfusion-weighted MR imaging. Their findings were compared with those of 15 age- and sex-matched control subjects. Regional cerebral blood volume (rCBV) and mean transit time (MTT) values were calculated in the middle cerebral artery and border zone territories. RESULTS: No significant difference was noted in rCBV and MTT values between the hemispheres in the symptomatic patients. There was a significant difference in MTT values in the border zones between patients and control subjects. MR images in patients and control subjects did not reveal large territorial infarcts and did reveal similar white matter lesion burdens. CONCLUSION: There is adequate compensation of unilateral stenosis when the stenosis is less than 90%. The risk of stroke is higher in patients with stenoses exceeding 70%, mostly because of decreased collateral reserve when confronted with emboli.