Early-versus-Late Endovascular Stroke Treatment: Similar Frequencies of Nonrevascularization and Postprocedural Cerebrovascular Complications in a Large Single-Center Cohort Study

BACKGROUND AND PURPOSE

Endovascular treatment of acute ischemic stroke is now performed more frequently in the late window in radiologically selected patients. However, little is known about whether the frequency and clinical impact of incomplete recanalization and postprocedural cerebrovascular complications differ between early and late windows in the real world.

MATERIALS AND METHODS

We retrospectively reviewed all patients with acute ischemic stroke receiving endovascular treatment within 24 hours from 2015 to 2019 and included in the Acute STroke Registry and Analysis of Lausanne. We compared rates of incomplete recanalization and postprocedural cerebrovascular complications (parenchymal hematoma, ischemic mass effect, and 24-hour re-occlusion) in the early (<6 hours) versus late window (6-24 hours, including patients with unknown onset) populations and correlated them with the 3-month clinical outcome.

RESULTS

Among 701 patients with acute ischemic stroke receiving endovascular treatment, 29.2% had late endovascular treatment. Overall, incomplete recanalization occurred in 56 patients (8%), and 126 patients (18%) had at least 1 postprocedural cerebrovascular complication. The frequency of incomplete recanalization was similar in early and late endovascular treatment (7.5% versus 9.3%, adjusted P =.66), as was the occurrence of any postprocedural cerebrovascular complication (16.9% versus 20.5%, adjusted P = .36). When analyzing single postprocedural cerebrovascular complications, rates of parenchymal hematoma and ischemic mass effect were similar (adjusted P = .71, adjusted P = .79, respectively), but 24-hour re-occlusion seemed somewhat more frequent in late endovascular treatment (4% versus 8.3%, unadjusted P = .02, adjusted P = .40). The adjusted 3-month clinical outcome in patients with incomplete recanalization or postprocedural cerebrovascular complications was comparable between early and late groups (adjusted P = .67, adjusted P = .23, respectively).

CONCLUSIONS

The frequency of incomplete recanalization and of cerebrovascular complications occurring after endovascular treatment is similar in early and well-selected late patients receiving endovascular treatment. Our results demonstrate the technical success and safety of endovascular treatment in well-selected late patients with acute ischemic stroke.

Predictors of Endovascular Treatment Procedural Complications in Acute Ischemic Stroke: A Single-Center Cohort Study

BACKGROUND AND PURPOSE

Procedural complications occur in 4%-29% of endovascular treatments in acute ischemic stroke. However, little is known about their predictors and clinical impact in the real world. We aimed to investigate the frequency and clinical impact of procedural complications of endovascular treatment and identify associated risk factors.

MATERIALS AND METHODS

From 2015-2019, we retrospectively reviewed all patients with acute ischemic stroke receiving endovascular treatment within 24 hours included in the Acute STroke Registry and Analysis of Lausanne. We identified patients having an endovascular treatment procedural complication (local access complication, arterial perforation, dissection or vasospasm, and embolization in a previously nonischemic territory) and performed logistic regression analyses to identify associated predictors. We also correlated procedural complications with long-term clinical outcome.

RESULTS

Of the 684 consecutive patients receiving endovascular treatment, 113 (16.5%) had at least 1 procedural complication. The most powerful predictors were groin puncture off-hours (OR = 2.24), treatment of 2 arterial sites (OR = 2.71), and active smoking (OR = 1.93). Patients with a complication had a significantly less favorable short-term clinical outcome (Δ-NIHSS score of -2.2 versus -4.33, P-value adjusted < .001), but a similar long-term clinical outcome (mRS at 3 months = 3 versus 2, P-value adjusted = .272).

CONCLUSIONS

Procedural complications are quite common in endovascular treatment and lead to a less favorable short-term but similar long-term outcome. Their association with treatment off-hours and at 2 arterial sites requires particular attention in these situations to optimize the overall benefit of endovascular treatment.

Pediatric cranial osteoblastoma: Technical note of surgical treatment and review of the literature

Osteoblastoma of the skull is a rare entity, and they account only for 2-4% of all the cases of osteoblastoma. We perform a comprehensive review of the pertinent literature on the subject and we report a case of a 3-year-old girl presenting with a 6-month history of a supraorbital mass and exophthalmos due to an osteoblastoma of the frontal and ethmoid bones involving the orbit and anterior skull base. A 3D printed model of the patient's skull was used for the preoperative planning and reconstruction strategy. Total en-bloc resection of the tumor followed by immediate reconstruction was achieved. No recurrence was detected 3 years after the surgery. Gross total resection is strongly advised with skull osteoblastoma, especially in young age, because of the risk of the recurrence and malignant transformation. 3D printing is proven to be a valuable tool to enhance surgical performance by avoiding complications while achieving total resection with accurate reconstruction. Long-term follow-up is important to detect recurrences and improve the management of these young patients.

Perfusion computed tomography in posterior circulation stroke: predictors and prognostic implications of focal hypoperfusion

BACKGROUND AND PURPOSE

The aim was to determine the predictors of focal hypoperfusion on computed tomography (CT) perfusion (CTP) in patients with acute posterior circulation stroke and its association with long-term outcome.

METHODS

Patients with posterior circulation stroke were selected from the Acute Stroke Registry and Analysis of Lausanne (ASTRAL) who underwent CTP within 24 h of stroke onset as part of the stroke imaging protocol. Hypoperfusion was defined as an area of visually well demarcated mean transit time prolongation corresponding to an arterial territory on standard reconstruction CTP imaging maps. Areas of hypoperfusion were assessed with the posterior circulation Acute Stroke Prognosis Early CT Score. Clinical and imaging associations with focal hypoperfusion were identified using multiple imputation analyses, and the adjusted functional outcome measured by the modified Rankin Scale at 3 and 12 months was determined.

RESULTS

Of the 3595 consecutive patients from the ASTRAL registry between 2003 and 2014, 1070 (29.7%) had a posterior circulation stroke and 436 of these (40.7%) patients had a good quality baseline CTP. 23.1% had early ischaemic changes and 37.4% had focal hypoperfusion. In multiple imputation analysis, visual field deficits, reduced level of consciousness, cardiac and multiple stroke mechanisms, significant vessel pathology and ischaemic changes visible on plain CT were associated with focal hypoperfusion. Focal hypoperfusion was independently associated with outcome at 12 months (odds ratio 2.04, 95% confidence interval 1.22-3.42, P < 0.01).

CONCLUSIONS

In posterior circulation stroke patients undergoing acute CTP, multiple clinical, aetiological and radiological variables were associated with focal hypoperfusion. Patients with focal hypoperfusion had a worse 12-month outcome.

Site and Rate of Occlusive Disease in Cervicocerebral Arteries: A CT Angiography Study of 2209 Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

CTA can rapidly and accurately detect and localize occlusive disease in patients with ischemic stroke. We have used CTA to assess arterial stenosis and occlusion in an ischemic stroke population arriving at a tertiary stroke center within 24 hours of symptom onset in order to obtain a comprehensive picture of occlusive disease pattern, and to determine the proportion of eligible candidates for endovascular treatment.

MATERIALS AND METHODS

Data from consecutive patients with acute ischemic stroke admitted to a single center between 2003 and 2012, collected in the Acute Stroke Registry and Analysis of Lausanne data base, were retrospectively analyzed. Patients with a diagnostic CTA within 24 hours of symptom onset were selected. Relevant extra- and intracranial pathology, defined as stenosis of ≥50% and occlusions, were registered and classified into 21 prespecified segments.

RESULTS

Of the 2209 included patients (42.1% women; median age, 72 years), 1075 (48.7%) had pathology in and 308 (13.9%) had pathology outside the ischemic territory. In the 50,807 arterial segments available for revision, 1851 (3.6%) abnormal segments were in the ischemic (symptomatic) territory and another 408 (0.8%) were outside it (asymptomatic). In the 1211 patients with ischemic stroke imaged within 6 hours of symptom onset, 40.7% had symptomatic large, proximal occlusions potentially amenable to endovascular therapy.

CONCLUSIONS

CTA in patients with acute ischemic stroke shows large individual variations of occlusion sites and degrees. Approximately half of such patients have no visible occlusive disease, and 40% imaged within 6 hours show large, proximal segment occlusions amenable to endovascular therapy. These findings show the importance of early noninvasive imaging of extra- and intracranial arteries for identifying occlusive disease, planning recanalization strategies, and designing interventional trials.

Added value of multimodal computed tomography imaging: analysis of 1994 acute ischaemic strokes

BACKGROUND AND PURPOSE

Multimodal computed tomography (CT) based imaging (MCTI) is widely used in acute ischaemic stroke. It was postulated that the use of MCTI is associated with improved patient outcome without causing harm.

METHODS

All patients with an acute ischaemic stroke and CT-based imaging within 24 h from the ASTRAL (Acute Stroke Registry and Analysis of Lausanne) registry were included. Preceding demographic, clinical, biological, radiological and follow-up data were collected. Significant predictors of MCTI use were identified retrospectively to go on to fit a multivariable analysis. Then, patients undergoing additional CT angiography (CTA) or CTA and perfusion CT (CTP) were compared with non-contrast CT only patients with regard to 3-month favourable outcome (modified Rankin Scale score ≤2), 12-month mortality, stroke mechanism, short-term renal failure, use of ancillary diagnostic tests, duration of hospitalization and 12-month stroke recurrence.

RESULTS

Of the 1994 included patients, 273 had only non-contrast CT, 411 had both non-contrast CT and CTA and 1310 had all three examinations. Factors independently associated with MCTI were younger age, low pre-stroke modified Rankin Scale score, low creatinine value, known stroke onset, anterior circulation stroke, anticoagulation or antihypertensive therapy (CTA only) and higher National Institutes of Health Stroke Scale scores (CTP only). After adjustment, MCTI was associated with a 50% reduction of 12-month mortality and a lower likelihood of unknown stroke mechanism. No association was found between MCTI and 3-month outcome, contrast-induced nephropathy, hospitalization duration, number of ancillary diagnostic tests or with stroke recurrence.

CONCLUSION

Our study shows an association of MCTI use with lower adjusted 12-month mortality, better identification of the stroke mechanism and no signs of harm.

Volumes of Chronic Traumatic Frontal Brain Lesions Measured by Mr Imaging and CBF Tomography

The volumes (ml) of chronic traumatic frontal brain lesions were compared measured “morphologically” with MR imaging (T1 and T2 weighted images) and “functionally” with a tomographic rCBF technique (SPECT with 133Xe i.v.). The T1 volumes varied between 11 and 220 ml. The correlation between T1 and T2 volumes was 0.95, the T2 volumes being 33% larger than T1 volumes (p < 0.001). The functional SPECT volumes were considerably larger (range 16–324 ml) than the MR volumes. The mean volume difference was 81% between T1 and SPECT images (p < 0.001), and 35% between T2 and SPECT images (p < 0.001). Correlations between the MR and SPECT volumes were also higher for T2 than T1 volumes. The volume difference is most likely explained by a functional decrease in regions around the lesion in which no morphologic change visible on MR images had taken place. MR and SPECT volume measurements were positively related to persistent lack of energy and personality changes, but only moderately related to duration of impaired consciousness and neuropsychologic outcome.

Transsynaptic Retrograde Degeneration: Clinical Evidence with Homonymous RGCL Loss on OCT

BACKGROUND

Retinal thinning after a retrogeniculate lesion (transsynaptic retrograde degeneration) was first described 50 years ago, but has long been a controversial issue. It is now possible to use OCT for the in vivo measurement of retinal thickness.

MATERIAL AND METHODS

This was a retrospective study of patients with homonymous visual field loss, with SD-OCT assessment (RNFL and RGCL measurements) in isolated retrogeniculate lesions, subsequently confirmed by a neuroradiologist.

RESULTS

Nine patients with vascular, inflammatory or tumour brain lesions were included in the study. Homonymous RGCL thinning was found in all patients, and correlated with the visual field defect. No correlation was found with RNFL.

CONCLUSIONS

The homonymous defect of RGCL in patients with retrogeniculate lesions demonstrates the presence of transsynaptic retrograde degeneration. RGCL is a better predictor of visual field defects than RNFL measurement.

Biphasic response of a tecto-mesencephalic pilocytic astrocytoma after Gamma Knife surgery--A case report

Biphasic response (shrinkage-regrowth-shrinkage) of tumors has never previously been reported in the postoperative course, neither after microsurgery, nor after Gamma Knife surgery (GKS). We present the case of an adult with dorsal midbrain syndrome resulting from a pilocytic astrocytoma centered on the mesencephalic tectum. The tumor extended to the third ventricle and the thalamus. Initially, due to tumor growth, a biopsy was performed and histology established. Later, a ventriculocisternostomy for obstructive hydrocephalus was performed. Finally, GKS was performed, as the tumor continued to grow. After GKS, the lesion exhibited a biphasic response, with a major shrinkage at 3 months, regrowth within the target volume at 6 and 9 months and a second phase of important shrinkage at 12 months, which persisted for the next two years. The possible mechanisms for this particular response pattern are discussed.

The 16p11.2 locus modulates brain structures common to autism, schizophrenia and obesity

Anatomical structures and mechanisms linking genes to neuropsychiatric disorders are not deciphered. Reciprocal copy number variants at the 16p11.2 BP4-BP5 locus offer a unique opportunity to study the intermediate phenotypes in carriers at high risk for autism spectrum disorder (ASD) or schizophrenia (SZ). We investigated the variation in brain anatomy in 16p11.2 deletion and duplication carriers. Beyond gene dosage effects on global brain metrics, we show that the number of genomic copies negatively correlated to the gray matter volume and white matter tissue properties in cortico-subcortical regions implicated in reward, language and social cognition. Despite the near absence of ASD or SZ diagnoses in our 16p11.2 cohort, the pattern of brain anatomy changes in carriers spatially overlaps with the well-established structural abnormalities in ASD and SZ. Using measures of peripheral mRNA levels, we confirm our genomic copy number findings. This combined molecular, neuroimaging and clinical approach, applied to larger datasets, will help interpret the relative contributions of genes to neuropsychiatric conditions by measuring their effect on local brain anatomy.

Improving prediction of recanalization in acute large-vessel occlusive stroke

BACKGROUND

Recanalization in acute ischemic stroke with large-vessel occlusion is a potent indicator of good clinical outcome.

OBJECTIVE

To identify easily available clinical and radiologic variables predicting recanalization at various occlusion sites.

METHODS

All consecutive, acute stroke patients from the Acute STroke Registry and Analysis of Lausanne (2003-2011) who had a large-vessel occlusion on computed tomographic angiography (CTA) (< 12 h) were included. Recanalization status was assessed at 24 h (range: 12-48 h) with CTA, magnetic resonance angiography, or ultrasonography. Complete and partial recanalization (corresponding to the modified Treatment in Cerebral Ischemia scale 2-3) were grouped together. Patients were categorized according to occlusion site and treatment modality.

RESULTS

Among 439 patients, 51% (224) showed complete or partial recanalization. In multivariate analysis, recanalization of any occlusion site was most strongly associated with endovascular treatment, including bridging therapy (odds ratio [OR] 7.1, 95% confidence interval [CI] 2.2-23.2), and less so with intravenous thrombolysis (OR 1.6, 95% CI 1.0-2.6) and recanalization treatments performed beyond guidelines (OR 2.6, 95% CI 1.2-5.7). Clot location (large vs. intermediate) and tandem pathology (the combination of intracranial occlusion and symptomatic extracranial stenosis) were other variables discriminating between recanalizers and non-recanalizers. For patients with intracranial occlusions, the variables significantly associated with recanalization after 24 h were: baseline National Institutes of Health Stroke Scale (NIHSS) (OR 1.04, 95% CI 1.02-1.1), Alberta Stroke Program Early CT Score (ASPECTS) on initial computed tomography (OR 1.2, 95% CI 1.1-1.3), and an altered level of consciousness (OR 0.2, 95% CI 0.1-0.5).

CONCLUSIONS

Acute endovascular treatment is the single most important factor promoting recanalization in acute ischemic stroke. The presence of extracranial vessel stenosis or occlusion decreases recanalization rates. In patients with intracranial occlusions, higher NIHSS score and ASPECTS and normal vigilance facilitate recanalization. Clinical use of these predictors could influence recanalization strategies in individual patients.

Combination of MRI and dynamic FET PET for initial glioma grading

AIM

MRI and PET with 18F-fluoro-ethyl-tyrosine (FET) have been increasingly used to evaluate patients with gliomas. Our purpose was to assess the additive value of MR spectroscopy (MRS), diffusion imaging and dynamic FET-PET for glioma grading.

PATIENTS, METHODS

38 patients (42 ± 15 aged, F/M: 0.46) with untreated histologically proven brain gliomas were included. All underwent conventional MRI, MRS, diffusion sequences, and FET-PET within 3±4 weeks. Performances of tumour FET time-activity-curve, early-to-middle SUVmax ratio, choline / creatine ratio and ADC histogram distribution pattern for gliomas grading were assessed, as compared to histology. Combination of these parameters and respective odds were also evaluated.

RESULTS

Tumour time-activity-curve reached the best accuracy (67%) when taken alone to distinguish between low and high-grade gliomas, followed by ADC histogram analysis (65%). Combination of time-activity-curve and ADC histogram analysis improved the sensitivity from 67% to 86% and the specificity from 63-67% to 100% (p < 0.008). On multivariate logistic regression analysis, negative slope of the tumour FET time-activity-curve however remains the best predictor of high-grade glioma (odds 7.6, SE 6.8, p = 0.022).

CONCLUSION

Combination of dynamic FET-PET and diffusion MRI reached good performance for gliomas grading. The use of FET-PET/MR may be highly relevant in the initial assessment of primary brain tumours.

Perfusion measurement in brain gliomas with intravoxel incoherent motion MRI

BACKGROUND AND PURPOSE

Intravoxel incoherent motion MRI has been proposed as an alternative method to measure brain perfusion. Our aim was to evaluate the utility of intravoxel incoherent motion perfusion parameters (the perfusion fraction, the pseudodiffusion coefficient, and the flow-related parameter) to differentiate high- and low-grade brain gliomas.

MATERIALS AND METHODS

The intravoxel incoherent motion perfusion parameters were assessed in 21 brain gliomas (16 high-grade, 5 low-grade). Images were acquired by using a Stejskal-Tanner diffusion pulse sequence, with 16 values of b (0-900 s/mm(2)) in 3 orthogonal directions on 3T systems equipped with 32 multichannel receiver head coils. The intravoxel incoherent motion perfusion parameters were derived by fitting the intravoxel incoherent motion biexponential model. Regions of interest were drawn in regions of maximum intravoxel incoherent motion perfusion fraction and contralateral control regions. Statistical significance was assessed by using the Student t test. In addition, regions of interest were drawn around all whole tumors and were evaluated with the help of histograms.

RESULTS

In the regions of maximum perfusion fraction, perfusion fraction was significantly higher in the high-grade group (0.127 ± 0.031) than in the low-grade group (0.084 ± 0.016, P < .001) and in the contralateral control region (0.061 ± 0.011, P < .001). No statistically significant difference was observed for the pseudodiffusion coefficient. The perfusion fraction correlated moderately with dynamic susceptibility contrast relative CBV (r = 0.59). The histograms of the perfusion fraction showed a "heavy-tailed" distribution for high-grade but not low-grade gliomas.

CONCLUSIONS

The intravoxel incoherent motion perfusion fraction is helpful for differentiating high- from low-grade brain gliomas.

Design, data management, and population baseline characteristics of the PERFORM magnetic resonance imaging project

Quantitative information from magnetic resonance imaging (MRI) may substantiate clinical findings and provide additional insight into the mechanism of clinical interventions in therapeutic stroke trials. The PERFORM study is exploring the efficacy of terutroban versus aspirin for secondary prevention in patients with a history of ischemic stroke. We report on the design of an exploratory longitudinal MRI follow-up study that was performed in a subgroup of the PERFORM trial. An international multi-centre longitudinal follow-up MRI study was designed for different MR systems employing safety and efficacy readouts: new T2 lesions, new DWI lesions, whole brain volume change, hippocampal volume change, changes in tissue microstructure as depicted by mean diffusivity and fractional anisotropy, vessel patency on MR angiography, and the presence of and development of new microbleeds. A total of 1,056 patients (men and women ≥ 55 years) were included. The data analysis included 3D reformation, image registration of different contrasts, tissue segmentation, and automated lesion detection. This large international multi-centre study demonstrates how new MRI readouts can be used to provide key information on the evolution of cerebral tissue lesions and within the macrovasculature after atherothrombotic stroke in a large sample of patients.

Early profiles of clinical evolution after intravenous thrombolysis in an unselected stroke population

BACKGROUND

Intravenous recombinant tissular plasminogen activator (rt-PA) is the only approved pharmacological treatment for acute ischaemic stroke. The authors aimed to analyse potential causes of the variable effect on early course and late outcome.

METHODS AND RESULTS

136 patients (42% women, 58% men) treated with intravenous rt-PA within 3 h of stroke onset in an acute stroke unit over a 3-year period, were included. Early clinical profiles of evolution at 48 h were divided into clinical improvement (CI) (decrease >4 points in the National Institute of Health Stroke Scale (NIHSS)); clinical worsening (CW) (increase >4 points NIHSS); clinical worsening after initial improvement (CWFI) (variations of >4 points in the NIHSS). Patients with clinical stability (no NIHSS modification or <4 points) were excluded. The patients showed in 66.9% CI, 13.2% CW 8.1 % CWFI and 11.8% remained stable. Female sex, no hyperlipaemia and peripheral arterial disease were associated with CW. Male sex and smoking were associated with CI. Absence of arterial occlusion on admission (28.4%) and arterial recanalisation at 24 h were associated with CI. Main causes of clinical deterioration included symptomatic intracranial haemorrhage (sICH), persistent occlusion and cerebral oedema. 23.5% developed ICH, 6.6% of which had sICH. At 3 months, 15.5% had died. Mortality was increased in CW, mainly related to sICH and cerebral oedema. The outcome of CWFI was intermediate between CW and CI.

CONCLUSIONS

Early clinical profiles of evolution in thrombolysed patients vary considerably. Even with CI, it is critical to maintain vessel permeability to avoid subsequent CW.

Atypical presentation of Prader-Willi syndrome with cerebral venous thrombosis: association or fortuity?

A newborn female born at term was admitted at 28 hours for seizures and generalized hypotonia. Cerebral ultrasound showed a right temporal echogenic lesion confirmed on MRI and thought to be secondary to thrombosis of the vein of Labbé. The EEG showed epileptic discharges over the right temporal region. Extensive thrombotic studies revealed a transiently decreased PTT consistent with a prothrombotic state. The hypotonia did not resolve after the acute phase as expected, raising the possibility of another underlying cause. Because of a peculiar phenotype with almond-shaped eyes and bitemporal depression, Prader-Willi syndrome (PWS) was suspected. Methylation analysis confirmed PWS, FISH analysis excluded a deletion in 15q11-q13, maternal uniparental disomy (UPD) was confirmed. To our knowledge, this is the first report of the association of a neonatal venous thrombosis and a PW Syndrome.

Progressive unilateral hemispheric atrophy in an infant with neurofibromatosis

INTRODUCTION

Cerebrovascular diseases are rarely seen in neurofibromatosis type 1. These include vascular occlusive disease, moyamoya vessels, aneurysms, arteriovenous malformations and fistulae.

CASE REPORT

We describe the case of an infant with genetically proven neurofibromatosis type 1 and progressive brain hemiatrophy over months, due to primary narrowing of intracranial carotid artery branches, as demonstrated by successive brain imaging. She presented with refractory seizures and a progressive hemiparesis associated with developmental delay. Surgical material from hemispherotomy done at 18 months showed severe abnormalities of the small vessels.

CONCLUSION

Cerebrovascular changes seen in neurofibromatosis can be diffuse and progressive, with secondary hemiparesis, epilepsy and developmental delay.

CT angiography and perfusion CT in cerebral vasospasm after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

We investigated the association of multisection CT angiography (MSCTA) and perfusion CT (PCT) for the characterization of vasospasm secondary to aneurysmal subarachnoid hemorrhage.

MATERIALS AND METHODS

Among 27 patients with symptomatic cerebrovascular vasospasm investigated by digital subtraction angiography (DSA), 18 underwent both cerebral PCT and MSCTA. For the remaining 9, only PCT or MSCTA could be performed. MSCTA was compared with DSA for the detection and characterization of vasospasm on 286 intracranial arterial segments. PCT maps were visually reviewed for mean transit time, relative cerebral blood flow, and relative cerebral blood volume abnormalities and were qualitatively compared with the corresponding regional vasospasm detected by DSA.

RESULTS

Vasospasm was grouped into 2 categories: mild-moderate and severe. The depiction of vasospasm by MSCTA showed the best sensitivity, specificity, and accuracy at the level of the A2 and M2 arterial segments (100% for each), in contrast to the carotid siphon (45%, 100%, and 85% respectively). The characterization of vasospasm severity by MSCTA showed a sensitivity, specificity, and accuracy of 86.8%, 96.8%, and 95.2%, respectively, for mild-moderate vasospasm, and 76.5%, 99.5%, and 97.5%, respectively, for severe vasospasm. The PCT abnormalities were related to severe vasospasm in 9 patients and to mild-to-moderate vasospasm in 2. The sensitivity, specificity, and accuracy of PCT in detecting vasospasm were 90%, 100%, and 92.3%, respectively, for severe vasospasm, and 20%, 100%, and 38.5%, respectively, for mild-moderate vasospasm.

CONCLUSION

MSCTA/PCT can assess the location and severity of cerebrovascular vasospasm and its related perfusion abnormalities. It can identify severe vasospasm with risk of delayed ischemia and can thus guide the invasive treatment.

Intentional motor phantom limb syndrome

OBJECTIVE

To investigate the clinical and anatomic correlates of a previously unreported form of chronic supernumerary phantom limb, which developed only in association with motor intent directed at a hemiplegic-anesthetic upper limb.

METHODS

We explored the phenomenology of the phantom illusion in the light of motor control models. Hemodynamic correlates of supernumerary phantom limb were studied with an fMRI sensorimotor paradigm consisting of finger-thumb opposition movements.

RESULTS

The kinesthetic-proprioceptive illusion of a third arm was triggered by any attempt to move the paretic limb, by bimanual actions, and by motor imagery involving the nonfunctional limb. The responsible lesion destroyed the posterior part of the posterior limb of the internal capsule on the opposite side, damaging corticospinal and thalamocortical tracts. Comparison between fMRI signals performed during virtual movement of the phantom hand vs imaginary movement of the paretic hand showed increased activation in thalamus and caudate nucleus in the first condition.

CONCLUSIONS

A preserved sense of agency provided by intact premotor processes translating intention into action may lead to the vivid feeling of movement in a paralyzed limb, similar to kinesthetic illusions in amputees. The interruption of thalamic afferences may explain the persistence and stability of the phantom by preventing any correction of the mismatch between expected and effective movement. The increased blood oxygen level-dependent (BOLD) signal in the basal ganglia-thalamus-cortex pathway during movement of the supernumerary hand may reflect an abnormal closed-loop functioning of the thalamocortical system underlying the phantom phenomenon.

Painful hand and moving finger treated by wearing a glove

The authors report a patient with unilateral painful hand and moving finger in whom tactile stimulation interrupted both the movement and the pain. This effect suggests a gating mechanism at a segmental level. The difference between afferent and efferent pathway levels and the delay of several months between trauma and occurrence of symptoms support a central mechanism, most probably involving sensorimotor reorganization at a segmental level.

[From the eye to the visual cortex: imaging of the visual pathways]

This paper aims to give an overview of the various methods used for imaging of the visual pathways from the globe to the visual cortex and some examples of the most commonly encountered lesions.

Cerebral vascular autoregulation assessed by perfusion-CT in severe head trauma patients

PURPOSE

To use perfusion-CT technique in order to characterize cerebral vascular autoregulation in a population of severe head trauma patients with features of cerebral edema either on the admission or on the follow-up conventional noncontrast cerebral CT.

MATERIAL AND METHODS

A total of 80 perfusion-CT examinations were obtained in 42 severe head trauma patients with features of cerebral edema on conventional noncontrast cerebral CT, either on admission or during follow-up. Perfusion-CT results, i.e. the regional cerebral blood volume (rCBV) and flow (rCBF), were correlated with the mean arterial pressure (MAP) measured during each perfusion-CT examination. Ratios were defined to integrate the concept of cerebral vascular autoregulation, and cluster analysis performed, which allowed identification of different subgroups of patients. MAP values and perfusion-CT results in these groups were compared using Kruskal-Wallis and Wilcoxon (Mann-Whitney) tests. Moreover, the functional outcome of the 42 patients was evaluated 3 months after trauma on the basis of the Glasgow Outcome Scale (GOS) score and similarly compared between groups.

RESULTS

Three main groups of patients were identified: 1) 22 perfusion-CT examinations were collected in 13 patients, characterized by high rCBV and rCBF values and by significant dependence of perfusion-CT rCBV and rCBF results on MAP values (p<0.001), 2) 23 perfusion-CT examinations collected in 19 patients showing perfusion-CT results similar to control trauma subjects, and 3) 33 perfusion-CT collected in 16 patients, with low rCBV and rCBF values and near-independence of perfusion-CT results with respect to MAP values. The first group was interpreted as showing impaired cerebral vascular autoregulation, which was preserved in the third group. The second group was associated with the best functional outcome; it was linked to the first group, because eight patients went from one group to the other from admission to follow-up.

CONCLUSION

Perfusion-CT in severe head trauma patients was able to provide direct and quantitative assessment of cerebral vascular autoregulation with a single measurement. It could hence be used as a guide for brain edema therapy, as well as to monitor the treatment efficiency.

Intracranial arterial and arteriovenous malformations presenting with infarction. Lausanne Stroke Registry study*

Cerebral aneurysms and arteriovenous malformations (AVMs) are well-known sources of intracranial hemorrhage, but can also manifest as other clinical symptoms or remain clinically asymptomatic. The aim was to document and analyze cases of aneurysm or AVM with brain infarction. Survey on 4804 stroke patients treated at the Department of Neurology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland between 1978 and 2000 using the Lausanne Stroke Registry. Twenty patients presented with cerebral aneurysm and 21 with cerebral AVM. Hemorrhage was present in 100% of the AVM and in 75% of the aneurysm patients; in one (5%) of the remaining aneurysm patients, aneurysm and infarction were located in different territories. Infarction associated with Sylvian artery aneurysm was found in three (15%), vertebrobasilar ischemia because of fusiform left vertebral artery aneurysm in one (5%), and dural fistula draining to the distal transversal and left sigmoid sinus associated with a stroke in the territory of the left anterior inferior cerebellar artery in one patient. Ischemic stroke is infrequent, but important, complication in unruptured intracranial aneurysms and AVMs. The early recognition and therapy of these vascular malformations in selected patients can avoid a major neurological deficit or death caused by their rupture.

Magnetic resonance artifact induced by the electrode Activa 3389: an in vitro and in vivo study

BACKGROUND

The electrode Activa 3389 is widely implanted for deep brain stimulation (DBS) and MRI is often used to control the position of the electrode. However, induced distorsion artifacts may result in imprecise localization and may lead to misinterpretations of the clinical effects and mechanisms of DBS.

METHODS

In vitro 3D MR study: the proximal and distal contacts of one electrode were spotted by two localizers. The maximal artifact height (MAH) and width (MAW: measured on distal contact), and the distances between the artifact and the localizers (proximal, distal and lateral) were measured on 2 transverse and sagittal MR sequences with 90 degrees rotation of frequency-encoded gradient and phase direction. In vivo 3D MR study: coronal and sagittal reconstructions along the main axis of the electrode were performed on 10 postoperative MR (20 electrodes) to measure MAH and MAW. A Student t test was used to compare in vitro and in vivo measurements.

FINDINGS

In vitro study: A MAH of 10.35 mm (+/-0.23) and MAW of 3.6 mm (+/-0.2) were found. We measured symmetrical extensions of the artifact over the distal contact. In vivo study: A MAH of 10.36 mm (+/-0.44) and MAW of 3.56 mm (+/-0.30) were obtained. No significant different artifact dimensions were measured between in vitro and in vivo studies (p<0.0001).

INTERPRETATION

Precise 3D localization of the electrode in implanted patients is provided by MR identification of the limits of the distal contact artifact. The position of the other contacts is deduced given the size of the contacts and the intercontact distance.

DTI mapping of human brain connectivity: statistical fibre tracking and virtual dissection

Several approaches have been used to trace axonal trajectories from diffusion MRI data. If such techniques were first developed in a deterministic framework reducing the diffusion information to one single main direction, more recent approaches emerged that were statistical in nature and that took into account the whole diffusion information. Based on diffusion tensor MRI data coming from normal brains, this paper presents how brain connectivity could be modelled globally by means of a random walk algorithm. The mass of connections thus generated was then virtually dissected to uncover different tracts. Corticospinal, corticobulbar, and corticothalamic tracts, the corpus callosum, the limbic system, several cortical association bundles, the cerebellar peduncles, and the medial lemniscus were all investigated. The results were then displayed in the form of an in vivo brain connectivity atlas. The connectivity pattern and the individual fibre tracts were then compared to known anatomical data; a good matching was found.

Strokes restricted to the insular cortex

OBJECTIVE

To characterize clinically acute insular strokes from four patients with a first ever acute stroke restricted to the insula on MRI.

METHODS

The authors studied the clinical presentation of four patients with a first ever acute stroke restricted to the insula on MRI.

RESULTS

The authors found five main groups of clinical presentations: 1) somatosensory deficits in three patients with posterior insular stroke (two with a transient pseudothalamic sensory syndrome, one with partial distribution); 2) gustatory disorder in a patient with left posterior insular infarct; 3) vestibular-like syndrome, with dizziness, gait instability, and tendency to fall, but no nystagmus, in three patients with posterior insular strokes; 4) cardiovascular disturbances, consisting of hypertensive episodes in a patient with a right posterior insular infarct; and 5) neuropsychological disorders, including aphasia (left posterior insula), dysarthria, and transient somatoparaphrenia (right posterior insula).

CONCLUSION

Strokes restricted to the posterior insula may present with pseudothalamic sensory and vestibular-like syndromes as prominent clinical manifestations, but also dysarthria and aphasia (in left lesions), somatoparaphrenia (right lesions) and gustatory dysfunction and blood pressure with hypertensive episodes in right lesions; we did not find acute dysphagia reported in anterior, insular strokes.

Comparison of admission perfusion computed tomography and qualitative diffusion- and perfusion-weighted magnetic resonance imaging in acute stroke patients

BACKGROUND AND PURPOSE

Besides classic criteria, cerebral perfusion imaging could improve patient selection for thrombolytic therapy. The purpose of this study was to compare quantitative perfusion CT imaging and qualitative diffusion- and perfusion-weighted MRI (DWI and PWI) in acute stroke patients at the time of their emergency evaluation.

METHODS

Thirteen acute stroke patients underwent perfusion CT and DWI or PWI on admission. The size of infarct and ischemic lesion (infarct plus penumbra) on the admission perfusion CT was compared with that of the MR abnormalities as shown on the DWI trace and on the relative cerebral blood volume, cerebral blood flow, time to peak, and mean transit time maps calculated from PWI studies.

RESULTS

The most significant correlation was found between infarct size on the admission perfusion CT and abnormality size on the admission DWI map (r=0.968, P<0.001). A significant correlation was also observed between the size of the ischemic lesion (infarct plus penumbra) on the admission perfusion CT and the abnormality size on the mean transit time map calculated from admission PWI (r=0.946, P<0.001). Information about cerebral infarct and total ischemia (infarct plus penumbra) carried by both imaging techniques was similar, with slopes of 0.913 and 0.905, respectively.

CONCLUSIONS

An imaging technique may be helpful in the identification of cerebral penumbra in acute stroke patients and thus in the selection of patients for thrombolytic therapy. Perfusion CT and DWI/PWI are equivalent in this task.

Postanoxic generalized dystonia improved by bilateral Voa thalamic deep brain stimulation

A patient with severe postanoxic dystonia and bilateral necrosis of the basal ganglia, who was confined to a wheelchair, underwent bilateral ventralis oralis anterior deep brain stimulation (Voa-DBS) after 6 weeks of unsuccessful bilateral pallidal DBS (GPi-DBS). After 4 months of high intensity Voa-DBS, cognitively unimpaired, he showed major improvement in dystonia, became ambulant, but committed suicide. Brain examination confirmed the correct location of the electrodes in GPi and Voa on both sides.

Quantitative assessment of regional cerebral blood flows by perfusion CT studies at low injection rates: a critical review of the underlying theoretical models

Viability of the cerebral parenchyma is dependent on cerebral blood flow (CBF), which is usually kept in a very narrow range due to efficient autoregulation processes and can be altered in a variety of pathological conditions. An accurate method allowing for a quantitative assessment of regional cerebral blood flows (rCBF) and available for the routine clinical practice would, for sure, greatly contribute to improving the management of patients with cerebrovascular diseases. Different imaging techniques are now available to evaluate rCBF: positron emission tomography; single photon emission CT; stable-xenon CT; perfusion CT; and perfusion MRI. Each of these imaging techniques uses an indicator, with specific biological properties, and is supported by a model, which consists of a few simplifying assumptions, necessary to state and solve the equations giving access to rCBF. The obtained results are more or less reliable, depending on whether modeling hypotheses are fulfilled by the used indicator. The purpose of this article is to review the various supporting models in the assessment of rCBF, with special emphasis on perfusion CT studies at low injection rates and on iodinated contrast material used as an indicator.

Vision after early-onset lesions of the occipital cortex: II. Physiological studies

In one of two patients (MS and FJ) with bilateral, early-onset lesion of the primary visual cortex, Kiper et al. (2002) observed a considerable degree of functional recovery. To clarify the physiological mechanisms involved in the recovery, we used fMRI and quantitative EEG to study both patients. The fMRI investigations indicated that in both patients, isolated islands of the primary visual cortex are functioning, in the right hemisphere in MS and in the left in FJ. The functional recovery observed in MS roughly correlated with the functional maturation of interhemispheric connections and might reflect the role of corticocortical connectivity in visual perception. The functionality of interhemispheric connections was assessed by analyzing the changes in occipital inter-hemispheric coherence of EEG signals (ICoh) evoked by moving gratings. In the patient MS, this ICoh response was present at 7:11 y and was more mature at 9:2 y. In the more visually impaired patient, FJ, a consistent increase in ICoh to visual stimuli could not be obtained, possibly because of the later occurrence of the lesion.

Vision after early-onset lesions of the occipital cortex: I. Neuropsychological and psychophysical studies

We analyzed the visual functions of two patients (MS, FJ) with bilateral lesion of the primary visual cortex, which occurred at gestational age 33 wk in MS and at postnatal month 7 in FJ. In both patients basic visual functions--visual acuity, contrast sensitivity, color, form, motion perception-are similarly preserved or modestly impaired. Functions requiring higher visual processing, particularly figure-ground segregation based on textural cues, are severely impaired. In MS, studied longitudinally, the deficits attenuated between the ages of 4.5 and 8 y, suggesting that the developing visual system can display a considerable degree of adaptive plasticity several years after the occurrence of a lesion. In FJ (age 18:9 to 20:6 y), who is more impaired, the recovery, if any, was less.

Functional activation of microgyric visual cortex in a human

We report on the case of a 20-year-old man with bilateral parasagittal parieto-occipital polymicrogyria and epilepsy. Functional magnetic resonance imaging responses to reversing checkerboard and interhemispheric electroencephalogram coherence changes to moving gratings were investigated. Results of both studies indicate that the polymicrogyric cortex was activated by visual stimuli, suggesting preserved function in the dysplastic area.

Three-dimensional computed tomography angiography and magnetic resonance angiography of carotid bifurcation stenosis

PURPOSE

To evaluate the role of computed tomography angiography (CTA) and magnetic resonance angiography (MRA) in the quantification of atherosclerotic stenosis of carotid artery bifurcation in comparison with digital substraction angiography (DSA) and Doppler sonography (DS).

MATERIALS AND METHODS

Twenty-five patients with atherosclerotic disease of the carotid arteries with proven stenosis by DSA, had spiral CTA, MRA using two- and three-dimensional time-of-flight gradient echo techniques, and DS using Doppler flow signal recording (total 47 carotid artery bifurcations). The degree of stenosis was measured according to the North American Symptomatic Carotid Endarterectomy Trial criteria: total occlusion (100%), severe (70-99%), moderate (30-69%) and mild (0-29%). The degree of stenosis measured by CTA, MRA and DS was compared to DSA, used as the gold standard.

RESULTS

Ninety-seven percent of MRA measures were equivalent to DSA, and 3% were underestimated; 96% of CTA measures were equivalent to DSA, and 4% were underestimated; 77% of DS measures were equivalent to DSA, 21% were overestimated and 2% were underestimated.

CONCLUSIONS

CTA and MRA are equally accurate methods in quantifying the degree of carotid bifurcation stenosis.

Brain involvement in haemolytic-uraemic syndrome: MRI features of coagulative necrosis

We describe radiological demonstration of brain involvement in haemolytic-uraemic syndrome (HUS) in two siblings with a very different clinical course. While the brother presented with a mild, reversible encephalopathy, his sister developed high-signal lesions in the cortex, putamen and caudate nucleus on T1-weighted images, seen as dense areas on CT. Biopsy revealed coagulative necrosis due to microthrombosis without haemorrhage, calcification or infection. These findings suggest a possible prognostic role for MRI in cases of encephalopathy due to HUS.

Simultaneous measurement of regional cerebral blood flow by perfusion CT and stable xenon CT: a validation study

BACKGROUND AND PURPOSE

Knowledge of cerebral blood flow (CBF) alterations in cases of acute stroke could be valuable in the early management of these cases. Among imaging techniques affording evaluation of cerebral perfusion, perfusion CT studies involve sequential acquisition of cerebral CT sections obtained in an axial mode during the IV administration of iodinated contrast material. They are thus very easy to perform in emergency settings. Perfusion CT values of CBF have proved to be accurate in animals, and perfusion CT affords plausible values in humans. The purpose of this study was to validate perfusion CT studies of CBF by comparison with the results provided by stable xenon CT, which have been reported to be accurate, and to evaluate acquisition and processing modalities of CT data, notably the possible deconvolution methods and the selection of the reference artery.

METHODS

Twelve stable xenon CT and perfusion CT cerebral examinations were performed within an interval of a few minutes in patients with various cerebrovascular diseases. CBF maps were obtained from perfusion CT data by deconvolution using singular value decomposition and least mean square methods. The CBF were compared with the stable xenon CT results in multiple regions of interest through linear regression analysis and bilateral t tests for matched variables.

RESULTS

Linear regression analysis showed good correlation between perfusion CT and stable xenon CT CBF values (singular value decomposition method: R(2) = 0.79, slope = 0.87; least mean square method: R(2) = 0.67, slope = 0.83). Bilateral t tests for matched variables did not identify a significant difference between the two imaging methods (P >.1). Both deconvolution methods were equivalent (P >.1). The choice of the reference artery is a major concern and has a strong influence on the final perfusion CT CBF map.

CONCLUSION

Perfusion CT studies of CBF achieved with adequate acquisition parameters and processing lead to accurate and reliable results.