Inter-dural spinal cyst with acute thoracic compressive myelopathy: anatomical aspects of spinal dura, case report and literature review.

INTRODUCTION: Inter-dural juxta-facet spinal cysts occur rarely. They form as part of the degenerative spinal disease process and can be misdiagnosed as synovial cysts or ganglion cysts. We report the case of a thoracic inter-dural juxta-facet spinal cyst causing acute compressive thoracic myelopathy. METHODS: The data was collected retrospectively from patient records. The literature review was performed in PubMed. RESULTS: We report a case of symptomatic inter-dural juxta-facet thoracic spinal cyst. The literature review showed a variety of different spinal cysts including arachnoid cyst, discal cyst, ganglion cyst, epidermoid cyst and synovial cysts. Micro-instability and repeated microtrauma associated with degenerative changes are most likely contributors to its formation. Asymptomatic cysts can show spontaneous resolution. When symptomatic, they can be managed with surgical excision with good patient outcome. CONCLUSION: Inter-dural spinal cysts can be diagnosed and surgically excised to produce excellent post-operative outcome. High pre-operative index of suspicion of this diagnosis together with good understanding of the intraoperative anatomy are essential to avoid inadvertent dural breach.

Reproducibility of MRI-based white matter tract estimation using multi-fiber probabilistic tractography: effect of user-defined parameters and regions.

OBJECTIVE: There is a pressing need to assess user-dependent reproducibility of multi-fibre probabilistic tractography in order to encourage clinical implementation of these advanced and relevant approaches. The goal of this study was to evaluate both intrinsic and inter-user reproducibility of corticospinal tract estimation. MATERIALS AND METHODS: Six clinical datasets including motor functional and diffusion MRI were used. Three users performed an independent tractography analysis following identical instructions. Dice indices were calculated to quantify the reproducibility of seed region, fMRI-based end region, and streamline maps. RESULTS: The inter-user reproducibility ranged 41-93%, 29-94%, and 50-92%, for seed regions, end regions, and streamline maps, respectively. Differences in streamline maps correlated with differences in seed and end regions. Good inter-user agreement in seed and end regions, yielded inter-user reproducibility close to the intrinsic reproducibility (92-97%) and in most cases higher than 80%. DISCUSSION: Uncertainties related to user-dependent decisions and the probabilistic nature of the analysis should be considered when interpreting probabilistic tractography data. The standardization of the methods used to define seed and end regions is a necessary step to improve the accuracy and robustness of multi-fiber probabilistic tractography in a clinical setting. Clinical users should choose a feasible compromise between reproducibility and analysis duration.

Intraoperative mapping of pre-central motor cortex and subcortex: a proposal for supplemental cortical and novel subcortical maps to Penfield's motor homunculus.

Penfield's motor homunculus describes a caricaturised yet useful representation of the map of various body parts on the pre-central cortex. We propose a supplemental map of the clinically represented areas of human body in pre-central cortex and a novel subcortical corticospinal tract map. We believe this knowledge is essential for safe surgery in patients with eloquent brain lesions. A single-institution retrospective cohort study of patients who underwent craniotomy for motor eloquent lesions with intraoperative motor neuromonitoring (cortical and subcortical) between 2015 and 2020 was performed. All positive cortical and subcortical stimulation points were taken into account and cartographic maps were produced to demonstrate cortical and subcortical areas of motor representation and their configuration. A literature review in PubMed was performed. One hundred and eighty consecutive patients (58.4% male, 41.6% female) were included in the study with 81.6% asleep and 18.4% awake craniotomies for motor eloquent lesions (gliomas 80.7%, metastases 13.8%) with intraoperative cortical and subcortical motor mapping. Based on the data, we propose a supplemental clinical cortical and a novel subcortical motor map to the original Penfield's motor homunculus, including demonstration of localisation of intercostal muscles both in the cortex and subcortex which has not been previously described. The supplementary clinical cortical and novel subcortical motor maps of the homunculus presented here have been derived from a large cohort of patients undergoing direct cortical and subcortical brain mapping. The information will have direct relevance for improving the safety and outcome of patients undergoing resection of motor eloquent brain lesions.

Clinical Non-Motor Phenotyping of Black and Asian Minority Ethnic Compared to White Individuals with Parkinson's Disease Living in the United Kingdom.

BACKGROUND: Ethnic phenotypic differences in Parkinson's disease (PD) are important to understand the heterogeneity of PD and develop biomarkers and clinical trials. OBJECTIVE: To investigate (i) whether there are non-motor symptoms (NMS)- and comorbidity-based phenotypic differences between Black, Asian and Minority Ethnic (BAME) and White PD patients and (ii) whether clinically available biomarkers may help differentiate and explain the differences between the groups. METHODS: This is a multicentre (four sites, London), real-life, cross-sectional study including PD patients of BAME or White ethnicity. The primary outcome was a detailed NMS assessment; additional measurements included disease and motor stage, comorbidity, sociodemographic parameters and brain MRI imaging. RESULTS: 271 PD patients (54 Asian, 71 Black, and 146 White) were included balanced for age, gender, and disease severity (HY). Black patients had a shorter disease duration compared to White and Asian populations. The SCOPA-Motor activities of daily living scores as well as the NMSS scores were significantly higher in both Black (total score and domain "miscellaneous") and Asian (total score and domains "sleep/fatigue", "mood/apathy" and "perception/hallucinations") than White individuals. Both BAME populations had higher prevalence of arterial hypertension, and the Black population had a higher prevalence of diabetes mellitus. Brain MRI revealed a greater severity of white matter changes in Black compared to the White and Asian cohorts. CONCLUSION: These findings suggest differences in phenotype of PD in BAME populations with greater burden of NMS and motor disability and a higher rate of cardiovascular comorbidities.

Radiological pseudoprogression post-radiotherapy in a child with pineal germ cell tumour.

Little is known about pseudoprogression in brain tumours other than gliomas. A 9-year-old male child with a pineal teratoma/germinoma underwent surgical resection followed by adjuvant chemo-radiotherapy. The magnetic resonance imaging scan 4 months post-radiotherapy showed a contrast-enhancing lesion within the surgical cavity suspicious of recurrence. These radiological findings subsequently resolved without any specific intervention. The child continues in remission 2 years post-treatment. This case illustrates the occurrence of pseudoprogression post-radiotherapy in intracranial GCT and highlights an unmet need for greater implementation of functional imaging techniques in paediatric neuro-oncology to avoid undue discontinuation of effective treatments or inappropriate enrolment in clinical trials.

Implementation of clinical tractography for pre-surgical planning of space occupying lesions: An investigation of common acquisition and post-processing methods compared to dissection studies.

BACKGROUND AND PURPOSE: There is limited standardization of acquisition and processing methods in diffusion tractography for pre-surgical planning, leading to a range of approaches. In this study, a number of representative acquisition variants and post processing methods are considered, to assess their importance when implementing a clinical tractography program. METHODS: Diffusion MRI was undertaken in ten healthy volunteers, using protocols typical of clinical and research scanning: a 32-direction diffusion acquisition with and without peripheral gating, and a non-gated 64 diffusion direction acquisition. All datasets were post-processed using diffusion tensor reconstruction with streamline tractography, and with constrained spherical deconvolution (CSD) with both streamline and probabilistic tractography, to delineate the cortico-spinal tract (CST) and optic radiation (OR). The accuracy of tractography results was assessed against a histological atlas using a novel probabilistic Dice overlap technique, together with direct comparison to tract volumes and distance of Meyer's loop to temporal pole (ML-TP) from dissections studies. Three clinical case studies of patients with space occupying lesions were also investigated. RESULTS: Tracts produced by CSD with probabilistic tractography provided the greatest overlap with the histological atlas (overlap scores of 44% and 52% for the CST and OR, respectively) and best matched tract volume and ML-TP distance from dissection studies. The acquisition protocols investigated had limited impact on the accuracy of the tractography. In all patients, the CSD based probabilistic tractography created tracts with greatest anatomical plausibility, although in one case anatomically plausible pathways could not be reconstructed without reducing the probabilistic threshold, leading to an increase in false positive tracts. CONCLUSIONS: Advanced post processing techniques such as CSD with probabilistic tractography are vital for pre-surgical planning. However, overall accuracy relative to dissection studies remains limited.

Implementation of clinically relevant and robust fMRI-based language lateralization: Choosing the laterality index calculation method.

The assessment of language lateralization has become widely used when planning neurosurgery close to language areas, due to individual specificities and potential influence of brain pathology. Functional magnetic resonance imaging (fMRI) allows non-invasive and quantitative assessment of language lateralization for presurgical planning using a laterality index (LI). However, the conventional method is limited by the dependence of the LI on the chosen activation threshold. To overcome this limitation, different threshold-independent LI calculations have been reported. The purpose of this study was to propose a simplified approach to threshold-independent LI calculation and compare it with three previously reported methods on the same cohort of subjects. Fifteen healthy subjects, who performed picture naming, verb generation, and word fluency tasks, were scanned. LI values were calculated for all subjects using four methods, and considering either the whole hemisphere or an atlas-defined language area. For each method, the subjects were ranked according to the calculated LI values, and the obtained rankings were compared. All LI calculation methods agreed in differentiating strong from weak lateralization on both hemispheric and regional scales (Spearman's correlation coefficients 0.59-1.00). In general, a more lateralized activation was found in the language area than in the whole hemisphere. The new method is well suited for application in the clinical practice as it is simple to implement, fast, and robust. The good agreement between LI calculation methods suggests that the choice of method is not key. Nevertheless, it should be consistent to allow a relative comparison of language lateralization between subjects.

Clinical utility of magnetic resonance imaging in first-episode psychosis.

BackgroundThere is no consensus as to whether magnetic resonance imaging (MRI) should be used as part of the initial clinical evaluation of patients with first-episode psychosis (FEP).Aims(a) To assess the logistical feasibility of routine MRI; (b) to define the clinical significance of radiological abnormalities in patients with FEP.MethodRadiological reports from MRI scans of two FEP samples were reviewed; one comprised 108 patients and 98 healthy controls recruited to a research study and the other comprised 241 patients scanned at initial clinical presentation plus 66 healthy controls.ResultsIn the great majority of patients, MRI was logistically feasible. Radiological abnormalities were reported in 6% of the research sample and in 15% of the clinical sample (odds ratio (OR)=3.1, 95% CI 1.26-7.57, χ2(1) = 6.63, P = 0.01). None of the findings necessitated a change in clinical management.ConclusionsRates of neuroradiological abnormalities in FEP are likely to be underestimated in research samples that often exclude patients with organic abnormalities. However, the majority of findings do not require intervention.

Active dendritic cell immunotherapy for glioblastoma: Current status and challenges.

Dendritic cell (DC) immunotherapy is developing as a promising treatment modality for patients with glioblastoma multiforme (GBM). The aim of this article is to review the data from clinical trials and prospective studies evaluating the safety and efficacy of DC vaccines for newly diagnosed (ND)- and recurrent (Rec)-GBM and for other high-grade gliomas (HGGs). By searching all major databases we identified and reviewed twenty-two (n=22) such studies, twenty (n=20) of which were phase I and II trials, one was a pilot study towards a phase I/II trial and one was a prospective study. GBM patients were exclusively recruited in 12/22 studies, while 10/22 studies enrolled patients with any diagnosis of a HGG. In 7/22 studies GBM was newly diagnosed. In the vast majority of studies the vaccine was injected subcutaneously or intradermally and consisted of mature DCs pulsed with tumour lysate or peptides. Median overall survival ranged between 16.0 and 38.4 months for ND-GBM and between 9.6 and 35.9 months for Rec-GBM. Vaccine-related side effects were in general mild (grade I and II), with serious adverse events (grade III, IV and V) reported only rarely. DC immunotherapy therefore appears to have the potential to increase the overall survival in patients with HGG, with an acceptable side effect profile. The findings will require confirmation by the ongoing and future phase III trials.

Cortical thickness, surface area and volume measures in Parkinson's disease, multiple system atrophy and progressive supranuclear palsy.

OBJECTIVE: Parkinson's disease (PD), Multiple System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP) are neurodegenerative diseases that can be difficult to distinguish clinically. The objective of the current study was to use surface-based analysis techniques to assess cortical thickness, surface area and grey matter volume to identify unique morphological patterns of cortical atrophy in PD, MSA and PSP and to relate these patterns of change to disease duration and clinical features. METHODS: High resolution 3D T1-weighted MRI volumes were acquired from 14 PD patients, 18 MSA, 14 PSP and 19 healthy control participants. Cortical thickness, surface area and volume analyses were carried out using the automated surface-based analysis package FreeSurfer (version 5.1.0). Measures of disease severity and duration were assessed for correlation with cortical morphometric changes in each clinical group. RESULTS: Results show that in PSP, widespread cortical thinning and volume loss occurs within the frontal lobe, particularly the superior frontal gyrus. In addition, PSP patients also displayed increased surface area in the pericalcarine. In comparison, PD and MSA did not display significant changes in cortical morphology. CONCLUSION: These results demonstrate that patients with clinically established PSP exhibit distinct patterns of cortical atrophy, particularly affecting the frontal lobe. These results could be used in the future to develop a useful clinical application of MRI to distinguish PSP patients from PD and MSA patients.

Diffusion tensor imaging of Parkinson's disease, multiple system atrophy and progressive supranuclear palsy: a tract-based spatial statistics study.

Although often clinically indistinguishable in the early stages, Parkinson's disease (PD), Multiple System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP) have distinct neuropathological changes. The aim of the current study was to identify white matter tract neurodegeneration characteristic of each of the three syndromes. Tract-based spatial statistics (TBSS) was used to perform a whole-brain automated analysis of diffusion tensor imaging (DTI) data to compare differences in fractional anisotropy (FA) and mean diffusivity (MD) between the three clinical groups and healthy control subjects. Further analyses were conducted to assess the relationship between these putative indices of white matter microstructure and clinical measures of disease severity and symptoms. In PSP, relative to controls, changes in DTI indices consistent with white matter tract degeneration were identified in the corpus callosum, corona radiata, corticospinal tract, superior longitudinal fasciculus, anterior thalamic radiation, superior cerebellar peduncle, medial lemniscus, retrolenticular and anterior limb of the internal capsule, cerebral peduncle and external capsule bilaterally, as well as the left posterior limb of the internal capsule and the right posterior thalamic radiation. MSA patients also displayed differences in the body of the corpus callosum corticospinal tract, cerebellar peduncle, medial lemniscus, anterior and superior corona radiata, posterior limb of the internal capsule external capsule and cerebral peduncle bilaterally, as well as the left anterior limb of the internal capsule and the left anterior thalamic radiation. No significant white matter abnormalities were observed in the PD group. Across groups, MD correlated positively with disease severity in all major white matter tracts. These results show widespread changes in white matter tracts in both PSP and MSA patients, even at a mid-point in the disease process, which are not found in patients with PD.

Vanishing white matter disease presenting as opsoclonus myoclonus syndrome in childhood--a case report and review of the literature.

BACKGROUND: Vanishing white matter disease is caused by mutations of the eukaryotic translation initiation factor 2B (EIF2B) and is a prevalent cause of inherited childhood leukoencephalopathy. Infantile and early childhood onset forms are associated with chronic progressive neurological signs, with episodes of rapid, neurological, and poor prognosis, with death in few months or years. In contrast, onset in late childhood and adult onset is rare and is associated with long-term survival because of milder signs and slow progression. PATIENT DESCRIPTION: We present a patient with a genetically proven vanishing white matter disease, typical brain MRI, presenting with opsoclonus myoclonus in early childhood and a delayed development of adult multifocal dystonia and schizoaffective disorder with continued survival. In addition we have also reviewed the relevant literature based on 42 previous articles summarizing clinical details of 318 individuals with vanishing white matter disease (single case reports to case series). In 283, genetic mutation of EIF2B was confirmed with the onset of vanishing white matter disease reported as antenatal (seven), infantile (eight), early childhood (107), between infantile and early childhood (20), late childhood (25), between early and late childhood (three), adult (68), and between late childhood and adult (21). CONCLUSIONS: Various movement disorders have been described with vanishing white matter disease either at presentation (mimicking an opsoclonus myoclonus syndrome) or in adulthood (dystonia and myoclonus) with continuing survival. Relatively preserved cognition is a novel presentation and is reported in this article along with a comprehensive literature review.

Determinants of mismatch in acute ischaemic stroke.

BACKGROUND: Multimodal CT or MR imaging may be helpful in guiding reperfusion therapy for stroke. However, access to multimodal imaging may frequently be limited. We hypothesised that certain clinical and non-enhanced CT (NECT) findings at initial assessment can potentially predict mismatch on CT perfusion (CTP) in patients with acute ischaemic stroke. METHODS: We undertook an analysis of prospectively collected clinical and imaging data of consecutive patients with anterior circulation ischaemic stroke who underwent CTP during their initial assessment. NECT was read for early ischaemic change as measured by the Alberta Stroke Program Early CT Score (ASPECTS), and for hyperdense middle cerebral artery sign (HMCAS). CTP images were evaluated for mismatch. Independent clinical and imaging predictors of a CTP mismatch were identified using stepwise logistic regression. RESULTS: Of the 202 patients, 92 (46%) demonstrated a mismatch, 23 (11%) a matched deficit, and 87 (43%) no perfusion deficit. HMCAS on NECT (OR 13.65, 95% CI 6.04-30.81, p<0.001), female gender (OR 2.37, 95% CI 1.19-4.72, p = 0.015), atrial fibrillation (OR 2.05, 95% CI 1.02-4.11, p = 0.044), and absence of a history of hypertension (OR 0.46, 95% CI 0.22-0.96, p = 0.037) were independent predictors of a CTP mismatch. HMCAS had 58% sensitivity, 91% specificity, 84% positive predictive value and 72% negative predictive value. CONCLUSIONS: A HMCAS on the initial NECT is associated with a high probability of mismatch in acute ischaemic stroke, and may identify patients most likely to benefit from recanalisation treatments when access to multimodal CT or MR facilities is limited.

Preoperative estimation of seizure control after resective surgery for the treatment of epilepsy.

PURPOSE: Predicting seizure control after epilepsy surgery is difficult. The objectives of this work are: (a) to estimate the value of surgical procedure, presence of neuroimaging abnormalities, need for intracranial recordings, resection lobe, pathology, durations of epilepsy and follow-up period to predict postsurgical seizure control after epilepsy surgery and (b) to provide empirical estimates of successful outcome after different combinations of the above factors in order to aid clinicians in advising patients presurgically about the likelihood of success under their patients' individual circumstances. METHODS: We report postsurgical seizure control from all 243 patients who underwent resective surgery for epilepsy at King's College Hospital between 1999 and 2011. Among the 243 patients, 233 had lobar or sub-lobar resections, 8 had multilobar resections and 2 had excision of a hypothalamic hamartoma. We examined the relation between postsurgical seizure control and type of surgical procedure, presence of neuroimaging abnormalities, pathology, resection lobe and the need of intra-cranial electrodes to identify seizure onset. RESULTS: Among the 243 patients, 126 (52%) enjoyed outcome grade I, 40 (16%) had grade II, 51 (21%) had grade III and 26 (11%) had grade IV (mean follow-up 41.1 months). Normal neuroimaging or need for intracranial recordings was not associated with poorer outcome. Patients undergoing temporal resections showed better outcome than those with frontal resections, due to the poor outcome seen in frontal patients with normal neuroimaging. Among temporal resections, there was no difference in outcome between patients with and without neuroimaging abnormalities. Among patients with lesions on imaging, temporal and frontal resections showed similar outcomes. Likelihood of favourable outcome under the patient's individual circumstances was estimated by the tables provided. There was an 8-9% decrease in the percentage of grade I between follow-up at 12 and >36 months. CONCLUSION: Overall, nearly 70% of patients undergoing resective surgery enjoy favourable post-surgical seizure control. Normal neuroimaging should not discourage surgery in temporal patients but is a negative prognostic sign in normal MRI frontal patients. There were no statistical differences in outcome between patients with neuroimaging lesions in frontal or temporal lobes.

A case-controlled comparison of thrombolysis outcomes between wake-up and known time of onset ischemic stroke patients.

BACKGROUND AND PURPOSE: Wake-up ischemic stroke (WUIS) patients are not thrombolysed even if they meet other criteria for treatment. We hypothesized that patients with WUIS showing no or early ischemic changes on brain imaging will have thrombolysis outcomes comparable with those with known time of symptom onset. METHODS: Consecutive sampling of a prospective registry of patients with stroke between January 2009 and December 2010 identified 394 thrombolysed patients meeting predefined inclusion criteria, 326 presenting within 0 to 4.5 hours of symptom onset (Reference Group) and 68 WUIS patients. Inclusion criteria were last seen normal<12 hours or >4.5 hours (WUIS) or presented <4.5 hours (Reference Group), had National Institutes of Health Stroke Scale score ≥5, and no or early ischemic changes on imaging at presentation. The primary outcome measure was the modified Rankin Scale of 0 to 2 at 90 days measured by trained assessors blinded to patient grouping. Other outcome measures were symptomatic intracerebral hemorrhage, modified Rankin Scale 0 to 1, and mortality at 90 days. RESULTS: The groups were comparable for mean age (72.8 versus 73.9 years; P=0.58) and baseline median National Institutes of Health Stroke Scale score (median 13 versus 12; P=0.34). The proportions of patients with modified Rankin Scale 0 to 2 (38% versus 37%; P=0.89) and modified Rankin Scale 0 to 1 (24% versus 16%; P=0.18) at 90 days, any ICH (20% versus 22%; P=0.42) and symptomatic intracerebral hemorrhage (3.4% versus 2.9%; P=1.0) were comparable after adjusting for age, stroke severity, and imaging changes. Only 9/394 (2%) patients were lost to follow-up. CONCLUSIONS: Thrombolysis in selected patients with WUIS is feasible, and its outcomes are comparable with those thrombolysed with 0 to 4.5 hours.

An observational study of thrombolysis outcomes in wake-up ischemic stroke patients.

BACKGROUND AND PURPOSE: Wake-up ischemic stroke (WUIS) patients are not eligible for thrombolysis; the a priori hypothesis was that thrombolysis of selected WUIS patients who meet clinical and imaging criteria for treatment is associated with better outcomes. METHODS: The sample consisted of consecutive WUIS patients who fulfilled predefined criteria: (1) were last seen normal >4.5 hours and <12 hours before presentation; (2) National Institute of Health Stroke Scale score ≥ 5; (3) No or early ischemic changes <1/3 middle cerebral artery territory on computed tomography imaging; (4) No absolute contraindications to thrombolysis. The primary outcome measure was the modified Rankin Scale of 0 to 2 at 90 days. Other outcome measures were mortality and symptomatic intracerebral hemorrhage. RESULTS: WUIS patients constituted 10.5% (193/1836) of all stroke admissions. Inclusion criteria were fulfilled by 122 (63%) patients, of whom 68 (56%) were thrombolysed. Thrombolysed and nonthrombolysed patients were comparable for baseline characteristics, but the median baseline National Institute of Health Stroke Scale score was higher in thrombolysed patients (9 versus 11.5; P=0.034). There was no difference in modified Rankin Scale 0 to 2 (25 [37%] versus 14 [26%]; P=0.346), death (10 [15%] versus 14 [26%]; P=0.122), and symptomatic intracerebral hemorrhage (2 versus 0; P=0.204) between thrombolysed and nonthrombolysed patients. After adjusting for age, sex, and baseline National Institute of Health Stroke Scale score thrombolysis was associated with odds ratio of 5.2 (95% confidence interval 1.3-20.3), P=0.017 for modified Rankin Scale 0 to 2 at 90 days and odds ratio of 0.09 (95% confidence interval 0.02-0.44), P=0.003 for death. CONCLUSIONS: Thrombolysis in selected WUIS patients is feasible and may have potential of benefit.

Safety and clinical outcome of thrombolysis in ischaemic stroke using a perfusion CT mismatch between 3 and 6 hours.

OBJECTIVE: It may be possible to thrombolyse ischaemic stroke (IS) patients up to 6 h by using penumbral imaging. We investigated whether a perfusion CT (CTP) mismatch can help to select patients for thrombolysis up to 6 h. METHODS: A cohort of 254 thrombolysed IS patients was studied. 174 (69%) were thrombolysed at 0-3 h by using non-contrast CT (NCCT), and 80 (31%) at 3-6 h (35 at 3-4.5 h and 45 at 4.5-6 h) by using CTP mismatch criteria. Symptomatic intracerebral haemorrhage (SICH), the mortality and the modified Rankin Score (mRS) were assessed at 3 months. Independent determinants of outcome in patients thrombolysed between 3 and 6 h were identified. RESULTS: The baseline characteristics were comparable in the two groups. There were no differences in SICH (3% v 4%, p = 0.71), any ICH (7% v 9%, p = 0.61), or mortality (16% v 9%, p = 0.15) or mRS 0-2 at 3 months (55% v 54%, p = 0.96) between patients thrombolysed at 0-3 h (NCCT only) or at 3-6 h (CTP mismatch). There were no significant differences in outcome between patients thrombolysed at 3-4.5 h or 4.5-6 h. The NIHSS score was the only independent determinant of a mRS of 0-2 at 3 months (OR 0.89, 95% CI 0.82-0.97, p = 0.007) in patients treated using CTP mismatch criteria beyond 3 h. CONCLUSIONS: The use of a CTP mismatch model may help to guide thrombolysis decisions up to 6 h after IS onset.

Optimal MRI methods for direct stereotactic targeting of the subthalamic nucleus and globus pallidus.

OBJECTIVE: Reliable identification of the subthalamic nucleus (STN) and globus pallidus interna (GPi) is critical for deep brain stimulation (DBS) of these structures. The purpose of this study was to compare the visibility of the STN and GPi with various MRI techniques and to assess the suitability of each technique for direct stereotactic targeting. METHODS: MR images were acquired from nine volunteers with T2- and proton density-weighted (PD-W) fast spin echo, susceptibility-weighted imaging (SWI), phase-sensitive inversion recovery and quantitative T1, T2 and T2* mapping sequences. Contrast-to-noise ratios (CNR) for the STN and GPi were calculated for all sequences. Targeting errors on SWI were evaluated on magnetic susceptibility maps. The sequences demonstrating the best conspicuity of DBS target structures (SWI and T2*) were then applied to ten patients with movement disorders, and the CNRs for these techniques were assessed. RESULTS: SWI offers the highest CNR for the STN, but standard PD-W images provide the best CNR for the pallidum. Susceptibility maps indicated that the GPi margins may be shifted slightly on SWI, although no shifts were seen for the STN. CONCLUSION: SWI may improve the visibility of the STN on pre-operative MRI, potentially improving the accuracy of direct stereotactic targeting.