Francisco Rubio

Analysis of automated methods for spatial normalization of lesioned brains.

Normalization of brain images is a crucial step in MRI data analysis, especially when dealing with abnormal brains. Although cost function masking (CFM) appears to successfully solve this problem and seems to be necessary for patients with chronic stroke lesions, this procedure is very time consuming. The present study sought to find viable, fully automated alternatives to cost function masking, such as Automatic Lesion Identification (ALI) and Diffeomorphic Anatomical Registration using Exponentiated Lie algebra (DARTEL). It also sought to quantitatively assess, for the first time, Symmetrical Normalization (SyN) with constrained cost function masking. The second aim of this study was to investigate the normalization process in a group of drug-resistant epileptic patients with large resected regions (temporal lobe and amygdala) and in a group of stroke patients. A dataset of 500 artificially generated lesions was created using ten patients with brain-resected regions (temporal lobectomy), ten stroke patients and twenty five-healthy subjects. The results indicated that although a fully automated method such as DARTEL using New Segment with an extra prior (the mean of the white matter and cerebro-spinal fluid) obtained the most accurate normalization in both patient groups, it produced a shrinkage in lesion volume when compared to Unified Segmentation with CFM. Taken together, these findings suggest that further research is needed in order to improve automatic normalization processes in brains with large lesions and to completely abandon manual, time consuming normalization methods.

Music-Supported Therapy induces plasticity in the sensorimotor cortex in chronic stroke: A single-case study using multimodal imaging (fMRI-TMS)

Primary objective: Music-Supported Therapy (MST) has been developed recently in order to improve the use of the affected upper extremity after stroke. This study investigated the neuroplastic mechanisms underlying effectiveness in a patient with chronic stroke. Methods: MST uses musical instruments, a midi piano and an electronic drum set emitting piano sounds, to retrain fine and gross movements of the paretic upper extremity. Data are presented from a patient with a chronic stroke (20 months post-stroke) with residual right-sided hemiparesis who took part in 20 MST sessions over the course of 4 weeks. Results: Post-therapy, a marked improvement of movement quality, assessed by 3D movement analysis, was observed. Moreover, functional magnetic resonance imaging (fMRI) of a sequential hand movement revealed distinct therapy-related changes in the form of a reduction of excess contralateral and ipsilateral activations. This was accompanied by changes in cortical excitability evidenced by transcranial magnetic stimulation (TMS). Functional MRI in a music listening task suggests that one of the effects of MST is the task-dependent coupling of auditory and motor cortical areas. Conclusions: The MST appears to be a useful neurorehabilitation tool in patients with chronic stroke and leads to neural reorganization in the sensorimotor cortex.

Clinical outcome of spontaneous non‐aneurysmal subarachnoid hemorrhage in 108 patients

Background:  The cause of spontaneous subarachnoid hemorrhage (SAH) is unknown in 15% of cases; idiopathic SAH has a better prognosis than aneurysmal SAH. When bleeding is confined to the perimesencephalic cisterns, SAH has an especially benign course.

Plasticity in the sensorimotor cortex induced by Music-supported therapy in stroke patients: a TMS study

Playing a musical instrument demands the engagement of different neural systems. Recent studies about the musicians brain and musical training highlight that this activity requires the close interaction between motor and somatosensory systems. Moreover, neuroplastic changes have been reported in motor-related areas after short and long-term musical training. Because of its capacity to promote neuroplastic changes, music has been used in the context of stroke neurorehabilitation. The majority of patients suffering from a stroke have motor impairments, preventing them to live independently. Thus, there is an increasing demand for effective restorative interventions for neurological deficits. Music-supported Therapy (MST) has been recently developed to restore motor deficits. We report data of a selected sample of stroke patients who have been enrolled in a MST program (1 month intense music learning). Prior to and after the therapy, patients were evaluated with different behavioral motor tests. Transcranial Magnetic Stimulation (TMS) was applied to evaluate changes in the sensorimotor representations underlying the motor gains observed. Several parameters of excitability of the motor cortex were assessed as well as the cortical somatotopic representation of a muscle in the affected hand. Our results revealed that participants obtained significant motor improvements in the paretic hand and those changes were accompanied by changes in the excitability of the motor cortex. Thus, MST leads to neuroplastic changes in the motor cortex of stroke patients which may explain its efficacy.

Music supported therapy promotes motor plasticity in individuals with chronic stroke.

Novel rehabilitation interventions have improved motor recovery by induction of neural plasticity in individuals with stroke. Of these, Music-supported therapy (MST) is based on music training designed to restore motor deficits. Music training requires multimodal processing, involving the integration and co-operation of visual, motor, auditory, affective and cognitive systems. The main objective of this study was to assess, in a group of 20 individuals suffering from chronic stroke, the motor, cognitive, emotional and neuroplastic effects of MST. Using functional magnetic resonance imaging (fMRI) we observed a clear restitution of both activity and connectivity among auditory-motor regions of the affected hemisphere. Importantly, no differences were observed in this functional network in a healthy control group, ruling out possible confounds such as repeated imaging testing. Moreover, this increase in activity and connectivity between auditory and motor regions was accompanied by a functional improvement of the paretic hand. The present results confirm MST as a viable intervention to improve motor function in chronic stroke individuals.

Overactivation of the supplementary motor area in chronic stroke patients

Stroke induces a loss of neural function, but it triggers a complex amount of mechanisms to compensate the associated functional impairment. The present study aims to increase our understanding of the functional reshape of the motor system observed in chronic stroke patients during the preparation and the execution of movements. A cohort of 14 chronic stroke patients with a mild-to-moderate hemiparesis and 14 matched healthy controls were included in this study. Participants were asked to perform a bimanual reaction time task synchronizing alternated responses to the presentation of a visual cue. We used Laplacian-transformed EEG activity (LT-EEG) recorded at the locations Cz and C3/C4 to study the response-locked components associated with the motor system activity during the performance of this task. Behaviorally, patients showed larger variable errors than controls in synchronizing the frequency of execution of responses to the interstimulus interval, as well as slower responses compared with controls. LT-EEG analysis showed that whereas control participants increased their supplementary motor area (SMA) activity during the preparation of all responses, patients only showed an increment of activity over this area during their first response of the sequence. More interestingly, patients showed a clear increment of the LT-EEG activity associated with SMA shortly after motor responses as compared to the control participants. Finally, patients showed a hand-dependent inhibitory activity over motor areas ipsilateral to the response hand. Overall, our findings reveal drastic differences in the temporal dynamics of the LT-EEG components associated with the activity over motor and premotor cortices in chronic stroke patients compared with matched control participants during alternated hand responses.

Laser evoked potentials and prepulse inhibition of the blink reflex in patients with Wallenberg's syndrome

&NA; Spinothalamic tract lesions in patients with Wallenbergs syndrome can be demonstrated by abnormalities in the laser evoked potentials (LEPs) to stimulation of the affected side. However, before reaching the structures generating LEPs, laser stimuli can induce effects at a subcortical level. We examined LEPs and laser‐induced prepulse inhibition of the blink reflex in seven patients with Wallenbergs syndrome within a month after the infarct. All patients had abnormally elevated thresholds for temperature and pain sensation, and for pinprick pain induced by laser stimuli, in the affected vs the non‐affected side. LEPs to stimulation of the affected side were abnormal because of absent, reduced or delayed responses. However, the same laser stimuli that were unable to induce LEPs generated normal inhibition of the blink reflex response when applied 250 ms before a trigeminal nerve electrical stimulus. The percentage inhibition induced in the R2 response of the blink reflex by laser stimulation of the affected side was not different from that induced by stimulation of the non‐affected side, or in control subjects. These results are compatible with either a different pathway for prepulse inhibition and evoked potentials or a reduced energy requirement of the sensory input generating prepulse inhibition in comparison to that generating evoked potentials.

Language recovery and evidence of residual deficits after nonthalamic subcortical stroke: A 1 year follow-up study

A variety of language disturbances including aphasia have been described after subcortical stroke but less is known about the factors that influence the long-term recovery of stroke-induced language dysfunction. We prospectively examined the role of the affected hemisphere and the lesion site in the occurrence and recovery of language deficits in nonthalamic subcortical stroke. Forty patients with unilateral basal ganglia stroke underwent language assessment within 1 week, 3 months and 1 year after stroke. Disturbances in at least one language domain were observed in 35 patients during the first week post stroke including aphasia diagnosed in 11 patients. Importantly, the appearance of deficits after stroke onset and the improvement of language function were not determined by the site of subcortical lesion, but instead were critically influenced by the affected hemisphere. In fact, the language impairments following left and right basal ganglia stroke mirrored the language dysfunction observed after cortical lesions

E-012 Urgent intra-arterial thrombectomy for stroke: technical complications

Introduction Since April 2010, a pilot experience has been set for offering intra-arterial treatment for stroke to a 3.5 million people population. We aim to share our experience from the standpoint of technical complications. Material and Methods The review of 122 patients (69 male and 53 female, mean age 65,4 years) show that twelve cases presented technical complications. In four patients, distal emboli to other territories than the occluded vessel were seen. Two of them were not specifically treated and showed a bad outcome, while the other two were successfully treated with good final Rankin Score. Hemorrhage during microcateterization was noted in four patients. Even though the bleeding was controlled with glue or coils, bad outcome was noted in those patients. One patient presented a femoral pseudoaneurysm related to the puncture site, with severe bleeding and other co-morbidity leading to death. Carotid stent issues in tandem lesions were seen in two patients. In one case, the thrombectomy device was let in place (M1) due to impossibility to retrieve it. Some subclinical incidences as balloon rupture (1 case), M1, M2 or M3 vasospasm, easily resolved with intraarterial nimodipine (3 cases) and some degree of vessel dissection without significant caliber reduction (3 cases) were also recorded. Results and Conclusion In our series, around a ten percent of intraarterial thrombectomy treatments presented procedure related complications. In our opinion, four of them can be attributed to our learning curve, leading to a theoretical complication risk of around a 7% for technical complications. Competing interests None.