Lewis-Sumner syndrome: contribution of diffusion tensor imaging in its differential diagnosis.

Lewis-Sumner syndrome (LSS) is an atypical variant of chronic inflammatory demyelinating polyneuropathy characterized by an asymmetric sensory-motor neuropathy with multifocal distribution. The diagnosis is typically clinical and electrophysiological but in some cases might be challenging causing a significant therapeutic delay. Diffusion tensor imaging (DTI) has been progressively used for the in vivo assessment of peripheral nerves integrity. In this study, we aimed to elucidate if DTI was able to detect the specific nerve damage in a patient with suspected LSS, and determine if DTI presented a specific pattern that could be useful in its differential diagnosis. A 38-year-old male with a right foot drop was studied. Physical examination, electrodiagnostic, and MRI studies were performed. MRI of the lower limb was acquired in a 3-T scanner and included T1-wi, T2-TSE-SPIR, and PD-TSE-SPAIR images in axial and coronal planes. Axial DTI was acquired using a single-shot EPI sequence with diffusion encoding in 32 directions. The electrodiagnostic tests suggested a demyelinating sensorimotor neuropathy with conduction blocks. Conventional MRI was normal. DTI showed pathological results in Tibial and Peroneal nerves consisting of thinning and discontinuities along both nerves but more significant in the Peroneal. Compared with MRI, DTI offered a significant improvement to detect the specific nerve damage and its characteristics. The observed nerve damage in DTI suggested polyneuropathy and was compatible with the electrophysiological findings, endorsing the LSS diagnosis. This is the first report in the literature presenting the DTI findings in LSS.

Time stability and connectivity analysis with an intracortical 96-channel microelectrode array inserted in human visual cortex.

Objective.Microstimulation via electrodes that penetrate the visual cortex creates visual perceptions called phosphenes. Besides providing electrical stimulation to induce perceptions, each electrode can be used to record the brain signals from the cortex region under the electrode which contains brain state information. Since the future visual prosthesis interfaces will be implanted chronically in the visual cortex of blind people, it is important to study the long-term stability of the signals acquired from the electrodes. Here, we studied the changes over time and the repercussions of electrical stimulation on the brain signals acquired with an intracortical 96-channel microelectrode array implanted in the visual cortex of a blind volunteer for 6 months.Approach.We used variance, power spectral density, correlation, coherence, and phase coherence to study the brain signals acquired in resting condition before and after the administration of electrical stimulation during a period of 6 months.Main results.Variance and power spectral density up to 750 Hz do not show any significant trend in the 6 months, but correlation coherence and phase coherence significantly decrease over the implantation time and increase after electrical stimulation.Significance.The stability of variance and power spectral density in time is important for long-term clinical applications based on the intracortical signals collected by the electrodes. The decreasing trends of correlation, coherence, and phase coherence might be related to plasticity changes in the visual cortex due to electrical microstimulation.

Visual percepts evoked with an intracortical 96-channel microelectrode array inserted in human occipital cortex.

BACKGROUNDA long-held goal of vision therapy is to transfer information directly to the visual cortex of blind individuals, thereby restoring a rudimentary form of sight. However, no clinically available cortical visual prosthesis yet exists.METHODSWe implanted an intracortical microelectrode array consisting of 96 electrodes in the visual cortex of a 57-year-old person with complete blindness for a 6-month period. We measured thresholds and the characteristics of the visual percepts elicited by intracortical microstimulation.RESULTSImplantation and subsequent explantation of intracortical microelectrodes were carried out without complications. The mean stimulation threshold for single electrodes was 66.8 ± 36.5 µA. We consistently obtained high-quality recordings from visually deprived neurons and the stimulation parameters remained stable over time. Simultaneous stimulation via multiple electrodes was associated with a significant reduction in thresholds (P < 0.001, ANOVA) and evoked discriminable phosphene percepts, allowing the blind participant to identify some letters and recognize object boundaries.CONCLUSIONSOur results demonstrate the safety and efficacy of chronic intracortical microstimulation via a large number of electrodes in human visual cortex, showing its high potential for restoring functional vision in the blind.TRIAL REGISTRATIONClinicalTrials.gov identifier NCT02983370.FUNDINGThe Spanish Ministerio de Ciencia Innovación y Universidades, the Generalitat Valenciana (Spain), the Europan Union's Horizon 2020 programme, the Bidons Egara Research Chair of the University Miguel Hernández (Spain), and the John Moran Eye Center of the University of Utah.

Toward Long-Term Communication With the Brain in the Blind by Intracortical Stimulation: Challenges and Future Prospects.

The restoration of a useful visual sense in a profoundly blind person by direct electrical stimulation of the visual cortex has been a subject of study for many years. However, the field of cortically based sight restoration has made few advances in the last few decades, and many problems remain. In this context, the scientific and technological problems associated with safe and effective communication with the brain are very complex, and there are still many unresolved issues delaying its development. In this work, we review some of the biological and technical issues that still remain to be solved, including long-term biotolerability, the number of electrodes required to provide useful vision, and the delivery of information to the implants. Furthermore, we emphasize the possible role of the neuroplastic changes that follow vision loss in the success of this approach. We propose that increased collaborations among clinicians, basic researchers, and neural engineers will enhance our ability to send meaningful information to the brain and restore a limited but useful sense of vision to many blind individuals.

When Playing Is a Problem: An Atypical Case of Alien Hand Syndrome in a Professional Pianist.

Alien hand syndrome (AHS) is a neurological illness characterized by limb movements which are carried out without being aware of it. Many patients describe these movements as aggressive and some perceive a strong feeling of estrangement and go so far as to deny ownership. The sense of body ownership is the perception that parts of one's body pertain to oneself, despite it is moving or not and if movement is intentional or unintentional. These anomalous self-experiences may arise in patients with focal brain lesions and provide unique opportunities to disclose the neural components underlying self-body perception. The feeling of foreignness described in AHS is often observed in post-central cortical lesions in the non-dominant hemisphere and is typical of the "posterior alien hand variant". We used Diffusion-Tensor magnetic resonance imaging (DT-MRI) in an unusual case of posterior AHS of the dominant hand in a professional pianist with corticobasal syndrome (CBS). The patient showed uncontrolled levitation with the right arm while playing the piano and perceived as if her hand had a "mind of its own" which prevented her from playing. MRI-scans show asymmetric brain atrophy, mainly involving left post-central regions and SPECT-Tc99m-ECD patterns of hypometabolism over the left parietal-occipital cortices. DT-MRI revealed extensive damage which comprised left fronto-temporal cortex and extends into the ipsilateral parietal cortex causing a disruption of corpus callosum (CC) projections from the rostrum to the splenium. Our case illustrates that posterior AHS may occur in the dominant hemisphere due to widespread damage, which exceed parietal cortex. The parietal lobe has been recognized as a multimodal association region that gets input from several networks and organizes motor output. We suggest that the disturbance to this pathway could result in disruption of motor output and associate an abnormal motor control and anomalous self-body perception.

Is diffusion tensor imaging useful in the assessment of the sciatic nerve and its pathologies? Our clinical experience.

OBJECTIVE: To evaluate the usefulness of diffusion tensor imaging (DTI) in the clinical setting as a complementary tool to conventional MRI in the study and assessment of the sciatic nerve and its pathologies. METHODS: 17 patients diagnosed with different types of sciatic neuropathy and 10 healthy controls underwent a conventional MRI and a DTI study in a 3-T MR scanner (Achieva(®) 3-T X-Series; Philips Healthcare, Netherlands). RESULTS: In the control group, we were able to track and visualize the common sciatic nerve and its main branches from hip to foot. In the patient group, the affected sciatic nerves presented statistically significant lower fractional anisotropy values and higher apparent diffusion coefficient values when compared with controls, suggesting nerve damage. In all cases, DTI offered complementary information for diagnosis and/or confirmation of the suspected pathology. When compared with conventional MRI, DTI showed higher sensitivity for nerve damage detection. CONCLUSION: DTI offers a significant improvement and an important complement to visualize the sciatic nerve and its main branches. In patients with sciatic nerve pathology DTI allows to a better detection and characterization of the nerve damage. ADVANCES IN KNOWLEDGE: DTI enables in vivo dissection of the sciatic nerve white matter fibres; its use offers a significant improvement and complement to conventional MRI.

Hearing colors: an example of brain plasticity.

Sensory substitution devices (SSDs) are providing new ways for improving or replacing sensory abilities that have been lost due to disease or injury, and at the same time offer unprecedented opportunities to address how the nervous system could lead to an augmentation of its capacities. In this work we have evaluated a color-blind subject using a new visual-to-auditory SSD device called "Eyeborg", that allows colors to be perceived as sounds. We used a combination of neuroimaging techniques including Functional Magnetic Resonance Imaging (fMRI), Diffusion Tensor Imaging (DTI) and proton Magnetic Resonance Spectroscopy ((1)H-MRS) to study potential brain plasticity in this subject. Our results suggest that after 8 years of continuous use of this device there could be significant adaptive and compensatory changes within the brain. In particular, we found changes in functional neural patterns, structural connectivity and cortical topography at the visual and auditive cortex of the Eyeborg user in comparison with a control population. Although at the moment we cannot claim that the continuous use of the Eyeborg is the only reason for these findings, our results may shed further light on potential brain changes associated with the use of other SSDs. This could help to better understand how the brain adapts to several pathologies and uncover adaptive resources such as cross-modal representations. We expect that the precise understanding of these changes will have clear implications for rehabilitative training, device development and for more efficient programs for people with disabilities.

Acute human brain responses to intracortical microelectrode arrays: challenges and future prospects.

The emerging field of neuroprosthetics is focused on the development of new therapeutic interventions that will be able to restore some lost neural function by selective electrical stimulation or by harnessing activity recorded from populations of neurons. As more and more patients benefit from these approaches, the interest in neural interfaces has grown significantly and a new generation of penetrating microelectrode arrays are providing unprecedented access to the neurons of the central nervous system (CNS). These microelectrodes have active tip dimensions that are similar in size to neurons and because they penetrate the nervous system, they provide selective access to these cells (within a few microns). However, the very long-term viability of chronically implanted microelectrodes and the capability of recording the same spiking activity over long time periods still remain to be established and confirmed in human studies. Here we review the main responses to acute implantation of microelectrode arrays, and emphasize that it will become essential to control the neural tissue damage induced by these intracortical microelectrodes in order to achieve the high clinical potentials accompanying this technology.

Efecto de la lacosamida sobre la calidad de vida del paciente con epilepsia / Effect of lacosamide on the quality of life of patients with epilepsy

Introducción. La epilepsia provoca trastornos psiquiátricos en un 20-40% de los pacientes y repercute de forma negativa en su calidad de vida. La lacosamida es un nuevo antiepiléptico que se utiliza como terapia añadida en crisis parciales con o sin generalización. Objetivo. Hemos realizado un estudio para valorar el impacto de la lacosamida en cuanto a la calidad de vida del paciente con epilepsia. Se han utilizado la escala hospitalaria de ansiedad y depresión (HADS) y la escala de calidad de vida en la epilepsia (QOLIE-10). Se ha valorado la eficacia y la tolerabilidad. Pacientes y métodos. Se recogen prospectivamente pacientes con epilepsia mal controlada y a los que se añade lacosamida. Se realiza una visita basal, a los tres y a los seis meses. Se cumplimentan los cuestionarios y se recaban los datos sobre la epilepsia. Resultados. Se incluyen 31 pacientes, con una edad media de 45,5 ± 17,2 años, un 64,5% varones. El número de crisis mensuales previas es de 1,6 ± 1,8. La HADS para ansiedad muestra una mejoría significativa a los tres y seis meses. La HADS para depresión refleja una mejoría significativa en los parámetros cualitativos. La QOLIE-10 muestra mejoría significativa para el grupo con baja calidad de vida previa a los tres y seis meses. Tras seis meses, el 61,3% de los pacientes presenta una reducción de las crisis igual o superior al 50%, y el 54,8% está libre de crisis. El mareo es el efecto secundario más frecuente (22,8%). El 74,2% continúa con el tratamiento. Conclusiones. La lacosamida podría mejorar la ansiedad, depresión y calidad de vida del paciente epiléptico con independencia del control de las crisis. La respuesta al tratamiento, la adhesión y los efectos secundarios son similares a estudios previos (AU)

Introduction. Epilepsy causes psychiatric disorders in 20-40% of patients impacting negatively on their quality of life. Lacosamide is a new antiepileptic as adjunctive therapy in partial seizures with or without generalization. Aim. We conducted a study to assess the impact of lacosamide as to the quality of life of epileptic patients. We used the HAD scale for anxiety and depression and QOLIE-10 scale for quality of life. We evaluated the efficacy and tolerability. Patients and methods. We collected prospectively poorly controlled epileptic patients are and added lacosamide treatment. Baseline visit, at 3 and 6 months were performed. The questionnaires are completed and the epilepsy information has been collected. Results. 31 patients, age 45.5 ± 17.2 years, 64.5% males are included. Number of previous monthly crisis 1.6 ± 1.8.HAD anxiety scale shows a significant improvement at 3 and 6 months. HAD scale for depression reflects a significant improvement in quality parameters. QOLIE-10 shows significant improvement for the group with low quality of life after 3 and 6 months. After 6 months 61.3% of patients have a seizure reduction equal or more than 50% and 54.8% are seizure free. Dizziness is the most common side effect (22.8%). 74.2% continued treatment. Conclusions. Lacosamide may improve anxiety, depression and quality of life of epileptic patients regardless of seizure control. Response to treatment, adherence and side effects are similar to previous studies (AU)

[Effect of lacosamide on the quality of life of patients with epilepsy]. / Efecto de la lacosamida sobre la calidad de vida del paciente con epilepsia.

INTRODUCTION: Epilepsy causes psychiatric disorders in 20-40% of patients impacting negatively on their quality of life. Lacosamide is a new antiepileptic as adjunctive therapy in partial seizures with or without generalization. AIM: We conducted a study to assess the impact of lacosamide as to the quality of life of epileptic patients. We used the HAD scale for anxiety and depression and QOLIE-10 scale for quality of life. We evaluated the efficacy and tolerability. PATIENTS AND METHODS: We collected prospectively poorly controlled epileptic patients are and added lacosamide treatment. Baseline visit, at 3 and 6 months were performed. The questionnaires are completed and the epilepsy information has been collected. RESULTS: 31 patients, age 45.5 ± 17.2 years, 64.5% males are included. Number of previous monthly crisis 1.6 ± 1.8. HAD anxiety scale shows a significant improvement at 3 and 6 months. HAD scale for depression reflects a significant improvement in quality parameters. QOLIE-10 shows significant improvement for the group with low quality of life after 3 and 6 months. After 6 months 61.3% of patients have a seizure reduction equal or more than 50% and 54.8% are seizure free. Dizziness is the most common side effect (22.8%). 74.2% continued treatment. CONCLUSIONS: Lacosamide may improve anxiety, depression and quality of life of epileptic patients regardless of seizure control. Response to treatment, adherence and side effects are similar to previous studies.

TITLE: Efecto de la lacosamida sobre la calidad de vida del paciente con epilepsia.Introduccion. La epilepsia provoca trastornos psiquiatricos en un 20-40% de los pacientes y repercute de forma negativa en su calidad de vida. La lacosamida es un nuevo antiepileptico que se utiliza como terapia añadida en crisis parciales con o sin generalizacion. Objetivo. Hemos realizado un estudio para valorar el impacto de la lacosamida en cuanto a la calidad de vida del paciente con epilepsia. Se han utilizado la escala hospitalaria de ansiedad y depresion (HADS) y la escala de calidad de vida en la epilepsia (QOLIE-10). Se ha valorado la eficacia y la tolerabilidad. Pacientes y metodos. Se recogen prospectivamente pacientes con epilepsia mal controlada y a los que se añade lacosamida. Se realiza una visita basal, a los tres y a los seis meses. Se cumplimentan los cuestionarios y se recaban los datos sobre la epilepsia. Resultados. Se incluyen 31 pacientes, con una edad media de 45,5 ± 17,2 años, un 64,5% varones. El numero de crisis mensuales previas es de 1,6 ± 1,8. La HADS para ansiedad muestra una mejoria significativa a los tres y seis meses. La HADS para depresion refleja una mejoria significativa en los parametros cualitativos. La QOLIE-10 muestra mejoria significativa para el grupo con baja calidad de vida previa a los tres y seis meses. Tras seis meses, el 61,3% de los pacientes presenta una reduccion de las crisis igual o superior al 50%, y el 54,8% esta libre de crisis. El mareo es el efecto secundario mas frecuente (22,8%). El 74,2% continua con el tratamiento. Conclusiones. La lacosamida podria mejorar la ansiedad, depresion y calidad de vida del paciente epileptico con independencia del control de las crisis. La respuesta al tratamiento, la adhesion y los efectos secundarios son similares a estudios previos.

Proton magnetic resonance spectroscopy (1H-MRS) reveals the presence of elevated myo-inositol in the occipital cortex of blind subjects.

This paper is addressed to investigate whether proton magnetic resonance spectroscopy ((1)H-MRS) may provide the means to investigate changes associated to alterations of neural activity and sensory experience in the blind. We examined the relationships between different brain metabolite levels in 10 blind volunteers and 10 sighted subjects matched for age and gender. Adjusted levels of N-acetylaspartate (NAA), creatine (Cr), choline (Cho), glutamate/glutamine (Glx) and myo-inositol (mIno) in the occipital cortex region were quantified in the water-suppressed spectrum using the AMARES estimation algorithms. An unpaired two-tailed t-test was used to determine any significant difference in metabolite ratios. Our results show that none of the blind volunteers presented atrophy or any other MRI detectable degenerative change of the occipital cortex. The main finding was a significant increase of myo-inositol (mIno), a glial marker, in blind subjects compared to sighted controls. This simple sugar-like molecule can be found mainly within astrocytes, and cannot cross the blood-brain barrier. Therefore its increase could reflect glial proliferation or an increase in glial cell size. These results show that (1)H-MRS may help to understand the complex mechanisms involved in brain plasticity and suggest an active role of glial cells in the reorganization of the brain in response to visual deprivation.

An atypical presentation of visual hallucinatory experiences following prolonged blindness.

We report a patient with long-standing blindness experiencing both simple and complex visual hallucinations secondary to a cortical arteriovenous malformation (AVM). The hallucinations were located in the right visual field corresponding to the contra-lateral site of cortical damage. This case contributes to our understanding of neurophysiological mechanisms underlying visual hallucinations and ongoing research investigating the phenomenology of hallucinations with respect to the cause and localization of neural damage.