The Experts below are selected from a list of 33 Experts worldwide ranked by ideXlab platform
Mohammad Maarouf - One of the best experts on this subject based on the ideXlab platform.
-
Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome.
Frontiers in human neuroscience, 2017Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad MaaroufAbstract:The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the fields of Forel, namely field H1, as a target for deep brain stimulation. The fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic Ventral Nuclear Group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients.
-
Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome
Frontiers Media S.A., 2017Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad MaaroufAbstract:The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation (DBS) is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the fields of Forel, namely field H1, as a target for DBS. The fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic Ventral Nuclear Group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients
Y. E. Lenz - One of the best experts on this subject based on the ideXlab platform.
-
Single unit analysis of the human Ventral thalamic Nuclear Group. Tremor-related activity in functionally identified cells.
Brain, 1994Co-Authors: Frederick Lenz, C. Kwan, R. Martin, Ronald R. Tasker, J. O. Dostrovsky, Y. E. LenzAbstract:During procedures for parkinsonian tremor, neurons in the thalamic Ventral Nuclear Group show periodic activity at tremor frequency (tremor-frequency activity). The tremor-frequency activity of some cells is significantly correlated with tremor. Cells in this region also display functional properties defined by activity related to somatosensory stimuli and to active movement. Cells with activity related to somatosensory stimulation were termed sensory cells while those with activity related to active movement were termed voluntary cells. Cells with activity related to both somatosensory stimulation and active movement were termed combined cells. Those with activity related to neither somatosensory stimulation nor active movement were termed no-response cells. Combined, voluntary and no-response cells were located in the region of thalamus where a lesion stops tremor and anterior to the region where sensory cells were found. Spectral cross-correlation analysis demonstrated that many combined, voluntary and no-response cells had a peak of activity at tremor frequency which was significantly correlated with electromyogram (EMG). Analysis of the phase of thalamic activity relative to EMG activity indicated that voluntary and combined cell activity usually led EMG during tremor. These results suggest that thalamic cells unresponsive to somatosensory stimulation (voluntary and no-response cells) and those responsive to somatosensory stimulation (combined cells) are involved in the mechanism of parkinsonian tremor. The activity of sensory cells frequently lagged behind tremor while activity of combined cells often led tremor. This finding suggests that the activity of these two cell types, both responding to sensory input, is related to tremor by different mechanisms.
Frederick Lenz - One of the best experts on this subject based on the ideXlab platform.
-
Thalamotomy for Tremor
2003Co-Authors: Sherwin E. Hua, Ira M. Garonzik, Jung-il Lee, Frederick LenzAbstract:Since the 1960s, stereotactic surgery for tremor has targeted the Ventral Nuclear Group of thalamus. According to Hassler’s classification (1), the nuclei in the Ventral Nuclear Group, from anterior to posterior, are a pallidal relay nucleus (Ventral oral, Vo), a cerebellar relay nucleus (Ventral intermediate, Vim), and the principal somatosensory nucleus (Ventral caudal, Vc) (2,3). On the basis of surgical experience, Hassler proposed that the anterior portion of Vo, the nucleus Ventralis oralis anterior (Voa), was a better target for rigidity, whereas the posterior portion, the nucleus Ventral oral posterior (Vop), was better for the relief of tremor. With the aid of microelectrode recordings, an area posterior to Vop was later found to have rhythmic bursting activity close to the frequency of tremor (4). Many subsequent studies have demonstrated that the nucleus in this location, Vim, is the target of choice for treatment of tremor of all types.
-
Patterns of bursting occurring in thalamic cells during parkinsonian tremor
Neuroscience, 1998Co-Authors: T. Ali Zirh, Stephen G. Reich, Frederick Lenz, Patrick M DoughertyAbstract:It has been proposed that parkinsonian tremor is produced either by the activity of an intrinsic thalamic pacemaker or by the oscillation of an unstable long loop reflex arc. The former (central) hypothesis proposes that overactivity of neurons in the internal segment of the globus pallidus inhibits or hyperpolarizes thalamic neurons. When hyperpolarized, thalamic cells oscillate with bursting of the type associated with low threshold calcium spikes (low threshold spike-bursts). Low threshold spike-bursts can be identified by particular patterns of interspike intervals within the burst. The alternative (peripheral) hypothesis proposes that tremor results from oscillation of a reflex arc transmitting activity from muscle stretch receptors to thalamus, motor cortex, and back to the stretched muscle. When the gain of this reflex is increased, the arc may become unstable and oscillate. Oscillations produced by peripheral inputs may produce an acceleration-deceleration pattern within the burst which results in sinusoidal modulation of a spike train if bursting is periodic. We have assessed these two hypotheses by studying the pattern of interspike intervals occurring within bursts recorded in patients with parkinsonian tremor. The spike trains were analysed for 118 cells located in the Ventral Nuclear Group including Ventralis intermedius (thalamic cerebellar relay nucleus, n=48) and Ventralis oralis posterior (thalamic pallidal relay nucleus, n=39) of patients with parkinsonian tremor. Two cells recorded in Ventralis intermedius of a sleeping patient with chronic pain showed bursting activity similar to the low threshold spike-bursts recorded in sleeping animals, suggesting a common mechanism for low threshold spike-bursts across species. Forty-two cells recorded in patients with parkinsonian tremor (Ventralis intermedius, n=19; Ventralis oralis posterior, n=12) were classified as tremor-related cells because their activity was characterized by both a concentration of power at tremor frequency and significant correlation with tremor. Eleven tremor-related cells, 10 located in Ventralis intermedius or Ventralis oralis posterior and most responding to sensory inputs, had an acceleration-deceleration pattern of intraburst firing. Only one cell, a tremor-related cell in Ventralis intermedius, showed the pattern expected of presumed low threshold spike-bursts. Therefore, intraburst interspike interval patterns consistent with either the central or the peripheral hypothesis were recorded in the thalamus of patients with parkinsonian tremor. Twenty-one tremor-related cells (15 cells in Ventralis intermedius or Ventralis oralis posterior) had bursts with intraburst interspike intervals which were independent of position of the interspike interval within the burst. Therefore, the activity of the majority of cells was not consistent with either hypothesis, suggesting that another oscillatory process may contribute to parkinsonian tremor.
-
Single unit analysis of the human Ventral thalamic Nuclear Group. Tremor-related activity in functionally identified cells.
Brain, 1994Co-Authors: Frederick Lenz, C. Kwan, R. Martin, Ronald R. Tasker, J. O. Dostrovsky, Y. E. LenzAbstract:During procedures for parkinsonian tremor, neurons in the thalamic Ventral Nuclear Group show periodic activity at tremor frequency (tremor-frequency activity). The tremor-frequency activity of some cells is significantly correlated with tremor. Cells in this region also display functional properties defined by activity related to somatosensory stimuli and to active movement. Cells with activity related to somatosensory stimulation were termed sensory cells while those with activity related to active movement were termed voluntary cells. Cells with activity related to both somatosensory stimulation and active movement were termed combined cells. Those with activity related to neither somatosensory stimulation nor active movement were termed no-response cells. Combined, voluntary and no-response cells were located in the region of thalamus where a lesion stops tremor and anterior to the region where sensory cells were found. Spectral cross-correlation analysis demonstrated that many combined, voluntary and no-response cells had a peak of activity at tremor frequency which was significantly correlated with electromyogram (EMG). Analysis of the phase of thalamic activity relative to EMG activity indicated that voluntary and combined cell activity usually led EMG during tremor. These results suggest that thalamic cells unresponsive to somatosensory stimulation (voluntary and no-response cells) and those responsive to somatosensory stimulation (combined cells) are involved in the mechanism of parkinsonian tremor. The activity of sensory cells frequently lagged behind tremor while activity of combined cells often led tremor. This finding suggests that the activity of these two cell types, both responding to sensory input, is related to tremor by different mechanisms.
Clemens Neudorfer - One of the best experts on this subject based on the ideXlab platform.
-
Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome.
Frontiers in human neuroscience, 2017Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad MaaroufAbstract:The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the fields of Forel, namely field H1, as a target for deep brain stimulation. The fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic Ventral Nuclear Group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients.
-
Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome
Frontiers Media S.A., 2017Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad MaaroufAbstract:The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation (DBS) is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the fields of Forel, namely field H1, as a target for DBS. The fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic Ventral Nuclear Group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients
Faycal El Majdoub - One of the best experts on this subject based on the ideXlab platform.
-
Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome.
Frontiers in human neuroscience, 2017Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad MaaroufAbstract:The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the fields of Forel, namely field H1, as a target for deep brain stimulation. The fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic Ventral Nuclear Group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients.
-
Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome
Frontiers Media S.A., 2017Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad MaaroufAbstract:The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation (DBS) is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the fields of Forel, namely field H1, as a target for DBS. The fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic Ventral Nuclear Group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients
