| 1. |
- Akbarian-Tefaghi, Ladan, et al.
(författare)
-
Refining the Deep Brain Stimulation Target within the Limbic Globus Pallidus Internus for Tourette Syndrome
- 2017
-
Ingår i: Stereotactic and Functional Neurosurgery. - : S. Karger. - 1011-6125 .- 1423-0372. ; 95:4, s. 251-258
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Deep brain stimulation (DBS) in patients with severe, refractory Tourette syndrome (TS) has demonstrated promising but variable results thus far. The thalamus and anteromedial globus pallidus internus (amGPi) have been the most commonly stimulated sites within the cortico-striato thalamic circuit, but an optimal target is yet to be elucidated.OBJECTIVES: This study of 15 patients with long-term amGPi DBS for severe TS investigated whether a specific anatomical site within the amGPi correlated with optimal clinical outcome for the measures of tics, obsessive compulsive behaviour (OCB), and mood.METHODS: Validated clinical assessments were used to measure tics, OCB, quality of life, anxiety, and depression before DBS and at the latest follow-up (17-82 months). Electric field simulations were created for each patient using information on electrode location and individual stimulation parameters. A subsequent regression analysis correlated these patient-specific simulations to percentage changes in outcome measures in order to identify any significant voxels related to clinical improvement.RESULTS: A region within the ventral limbic GPi, specifically on the medial medullary lamina in the pallidum at the level of the AC-PC, was significantly associated with improved tics but not mood or OCB outcome.CONCLUSIONS: This study adds further support to the application of DBS in a tic-related network, though factors such as patient sample size and clinical heterogeneity remain as limitations and replication is required.
|
|
| 2. |
- Akram, Harith, et al.
(författare)
-
Aim for the Suprasternal Notch : Technical Note to Avoid Bowstringing after Deep Brain Stimulation
- 2015
-
Ingår i: Stereotactic and Functional Neurosurgery. - : S. Karger AG. - 1011-6125 .- 1423-0372. ; 93:4, s. 227-230
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Bowstringing may occur when excessive fibrosis develops around extension cables in the neck after deep brain stimulation (DBS) surgery. Though the occurrence of this phenomenon is rare, we have noted that it tends to cause maximal discomfort when the cables cross superficially over the convexity of the clavicle. We hypothesise that bowstringing may be avoided by directing the extension cables towards the suprasternal notch. Methods: When connecting DBS leads to an infraclavicular pectoral implantable pulse generator (IPG), tunnelling is directed towards the suprasternal I notch, before being directed laterally towards the IPG pocket. In previously operated patients with established fibrosis, the fibrous tunnel is opened and excised as far cranially as possible, allowing medial rerouting of cables. Using this approach, we reviewed our series of patients who underwent DBS surgery over 10 years. Results: In 429 patients, 7 patients (2%) with cables tunnelled over the convexity of the clavicle complaining of bowstringing underwent cable exploration and rerouting. This eliminated bowstringing and provided better cosmetic results. When the cable trajectory was initially directed towards the suprasternal notch, no bowstringing was observed. Conclusion:The tunnelling trajectory appears to influence postoperative incidence of fibrosis associated with DBS cables. Modifying the surgical technique may reduce the incidence of this troublesome adverse event. (C) 2015 S.Karger AG, Basel
|
|
| 3. |
|
|
| 4. |
- Akram, Harith, et al.
(författare)
-
Connectivity derived thalamic segmentation in deep brain stimulation for tremor
- 2018
-
Ingår i: NeuroImage. - : Elsevier. - 2213-1582. ; 18, s. 130-142
-
Tidskriftsartikel (refereegranskat)abstract
- The ventral intermediate nucleus (VIM) of the thalamus is an established surgical target for stereotactic ablation and deep brain stimulation (DBS) in the treatment of tremor in Parkinson's disease (PD) and essential tremor (ET). It is centrally placed on a cerebello-thalamo-cortical network connecting the primary motor cortex, to the dentate nucleus of the contralateral cerebellum through the dentato-rubro-thalamic tract (DRT). The VIM is not readily visible on conventional MR imaging, so identifying the surgical target traditionally involved indirect targeting that relies on atlas-defined coordinates. Unfortunately, this approach does not fully account for individual variability and requires surgery to be performed with the patient awake to allow for intraoperative targeting confirmation. The aim of this study is to identify the VIM and the DRT using probabilistic tractography in patients that will undergo thalamic DBS for tremor. Four male patients with tremor dominant PD and five patients (three female) with ET underwent high angular resolution diffusion imaging (HARDI) (128 diffusion directions, 1.5 mm isotropic voxels and b value = 1500) preoperatively. Patients received VIM-DBS using an MR image guided and MR image verified approach with indirect targeting. Postoperatively, using parallel Graphical Processing Unit (GPU) processing, thalamic areas with the highest diffusion connectivity to the primary motor area (M1), supplementary motor area (SMA), primary sensory area (S1) and contralateral dentate nucleus were identified. Additionally, volume of tissue activation (VTA) corresponding to active DBS contacts were modelled. Response to treatment was defined as 40% reduction in the total Fahn-Tolosa-Martin Tremor Rating Score (FTMTRS) with DBS-ON, one year from surgery. Three out of nine patients had a suboptimal, long-term response to treatment. The segmented thalamic areas corresponded well to anatomically known counterparts in the ventrolateral (VL) and ventroposterior (VP) thalamus. The dentate-thalamic area, lay within the M1-thalamic area in a ventral and lateral location. Streamlines corresponding to the DRT connected M1 to the contralateral dentate nucleus via the dentate-thalamic area, clearly crossing the midline in the mesencephalon. Good response was seen when the active contact VTA was in the thalamic area with highest connectivity to the contralateral dentate nucleus. Non-responders had active contact VTAs outside the dentate-thalamic area. We conclude that probabilistic tractography techniques can be used to segment the VL and VP thalamus based on cortical and cerebellar connectivity. The thalamic area, best representing the VIM, is connected to the contralateral dentate cerebellar nucleus. Connectivity based segmentation of the VIM can be achieved in individual patients in a clinically feasible timescale, using HARDI and high performance computing with parallel GPU processing. This same technique can map out the DRT tract with clear mesencephalic crossing.
|
|
| 5. |
- Akram, Harith, et al.
(författare)
-
L-Dopa Responsiveness Is Associated With Distinctive Connectivity Patterns in Advanced Parkinson's Disease
- 2017
-
Ingår i: Movement Disorders. - : Wiley-Blackwell. - 0885-3185 .- 1531-8257. ; 32:6, s. 874-883
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Neuronal loss and dopamine depletion alter motor signal processing between cortical motor areas, basal ganglia, and the thalamus, resulting in the motor manifestations of Parkinson's disease. Dopamine replacement therapy can reverse these manifestations with varying degrees of improvement. Methods: To evaluate functional connectivity in patients with advanced Parkinson's disease and changes in functional connectivity in relation to the degree of response to L-dopa, 19 patients with advanced Parkinson's disease underwent resting-state functional magnetic resonance imaging in the on-medication state. Scans were obtained on a 3-Tesla scanner in 3x3x2.5mm(3) voxels. Seed-based bivariate regression analyses were carried out with atlas-defined basal ganglia regions as seeds, to explore relationships between functional connectivity and improvement in the motor section of the UPDRS-III following an L-dopa challenge. False discovery rate-corrected P was set at < 0.05 for a 2-tailed t test. Results: A greater improvement in UPDRS-III scores following L-dopa administration was characterized by higher resting-state functional connectivity between the prefrontal cortex and the striatum (P=0.001) and lower resting-state functional connectivity between the pallidum (P=0.001), subthalamic nucleus (P=0.003), and the paracentral lobule (supplementary motor area, mesial primary motor, and primary sensory areas). Conclusions: Our findings show characteristic basal ganglia resting-state functional connectivity patterns associated with different degrees of L-dopa responsiveness in patients with advanced Parkinson's disease. L-Dopa exerts a graduated influence on remapping connectivity in distinct motor control networks, potentially explaining some of the variance in treatment response.
|
|
| 6. |
- Akram, Harith, et al.
(författare)
-
Optimal deep brain stimulation site and target connectivity for chronic cluster headache
- 2017
-
Ingår i: Neurology. - : LIPPINCOTT WILLIAMS & WILKINS. - 0028-3878 .- 1526-632X. ; 89:20, s. 2083-2091
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate the mechanism of action of deep brain stimulation for refractory chronic cluster headache and the optimal target within the ventral tegmental area. Methods: Seven patients with refractory chronic cluster headache underwent high spatial and angular resolution diffusion MRI preoperatively. MRI-guided and MRI-verified electrode implantation was performed unilaterally in 5 patients and bilaterally in 2. Volumes of tissue activation were generated around active lead contacts with a finite-element model. Twelve months after surgery, voxel-based morphometry was used to identify voxels associated with higher reduction in headache load. Probabilistic tractography was used to identify the brain connectivity of the activation volumes in responders, defined as patients with a reduction of >= 30% in headache load. Results: There was no surgical morbidity. Average follow-up was 34 +/- 14 months. Patients showed reductions of 76 +/- 33% in headache load, 46 +/- 41% in attack severity, 58 +/- 41% in headache frequency, and 51 +/- 46% in attack duration at the last follow-up. Six patients responded to treatment. Greatest reduction in headache load was associated with activation in an area cantered at 6 mm lateral, 2 mm posterior, and 1 mm inferior to the midcommissural point of the third ventricle. Average responders' activation volume lay on the trigeminohypothalamic tract, connecting the trigeminal system and other brainstem nuclei associated with nociception and pain modulation with the hypothalamus, and the prefrontal and mesial temporal areas. Conclusions: We identify the optimal stimulation site and structural connectivity of the deep brain stimulation target for cluster headache, explicating possible mechanisms of action and disease pathophysiology.
|
|
| 7. |
- Akram, Harith, et al.
(författare)
-
Subthalamic deep brain stimulation sweet spots and hyperdirect cortical connectivity in Parkinson's disease
- 2017
-
Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 158, s. 332-345
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: Firstly, to identify subthalamic region stimulation clusters that predict maximum improvement in rigidity, bradykinesia and tremor, or emergence of side-effects; and secondly, to map-out the cortical fingerprint, mediated by the hyperdirect pathways which predict maximum efficacy.Methods: High angular resolution diffusion imaging in twenty patients with advanced Parkinson's disease was acquired prior to bilateral subthalamic nucleus deep brain stimulation. All contacts were screened one-year from surgery for efficacy and side-effects at different amplitudes. Voxel-based statistical analysis of volumes of tissue activated models was used to identify significant treatment clusters. Probabilistic tractography was employed to identify cortical connectivity patterns associated with treatment efficacy.Results: All patients responded well to treatment (46% mean improvement off medication UPDRS-III [p < 0.0001]) without significant adverse events. Cluster corresponding to maximum improvement in tremor was in the posterior, superior and lateral portion of the nucleus. Clusters corresponding to improvement in bradykinesia and rigidity were nearer the superior border in a further medial and posterior location. The rigidity cluster extended beyond the superior border to the area of the zona incerta and Forel-H-2 field. When the clusters where averaged, the coordinates of the area with maximum overall efficacy was X = -10(-9.5), Y = -3(-1) and Z = -7(-3) in MNI(AC-PC) space. Cortical connectivity to primary motor area was predictive of higher improvement in tremor; whilst that to supplementary motor area was predictive of improvement in bradykinesia and rigidity; and connectivity to prefrontal cortex was predictive of improvement in rigidity.Interpretation: These findings support the presence of overlapping stimulation sites within the subthalamic nucleus and its superior border, with different cortical connectivity patterns, associated with maximum improvement in tremor, rigidity and bradykinesia.
|
|
| 8. |
- Cappon, Davide, et al.
(författare)
-
Deep Brain Stimulation of the Nucleus Basalis of Meynert for Parkinson's Disease Dementia : A 36 Months Follow Up Study
- 2022
-
Ingår i: Movement Disorders Clinical Practice. - : John Wiley & Sons. - 2330-1619. ; 9:6, s. 765-774
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Degeneration of the nucleus basalis of Meynert (NBM) and cortical cholinergic dysfunction are hallmarks of Parkinson's disease dementia (PDD). There is no effective therapy for PDD. Deep brain stimulation of the NBM (NBM-DBS) has been trialed as a potential treatment.Objective: Our primary aim was to evaluate the sustained tolerability of NBM-DBS in PDD, and its impact on global cognition, behavioral symptoms, quality of life and caregiver burden and distress. Second, we aimed to determine whether baseline measures of arousal, alertness, and attention were predictive of the three year response to NBM-DBS in PDD patients.Methods: Five of the six PDD patients who completed the baseline assessment participated in a 3 year follow up assessment. We assessed the participants after three years of NBM-DBS on the Mini Mental State Examination, Dementia Rating Scale-2, Blessed Dementia Rating Scale, Neuropsychiatric Inventory, and the SF36.Results: The five patients showed varying trajectories of cognitive decline, with two showing a slower progression over the three-year follow-up period. A slower progression of decline on global cognition was associated with higher baseline accuracy on the Posner covert orienting of attention test, and less daytime sleepiness.Conclusions: Whether slower progression of cognitive decline in two patients was in any way related to individual variability in responsiveness to NBM-DBS requires confirmation in a larger series including an unoperated PDD control group. Higher accuracy in covertly orienting attention and better sleep quality at baseline were associated with better cognitive outcomes at 36 months assessment. These results require validation in future studies with larger samples.
|
|
| 9. |
- Cappon, Davide, et al.
(författare)
-
Globus pallidal deep brain stimulation for Tourette syndrome : Effects on cognitive function
- 2019
-
Ingår i: Parkinsonism & Related Disorders. - : Elsevier. - 1353-8020 .- 1873-5126. ; 69, s. 14-18
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: In a double-blind randomized crossover trial, we previously established that bilateral deep brain stimulation of the anteromedial globus pallidus internus (GPiam-DBS) is effective in significantly reducing tic severity in patients with refractory Tourette syndrome (TS). Here, we report the effects of bilateral GPiam-DBS on cognitive function in 11 of the 13 patients who had participated in our double-blind cross-over trial of GPi-DBS.Methods: Patients were assessed at baseline (4 weeks prior to surgery) and at the end of each of the three-month blinded periods, with stimulation either ON or OFF. The patients were evaluated on tests of memory (California Verbal Learning Test-II (CVLT-II); Corsi blocks; Short Recognition Memory for Faces), executive function (D-KEFS Stroop color-word interference, verbal fluency, Trail-making test, Hayling Sentence Completion test), and attention (Paced Auditory Serial Addition Test, Numbers and Letters Test).Results: GPiam-DBS did not produce any significant change in global cognition. Relative to pre-operative baseline assessment verbal episodic memory on the CVLT-II and set-shifting on the Trail-making Test were improved with DBS OFF. Performance on the cognitive tests were not different with DBS ON versus DBS OFF. GPiam-DBS did not alter aspects of cognition that are impaired in TS such as inhibition on the Stroop interference task or the Hayling Sentence Completion test.Conclusions: This study extends previous findings providing data showing that GPiam-DBS does not adversely affect cognitive domains such as memory, executive function, verbal fluency, attention, psychomotor speed, and information processing. These results indicate that GPiam-DBS does not produce any cognitive deficits in TS.
|
|
| 10. |
- Dayal, Viswas, et al.
(författare)
-
Pedunculopontine nucleus deep brain stimulation for parkinsonian disorders : a case series
- 2021
-
Ingår i: Stereotactic and Functional Neurosurgery. - : S. Karger. - 1011-6125 .- 1423-0372. ; 99:4, s. 287-294
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) has been investigated for the treatment of levodopa-refractory gait dysfunction in parkinsonian disorders, with equivocal results so far.Objectives: To summarize the clinical outcomes of PPN-DBS-treated patients at our centre and elicit any patterns that may guide future research.Materials and Methods: Pre- and post-operative objective overall motor and gait subsection scores as well as patient-reported outcomes were recorded for 6 PPN-DBS-treated patients, 3 with Parkinson's disease (PD), and 3 with progressive supranuclear palsy (PSP). Electrodes were implanted unilaterally in the first 3 patients and bilaterally in the latter 3, using an MRI-guided MRI-verified technique. Stimulation was initiated at 20-30 Hz and optimized in an iterative manner.Results: Unilaterally treated patients did not demonstrate significant improvements in gait questionnaires, UPDRS-III or PSPRS scores or their respective gait subsections. This contrasted with at least an initial response in bilaterally treated patients. Diurnal cycling of stimulation in a PD patient with habituation to the initial benefit reproduced substantial improvements in freezing of gait (FOG) 3 years post-operatively. Among the PSP patients, 1 with a parkinsonian subtype had a sustained improvement in FOG while another with Richardson syndrome (PSP-RS) did not benefit.Conclusions: PPN-DBS remains an investigational treatment for levodopa-refractory FOG. This series corroborates some previously reported findings: bilateral stimulation may be more effective than unilateral stimulation; the response in PSP patients may depend on the disease subtype; and diurnal cycling of stimulation to overcome habituation merits further investigation.
|
|
