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  • 1. Akram, Harith
    et al.
    Dayal, Viswas
    Mahlknecht, Philipp
    Georgiev, Dejan
    Hyam, Jonathan
    Foltynie, Thomas
    Limousin, Patricia
    De Vita, Enrico
    Jahanshahi, Marjan
    Ashburner, John
    Behrens, Tim
    Hariz, Marwan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience. Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK.
    Zrinzo, Ludvic
    Connectivity derived thalamic segmentation in deep brain stimulation for tremor2018In: NeuroImage: Clinical, ISSN 0353-8842, E-ISSN 2213-1582, Vol. 18, p. 130-142Article in journal (Refereed)
    Abstract [en]

    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.

  • 2. Akram, Harith
    et al.
    Hariz, Marwan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Zrinzo, Ludvic
    Connectivity derived thalamic segmentation: Separating myth from reality2019In: NeuroImage: Clinical, ISSN 0353-8842, E-ISSN 2213-1582, Vol. 22, article id UNSP 101758Article in journal (Refereed)
  • 3. Cappon, Davide
    et al.
    Beigi, Mazda
    Kefalopoulou, Zinovia
    Zrinzo, Ludvic
    Candelario, Joseph
    Milabo, Catherine
    Akram, Harith
    Dayal, Viswas
    Hyam, Jonathan
    Kass-Iliyya, Lewis
    Silverdale, Monty
    Evans, Julian
    Limousin, Patricia
    Hariz, Marwan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience. Unit of Functional Neurosurgery, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, National Hospital for Neurology and Neurosurgery, London, UK.
    Joyce, Eileen
    Foltynie, Thomas
    Jahanshahi, Marjan
    Globus pallidal deep brain stimulation for Tourette syndrome: Effects on cognitive function2019In: Parkinsonism & Related Disorders, ISSN 1353-8020, E-ISSN 1873-5126, Vol. 69, p. 14-18Article in journal (Refereed)
    Abstract [en]

    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.

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