Neurosurgery Unit, Fundação de Beneficiência Hospital de Cirurgia, Cirurgia, Aracaju, Sergipe, Brazil.
Division of Functional Neurosurgery, Department of Neurology, University of São Paulo, School of Medicine, Sao Paulo, São Paulo, Brazil.
J Neurol Surg A Cent Eur Neurosurg. 2022 Jul;83(4):361-367. doi: 10.1055/s-0041-1735856. Epub 2021 Nov 22.
Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a highly effective therapy for primary generalized and focal dystonias, but therapeutic success is compromised by a nonresponder rate of up to 20%. Variability in electrode placement and in tissue stimulated inside the GPi may explain in part different outcomes among patients. Refinement of the target within the pallidal area could be helpful for surgery planning and clinical outcomes. The objective of this study was to discuss current and potential methodological (somatotopy, neuroimaging, and neurophysiology) aspects that might assist neurosurgical targeting of the GPi, aiming to treat generalized or focal dystonia.
We selected published studies by searching electronic databases and scanning the reference lists for articles that examined the anatomical and electrophysiologic aspects of the GPi in patients with idiopathic/inherited dystonia who underwent functional neurosurgical procedures.
The sensorimotor sector of the GPi was the best target to treat dystonic symptoms, and was localized at its lateral posteroventral portion. The effective volume of tissue activated (VTA) to treat dystonia had a mean volume of 153 mm in the posterior GPi area. Initial tractography studies evaluated the close relation between the electrode localization and pallidothalamic tract to control dystonic symptoms.Regarding the somatotopy, the more ventral, lateral, and posterior areas of the GPi are associated with orofacial and cervical representation. In contrast, the more dorsal, medial, and anterior areas are associated with the lower limbs; between those areas, there is the representation of the upper limb. Excessive pallidal synchronization has a peak at the theta band of 3 to 8 Hz, which might be responsible for generating dystonic symptoms.
Somatotopy assessment of posteroventral GPi contributes to target-specific GPi sectors related to segmental body symptoms. Tractography delineates GPi output pathways that might guide electrode implants, and electrophysiology might assist in pointing out areas of excessive theta synchronization. Finally, the identification of oscillatory electrophysiologic features that correlate with symptoms might enable closed-loop approaches in the future.
深部脑刺激（DBS）内侧苍白球（GPi）是原发性全身性和局灶性肌张力障碍的一种非常有效的治疗方法，但治疗成功率受到高达 20%的无反应率的限制。电极放置的变异性和在 GPi 内刺激的组织可能部分解释了患者之间的不同结果。在苍白球区域内对目标的细化可能有助于手术计划和临床结果。本研究的目的是讨论当前和潜在的方法学（躯体感觉定位、神经影像学和神经生理学）方面，这些方面可能有助于 GPi 的神经外科靶向，旨在治疗全身性或局灶性肌张力障碍。
我们通过搜索电子数据库并扫描文章的参考文献，选择了发表的研究，这些研究检查了接受功能性神经外科手术的特发性/遗传性肌张力障碍患者的 GPi 的解剖和电生理方面。
GPi 的感觉运动区是治疗肌张力障碍症状的最佳靶点，位于其外侧后腹侧部分。治疗肌张力障碍的有效组织激活体积（VTA）在后 GPi 区域的平均体积为 153mm。最初的轨迹研究评估了电极定位与苍白球丘脑束之间的密切关系，以控制肌张力障碍症状。关于躯体感觉定位，GPi 的更腹侧、更外侧和更后部分与口面和颈部代表有关。相比之下，更背侧、更内侧和更前部分与下肢有关；在这些区域之间，有上肢的代表。过度苍白球同步在 3 到 8Hz 的 theta 波段达到峰值，这可能是产生肌张力障碍症状的原因。
GPi 后腹侧的躯体感觉定位有助于与节段性躯体症状相关的特定 GPi 区域。轨迹描绘了 GPi 输出通路，可能指导电极植入，而电生理学可能有助于指出过度 theta 同步的区域。最后，识别与症状相关的振荡电生理特征可能使未来能够实现闭环方法。
