Globus Pallidus Internus (GPi)
Disorders Treated with Stimulation
- Primary indications: Parkinson's disease, dystonia, and other movement disorders [1]
- Investigational applications: May be effective in treating Tourette's syndrome [2,3]
Location
- The GPi nucleus is located between the globus pallidus externus (GPe) and posterior limb internal capsule (PLIC). The GPi is separated from the GPe by the thin, FGATIR dark internal medial medullary lamina. The medial border of the GPi is the PLIC.
Associated Tracts
- Pallidothalamic Connections: These are comprised of the ansa lenticularis (AL), fasciculus lenticularis (FL), and ansa subthalamica (AS). The AL and FL extend from the GPi to the ventro-oralis (VO) nucleus, and the AS extends from the GPi to the subthalamic nucleus (STN). [1,4]
- Thalamic Fasciculus: The AL and FL join the dentatorubrothalamic tract (DRTT) to collectively form the thalamic fasciculus. [1,4]
- The GPi plays a critical role in both direct and indirect pathways of the basal ganglia circuitry. These pathways work in a delicate balance to regulate movement, with the direct pathway promoting movement and the indirect pathway inhibiting it. [4,5] On DTI, the GPi has many connections to deep structures (including the thalamus, STN, SN) and cortical regions (including the primary motor cortex and prefrontal cortext). Relevant to DBS, the corticopallidal tract (not shown) originating from the M1 area extends to the posterior-ventral portion of the GPi to increase the efficacy of GPi DBS in PD, though the role of the corticpoallidal tract is still under investigation.
References
- Middlebrooks EH, Domingo RA, Vivas-Buitrago T, Okromelidze L, Tsuboi T, Wong JK, Eisinger RS, Almeida L, Burns MR, Horn A, Uitti RJ, Wharen RE Jr, Holanda VM, Grewal SS. Neuroimaging Advances in Deep Brain Stimulation: Review of Indications, Anatomy, and Brain Connectomics. AJNR Am J Neuroradiol. 2020 Sep;41(9):1558-1568. doi: 10.3174/ajnr.A6693. Epub 2020 Aug 13. PMID: 32816768; PMCID: PMC7583111
- Dehning, S., et al., Therapy-refractory Tourette syndrome: beneficial outcome with globus pallidus internus deep brain stimulation. Mov Disord, 2008. 23(9): p. 1300-2
- Lee DJ, Lozano CS, Dallapiazza RF, Lozano AM. Current and future directions of deep brain stimulation for neurological and psychiatric disorders. J Neurosurg. 2019 Aug 1;131(2):333-342. doi: 10.3171/2019.4.JNS181761. PMID: 31370011
- Middlebrooks EH, Tuna IS, Grewal SS, Almeida L, Heckman MG, Lesser ER, Foote KD, Okun MS, Holanda VM. Segmentation of the Globus Pallidus Internus Using Probabilistic Diffusion Tractography for Deep Brain Stimulation Targeting in Parkinson Disease. AJNR Am J Neuroradiol. 2018 Jun;39(6):1127-1134. doi: 10.3174/ajnr.A5641. Epub 2018 Apr 26. PMID: 29700048; PMCID: PMC7410622
- Javed N, Cascella M. Neuroanatomy, Globus Pallidus. [Updated 2023 Feb 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557755/