title: The nondecussating pathway of the dentatorubrothalamic tract in humans: human connectome-based tractographic study and microdissection validation.
abstract: OBJECT The dentatorubrothalamic tract (DRTT) is the major efferent cerebellar pathway arising from the dentate nucleus (DN) and decussating to the contralateral red nucleus (RN) and thalamus. Surprisingly, hemispheric cerebellar output influences bilateral limb movements. In animals, uncrossed projections from the DN to the ipsilateral RN and thalamus may explain this phenomenon. The aim of this study was to clarify the anatomy of the dentatorubrothalamic connections in humans. METHODS The authors applied advanced deterministic fiber tractography to a template of 488 subjects from the Human Connectome Project (Q1-Q3 release, WU-Minn HCP consortium) and validated the results with microsurgical dissection of cadaveric brains prepared according to Klingler's method. RESULTS The authors identified the "classic" decussating DRTT and a corresponding nondecussating path (the nondecussating DRTT, nd-DRTT). Within each of these 2 tracts some fibers stop at the level of the RN, forming the dentatorubro tract and the nondecussating dentatorubro tract. The left nd-DRTT encompasses 21.7% of the tracts and 24.9% of the volume of the left superior cerebellar peduncle, and the right nd-DRTT encompasses 20.2% of the tracts and 28.4% of the volume of the right superior cerebellar peduncle. CONCLUSIONS The connections of the DN with the RN and thalamus are bilateral, not ipsilateral only. This affords a potential anatomical substrate for bilateral limb motor effects originating in a single cerebellar hemisphere under physiological conditions, and for bilateral limb motor impairment in hemispheric cerebellar lesions such as ischemic stroke and hemorrhage, and after resection of hemispheric tumors and arteriovenous malformations. Furthermore, when a lesion is located on the course of the dentatorubrothalamic system, a careful preoperative tractographic analysis of the relationship of the DRTT, nd-DRTT, and the lesion should be performed in order to tailor the surgical approach properly and spare all bundles.
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center;|Department of Neurosurgery, University of Pisa, Italy; and.
authors.forename: Antonio
authors.initials: A
authors.lastname: Meola
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center;|Department of Anatomy, Ankara University School of Medicine, Ankara, Turkey.
authors.forename: Ayhan
authors.initials: A
authors.lastname: Comert
authors.affiliation: Department of Psychology, Carnegie Mellon University, Pittsburgh, Pennsylvania;
authors.forename: Fang-Cheng
authors.initials: FC
authors.lastname: Yeh
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center;
authors.forename: Sananthan
authors.initials: S
authors.lastname: Sivakanthan
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center;
authors.forename: Juan C
authors.initials: JC
authors.lastname: Fernandez-Miranda
mesh_terms: D000328:Adult; D001933:Brain Stem / Q000033:anatomy & histology* / Q000601:surgery*; D002529:Cerebellar Nuclei / Q000033:anatomy & histology* / Q000601:surgery*; D063132:Connectome; D038524:Diffusion Magnetic Resonance Imaging; D004292:Dominance, Cerebral / Q000502:physiology*; D004525:Efferent Pathways / Q000033:anatomy & histology* / Q000601:surgery*; D005121:Extremities / Q000294:innervation; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D042282:Microdissection; D009412:Nerve Fibers / Q000502:physiology / Q000648:ultrastructure; D009434:Neural Pathways / Q000033:anatomy & histology* / Q000601:surgery*; D012012:Red Nucleus / Q000033:anatomy & histology* / Q000601:surgery*; D013788:Thalamus / Q000033:anatomy & histology* / Q000601:surgery*
keywords: 18FDG = 18-fluoro-deoxyglucose; DN = dentate nucleus; DRT = dentatorubro tract; DRTT = dentatorubrothalamic tract; HCP = Human Connectome Project; HCP-488 = HCP 488-subject template; ICP = inferior cerebellar peduncle; LL = lateral lemniscus; MCP = middle cerebellar peduncle; RN = red nucleus; ROI = region of interest; SCP = superior cerebellar peduncle; anatomy; dentate nucleus; fMRI = functional MRI; fiber dissection; fiber tractography; fiber tracts; nd-DRT = nondecussating DRT; nd-DRTT = nondecussating DRTT; rTMS = repetitive transcranial magnetic stimulation; red nucleus; thalamus