title: Effect of ventralis intermedius thalamotomy on the area in the sensorimotor cortex activated by passive hand movements: fMR imaging study.
abstract: Stereotactic ventralis intermedius (Vim) thalamotomy is effective for essential tremor (ET) of the limb, but the effect on the activity of the sensorimotor cortex is still unclear. The functional changes in this cortical area of patients with ET after Vim thalamotomy were investigated using functional magnetic resonance (fMR) imaging. Six patients underwent Vim thalamotomy for medically intractable ET, predominantly in the right hand. 1.5-tesla fMR imaging was performed using the blood oxygenation level-dependent sequence, before and after Vim thalamotomy, during passive movements with right wrist flexion and extension. Before and after images were analyzed using SPM99 software. Activation in the sensorimotor cortex and supplementary motor area evoked by wrist passive movement was observed both before and after surgery. Group analysis of changes in the blood oxygenation level-dependent response revealed a significantly smaller activated area postoperatively. Activation at the fundus of the central sulcus was characteristically decreased. All patients showed marked improvement in tremor after Vim thalamotomy. No patient experienced neurological deficits. fMR imaging showed that activation at the fundus of the central sulcus evoked by passive wrist movement was suppressed after Vim thalamotomy in ET patients, probably due to disruption of the thalamocortical pathway. The fundus of the central sulcus (Brodmann area 3a) is likely to be one of the key relays in the tremor circuit.
authors.affiliation: Department of Neurosurgery, Gunma University School of Medicine, Maebashi, Japan. miyagisi@med.gunma-u.ac.jp
authors.forename: Takaaki
authors.initials: T
authors.lastname: Miyagishima
authors.forename: Akio
authors.initials: A
authors.lastname: Takahashi
authors.forename: Senichiro
authors.initials: S
authors.lastname: Kikuchi
authors.forename: Katsushige
authors.initials: K
authors.lastname: Watanabe
authors.forename: Masafumi
authors.initials: M
authors.lastname: Hirato
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Saito
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Yoshimoto
mesh_terms: D000328:Adult; D000344:Afferent Pathways / Q000503:physiopathology; D000368:Aged; D001931:Brain Mapping; D003714:Denervation; D006225:Hand / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009038:Motion; D009044:Motor Cortex / Q000503:physiopathology*; D019635:Neurosurgical Procedures; D013003:Somatosensory Cortex / Q000503:physiopathology*; D014202:Tremor / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D020651:Ventral Thalamic Nuclei / Q000601:surgery*