title: Corticospinal descending direct wave elicited by subcortical stimulation.
abstract: Recent studies have indicated the importance of subcortical mapping of the corticospinal tract (CT) during tumor resection close to the primary motor area. It is substantial evidence that the corticospinal descending direct wave (D-wave) can be used as a guide for mapping of the primary motor cortex (M1) and for monitoring of the CT functional integrity. In the present study, the authors investigated the feasibility of D-wave recordings after subcortical stimulation. The authors examined 14 patients with brain tumors close to the M1 and/or CT, who exhibited no obvious motor deficit before surgery. Subcortical white matter was electrically stimulated in monopolar or bipolar fashion by recording the descending wave (D-wave) from the spinal epidural space using a catheter-type electrode. Subcortical D-wave was more clearly recorded after monopolar stimulation than after bipolar stimulation. The features of the subcortical D-wave, including its waveform, conduction velocity, and latency, were nearly identical to those of the corticospinal D-wave recorded after M1 stimulation. Subcortical D-wave amplitude was prone to change depending on the distance from the stimulation points to the CT. Changes in parameters of subcortical D-wave may provide valuable information to prevent postoperative motor deficit. Further studies are required to clarify the relationship between the distance from the stimulating point to the CT and the amplitude of the subcortically elicited D-wave.
authors.affiliation: Department of Neurological Surgery, Nihon University School of Medicine, Tokyo, Japan. chikashi@med.nihon-u.ac.jp
authors.forename: Chikashi
authors.initials: C
authors.lastname: Fukaya
authors.forename: Koichiro
authors.initials: K
authors.lastname: Sumi
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Otaka
authors.forename: Katsunori
authors.initials: K
authors.lastname: Shijo
authors.forename: Takafumi
authors.initials: T
authors.lastname: Nagaoaka
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Hideki
authors.initials: H
authors.lastname: Oshima
authors.forename: Takao
authors.initials: T
authors.lastname: Watanabe
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Katayama
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000503:physiopathology*; D046690:Deep Brain Stimulation / Q000379:methods*; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011712:Pyramidal Tracts / Q000503:physiopathology*