title: Functional variability of the human cortical motor map: electrical stimulation findings in perirolandic epilepsy surgery.
abstract: The purpose of this study was to assess the cortical representation of sensorimotor functions in patients undergoing perirolandic epilepsy surgery, focusing on somatotopy, mosaicism, and variability of function in relation to the classic motor homunculus. The authors studied 36 patients in whom intraoperative or extraoperative electrical cortical stimulation to map motor functions was performed. A computer program was devised to register electrode number, stimulation parameters, and response to each stimulus. Electrode position was represented graphically whenever a stimulus was delivered. A total of 43 maps from 36 patients were analyzed. The authors found variations in the organization of M1 (primary motor cortex) in seven patients (19.4%). Four patients (11.1%) presented mosaicism (overlapping of functional areas), two (5.6%) presented variability (inverted disposition of M1 functional areas), and one (2.8%) had both. The results of this study challenge the notion of orderly topographic relationships between the human sensorimotor functions and their representation in the primary motor cortex. These results confirm those of other studies with animals and humans using novel imaging techniques, suggesting that the motor homunculus may not always be considered a definite and absolute representation of M1.
authors.affiliation: Porto Alegre Epilepsy Surgery Program, Hospital São Lucas, School of Medicine, Pontificia Universidade Católica do Rio Grande do Sul, Alegre, Brazil.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Branco
authors.forename: Tatiana M
authors.initials: TM
authors.lastname: Coelho
authors.forename: Bianca M
authors.initials: BM
authors.lastname: Branco
authors.forename: Letícia
authors.initials: L
authors.lastname: Schmidt
authors.forename: Maria E
authors.initials: ME
authors.lastname: Calcagnotto
authors.forename: Mirna
authors.initials: M
authors.lastname: Portuguez
authors.forename: Eliseu Paglioli
authors.initials: EP
authors.lastname: Neto
authors.forename: Eduardo
authors.initials: E
authors.lastname: Paglioli
authors.forename: André
authors.initials: A
authors.lastname: Palmini
authors.forename: José V
authors.initials: JV
authors.lastname: Lima
authors.forename: Jaderson C
authors.initials: JC
authors.lastname: Da Costa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D004558:Electric Stimulation / Q000379:methods*; D019305:Epilepsy, Rolandic / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D012680:Sensitivity and Specificity