Young patients with focal seizures may have the primary motor area for the hand in the postcentral gyrus

Abstract

SummaryObjective: We determined whether the primary motor hand area was most frequently located in the precentral gyrus in young patients with intractable focal seizures. Methods:Sixty-five patients with focal seizures aged between 5 months and 20 years who underwent a two-stage epilepsy surgery using chronic subdural-EEG monitoring were studied. Pairs of subdural electrodes were electrically stimulated, and the brain region with contralateral hand movement induced by the lowest-intense stimulus was defined as the primary motor hand area.Results: Contralateral hand movement was induced without afterdischarges in 50 children but not in the remaining 15 children. The unpaired t-test revealed that failure to induce contralateral hand motor movement was associated with younger age of subjects. Among the 50 patients with a positive motor response, the primary motor hand area was confined to the precentral gyrus in 9 patients, confined to the postcentral gyrus in 24, and located in both the pre-and post-central gyri in the remaining 17. The McNemar's test revealed that the observed frequency of 24 patients showing the primary motor hand area confined to the postcentral gyrus was larger than chance frequency. Logistic regression analysis failed to demonstrate that the observation of the primary motor hand area confined to the postcentral gyrus was associated with the age, the presence of dysplastic lesion or the seizure onset involving the frontal lobe. Conclusion:Our study failed to support the traditionally-accepted notion that the primary motor hand area is most frequently located in the precentral gyrus but rather demonstrated that a substantial proportion of young patients had the primary motor hand area in the postcentral gyrus.

Revealing humans’ sensorimotor functions with electrical cortical stimulation

“…More generally, recent data have also suggested that the functional segregation between M1 and S1 might not be as strict as initially postulated by Penfield [53]. In humans, in particular, it was found that the hand 'hot spot', defined as the cortical area that evokes hand or finger responses at the lowest electrical intensity, was located in the post-central gyrus in a significant fraction of subjects [54,55]. At a first level, this puzzling result highlights the necessity of considering Penfield's anatomical maps with caution.…”

Quantification of primary motor pathways using diffusion MRI tractography and its application to predict postoperative motor deficits in children with focal epilepsy

“…ESM, using the method previously established [Fukuda et al, 2008; Haseeb et al, 2007], was performed as part of the clinical care during extraoperative electrocorticography recordings. A pair of subdural electrodes was stimulated by an electrical pulse-train of 5-s maximum duration using pulses of 300 μs duration and frequency of 50 Hz.…”

“…However, ESM is not an ideal diagnostic modality, because of its insensitivity to find the motor areas in young children [Chitoku et al, 2001; Haseeb et al, 2007; Wylle and Awad, 1991]. A previous study reported that no contralateral hand movement was elicited by electrical stimulation in 15 of 65 children, and that the average age of these 15 patients was 3.4 years [Haseeb et al, 2007]. Inevitable limitations of ESM also include sampling errors; for example, the primary motor leg area is difficult to localize by ESM, unless subdural electrodes are placed exactly on the cortical tissues of interest in the interhemispheric fissure.…”

Automatic Seizure Detection Using Higher Order Moments

“…It is the third standardized moment, γ 1 and is defined as: (2) where 3 μ is the third moment about the mean and σ is the standard deviation. …”

“…Newer methods where parts of the brain are electrically stimulated to avoid the onset of seizure are being developed [2]. Automatic detection of seizures forms an integral part of such methods.…”