frontal lobe seizure primary sensorimotor cortex seizure true true Primary sensorimotor cortex seizures are focal motor seizures characterized by localized clonic, tonic-clonic, tonic or myoclonic activity. They may exhibit features of a Jacksonian march where unilateral tonic-clonic movements start in one muscle group and spread systematically to adjacent groups reflecting the spread of ictal activity through the motor cortex according to the homunculus. There may be focal somatosensory features alone, such as unilateral tingling, or in combination with motor features. Negative motor features such as focal atonic features may also occur. https://www.ncbi.nlm.nih.gov/pubmed/10908200