What type of seizures involve only a portion of the brain?

Partial seizures involve only a portion of the brain, which distinguishes them from generalized seizures that affect the entire brain. These seizures can arise from abnormal electrical activity in one hemisphere or a specific area of the cortex. Depending on the region of the brain that is affected, partial seizures can manifest with various symptoms, including localized motor movements, sensory changes, or alterations in consciousness.

When considering the other types of seizures listed, generalized seizures engage both hemispheres from the onset and typically result in loss of consciousness. Complex seizures are a type of partial seizure characterized by impaired consciousness but still originate from a specific part of the brain. Generalized tonic-clonic seizures, which represent a severe form of generalized seizure, also impact the entire brain and lead to a loss of consciousness and convulsions. Therefore, the defining characteristic of partial seizures, involving only a portion of the brain, aligns precisely with the criteria needed to identify the correct answer.