- A seizure is a neurological event characterized by sudden, excessive, and uncontrolled neuronal activity in the brain, which can cause loss of consciousness and convulsive movements.
- Unlike syncope, which is a transient loss of consciousness due to cerebral hypoperfusion without convulsions, seizures often include tonic-clonic muscle activity.
- The presence of convulsions alongside loss of consciousness is a hallmark that differentiates seizures from vasovagal syncope or cardiac causes.
- This motor activity results from abnormal cortical electrical discharge, confirming a neurological rather than vascular origin of the event.

Reference: Davidson’s Principles and Practice of Medicine, 23rd Edition, Chapter: Disorders of the Nervous System, Page 660.