Partial seizure

Focal seizures (also called partial seizures and localized seizures) are seizures which affect initially only one hemisphere of the brain. The brain is divided into two hemispheres, each consisting of four lobes – the frontal, temporal, parietal and occipital lobes. In partial seizures the seizure is generated in and affects just one part of the brain – the whole hemisphere or part of a lobe. Symptoms will vary according to where the seizure occurs. In the frontal lobe symptoms may include a wave-like sensation in the head; in the temporal lobe, a feeling of déjà vu; in the parietal lobe, a numbness or tingling; and in the occipital lobe, visual disturbance or hallucination.

Partial seizures are split into two main categories; simple partial seizures and complex partial seizures. A new classification system for partial seizures has been described in the 18th Edition of Harrison's Principles of Internal Medicine (released July 2011). The new classification splits partial seizures into "partial seizures with dyscognitive features" and "partial seizures without dyscognitive features".