Seizures are abnormal, excessive synchronous discharges in a group of neurons. They are always a symptom of underlying gray matter. If seizures occur repeatedly and no cause is found, the patient receives the diagnosis of idiopathic epilepsy. Seizures are described as ictal because of their sudden onset. They rarely last longer than 1-2 minutes. However, seizures are followed by a depression of function lasting minutes to hours. This is called the postictal state.

Paroxysmal Discharges and the Emergence of Seizure
Experimental studies of seizure have identified the occurrence of small abnormal discharges of electrical activity during the period between seizures (the interictal period). These are called paroxysmal discharges. They indicate a small group of cells that are discharging abnormally. This interictal discharge may propogate similar discharges in surrounding neurons and further develop as a complete tonic-clonic seizure episode (see above). The smaller group of neurons is called the seizure focus. It presumably represents a cluster of cells that have been injured or have developed abnormally.

Seizures may cause abnormal actions, sensory experiences, amnesia or depression of cerebral functions. The dysfunction associated with seizures varies with the cerebral systems involved. Partial seizures are those that begin in a discrete cortical area and have restricted clinical manifestations. Simple partial seizures have discreet symptoms without loss of consciousness. A complex partial seizure results in discreet symptoms with disturbance but not loss of consciousness.

The aura is a strange sensation or emotional response that may initiate a complex partial seizure. Loss or disturbance or consciousness will usually follow the aura. For example, patients may hear an odd sound, smell something strange, or experience a sense of extreme fear. Following the aura some patients with complex partial seizures will exhibit automatisms. These are stereotyped, involuntary motor actions, such as lip smacking, or writhing hand movements.

Both simple and complex partial seizures can spread from a single focus to involve the whole brain and cause generalized seizures. Generalized seizures are represented bilaterally from the outset. Nonconvulsive, generalized seizures (also called absence, or petit mal) are characterized by 5 to 10 second periods of disturbed consciousness with stereotyped eye movements and clonic components.

Convulsive generalized seizures (grand mal, or tonic-clonic) are characterized by rigid extension of the body, unconsciousness, loss of bowel and bladder control, and salivation (tonic phase; 10 seconds). This is followed by rhythmic limb contraction (clonic phase; 20 - 30 seconds). Following the seizure the patient slowly regains consciousness but remains sleepy.

With repeated seizures, the propagation of the seizure through groups of neurons becomes more efficient. This is called kindling. The recurrence of seizures at a rate so rapid that consciousness does not return is called status epilepticus.

Seizure Classification:
Partial Seizures
   1. Simple partial seizures
      a. focal motor seizures
      b. focal sensory seizures
   2. Complex partial seizures
Generalized
   1. Nonconvulsive (petit mal)
   2. Convulsive
      a. Tonic-clonic (grand mal)
      b. Myoclonic

Causes of Seizures:

• Maldevelopment
• Hypocalcemia
• Hypoglycemia
• Infections: Encephalitis, Meningitis
• Brain tumor
• Arteriovenous Malformation
• Post stroke defects
• Traumatic brain injury
• Withdrawal from alcohol and sedatives

Diagnosis: The Electroencephalogram (EEG) monitors changes in electrical current among large groups of neurons in the brain. It is unreliable as a diagnostic test unless the patient has a seizure while the EEG is being monitored. Many patients with documented seizure disorder will have a normal EEG during the period between seizures.

Careful documentation of the history of seizures and neurological symptoms is crucial for diagnosis. The incidence of seizures and the patients symptoms and behavior during a seizure are important elements in diagnosis.

Important features to note from the history:
1) Focal or partial onset. Does the patient have focal symptoms, such as movement on one side of the body or unusual sensory perceptions at the onset of the seizure?
2) Disturbance or loss of consciousness
3) Family history of seizures
4) History of any illness
5) In the case of children, the pregnancy and perinatal history.

The neurological examination may reveal indications of focal or lateralized lesions. Neuroimaging (CT, MRI, SPECT, or PET) may reveal other pathology that is causing the seizure, such as brain tumor or traumatic injury. The focus of idiopathic seizures is rarely discovered using neuro-imaging studies.

Treatment: Since seizures are symptoms of many other brain illnesses, the seizures are affected by treatment of these underlying diseases. A variety of medications are available for seizure treatment. There is some specialization of drug for seizure type. Phenytoin (Dilantin), Carbamazepine (Tegretol) and Phenobarbitol are commonly used to treat convulsive generalized seizures. Ethosuximide (Zarontin) is often used to treat nonconvulsive generalized seizures. Seizure disorder is sometimes treated by surgery excision if the seizure focus is well localized and accessible.