Epilepsy â€” Signs, Symptoms, and Pathophysiology
Epilepsy is a term which is used to define a disorder characterized by recurrent, usually transient seizures having a sudden onset and a spontaneous resolution. Actually its not a disease but rather a condition in which a patient suffers from a complex set of symptoms. Epilepsy due to unknown cause is called primary or idiopathic epilepsy, whereas secondary or organic epilepsy exist along with an identifiable precipitating factor.
Nerve impulse propagates in the brain in a synchronous manner and for that the electrical potential reaches to zero. Any type of process which damages or cause irritation to the grey matter of the brain may cause activation or inactivation of neurons causes by unknown mechanism. This leads to sudden, excessive, synchronous discharge which results in an electrical potential. If the discharge remains localized it results in partial seizures or it may spread and involve the entire cerebrum causing generalized seizures.
Imbalance of excitatory transmitters such as G-amino butyric acid and selective central nervous system, calcium channel blockers may be involved in the seizure disorders. The excessive neuronal disorderly discharge involving in the entire brain results in loss of consciousness, disturbances in sensation and conclusive movements. After peak of seizures there is decrease in frequency of neuronal discharge. It leads to the end of seizures .The seizure may be ending due to loss of cerebral energy reserves, local tissue anoxia, accumulation of toxic metabolites of neuronal metabolism and inhibitory neuronal feed back mechanisms.
Signs and symptoms of epilepsy differ with the type. The generalized seizures involves in cerebral cortex. These may be Grand mal and Petit mal. In Grand mal epilepsy there is sudden lose of consciousness, clonic movement of muscles and incontinence of sphincters. Patient may remain unconscious for a long time .After awaking the patient has no recollection of the preceding events. He usually complains about light headache. The loss of consciousness is for about half an hour. But in Petit Mal the loss of consciousness is for few seconds with no much facial expressions, only blinking of eye and jerking of arm may occur. The partial seizures involves convulsions of voluntary muscles, mainly clonic in nature, it generally last for a few minutes, it may spread like a old fashion manner to the adjacent muscle group called as jacksonian seizures .Sometimes it may become generalized. The electroencephalogram is characteristically abnormal during a seizure but may show normalcy in between seizures.