Convulsions / Seizures / Fits

A seizure or a convulsion is a result of abnormal electrical activity in the brain. It can affect an individual at any age. However, not all convulsions amount to epilepsy. The term ‘epilepsy’ is used when the person suffers from 2 or more apparently unprovoked seizures at an interval of at least 24 hours.

Repeated seizures can cause brain damage; hence it is necessary to diagnose the cause and treat it. In some cases, where the cause of seizures is not known, it is necessary to prevent seizures from recurring by taking daily medications.

Seizures may be focal (partial) or generalized. In partial seizures, jerking is observed in a limb or a part of the body. Such seizures are seen when a part of the brain is affected. On the other hand, generalized seizures affect the whole body. Generalized seizures occur when both sides of the brain are affected. The patient often loses consciousness.

Types of generalized seizures are:

 Tonic / Clonic Convulsions: The patient may experience a premonition just before the seizure. This is followed by the stiffening of limbs in the tonic phase. The tonic phase is followed by the clonic phase in which the person starts shaking and jerking. The patient may bite his /her tongue. This stage is followed by deep sleep. Loss of bladder and bowel control may be seen during the seizure.

 Absence Seizures: Absence seizures more commonly affect children. The child may show a temporary blackout that lasts for a short duration. 

 Atonic Seizures: During an atonic seizure, the tone of the muscles is lost and the person goes floppy and may fall down. 

 Myoclonic Seizures: In myoclonic seizures, the legs, arms, head or whole body will jerk up, often after the patient has just woken up. 

Types of partial seizures are: 

 Simple Partial Seizures: Simple partial seizures are when one part of the body like the face, arms or legs are affected but consciousness is not lost.

 Complex Partial Seizures: Complex partial seizures are localized seizures with impairment of consciousness.

Status Epilepticus: Status epilepticus is a condition where a patient suffers from repeated partial or generalized seizures without regaining consciousness between the seizures.

Tests used to diagnose the presence of epilepsy or the causes of seizures are:

 EEG Monitoring: An EEG (Electroencephalography) is a test used to record the electrical activity of the brain. It should ideally be performed within the first 24 hours of a patient suffering from a seizure. It may be abnormal in an epileptic patient, even while the patient is not suffering from the seizure.

 Brain Scans: Brain scans like CT and MRI can detect structural abnormalities of the brain like tumors and cysts. PET scan is used to monitor the brain’s activity. SPECT scan is sometimes used to localize the seizure focus in the brain.

 Blood Tests: Blood tests help to detect metabolic or genetic disease. They also help to detect conditions like infections, lead poisoning, anemia, and diabetes that may cause the seizure.

Causes 

In many cases, the cause of seizures cannot be detected despite all tests. In some other cases like genetic, the cause can be detected but cannot be completely eliminated. These patients are controlled using antiseizure drugs. In some other cases like brain tumor and low blood sugar levels, the seizures may stop after the cause is treated, provided there has been no damage to the brain. Some of the causes of seizures are listed below:

 Genetic Causes: Mutations in the genes may make a person more susceptible to seizures. Conditions like Lafora disease and myoclonus epilepsy are caused due to genetic abnormalities. More than themselves causing seizures, these genetic abnormalities may make a person more prone to seizures in the presence of another provoking factor like a head injury. Epilepsy of genetic origin sometimes runs in families, but this depends on a variety of factors including the type of epilepsy.

 Head Injury: Head injury may result in a single seizure or an epileptic syndrome within 2 years following the injury. In some cases, it can cause a bleed within the skull, resulting in seizures. A history of head injury can be elicited in these patients. Head injuries may occur during birth resulting in seizures that usually manifest in infancy or early childhood.

 Metabolic Disorders: Metabolic disorders can cause seizures in individuals of any age. Many of these seizures can be controlled by treating the metabolic disorder. For example, low or high blood sugar levels in diabeticscan cause seizures. Kidney failure can cause increased urea levels and electrolyte abnormalities, which can precipitate seizures. Phenylketonuria is an inherited condition where there is lack of an enzyme called phenylalanine hydroxylase. This results in accumulation of a substance called phenylalanine in the blood, which could result in seizures. Symptoms in patients with classical phenylketonuria usually manifest when the child is a few months old. Besides seizures, the child may develop behavioral problems and psychiatric disorders. The excess phenylketonuria may cause a musty or mouse-like odor. The skin and hair may be lighter and the children may also suffer from eczema.

 Drugs, Alcohol and Poisons: Sudden withdrawal from alcohol and drugs acting on the brain could precipitate generalized seizures. Seizures may follow lead or carbon monoxide poisoning, exposure to street drugs and medications like antidepressants.

 Brain Tumors: Tumors affecting the brain can result in seizures. Middle aged and older patients suffering from seizures should be particularly investigated using imaging studies like CT scan and MRI to rule out brain tumors. The seizures are usually focal in nature and symptoms depend on the location of the tumor.

 Brain Infections: Brain infections can cause seizures. These infections may be due to bacteria like meningitis or brain abscess or virus like herpes encephalitis. A lumbar puncture is useful in diagnosing these infections. Patients with AIDS may suffer from seizures due to toxoplasmosis, cyptococcal meningitis, viral encephalitis or other infections. Neurocysticercosis is a parasitic infection that results in the formation of cysts in the brain. This condition affects pork eaters. The cyst can be diagnosed using imaging studies.

 Conditions Affecting Blood Supply to the Brain: Vascular disorders are the most common cause of seizures in individuals over the age of 60 years. Strokes and heart attacks reduce oxygen supply to the brain and can result in seizures. Bleeding within the skull can also reduce the blood supply and can occur at any age from infancy to adulthood.

 Congenital Abnormalities: Epilepsies due to congenital malformations in the brain usually manifest during infancy or childhood.

 Brain Degenerative Diseases: Brain degenerative diseases like Alzheimer’s disease can result in seizures in older individuals. Features of the underlying degenerative disease are usually obvious in these patients.

 Febrile Seizures: Febrile seizures are triggered by a fever and most commonly occur in children.. Most children with a febrile seizure usually do not suffer from a repeat seizure, unless they have some predisposing factors.

 Eclampsia: Eclampsia is a life-threatening condition that occurs in some pregnant women. The patient suffers from very high blood pressure and seizures during pregnancy. It usually does not result in additional seizures once the pregnancy is over.

 Psychogenic Seizures: Psychogenic non-epileptic seizures are seizures that are not associated with abnormal electrical activity of the brain. The condition may be precipitated by a need for attention, avoidance of stressful situations, or specific psychiatric conditions. This condition is treated by a psychiatrist.

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