Overview
A seizure occurs when a person has an episode of excessive and abnormal electrical discharges in the brain. This can result in various symptoms, including tonic (rigid) posturing, clonic (shaking) activity, staring, repetitive behaviors, or other symptoms. These symptoms may involve the whole body or only part of the body.
Epilepsy – the medical term for a seizure disorder – is diagnosed when a person has two or more seizure spells that are not provoked by reversible causes or have one seizure and discovery of an underlying condition that puts the person at high risk for having another seizure. About 3% of the US population has Epilepsy at some point in life.
Types of Seizures
Focal seizures
Focal seizures refer to seizures where the extra electrical activity comes from a specific localized area of the brain. This can be seen in Electroencephalogram (EEG), and these symptoms the person experiences can vary greatly based on which area of the brain is involved. Other terms for a focal seizure include localization-related seizure or partial seizure.
Simple Focal Seizures
Simple focal seizures involve a partial seizure where consciousness – or the ability of the person to be aware of surroundings or remember the event – is still intact. This can involve sensory seizures (where numbness or tingling spreads), motor seizures (where there is fine twitching in one part of the body that may spread slowly, called a “Jacksonian” seizure), or other symptoms.
Complex Focal Seizures
Complex focal seizures involve a partial seizure where consciousness is lost, or the patient “passes out.” This is the most common type of seizure in adults. In this case, there often is stiffening and/or shaking activity of part of the body while the person is unconscious. In this case, the person will not remember the seizure.
Secondary Generalized Seizures
Secondary generalized seizures involve a focal seizure (as above) where the extra electrical activity spreads to a larger part of the brain, eventually involving both hemispheres of the brain. This results in the whole body having seizure activity.
Generalized Seizures
Generalized seizures are seizures that involve the whole brain. In contrast to the focal seizures, there is no consistent area of the brain that starts the seizure.
Tonic-clonic (grand mal) Seizures
Tonic-clonic (grand mal) seizures involve a pattern in which the person first has stiffening of all of the extremities (called “tonic” posturing) followed by rhythmic shaking activity of the extremities (called “clonic” activity).
Clonic Seizures
Clonic seizures are a type of epileptic seizure characterized by rhythmic, repetitive muscle contractions and relaxations. These involuntary movements often manifest as jerking or twitching and are typically brief in duration.
Atonic Seizures
Atonic seizures involve the sudden loss of tone in the muscles. This results in a person losing their posture and can result in “drop attacks,” where a person suddenly falls.
Myoclonic Seizures
Myoclonic seizures are characterized by brief, involuntary muscle jerks or twitches that can affect various parts of the body. These seizures often appear as sudden and unpredictable movements and can be associated with various neurological conditions, including epilepsy.
Absence Seizures
Absence seizures involve a brief loss of consciousness. There is no clear stiffening or jerking of the body. It may appear as if the person is suddenly briefly “staring.” These are also called “petit mal” seizures.
Single seizure spells can occasionally be caused by reversible states, such as very low blood sugar (hypoglycemia), alcohol withdrawal, certain medications that can lower the "seizure threshold," or other causes. Epilepsy can be due to hereditary or acquired causes.
Most hereditary or genetic causes of epilepsy result in seizures in childhood. Examples include Idiopathic generalized epilepsy, Generalized epilepsy with febrile seizures, Juvenile myoclonic epilepsy, Dravet syndrome, or neurofibromatosis. While these seizure disorders have known gene mutations associated with them, the risk of developing epilepsy depends on various inheritance patterns. In many of these conditions, the cause of the seizure relates to a "channelopathy," or abnormality in how signals are sent or activated in neurons, the brain's cells.
If a person has a first-degree relative with a seizure disorder, the risk to the person is less than a 1 in 20 chance of developing a seizure disorder by age 40. About 2-5% of children experience seizures in the setting of fever as a young child despite having standard neurological systems. Of these children, about 90% never have another seizure after age 6. Some childhood seizure disorders can also be due to acquired conditions, such as a stroke in early childhood, a hypoxic (low-oxygen) event around birth, or a traumatic brain injury. There can also be abnormal brain development in childhood that can predispose one to seizures, such as mesial temporal sclerosis, where the inner part of the temporal lobe develops scar tissue.
As a person ages, it is more likely that the seizures would be from an acquired condition. Examples in adulthood include following a stroke, in the setting of a brain mass, following a traumatic brain injury, or in the vicinity of brain atrophy. These acquired conditions irritate the brain, which can lead to excessive electrical activity. Other causes of epilepsy can be non-hereditary and without a clear cause. The medical term for this is "idiopathic."
Causes of Seizures
Signs & Symptoms of Seizures
Seizure symptoms exhibit a remarkable diversity, ranging from subtle premonitory signals known as "auras," such as unusual odors like "burnt toast" or peculiar tastes like "metal," which can mark the onset of the seizure. The spectrum of common seizure manifestations encompasses muscle rigidity ("tonic" posturing), rhythmic muscular contractions ("clonic" movements), and periods of vacant staring. Notably, frontal lobe seizures may be accompanied by repetitive, automatic actions like lip smacking, termed "automatisms." Beyond the conventional, there exist more uncommon and intriguing seizure symptoms such as bouts of laughter (gelastic seizures), impulsive running (cursive seizures), and vivid visual alterations (occipital lobe seizures), among other variations.
A pivotal principle in recognizing potential seizures is identifying behaviors that deviate from the norm and recur stereotypically. Whenever a behavior displays a consistent pattern, seizure activity should be considered. The precise symptomatic presentation of a seizure is intricately linked to the origin site within the brain. Neurologists adeptly extract comprehensive patient histories to decode these clues, discerning the seizure's point of origin and devising tailored treatment strategies. By unraveling the intricate tapestry of seizure symptoms, medical professionals endeavor to illuminate the enigmatic realm of neurological disturbances, facilitating accurate diagnosis and effective management.
Diagnosing seizure disorders involves a multifaceted approach that goes beyond just collecting a detailed history from the individual experiencing the seizures and their observers. Diagnostic testing plays a crucial role in providing a comprehensive understanding of the condition. Neuroimaging techniques, including brain MRI, serve as pivotal tools to assess potential structural abnormalities within the brain that might underlie the seizures. Specialized seizure-specific MRI protocols focus on regions prone to seizure initiation. Functional MRI, which compares brain metabolism, and volumetric MRI, offering detailed brain volume measurements, provide further insights.
The Electroencephalogram (EEG) emerges as the cornerstone for confirming the seizure diagnosis and distinguishing between focal and generalized seizures. Through the placement of small electrodes on the scalp connected to wires, EEG records electrical brain activity. Even between seizure episodes, around 50% of individuals with Epilepsy display EEG abnormalities. The test's diagnostic utility amplifies during an ongoing seizure, and methods like light stimulation, sleep deprivation, or hyperventilation can be employed to provoke seizures during EEG monitoring. The EEG pattern also aids in selecting appropriate seizure medications. In complex cases, advanced EEG monitoring using deeper implanted electrodes might be considered.
Depending on the clinical history, supplementary tests such as lumbar puncture to analyze cerebrospinal fluid or blood antibody testing for autoimmune markers related to seizure-associated conditions may be warranted. This comprehensive diagnostic toolkit equips medical professionals with a spectrum of insights necessary to unravel the intricacies of seizure disorders, facilitating accurate diagnosis and tailored treatment strategies.
Diagnosis of Seizures
Treatment of Seizures
The treatment and management of diverse seizure types encompass a range of strategies tailored to the individual's specific condition and needs. For many, antiepileptic medications form the cornerstone of seizure control. These medications are selected based on the seizure type, underlying cause, potential side effects, and the patient's overall health. Close monitoring and periodic adjustments are crucial to achieve optimal seizure management while minimizing side effects.
In cases where medication alone proves ineffective, alternative interventions come into play. For some focal seizures that are resistant to medication, surgical options might be considered. Surgical procedures, such as resection of the seizure focus or the placement of responsive neurostimulation devices, aim to disrupt abnormal neural activity. Ketogenic diets, which involve high fat and low carbohydrate consumption, have shown efficacy in managing drug-resistant epilepsy, particularly in children.
In addition to medical and surgical avenues, lifestyle modifications contribute significantly to seizure control. Consistent sleep patterns, stress management techniques, and avoiding triggers are essential components. Moreover, for certain seizure disorders like absence seizures, biofeedback and relaxation therapies can be beneficial.
The evolving field of neuromodulation introduces innovative approaches like transcranial magnetic stimulation and vagus nerve stimulation, offering non-invasive methods to modulate brain activity and potentially reduce seizure frequency.
Collaboration among neurologists, epileptologists, and healthcare teams is pivotal for devising comprehensive treatment plans that encompass medical, surgical, lifestyle, and emerging therapeutic interventions. Through these multifaceted approaches, individuals with various seizure types can strive for improved quality of life with better seizure control and reduced interference from these neurological disruptions.
The prognosis varies widely depending on several factors, including the underlying cause, seizure type, response to treatment, and individual characteristics. Many people with epilepsy, characterized by recurrent seizures, can achieve effective seizure control through medication, lifestyle adjustments, and medical interventions. Appropriate treatment allows many individuals to experience prolonged periods without seizures or achieve complete seizure freedom.
However, the prognosis may be less favorable for those with certain seizures resistant to standard treatments. Drug-resistant epilepsy poses challenges, and additional interventions, such as surgical options or neuromodulation techniques, might be considered. The success of these interventions varies and depends on the specific circumstances of each case.
Early diagnosis and timely initiation of appropriate treatment can be crucial in improving the prognosis. In cases where seizures are secondary to reversible causes, such as infections or metabolic disturbances, addressing the underlying condition can lead to a more favorable outcome.
It's important to note that managing seizures is not just about seizure control; it also involves addressing the potential impact on quality of life, cognitive function, and mental health. Regular medical follow-up, medication adherence, and open communication with healthcare providers contribute to achieving the best possible prognosis for individuals affected by seizures.