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Electrical Storms in the Brain, Understanding Epilepsy
Epilepsy is a chronic neurological disorder characterised by recurrent epileptic seizures occurring over time in the absence of an immediate or identifiable provoking factor. The underlying pathophysiology lies in persistent dysregulation of cerebral electrical activity, resulting in repeated abnormal synchronous neuronal discharges even without external stimulation, thereby triggering epileptic seizures.
A Single Seizure Does Not Necessarily Indicate Epilepsy
According to data from the World Health Organization (WHO), approximately 50 million people worldwide are affected by epilepsy, making it one of the most common and significant neurological disorders globally. Epilepsy affects individuals across all age groups and has a substantial impact on both public health and personal quality of life.
Despite its prevalence, public understanding of the causes, symptoms, diagnosis, treatment, and effective management of epilepsy remains limited. In practice, a single epileptic seizure does not necessarily constitute a diagnosis of epilepsy unless seizures recur. Medical statistics indicate that even among otherwise healthy individuals, the lifetime risk of experiencing at least one seizure is approximately 10 to 15 percent, meaning that around one in seven people may experience a seizure at some point in their lives. However, the risk of recurrent seizures leading to a formal diagnosis of epilepsy is considerably lower, at approximately 3 to 5 percent.
According to the diagnostic criteria established by the International League Against Epilepsy (ILAE) and the WHO, a diagnosis of epilepsy requires either at least two unprovoked seizures occurring more than 24 hours apart, or the presence of an enduring predisposition to seizures, such as known structural abnormalities of the brain. These may include cerebral malformations, tumours, or traumatic brain injuries. A definitive diagnosis must be based on seizure patterns, frequency, underlying aetiology, and relevant investigative findings, and must be made by a medical specialist.
As epilepsy requires long-term care and management, patients should work closely with specialists to develop an individualised treatment plan. This may include pharmacological therapy, surgical intervention, or adjunctive treatments, with the aim of effectively reducing seizure frequency and severity and improving overall quality of life.
Mechanisms and Symptoms of Epileptic Seizures
Epileptic seizures originate when neurons within a specific region of the brain generate abnormal electrical activity in the absence of external stimuli. These abnormal electrical discharges may remain localised or propagate to other brain regions, activating previously quiescent neurons. This process results in a surge of synchronised neuronal firing, which transiently disrupts or interrupts normal cerebral function and coordination, leading to the clinical manifestations of a seizure.
The symptoms, duration, and severity of epileptic seizures vary depending on the brain regions involved and the seizure type. Clinical manifestations are diverse and may include motor symptoms such as sudden violent tremors, limb jerking, tonic–clonic muscle rigidity, and loss of voluntary muscle control, with severe cases resulting in urinary or faecal incontinence. Sensory disturbances may include paraesthesia, numbness, pain, hallucinations, or visual changes. Autonomic symptoms may present as fluctuations in heart rate, sweating, or nausea. Altered consciousness or behavioural abnormalities may occur, including staring spells or confusion. Loss of consciousness may also occur, with patients often experiencing profound fatigue following the seizure.
Epileptic seizures typically exhibit several characteristic features, including sudden onset without warning, a brief duration ranging from seconds to a few minutes, and subsequent recovery of normal cerebral function. However, some patients may experience postictal confusion or prolonged fatigue.
Classification of Seizure Severity
As previously described, seizure manifestations depend on the affected brain regions, with considerable variation in presentation and severity. Epileptic seizures are broadly classified into two main categories:
Focal Seizures
Focal seizures originate from a specific area within one cerebral hemisphere and affect only that side of the brain. Based on the level of awareness, they may be further classified into focal aware seizures, in which consciousness is preserved and symptoms include localised muscle twitching, abnormal sensations, or dizziness; and focal impaired awareness seizures, in which consciousness is affected. These may present with convulsive movements, altered awareness, staring, delayed responsiveness, or transient loss of consciousness.
Generalised Seizures
Generalised seizures involve abnormal electrical activity affecting both cerebral hemispheres simultaneously, resulting in widespread and often severe symptoms. These include absence seizures, characterised by brief lapses in awareness often mistaken for daydreaming; myoclonic seizures, presenting as sudden brief muscle jerks; atonic seizures, marked by sudden loss of muscle tone leading to falls; and tonic–clonic seizures, which involve muscle rigidity, convulsions, loss of consciousness, and possible incontinence, commonly referred to as major epileptic seizures.
Distinguishing between a single epileptic seizure and recurrent epileptic seizures is crucial for the diagnosis of epilepsy. Recurrent epilepsy involves repeated unprovoked seizures and constitutes a chronic neurological disorder that requires long term care and treatment.
The image on the left shows a generalised epileptic seizure, while the image on the right shows a focal epileptic seizure.
Differences between Seizures and Epilepsy
Seizures
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Definition: Sudden abnormal electrical activity in the brain resulting in transient neurological symptoms
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Occurrence: May occur as a single isolated event
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Cause: Commonly related to transient factors or specific acute insults
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Diagnosis: Based on observation and investigation of the seizure event
Epilepsy
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Definition: A neurological disorder characterised by recurrent unprovoked seizures
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Occurrence: Occurs repeatedly over time, with multiple seizure episodes
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Cause: Commonly associated with chronic structural or genetic abnormalities of the brain
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Diagnosis: Diagnosed through seizure history and comprehensive diagnostic assessment demonstrating recurrent epilepsy
During an epileptic seizure, sudden abnormal electrical activity occurs in the brain, which may result in tonic–clonic limb convulsions and can also impair consciousness.