An epileptic event is the outward physical manifestation of abnormal electric discharges that get generated inside the brain's neuronal circuits.
The physical symptoms that occur as a result of the abnormal electrical activity in the brain, which we call a seizure or a fit, depending on which area of the brain is involved or whether the abnormal electric activity remains confined to a local area of the brain circuitry when it is called a focal seizure or spreads to involve the entire brain ie secondarily generalises or is generated in both sides of the brain simultaneously when it is called a generalised seizure.Causes
A good number of cases have no identifiable cause. There is often an underlying hereditary factor.
Seizures can occur as a result of metabolic disturbances like hypoglycemia, hyperglycemia, hypertensive encephalopathy, hyponatremia, hypernatremia, hypo or hyper-calcemia, or other electrolyte disturbances, hypoxia-ischemia, sepsis, liver or kidney failure, cerebral malaria or other systemic infections, alcohol abuse or withdrawal, drugs abuse, toxins, or due to brain tumour or metastases, brain infections like meningitis or encephalitis, parasitic infections, systemic or cerebral vasculitis, autoimmune encephalitis, ischemic or haemorrhagic strokes, cerebral venous thrombosis, aneurysms or arteriovenous malformations, head injury etc.
Also, there is an inherited predisposition for epilepsy for eg Juvenile myoclonic epilepsy, juvenile absence epilepsy, genetic causes as in epilepsy syndromes like Lennox Gestaut syndrome, inborn errors of metabolism, mitochondrial disorders etc.
Who is more likely to suffer?
Seizures can occur at any age including infancy, childhood, adulthood or old age. The causes may differ based on the age group and underlying medical conditions.
Febrile seizures in childhood may become a reason for developing sclerosis of temporal lobes leading to mesial temporal lobe epilepsy.
People with a family history of epilepsy may be more prone to have seizures in younger age groups. Uncontrolled blood pressure and blood sugars put people at higher risk of getting seizures. During pregnancy, eclampsia may be the cause of seizures. Head injuries leading to eventual brain haemorrhage or scarring can become a life-long cause of seizures. Alcohol and drug abuse is one of the common causes of seizures.
Early signs, symptoms
In focal seizures there is a localised involvement of some part of the brain, for example, when the temporal lobe is involved, one may experience transient behavioural disturbances like fear, rage, laughter etc with or without a sense of disconnect from the surroundings, some involuntary movements like lip smacking, eye blinking, repetitive hand movements etc, or abnormal sensory experiences like smelling of burnt rubber, formed hallucinations etc. If the frontal or parietal lobes are involved, one may experience involuntary abnormal twisting, twitching or turning of limbs and/or face, head, eyes, or making involuntary sounds, tingling sensation on one side of the body and so on and if the occipital lobe is involved one may experience visual phenomena like flashing lights or seeing colours transiently for a few seconds to usually less than a minute.
The above phenomena may generalise to involve the whole brain and progress to cause loss of consciousness, followed by tonic-clonic limb movements associated with tongue bite, eye uprolling, frothing from the mouth etc.
If to begin with the entire brain circuitry gets activated abnormally due to dysregulated neuronal transmission, one may have a generalised tonic-clonic seizure as described above at the onset. This usually lasts for less than a minute and is followed by a postictal phase involving urinary and/or stool incontinence, confusion, vomiting, headache etc lasting for variable periods.
There are other types of generalised seizures which are called absence seizures, myoclonic jerks and tonic and atonic seizures.
Absence seizures usually occur in children which involve sudden episodes of getting blank for a few seconds and then continuing to do the task at hand. These episodes can occur multiple times a day and can impair a child's academic performance due to repeated breaks in consciousness occurring due to the seizure phenomenon. Myoclonic jerks occur usually as part of idiopathic generalised epilepsies and involve a sudden jerk of body/body parts leading to fall of objects from hands if holding something.
Absence and myoclonic seizure have typical appearances on electroencephalography which focal seizures show epileptiform discharges arising from involved area of the brain.
How to manage?
When a generalised seizure occurs the priority is to protect the person from getting injured. One should put the person on his side to avoid choking on his or her own secretions, loosen any tight clothing, avoid a fall by placing the person in a safe place and try to prevent tongue bite by putting a soft cloth in the mouth but never insert a hard object between teeth due to the risk of injury.
Midazolam sprays are available which can be kept handy and sprayed in the nose to abort a seizure.
Usually, a seizure does not last longer than a minute but if repeated seizures occur or if a seizure continues for more than 5 minutes then one should immediately shift a person to the nearest hospital with emergency medical services, for intravenous antiseizure medications and managing any other complications related to continuing seizure activity like hypoxia or aspiration pneumonia. Also, the cause for seizures has to be looked for by testing for blood sugar, electrolytes, renal or liver disturbances or thiamine deficiency which is possible in alcoholics.
For evaluation of seizures, one requires to do a neuroimaging like CT scan or MRI of the brain and EEG.
As per the underlying cause and diagnosis, the doctor decides about the appropriate seizure medications which usually need to be continued for variable periods. If the cause of seizures has been a transient metabolic cause one may not need very long-term medications while if an underlying scar or sclerosis is found, or a diagnosis of an epilepsy syndrome is made one may need antiseizure medications for indefinite periods, sometimes lifelong.
Usually after a seizure-free period of three to five years a taper of antiseizure medicines is often attempted after appropriate evaluation and risk assessment of seizure recurrence.
Certain epilepsies are drug refractory which means a reasonable seizure control is not achieved despite use of three appropriate anti-seizure medications. These patients are recommended to be evaluated for epilepsy surgery which may lead to better seizure control and reduction in doses of medications and occasionally seizure freedom.
(The author is Consultant – Neurology at Manipal Hospitals Goa)
