La epilepsia es un trastorno que se caracteriza por la comunicación incontrolada y desorganizada entre las células nerviosas en el cerebro. En alrededor de la mitad de las personas diagnosticadas con epilepsia , la causa es desconocida. Para la otra mitad, la causa puede atribuirse a uno o más factores específicos, como la genética, la lesión o daño cerebral , los cambios estructurales en el cerebro, ciertas afecciones y enfermedades y los trastornos del desarrollo.
Epilepsy is a complex disorder with a variety of causes. Anything that disrupts the brain’s normal electrical pattern can lead to seizures. Around half of epilepsy cases can be linked to specific factors, including:
- Genetics: Most genetic epilepsies begin in childhood and are caused by a genetic defect in the ion channels or receptors. It’s important to note that for most people with a genetic form of epilepsy, genes are not the only cause. See below for more information on genetics.
- Brain damage: Conditions that cause damage to your brain, such as strokes, tumors, or traumatic injuries to your head can cause epilepsy. This also includes brain damage that occurs before birth from causes such as being deprived of oxygen or your mother having an infection. Stroke is the leading cause of epilepsy in adults who are diagnosed at age 65 or older.
- Brain infections: Infections that affect and inflame your brain, such as meningitis, viral encephalitis, tuberculosis, and acquired immunodeficiency syndrome (AIDS), can all cause epilepsy.
- Developmental disorders: Epilepsy appears to be more common in people with certain developmental disorders such as autism, Down syndrome, cerebral palsy, and intellectual disability.
- Structural changes in the brain: Certain differences in the structure of your brain that either develops over time or that you are born with, like hippocampal sclerosis (a shrunken hippocampus, a part of your brain that plays a major role in learning, memory, and emotions) or neurodevelopmental malformations, can cause seizures.
- Alcohol: Some studies have shown that chronic abuse of alcohol may be associated with the development of epilepsy in some people. This research suggest that repeated alcohol withdrawal seizures may make the brain more excitable overtime. In addition, this population also has a higher incidence of traumatic brain injury that can also cause epilepsy.
These are all risk factors as well as causes since any of these conditions may increase your likelihood of developing epilepsy.
If epilepsy runs in your family, it most likely has a genetic component. Some epilepsies with unknown causes may also have a genetic component that’s not clear yet.
That said, though some specific genes are linked to certain types of epilepsy, in most cases, genes don’t necessarily cause epilepsy—they may just make it more likely to occur under the right circumstances. For instance, if you get a traumatic head injury and you have a family history of epilepsy, you may be more likely to develop it. Genes are only a piece of the complex puzzle for most people.
Some of the specific syndromes and types of epilepsy that are known to have a genetic component include:
- Familial neonatal epilepsy: Seizures usually start between four and seven days after a baby is born and most stop around six weeks after birth, though they may not stop until 4 months of age. Some babies may end up having seizures later in life as well. Mutations in the KCNQ2 gene are most often the cause, though mutations in the KCNQ3 gene can also be a factor.
- Genetic epilepsy with febrile seizures plus (GEFS+): GEFS+ is a spectrum of seizure disorders. Seizures usually start between the ages of 6 months and 6 years when the child has a fever, called a febrile seizure. Some kids also develop seizures without fever, usually generalized seizures such as absence, tonic-clonic, myoclonic, or atonic. The seizures typically stop during early adolescence. SCN1A, SCN1B, GABARG2, and PCDH19 are some of the genes that have been linked to GEFS+.
- Dravet syndrome: This syndrome is considered to be on the severe side of the GEFS+ spectrum. Seizures usually begin around the age of 6 months. Many kids with this syndrome have their first seizure when they have a fever. Myoclonic, tonic-clonic, and atypical absence seizures also develop, which are difficult to control and may get worse as the child gets older. Intellectual disability is common. More than 80 percent of people with Dravet syndrome have mutations in the sodium channel gene SCN1A.
- Ohtahara syndrome: In this rare syndrome, tonic seizures usually start within the first month after birth, though this may happen up to three months later. One out of three babies may also develop focal, atonic, myoclonic, or tonic-clonic seizures. Some infants die before the age of 2 years and some may develop West syndrome or Lennox-Gastaut syndrome. There are a number of genes that have been associated with Ohtahara syndrome, including STXBP1, SLC25A22, CDKL5, ARX, SPTAN1, PCDH19, KCNQ2, and SCN2A.
- Juvenile myoclonic epilepsy: One of the most common generalized epilepsies with a genetic component, juvenile myoclonic epilepsyconsists of tonic-clonic, absence, and myoclonic seizures that begin any time from the ages of 5 to 16 years. Seizures tend to be well-controlled with medication and seem to improve when you reach your 40s. The genes associated with this syndrome are CACNB4, GABRA1, GABRD, and EFHC1, though the patterns tend to be complex.
- Autosomal dominant nocturnal frontal lobe epilepsy: Seizures typically start around the age of 9 years and the majority start by age 20. They occur briefly, multiple times during sleep, and range from simply waking you up to causing screaming, wandering, twisting, crying, or other focal responses. Though this syndrome is lifelong, seizures won’t get any worse and may actually become less frequent and milder with age. They’re also usually well-controlled with medication. This epilepsy isn’t very common and it’s almost always inherited. Mutations in the nicotinic receptor subunit genes CHRNA4, CHRNB2, CHRNA2, and DEPDC5 have been linked to this syndrome.
- Childhood absence epilepsy: Absence seizures usually begin between the ages of 2 and 12 years and are often genetic. In around 2 out of 3 children, the seizures stop in adolescence. Some go on to develop other types of seizures. Genes that are associated with childhood absence epilepsy include GABRG2 and CACNA1A.
- Juvenile absence epilepsy: This syndrome begins later in life and the seizures tend to last longer than in childhood absence epilepsy. It’s also usually a lifelong condition, whereas kids with childhood absence epilepsy tend to outgrow their seizures. Absence seizures usually start between the ages of 9 and 13 years, though they can begin anywhere from age 8 to 20. Tonic-clonic seizures, typically when waking up, are also seen in around 80 percent of people with this syndrome. The cause is often genetic, and the genes linked to juvenile absence epilepsy are also GABRG2 and CACNA1A, as well as others.
- Epilepsy with generalized tonic-clonic seizures alone: Tonic-clonic seizures can start anywhere from the age of 5 to 40 years, though most start between 11 and 23. Seizures usually happen within two hours of waking up. Sleep deprivation, fatigue, alcohol, menstruation, flashing lights, and fever are often triggered, and most people will need medication for their whole lives. The main gene associated with this syndrome is CLCN2.
- Familial temporal lobe epilepsy: If you have focal seizures that begin in the temporal lobe and a family history of similar seizures, you’re considered to have this syndrome. The seizures tend to be fairly rare and mild; so mild, in fact, that they may not be recognized. Seizures usually start after age 10 and are easily controlled with medication. The associated gene in this hereditary epilepsy is DEPDC5.
- Familial focal epilepsy with variable foci: This inherited epilepsy typically consists of one specific type of focal seizure. Those in a family who have epilepsy all have one single type of focal seizure, but the seizures may start in different parts of their brains. The seizures are typically easy to control with medication and are usually infrequent. The DEPDC5 gene is also linked to this syndrome.
- West syndrome: Infantile spasms begin in the first year of life and usually stop between the ages of 2 and 4 years. Abnormalities in the genes ARX, CDKL5, SPTAN1, and STXBP1 have been found in this syndrome, though other causes include brain structure abnormalities, sometimes genetic in nature, and chromosomal abnormalities.
- Benign Rolandic epilepsy: Also known as childhood epilepsy with centrotemporal spikes, this syndrome affects around 15 percent of children with epilepsy and is more common in kids with close relatives who have epilepsy. Most outgrow it by the age of 15 years. The gene associated with this syndrome is GRIN2A, though this is another case where the genetic pattern is extremely complex.
All of the common causes mentioned above are also risk factors for epilepsy since any of the conditions listed may increase your risk of developing the disorder. There are other factors that may increase your risk as well, including:
- Age: Though it can start at any age, epilepsy tends to show up more often in children and older adults.
- Family history: If anyone in your family has epilepsy, your risk of developing it may be higher.
- History of head injuries: Seizures can develop hours, days, months, or even years after a head trauma, and the risk may be higher if you also have a family history of epilepsy.
- Dementia: Having dementia is a risk factor for epilepsy in older adults.
- Seizures in childhood: If you had a long seizure or another nervous condition in childhood, your risk for epilepsy is higher. This doesn’t include febrile seizures, which occur when you have a high fever unless they were abnormally long.
- Birth factors: If you were small for your age when you were born; you were deprived of oxygen at any point before, during, or after your birth; you had seizures within the first month after you were born; or you were born with abnormalities in your brain, your risk of epilepsy is higher.
- Certain conditions: The later stages of Alzheimer’s and brain tumors, including neurofibromatosis and tuberous sclerosis complex, both of which are genetic, are risk factors for developing epilepsy since they can interfere with your brain’s normal activity.
Certain circumstances or situations may increase the likelihood that you’ll have a seizure. These are known as triggers and if you’re able to figure out what yours are, that information can help you manage and potentially prevent more seizures. Factors that may contribute to seizures include:
- Sleep deprivation, whether it’s disrupted or missed
- Missing or skipping your medication
- Being sick, with or without a fever
- Feeling stressed
- Any medications, whether over-the-counter, prescription, or nutritional supplements, that may interfere with the effectiveness of your seizure medication
- Not getting enough vitamins and minerals
- Not eating or drinking enough
- Menstrual cycles and/or hormonal changes such as puberty and menopause
- Flashing lights or specific visual patterns, such as in video games (photo convulsive epilepsy)
- Certain foods, activities, or noises
- Drinking alcohol heavily or withdrawing from alcohol
- Using recreational drugs