Development and Epileptic Encephalopathy

Lennox-Gastaut Syndrome (LGS) is a severe form of childhood epilepsy with multiple types of seizures. Seizure types in LGS include tonic, atonic or drop attacks, atypical absence, myoclonic, and generalized tonic-clonic seizures starting in childhood. Seizures begin in childhood, but different types may emerge over time. Focal (one area of the brain) seizures become more common in teens and adults.

About 2 to 5% of children with epilepsy have LGS. LGS typically persists through childhood and adolescence to adult years and commonly includes an impairment or delay to intellectual development that worsens over time. Children with LGS experience frequent seizures and very abnormal EEG (electroencephalograph) activity worsens cognitive and behavioral problems. Among them, hyperactivity, agitation, aggression, and autism are the most common.

Dravet Syndrome a rare, drug-resistant epilepsy that begins in the first year of life in an otherwise healthy infant is a lifelong condition. Dravet syndrome usually presents with a prolonged seizure with fever that affects one side of the body. Infants have normal development when seizures begin yet, as seizures continue, most children develop some level of developmental disability.

By later childhood, most children also develop a crouched walk. Approximately 8 out of 10 people with Dravet syndrome have a gene mutation in SCN1A that causes problems in the way ion channels in the brain work. But not all SCN1A mutations are associated with Dravet syndrome. This mutation is most often not inherited from the parents, it is considered a de novo mutation in the child. Those with Dravet syndrome generally experience seizures within the first year of life, and the initial seizure often happens with a fever and may be a tonic-clonic seizure or a seizure involving clonic (jerking) movements on one side of the body. These seizures are often long, lasting more than 5 minutes, and can result in status epilepticuswhen seizures do not stop or occur close together. Such seizures typically recur every few weeks in infancy and early childhood.

Other seizure types seen in children with Dravet syndrome include: 

  • Myoclonic seizures (brief shock-like jerks of a muscle or group of muscles) starting between 1 and 5 years in 85% of children with Dravet syndrome.
  • Tonic-clonic seizures.
  • Atypical absence seizures.
  • Atonic seizures.
  • Focal aware or impaired awareness seizures (previously called partial seizures)
  • Tonic seizures, mainly in sleep, may appear in later childhood.
  • Non-convulsive status epilepticus where the child has decreased responsiveness associated with eye flutter and twitching of the body for prolonged periods of time.

After the first febrile seizure, seizures can happen without a fever. However, these children are very sensitive to infections and frequently have seizures when they are ill or have a fever. Seizures can also be triggered by slight changes in body temperature that are not caused by infection, for example a warm or hot bath water, or hot weather. Many children have photosensitive seizures triggered by flashing lights, patterns, or similar photic triggers.

CDKL5 deficiency disorder is characterized by seizures that begin in infancy, followed by significant delays in many aspects of development. The types of seizures change with age and may follow a predictable pattern. 

The most common types are generalized tonic-clonic seizures, which involve a loss of consciousness, muscle rigidity, and convulsions; tonic seizures, which are characterized by abnormal muscle contractions; and epileptic spasms, which involve short episodes of muscle jerks. Seizures occur daily in most people with CDKL5 deficiency disorder, although they can have periods when they are seizure-free. 

Behavioral epileptic seizures (BES) consist of various clinical signs comprising mood change, sudden agitation, unexpected quietness, and subtle change of awareness or awakening affect children with epilepsy. As with other manifestations, epilepsy's psychological effects are highly variable. While some people with epilepsy experience few if any mental health issues, others may suffer debilitating problems of inattention, anxiety, or mood disorders such as aggression. It is important to address these issues early and with appropriate forms of intervention to reduce the consequences they might have on an individual's long-term quality of life.