SLH refers to generalized symptomatic epileptic syndromes and is characterized by a combination of several types of generalized seizures, a special type of high-amplitude EEG (gypsarhythmia), and mental and motor developmental delay.
According to S. Shinnar (1994), “to study the clinical picture of ten patients with SLH is to learn all the children’s neuroscience”.
The first description of the clinical manifestations of SLH was made by Tisot in 1770 in the book “Treatise on Epilepsy”. In 1945, Lennox and in 1950 Lennox & Davis described a triad of symptoms:
slow peak-wave activity on EEG;
defect of intelligence;
three types of seizures (atypical absansy, myoclonic and kiivannye attacks,
ending with tonic convulsions and falling).
Frequency. The prevalence of SLH in the population is unknown due to the polymorphism of the clinical manifestations. The frequency of diagnosis of SLH is about 7.5% (3-10%) of all epilepsy cases in childhood.
Genetics. Family cases of epilepsy or febrile seizures, but not SLH, are detected with a frequency of 2.5 to 47.8%.
Clinic. SLH manifests in children aged 1 to 8 years, but mostly in children at preschool age (3-5 years).
According to Aicardi (1996), 25-30% of children have anamnesis and even a thorough study do not reveal any neurological pathology or brain damage, including neuroimaging methods (cryptogenic cases). Approximately 70% of children have a history of developmental delay (before the onset of epileptic seizures), resistant forms of epilepsy (West syndrome), as well as organic brain pathology identified by neuroimaging. These cases are defined as symptomatic.
The clinical picture is polymorphic, and the manifestations are dramatic and are characterized by repeated daily attacks, a decrease in cognitive functions.
The most common types of seizures in SLH are tonic-axial, atypical absences, but there may also be myoclonic generalized tonic-clonic or partial seizures (the latter are rare and characterize an unfavorable course of the disease). The frequency of attacks is high, and epileptic status is often encountered (stupor status with myoclonias, tonic and atonic seizures).
Tonic seizures. Presented in 90% of cases. The axial type of attack is characterized by flexion movements of the head and torso as a result of a short but pronounced bilateral symmetric resistance of the axial muscles, usually associated with clouding of consciousness and with automatic manifestation. There may be seizures with abduction, raising hands and falling as a result of a tonic attack if the child is standing. Seizures in the form of atypical absences can be moderately expressed and difficult to determine clinically. Their beginning and ending is sudden. Loss of consciousness is incomplete, which allows the child to continue an active lifestyle. Impaired consciousness may be associated with loss of muscle tone, uneven myoclonic twitching, moderate hypertonicity of the muscles of the neck or back.
In 50-75% of cases with SLH, episodes of non-convulsive epileptic status are encountered. The most common combination of atypical absences with tonic seizures. The status of tonic seizures can be life threatening.
Mental retardation in SLH is observed in 90% of children. The earlier the seizures began, the more pronounced the decrease in intelligence.
Moreover, it was established that the intellect is reduced to a certain level (IQ from 50 to 25), and then this process does not progress. Clinical observations show that when control of seizures is achieved, a violation of intelligence can be reversible, especially if treatment is started early and lamotrigine is included in the treatment. In addition to intellectual impairments, autistic character traits, attention deficit, hyperactivity, and aggressiveness are often noted, which disrupt social adaptation and reduce school performance, even with moderate intellectual deficit.
EEG. On the EEG in SLH, there is a marked slowdown in the main activity of the background recording. Slow peak-to-wave complexes, often more generalized with regional or bifrontal amplitude predominance, less often focal or multifocal. The frequency of the complexes is 1.5-2.5 Hz. The phenomenon of gypsarhythmia is a consequence of the lack of bilateral synchrony of the main activity
- Characteristics of seizures: tonic spasms, tonic seizures, atypical absences, frequent minor generalized seizures, atonic seizures, myoclonic seizures, astatic and combined seizures.
- EEG. Interictal diffuse slow peak-wave activity.
Ii. Additional criteria
- Beginning in 3-5 years.
- Mental, backwardness.
- Fast rhythm on EEG during sleep.
- Anomalies detected by neuroimaging methods; brain atrophy. 5. Neurological disorders.
- Poor prognosis, difficulty in relieving seizures.
Iii. Conditional criteria
The onset of the disease in 1-6 years.
Clinical seizures: multiple minor generalized, mostly tonic
spasms, sometimes in combination with other types of seizures (generalized or partial). 4. Frequent development of non-convulsive status epilepticus.
On interictal EEG: focal or multifocal adhesions on the background of slow
diffuse peak-wave activity.
During an attack: with tonic seizures or tonic spasms
generalized or bilateral synchronous rhythm or “recruiting rhythm” (short episodes of fast peak-wave activity with a frequency of 10-20 Hz).
Transition from West syndrome.
Treatment. Given the polymorphism of seizures, the base are preparations of a wide spectrum of action – conjunctiva and valproic acid derivatives or lamotrigine. The average therapeutic dose of valproate is 30-100 mg / kg / day.
The combination of valproate and lamictal is used more often (the dose of lamotrigine should be less than the therapeutic one due to possible interaction). Approximate doses of lamotrigine (children under 12 years of age with combination with valproate): the first two weeks are 0.2 mg / kg / day;
the second two weeks – 0.5 mg / kg / day. Maintenance dose of 1-5 mg / kg / day in 1-2 doses.
When you achieve a preliminary effect, you can add other drugs aimed at
specific type of seizures. So, taking benzodiazepines at night reduces the frequency of tonic attacks on awakening and / or compensates for the difficulty of falling asleep. Succinimides can be used as an adjunct to valproate or lamotrigine in the treatment of atypical absences. ACTH (synacthen depot) is also applicable to SLG.
Cannot be used in the treatment of more than three drugs at the same time.
Effective combinations, depending on the predominance of certain attacks are:
valproate + lamotrigine (0.2–5 mg / kg / day); valproate + succinimides (15-30 mg / kg / day); valproate + carbamazepine (15-30 mg / kg / day); valproate + clonazepam (0.15-0.25 mg / kg / day).
The prognosis in most cases is unfavorable. Approximately half of the cryptogenic and overwhelmingly symptomatic variants of SLG remission can not be achieved, even with the use of a wide arsenal of modern AED. Up to 10% of children die in the first 10 years of life.