Prognosis

Some children experience good recovery, but many are left with significant residual impairments, and it may be that there is a critical period for recovery, outside which children are left with irreparable damage. Outcome appears to be related to the length of time of the active phase of LKS. It is generally better in children with late-onset disease (language loss after the age of about 5 years), and in those with shorter periods of documented electrical status epilepticus in sleep – ESES (there is research suggesting that children with ESES lasting less than three years have better outcome). Related to this, children who respond to medical treatment of the regressions and of the ESES tend to have better prognosis, although response to treatment of the clinically visible seizures, does not generally affect outcome. In a small number of children, clinical seizures are a significant and continuing problem in their own right.

The developmental profile also has an effect on prognosis. Children who are known to have had difficulties in their early language development, prior to LKS onset, appear to have a worse outcome. LKS itself often causes difficulties in many developmental areas. Those children where the acquired difficulties are limited to language appear to do better and often respond better to medical treatment. For those children with additional acquired impairments, it is often the difficulties in social communication and interaction or general learning problems that pose the greatest barriers to recovery.

LKS may be best thought of as a spectrum, in which language tends to be first and most severely affected, but in which many other skills may be involved. Given this, it is very difficult to predict outcome, as it depends on the particular child’s skill profile, the disease process (age of onset, number and severity of regressions, length of active disease, response to treatment), and their progress in different skill areas over time. The active phase of the epileptic disease typically ends around adolescence and the child’s good skills, and remaining areas of difficulty should become clearer. However there is some evidence that some recovery can continue into adult life.

It is thought that in general terms, about half of the children make a reasonable recovery, a quarter have a partial recovery and a further quarter have very significant persisting difficulties.

Language outcome varies significantly. Children with a good outcome are in the minority but they usually regain competence in spoken language and tend to score within the normal range on formal assessments. Even those with good outcome however, may experience difficulties of a more subtle nature, such as problems with short-term memory and difficulties listening in the presence of noise. Those with a moderate outcome will demonstrate some degree of language impairment but spoken language will usually be their self-chosen means of communication. Those with a poor outcome may never regain spoken language but may be able to develop skills using other communication modes such as sign language, pictures or symbols. However, because of additional difficulties with gesture and fine manipulation, signing may not be successful, and there are reports that lip-reading skills may also be difficult for the children to acquire.