Physicians and scientists have long been intrigued by the variety of ways that language can be affected by brain disease. It is clear that epilepsy can affect language, but the extent and nature of the language disturbance varies widely according to the type, severity, and cause of the epilepsy.
How does epilepsy affect language in children?
When epilepsy develops in early childhood, the patterns of language areas in the brain may be out of the ordinary and developmental difficulties may emerge, in which the child has difficulty in acquiring communication skills at a rate and in a manner that is similar to what is seen in most children. This happens more often with partial epilepsy arising in the left hemisphere. In many of these cases, the language disturbance takes the form of a general reduction in a large class of verbally based skills. This disturbance can eventually extend to effects on reading and writing.
Many forms of generalized epilepsy have nonspecific effects on a range of functions, including those involving language. But other forms of epilepsy produce definite patterns of language disturbance. Aphasia is an acquired disorder of language or symbolic processing. There are many specific types of aphasia, defined according to the type of function that is lost. A person with a diagnosis of aphasia is assumed to have achieved normal language functioning before the onset of illness.
Some childhood disorders can produce very specific and profound types of aphasia. The Landau-Kleffner syndrome is a condition characterized by seizures and a distinctive pattern of EEG abnormalities evolving from the left temporal-parietal region, near Wernicke's area. Children with this condition start out with normal language development, followed by a severe progressive decline. They begin to have difficulties in understanding speech and progress to a more generalized language disturbance. Many nonverbal skills are left unaffected.
What about adults?
Adults with epilepsy often complain of difficulties with language (especially difficulties in coming up with words), but for most of them the problems are not severe enough to be classified as a bona fide aphasia. The exceptions are those whose seizures develop as a result of a specific lesion, such as a stroke or brain tumor, that affects the language zones in the area of their left temporal lobe.
Some people with partial forms of epilepsy claim to have problems with comprehending language, but these symptoms nearly always are mislabeled. Instead of a language disturbance in itself, most of these people are reporting a difficulty with comprehension because they have a problem in some other area of cognition. Reduced attention or memory impairment is commonly at the root of the trouble.
Medications also can cause language disturbances. Some people who take Topamax (topiramate), for instance, experience problems with speech and language (especially word-finding) that go away when the Topamax is stopped or the dosage is lowered. There is some debate about the specific cause of these problems.