Purpose: To obtain systematic knowledge of language development before and after epilepsy surgery in regions that, if damaged, are known to entail language impairment in adults.
Methods: Twenty-four children (mean age 11 years; range 5.8-15.7 years) with pharmacologically intractable epilepsy participated prior to (the majority) anterior temporal lobectomy and 6, 12, and 24 months thereafter. Reception and production of lexicon (vocabulary) and syntax (sentence structure including grammar) were examined using developmental language tests that provide normative data.
Results: Prior to surgery the mean language delay varied from 1.7 years (productive syntax) to 3.5 years (productive lexicon). For lexicon, language delay was larger, the older the children; for syntax it was smaller in children with mothers with higher education. Over the 2 years following surgery, the children developed in all four language components. Development was, however, slower than normal, that is, language delay increased, in three of the four components: in productive lexicon it continued to increase, and in receptive lexicon and productive syntax it appeared to stabilize during the second year. Receptive syntax developed at a normal pace. The development of productive lexicon was remarkably slow when surgery and language mediation were both in the left hemisphere.
Discussion: Pharmacologically intractable epilepsy of the temporal lobe, or the underlying condition, is a significant risk factor for delayed language development. Temporal epilepsy surgery does not result in acceleration of language development. If language is still mediated in the operated left hemisphere, development of particular language components may slow down after surgery.