The interictal language profile in adult epilepsy

Objective: The purpose of this study was to systematically review the literature on the interictal language profile in adult patients with epilepsy.

Methods: An extensive literature search was performed using MEDLINE, Embase, PsycINFO, Cochrane Central Register of Controlled Trials, PASCAL, and PSYNDEXplus databases. Key aspects of inclusion criteria were adult patients with epilepsy, patient number >10, and in-depth qualitative investigations of a specific language modality or administration of tests of at least two different language modalities, including comprehension, naming, repetition, reading, writing, and spontaneous speech.

Results: Our search strategy yielded 933 articles on epilepsy and language. Of these, 31 met final eligibility criteria. Most included articles focused on temporal lobe epilepsy; only three studies were interested in the language profile of patients with idiopathic generalized epilepsies, and one study on frontal lobe epilepsy met inclusion criteria. Study results showed a pronounced heterogeneity of language abilities in patients with epilepsy, varying from intact language profiles to impairment in several language functions. However, at least 17% of patients displayed deficits in more than one language function, with naming, reading comprehension, spontaneous speech, and discourse production being most often affected.

Significance: This review underscores the need to evaluate different language functions-including spontaneous speech, discourse abilities, naming, auditory and reading comprehension, reading, writing, and repetition-individually in order to obtain a reliable profile of language functioning in patients with epilepsy. Moreover, our findings show that in contrast to the huge scientific interest of memory functions in epilepsy, the examination of language functions so far played a minor role in epilepsy research, emphasizing the need for future research activities in this field.