Uncovering language deficits in focal epilepsy: Beyond the limits of noun naming and verbal fluency

Background: A range of language impairments have been reported in people with epilepsy both pre- and post-surgically, however language is not routinely comprehensively assessed in epilepsy clinics. When language is assessed, this is typically as part of a broader neuropsychological battery of assessment, often limited to tests of noun naming and/or verbal fluency, despite evidence to suggest these tests are not sufficiently sensitive to detect the often-subtle deficits present in chronic focal epilepsy. Many areas of language function, including the production of connected speech, have also not been adequately explored in this population, and research relating to subjective report of language and communication difficulties is limited. A more comprehensive assessment of language, which includes patient report, is required to determine the presence and extent of language impairment in people with focal epilepsy.

Aim: The aim of the present study was to systematically investigate the prevalence and pattern of language impairment in a group of people with chronic focal epilepsy using a comprehensive aphasia battery and a patient reported outcome measure.

Method: Language skills were assessed in 26 right-handed people with chronic focal epilepsy using the Comprehensive Aphasia test (CAT), in addition to standard clinical assessments of noun naming and verbal fluency. Participants' self-report of their language and communication skills was also collected, using the La Trobe Communication Questionnaire (LCQ).

Outcomes and results: 85% of participants with focal epilepsy were impaired on one or more language subtests of the CAT. In contrast, only 15% of participants were impaired on tests of confrontation noun naming, and none were impaired on a test of verbal fluency. The CAT findings were supported by subjective data, with 82% of participants self-reporting a communication difficulty.

Conclusions: Our results show that current approaches to language assessment are inadequate for identifying language impairments in people with focal epilepsy, and likely underestimate the prevalence of language impairment in this population. In particular, verb naming and picture description subtests revealed deficits across the majority of the sample, highlighting the need for more comprehensive assessment of language to be routinely conducted in this population.