Macrolinguistic function in temporal lobe epilepsy: a reinterpretation of circumstantiality

BackgroundWhile language is frequently explored in stroke and focal lesions, complex language disorders in paroxysmal conditions remain relatively underexplored. Individuals with temporal lobe epilepsy (TLE) often have an impairment of conversational language manifesting as verbosity and attributable to disruption of cognitive-linguistic networks. The micro- and macrolinguistic underpinnings of this disturbance, and the role of epilepsy and cognitive variables, are yet to be explored.Methods and ProceduresWe examined the elicited language output of 16 individuals with TLE and 14 healthy controls under separate monologic discourse tasks: a structured and constrained context, elicited by description of the 'Cookie Theft' picture, and an unstructured, unconstrained context, elicited by description of a 'Typical Day'. We hypothesised that language output in the unstructured context would be characterised by verbosity to a greater extent than language elicited in a structured context.Outcomes and ResultsFollowing transcription and coding, detailed multi-level discourse analysis suggested that a constrained context gives rise to microlinguistic disturbances in individuals with TLE, reducing fluency, with more pauses and fillers. Under an unconstrained context, as anticipated, classical aspects of verbosity emerge in those with TLE, manifesting as longer speaking time, a longer duration of pauses, and a higher proportion of repetitive or redundant statements. Macrolinguistic elements such as coherence and informativeness are widely impacted, particularly disturbing language formulation. Correlations suggest that microlinguistic disturbances are closely linked with the immediate impact of seizures on cognitive-linguistic function, while macrolinguistic disturbances are more broadly impacted by disorder severity and word retrieval deficits.ConclusionsThese findings suggest that cognitive-linguistic disturbances in TLE produce vulnerability to different psycholinguistic impairments as a function of differing linguistic challenges imposed by constrained and unconstrained discourse contexts. Where constrained, output fluency is primarily affected, while in an unconstrained context disturbed discourse planning and organisation declares itself. We conclude that these patterns reflect a dynamic linguistic system taking shape under specific contextual conditions.