Language cortex representation: Effects of developmental versus acquired pathology

Abstract

Relatively little is known about language cortex representation in patients with developmental pathology and epilepsy. We report the results of mapping language by electrical stimulation of chronically implanted subdural electrodes in 34 patients (mean age, 12.2 years) evaluated for epilepsy surgery, 28 of whom had magnetic resonance imaging or histological evidence of developmental tumors or cortical dysplasia. Language cortex was identified in the temporal or frontal lobe of 19 patients (left hemisphere in 17, right hemisphere in 2), and overlapped or bordered the epileptogenic region in 12. Language cortex was not found in the frontal or temporal lobe of 15 patients (left hemisphere in 4, right hemisphere in 11) and was presumed to be contralateral to grid placement. Three patients with left-hemisphere perinatal or postnatal cerebral insults before the age of 5 years had no language in the left hemisphere, while 3 patients with insults between the ages of 6 and 16 years had preserved left-hemisphere language. Developmental lesions and early-onset seizures do not displace language cortex from prenatally determined sites, whereas lesions acquired before the age of 5 years may cause language to relocate to the opposite hemisphere, but only when language cortex is destroyed.

Do quiescent arachnoid cysts alter CNS functional organization?

“…On the contrary, the expected asymmetry of a left hemisphere dominance was preserved, in spite of distorted anatomic structures and in spite of significant morphometric changes. This finding is in accordance with an earlier electrophysiologic investigation of language organization in patients with epilepsy, 20 which demonstrated that developmental lesions do not displace language cortices from prenatally determined sites when the language cortex is structurally intact. Similar results of a preserved language dominance in the left hemisphere in patients with left temporal AC were reported in a PET study.…”

Language brain dominance in patients with refractory temporal lobe epilepsy: a comparative study between functional magnetic resonance imaging and dichotic listening test

“…These results support the theory of brain reorganization (neuronal plasticity) mentioned by Springer et al 10 and Janszky et al 28 , as well as the theory proposed by Duchowny et al 29 , stating that only damages on the first years of life result in consistent contralateral reorganization of language. Risse et al 30 emphasize that the incidence of atypical language is much more frequent in patients with a history of left hemisphere early lesions (from childhood).…”

“…In a study with refractory epilepsy patients, Duchowny et al 29 concluded that language transfer to the right hemisphere happens only in cases of lesions occurring before five years of age and in which the language cortex is destroyed, and not in cases of development lesions and epileptogenic discharges.…”

Case Report: Practicability of functionally based tractography of the optic radiation during presurgical epilepsy work up

“…In patients with focal epilepsy the determination of eloquent cortices can be further complicated by a commonly observed anatomical alteration of the eloquent cortex, which is driven by at least two interacting factors: (1) The epileptogenic lesion itself is identical with or forms a large part of the anatomical alteration. This has been observed in lesions which originate from an early disturbance in the individual's development, such as prenatal or infant cerebral insults [23,24], cortical malformations or developmental tumors [25,26]. (2) An anatomical alteration of the eloquent cortex was also observed in patients with epileptogenic lesions remote to the eloquent cortex [27], suggesting that the seizures, interictal cortical activity or other functional abnormality of the cortex lead to alteration of functional localization [28].…”