NEURAL CORRELATES OF CONNECTED SPEECH DEFICITS AFTER LEFT HEMISPHERE RESECTIVE SURGERY

Abstract

Transient aphasias are very common in patients during the acute days following neurosurgical resection in the language-dominant hemisphere. This study used quantitative analysis of connected speech to characterize the incidence and nature of these aphasias, to assess their recovery over time, and to determine whether there are systematic relationships between the location of surgical resection and specific deficits in various language domains. A cohort of 114 patients underwent neurosurgical resection in the language-dominant hemisphere. Language was evaluated by means of standardized assessment and connected speech elicitation prior to surgery, 2-3 days post-surgery and 1 month post-surgery. Voxel-based lesion-symptom mapping was used to elucidate any relationships between site of lesion and the specific language deficits identified by the connected speech analysis. High proportions of closed class words were associated with resections of the left middle and inferior temporal gyrus. Low proportions of closed class words were associated with resections of the left inferior frontal gyrus. Most language deficits observed 2-3 days post-surgery resolved by 1 month post-surgery. However, still present at one month were disruptions to fluency (including increased incidence of retracings and false starts),lexical access impairments, and speech sound errors (including increased incidence of phonological errors and distortions). These findings demonstrate that transient aphasias generally resolve within one month post-surgery. However, subtle language deficits left undetected by standardized language assessments sometimes persist beyond 1 month post-surgery.