Words are not enough: nonword repetition as an indicator of arcuate fasciculus integrity during brain tumor resection

Abstract

OBJECTIVE Subcortical electrical stimulation during brain surgery may allow localization of functionally crucial white matter fibers and thus tailoring of the tumor resection according to its functional limits. The arcuate fasciculus (AF) is a white matter bundle connecting frontal, temporal, and parietal cortical areas that is often disrupted by left brain lesions. It plays a critical role in several cognitive functions related to phonological processing, but current intraoperative monitoring methods do not yet allow mapping of this tract with sufficient precision. In the present study the authors aimed to test a new paradigm for the intraoperative monitoring of the AF. METHODS In this report, the authors studied 12 patients undergoing awake brain surgery for tumor resection with a related risk of AF damage. To preserve AF integrity and the cognitive processes sustained by this tract in the intraoperative context, the authors used real word repetition (WR) and nonword repetition (NWR) tasks as complements to standard picture naming. RESULTS Compared with the errors identified by WR or picture naming, the NWR task allowed the detection of subtle errors possibly related to AF alterations. Moreover, only 3 patients demonstrated phonological paraphasias in standard picture naming, and in 2 of these patients the paraphasias co-occurred with the total loss of WR and NWR ability. Before surgery, lesion volume predicted a patient's NWR performance. CONCLUSIONS The authors suggest that monitoring NWR intraoperatively may complement the standard naming tasks and could permit better preservation of the important language production functions subserved by the AF.

Changes in language white matter tract microarchitecture associated with cognitive deficits in patients with presumed low-grade glioma

“…The AF, also known as the dorsal pathway in the dual-stream model of Hickok and Poeppel, 13 is associated with mapping sound to articulatory-based representations (e.g., phonology), which explains the functional association between microstructural changes and phonological deficits observed here. Our findings also support recent results from Sierpowska et al, 29 who reported that monitoring (non)word repetition is relevant near the AF during electro(sub)cortical stimulation for the preservation of language production and, in particular, phonological performance. 25,29 Deficits in language repetition in combination with relatively intact comprehension, as observed in our patient group, are "classically" known in the stroke literature as conduction aphasia.…”

“…Our findings also support recent results from Sierpowska et al, 29 who reported that monitoring (non)word repetition is relevant near the AF during electro(sub)cortical stimulation for the preservation of language production and, in particular, phonological performance. 25,29 Deficits in language repetition in combination with relatively intact comprehension, as observed in our patient group, are "classically" known in the stroke literature as conduction aphasia. Several studies in patients with a different etiology found a link between this specific aphasia type and damage to the AF (e.g., tumor infiltration, WM tract compression).…”

Theta Coherence Asymmetry in the Dorsal Stream of Musicians Facilitates Word Learning

“…In fact, previous MEG source-imaging studies reported that during both verbal 55 and non-verbal 34 , 52 , 56 tasks, brain activity in pST and IP regions as well as in Broca’s area was modulated as a function of working memory load. This perspective is also in line with clinical observations showing that patients with lesions encompassing the left AF often demonstrate impaired working memory functions 57 – 60 and that intraoperative stimulation in awake brain tumor patients in the vicinity of the AF disrupts non-word repetition 61 . Furthermore, the dorsal stream has previously been shown to contribute to complex sequencing in the verbal domain 62 .…”

Tracting the neural basis of music: Deficient structural connectivity underlying acquired amusia

“…The arcuate fasciculus (AF) comprises three pathways: (i) a long direct segment connecting the temporal lobe to the frontal lobe, (ii) an anterior indirect segment connecting the frontal lobe and the inferior parietal lobule (IPL), and (iii) a posterior indirect segment connecting the temporal lobe and the IPL (Catani et al, 2005). To dissect these three AF segments, we used a three-ROI approach (Catani et al, 2005;Glasser and Rilling, 2008;Vaquero et al, 2016;Francois et al, 2016;Sierpowska et al, 2017), where the first ROI was drawn on a coronal plane to capture all the fibers running in the anteriorposterior direction using a DTI FA color map, the second ROI on an axial plane near temporo-parietal junction to capture fibers running to the temporal lobe, and the third ROI on a sagittal plane to capture fibers connecting to the IPL.…”