The Supplementary Motor Area Responsible for Word Retrieval Decline After Acute Thalamic Stroke Revealed by Coupled SPECT and Near-Infrared Spectroscopy

Obayashi, Shigeru

doi:10.3390/brainsci10040247

Cited by 15 publications

(17 citation statements)

References 34 publications

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“…Single-photon emission computed tomography and functional near-infrared spectroscopy suggested that FAT may play a crucial role in word retrieval difficulty in acute thalamic stroke survivors; furthermore, SMA may contribute to improve word retrieval difficulty ( 65 ). No correlation between FAT and apraxia of speech ( 66 ) or syntax ( 67 ) has been noticed.…”

Section: Discussionmentioning

confidence: 99%

The Frontal Aslant Tract: A Systematic Review for Neurosurgical Applications

et al. 2021

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The frontal aslant tract (FAT) is a recently identified white matter tract connecting the supplementary motor complex and lateral superior frontal gyrus to the inferior frontal gyrus. Advancements in neuroimaging and refinements to anatomical dissection techniques of the human brain white matter contributed to the recent description of the FAT anatomical and functional connectivity and its role in the pathogenesis of several neurological, psychiatric, and neurosurgical disorders. Through the application of diffusion tractography and intraoperative electrical brain stimulation, the FAT was shown to have a role in speech and language functions (verbal fluency, initiation and inhibition of speech, sentence production, and lexical decision), working memory, visual–motor activities, orofacial movements, social community tasks, attention, and music processing. Microstructural alterations of the FAT have also been associated with neurological disorders, such as primary progressive aphasia, post-stroke aphasia, stuttering, Foix–Chavany–Marie syndrome, social communication deficit in autism spectrum disorders, and attention–deficit hyperactivity disorder. We provide a systematic review of the current literature about the FAT anatomical connectivity and functional roles. Specifically, the aim of the present study relies on providing an overview for practical neurosurgical applications for the pre-operative, intra-operative, and post-operative assessment of patients with brain tumors located around and within the FAT. Moreover, some useful tests are suggested for the neurosurgical evaluation of FAT integrity to plan a safer surgery and to reduce post-operative deficits.

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Section: Discussionmentioning

confidence: 99%

The Frontal Aslant Tract: A Systematic Review for Neurosurgical Applications

et al. 2021

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“…We identified a new characteristic of disorders derived from thalamic stroke, namely “difficulty in word retrieval”, which may involve both executive function and speech production. Word retrieval disability was associated with supplementary motor area (SMA) responses, as shown by our recent f-NIRS results [12] . We focused on the association of SMA and the inferior frontal gyrus (IFG) via the frontal aslant tract (FAT) with word retrieval disability, and we will discuss the possible mechanism underlying cognitive dysfunction affected by thalamic stroke.…”

Section: Introductionmentioning

confidence: 61%

“…Our SPECT results from 16 patients in acute phase of thalamic stroke yielded diffuse cerebral perfusion abnormality in bilateral hemispheres, including the frontal cortices, superior temporal cortices, parietal cortices and cerebellum [12] . Most notably, damage to the thalamus commonly affected left language-related cortical areas and right homologous regions, including Broca's area (left 44, 45), Wernicke's area (22, 42), angular gyrus (39), and supramarginal gyrus (40).…”

Section: Word Retrieval Difficulty Due To Thalamic Stroke and Neural ...mentioning

confidence: 67%

“…On the other hand, we demonstrated that 25 of a total 27 patients with acute thalamic stroke (92.6%) had affected cognition including inattention (18 patients), memory disturbance (15), executive dysfunction (11) and social behavioral disturbance (1). Three patients presented with dysphasia [12] .…”

Section: Cognitive and Linguistic Domains Affected By Thalamic Strokementioning

confidence: 99%

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Cognitive and linguistic dysfunction after thalamic stroke and recovery process: possible mechanism

Obayashi

2021

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<abstract> <p>Thalamic stroke may result in cognitive and linguistic problems, but the underlying mechanism remains unknown. Especially, it is still a matter of debate why thalamic aphasia occasionally occurs and then mostly recovers to some degree. We begin with a brief overview of the cognitive dysfunction and aphasia, and then review previous hypotheses of the underlying mechanism. We introduced a unique characteristic of relatively transient “word retrieval difficulty” of patients in acute phase of thalamic stroke. Word retrieval ability involves both executive function and speech production. Furthermore, SMA aphasia and thalamic aphasia may resemble in terms of the rapid recovery, thus suggesting a shared neural system. This ability is attributable to the supplementary motor area (SMA) and inferior frontal cortex (IFG) via the frontal aslant tract (FAT). To explore the possible mechanism, we applied unique hybrid neuroimaging techniques: single-photon emission computed tomography (SPECT) and functional near-infrared spectroscopy (f-NIRS). SPECT can visualize the brain distribution associated with word retrieval difficulty, cognitive disability or aphasia after thalamic stroke, and f-NIRS focuses on SMA and monitors long-term changes in hemodynamic SMA responses during phonemic verbal task. SPECT yielded common perfusion abnormalities not only in the fronto–parieto–cerebellar–thalamic loop, but also in bilateral brain regions such as SMA, IFG and language-relevant regions. f-NIRS demonstrated that thalamic stroke developed significant word retrieval decline, which was intimately linked to posterior SMA responses. Word retrieval difficulty was rapidly recovered with increased bilateral SMA responses at follow-up NIRS. Together, we propose that the cognitive domain affected by thalamic stroke may be related to the fronto–parieto–cerebellar–thalamic loop, while the linguistic region may be attributable to SMA, IFG and language-related brain areas. Especially, bilateral SMA may play a crucial role in the recovery of word retrieval, and right language-related region, including IFG, angular gyrus and supramarginal gyrus may determine recovery from thalamic aphasia.</p> </abstract>

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“…Other studies of speech processing after stroke have also reported enhanced SMA activation during overt speech production in patients with left inferior frontal lesions ( Rosen et al, 2000 ) and during the recovery of speech comprehension in patients with a range of different left hemisphere lesions ( Stockert et al, 2020 ). Likewise, Obayashi (2020) reported that SMA activation was higher in patients with thalamic lesions who had better verbal fluency. Additionally, enhanced SMA activation after stroke is not limited to speech tasks.…”

Section: Discussionmentioning

confidence: 95%