Speech apraxia and oral apraxia: association or dissociation? A multivariate lesion–symptom mapping study in acute stroke patients

Abstract

The anatomical relationship between speech apraxia (SA) and oral apraxia (OA) is still unclear. To shed light on this matter we studied 137 patients with acute ischaemic left-hemisphere stroke and performed support vector regression-based, multivariate lesion–symptom mapping. Thirty-three patients presented with either SA or OA. These two symptoms mostly co-occurred (n = 28), except for few patients with isolated SA (n = 2) or OA (n = 3). All patient with either SA or OA presented with aphasia (p < 0.001) and these symptoms were highly associated with apraxia (p < 0.001). Co-occurring SA and OA were predominantly associated with insular lesions, while the insula was completely spared in the five patients with isolated SA or OA. Isolated SA occurred in case of frontal lesions (prefrontal gyrus and superior longitudinal fasciculus), while isolated OA occurred in case of either temporoparietal or striatocapsular lesions. Our study supports the notion of a predominant, but not exclusive, role of the insula in verbal and non-verbal oral praxis, and indicates that frontal regions may contribute exclusively to verbal oral praxis, while temporoparietal and striatocapsular regions contribute to non-verbal oral praxis. However, since tests for SA and OA so far intrinsically also investigate aphasia and apraxia, refined tests are warranted.

Gesture meaning modulates the neural correlates of effector-specific imitation deficits in left hemisphere stroke

“…Consistent with our data, previous studies have revealed that bucco-facial apraxic deficits are associated with lesions in the IFG, the insular region and adjacent subcortical regions ( Alexander et al, 1992 , Conterno et al, 2022 , Maeshima et al, 1997 , Raade et al, 1991 , Scandola et al, 2021 , Tognola and Vignolo, 1980 ). These results align with the here identified lesion correlates for bucco-facial gesture imitation deficits located more anterior than lesions associated with arm/hand imitation deficits.…”

“…Besides temporo-parietal and frontal lesions, bucco-facial apraxia has been associated with striato-capsular lesions ( Conterno et al, 2022 , Raade et al, 1991 , Schmidt et al, 2022 ), consistent with the here revealed subcortical lesion correlates of bucco-facial gesture imitation deficits (including the basal ganglia).…”

“…The insula, a region crucial for speech production ( Dronkers, 1996 ), has also been implicated in non-speech oral motor functions ( Ackermann & Riecker, 2010 ) and facial imitation accuracy ( Braadbaart et al, 2014 ). Hence,the insular lesion correlate for bucco-facial imitation deficits corroborates the proposal that this region is a crucial integrator for bucco-facial praxis ( Conterno et al, 2022 ).…”

“…These results align with the here identified lesion correlates for bucco-facial gesture imitation deficits located more anterior than lesions associated with arm/hand imitation deficits. A recent lesion analysis in 137 LH stroke patients revealed associations of bucco-facial apraxia with large portions of the insula, the precentral gyrus and IFG, the STG, and white matter tracts such as the corona radiata and internal capsule ( Conterno et al, 2022 ). The insula, a region crucial for speech production ( Dronkers, 1996 ), has also been implicated in non-speech oral motor functions ( Ackermann & Riecker, 2010 ) and facial imitation accuracy ( Braadbaart et al, 2014 ).…”

Clinicopathologic and Neuroimaging Correlations of Nonverbal Oral Apraxia in Patients With Neurodegenerative Disease

“…4,8,9 When neurodegenerative, NVOA can occur with other features such as apraxia of speech (AOS), aphasia, or ideomotor limb apraxia. 2,4,10 It rarely occurs in isolation, and it usually follows a progressive worsening pattern. 2,4,11,12 Most studies evaluating the associations of NVOA have examined clinical syndromes and, less frequently, pathologic outcomes.…”