Serena De Pellegrin

Right parietal cortex and calculation processing: intraoperative functional mapping of multiplication and addition in patients affected by a brain tumor

OBJECT The role of parietal areas in number processing is well known. The significance of intraoperative functional mapping of these areas has been only partially explored, however, and only a few discordant data are available in the surgical literature with regard to the right parietal lobe. The purpose of this study was to evaluate the clinical impact of simple calculation in cortical electrostimulation of right-handed patients affected by a right parietal brain tumor. METHODS Calculation mapping in awake surgery was performed in 3 right-handed patients affected by high-grade gliomas located in the right parietal lobe. Preoperatively, none of the patients presented with calculation deficits. In all 3 cases, after sensorimotor and language mapping, cortical and intraparietal sulcus areas involved in single-digit multiplication and addition calculations were mapped using bipolar electrostimulation. RESULTS In all patients, different sites of the right parietal cortex, mainly in the inferior lobule, were detected as being specifically related to calculation (multiplication or addition). In 2 patients the intraparietal sulcus was functionally specific for multiplication. No functional sites for language were detected. All sites functional for calculation were spared during tumor resection, which was complete in all cases without postoperative neurological deficits. CONCLUSIONS These findings provide intraoperative data in support of an anatomofunctional organization for multiplication and addition within the right parietal area. Furthermore, the study shows the potential clinical relevance of intraoperative mapping of calculation in patients undergoing surgery in the right parietal area. Further and larger studies are needed to confirm these data and assess whether mapped areas are effectively essential for function.

Telerehabilitation in Poststroke Anomia

Anomia, a word-finding difficulty, is a frequent consequence of poststroke linguistic disturbance, associated with fluent and nonfluent aphasia that needs long-term specific and intensive speech rehabilitation. The present study explored the feasibility of telerehabilitation as compared to a conventional face-to-face treatment of naming, in patients with poststroke anomia. Five aphasic chronic patients participated in this study characterized by: strictly controlled crossover design; well-balanced lists of words in picture-naming tasks where progressive phonological cues were provided; same kind of the treatment in the two ways of administration. ANOVA was used to compare naming accuracy in the two types of treatment, at three time points: baseline, after treatment, and followup. The results revealed no main effect of treatment type (P = 0.844) indicating that face-to-face and tele-treatment yielded comparable results. Moreover, there was a significant main effect of time (P = 0.0004) due to a better performance immediately after treatment and in the followup when comparing them to baseline. These preliminary results show the feasibility of teletreatment applied to lexical deficits in chronic stroke patients, extending previous work on telerehabilitation and opening new vistas for future studies on teletreatment of language functions.

Compounds in different aphasia categories: A study on picture naming

This study investigated the production of compounds in Italian-speaking patients affected by different aphasia categories (i.e., Brocas, Wernickes, and anomic aphasia) in a confrontation naming task. Questions of theoretical interest concerning the processing of compounds within the framework of the “lemma theory” as well as the role of morphological productivity in compound processing are addressed. Results indicate that all persons with aphasia retain knowledge of the morphological status of words, even when they fail to retrieve the corresponding phonological form (the “compound effect”). A difference was found among aphasia categories in the type of errors produced (omission vs. substitution) and in the position (first or second) of these errors within the compound words. In Brocas aphasia, the first component is omitted more frequently than the second one, but only in verb–noun compounds. Anomic and Wernickes aphasia, unlike in Brocas aphasia, seem to retain sensitivity to morphological productivity.

Functional mapping of left parietal areas involved in simple addition and multiplication. A single-case study of qualitative analysis of errors

All electrostimulation studies on arithmetic have so far solely reported general errors. Nonetheless, a classification of the errors during stimulation can inform us about underlying arithmetic processes. The present electrostimulation study was performed in a case of left parietal glioma. The patients erroneous responses suggested that calculation was mainly applied for addition and a combination of retrieval and calculation was mainly applied for multiplication. The findings of the present single-case study encourage follow up with further data collection with the same paradigm.

Cognitive improvement after cranioplasty: A possible volume transmission-related effect

Dear Editor, The sinking skin flap/trephined syndrome is a complication of craniectomy characterized by neurological symptoms, including cognitive deficits, that may be relieved by skull breach repair [3, 4, 7]. We report on a patient with decompressive craniectomy after a traumatic brain injury (TBI) who experienced cognitive improvement along with increased cerebral blood flow (CBF) after cranioplasty. A 29-year-old right-handed woman was admitted to the emergency room in a comatose state (E2V1M6) after TBI. Cerebral hypertension refractory to medical treatment required a left fronto–temporo–parietal craniectomy. One month later, a control brain CT showed a large neurodegenerative lesion in the left fronto-temporo-parietal regions. She was alert, with right hemiparesis and severe impairment of verbal communication. She started intensive long-term physical and language rehabilitation. Nine months after the TBI, a cranioplasty with a hydroxyapatite implant was performed. An extensive neuropsychological evaluation, brain MRI scan and cerebral Tc-HMPAO single photon emission computed tomography (SPECT) study were performed within 1 week before the cranioplasty and repeated 3 months later. In the month before cranioplasty and in the 3 months thereafter the patient received the same language and cognitive rehabilitation therapy 2 h per week. The neuropsychological tests assessed the following cognitive domains: (1) global cognitive functions with the Mini Mental State Examination (MMSE) test [6], (2) attention and executive functions, (3) visual-spatial capacities, (4) delayed recall for visual-spatial memory and (5) language abilities. Post-cranioplasty the patient’s global cognitive performance improved (the MMSE increased from 16/30 to 21/30). Visual-constructive functions achieved the normal level of performance. Attention, visual-spatial abilities and spatial long-term memory improved by 42%, 26% and 14%, respectively, compared to pre-cranioplasty. The language abilities improved in denomination, comprehension, repetition and reading, although the degree of impairment remained severe. Before cranioplasty, brain MRI revealed the severe post-contusional atrophic lesion in the left frontotemporo-parietal regions with a midline shift of the left hemisphere (Fig. 1a). After cranioplasty, the midline shift disappeared, while the atrophic lesion with ex-vacuo dilatation of the left frontal horn became evident (Fig. 1c). N. Jelcic :A. Cagnin IRCCS San Camillo Foundation, Venice, Italy

Addressing the selective role of distinct prefrontal areas in response suppression: A study with brain tumor patients

&NA; The diverging evidence for functional localization of response inhibition within the prefrontal cortex might be justified by the still unclear involvement of other intrinsically related cognitive processes like response selection and sustained attention. In this study, the main aim was to understand whether inhibitory impairments, previously found in patients with both left and right frontal lesions, could be better accounted for by assessing these potentially related cognitive processes. We tested 37 brain tumor patients with left prefrontal, right prefrontal and non‐prefrontal lesions and a healthy control group on Go/No‐Go and Foreperiod tasks. In both types of tasks inhibitory impairments are likely to cause false alarms, although additionally the former task requires response selection and the latter target detection abilities. Irrespective of the task context, patients with right prefrontal damage showed frequent Go and target omissions, probably due to sustained attention lapses. Left prefrontal patients, on the other hand, showed both Go and target omissions and high false alarm rates to No‐Go and warning stimuli, suggesting a decisional rather than an inhibitory impairment. An exploratory whole‐brain voxel‐based lesion‐symptom mapping analysis confirmed the association of left ventrolateral and dorsolateral prefrontal lesions with target discrimination failure, and right ventrolateral and medial prefrontal lesions with target detection failure. Results from this study show how left and right prefrontal areas, which previous research has linked to response inhibition, underlie broader cognitive control processes, particularly involved in response selection and target detection. Based on these findings, we suggest that successful inhibitory control relies on more than one functionally distinct process which, if assessed appropriately, might help us to better understand inhibitory impairments across different pathologies. HighlightsInhibitory and other co‐occurring processes were investigated in brain tumor patients.Attentional lapses in terms of target misses were observed in right frontal patients.Decisional impairment concerning response selection was found in left frontal patients.These results were confirmed by a voxel‐based lesion‐symptom mapping analysis.Broader cognitive control deficits can account for errors in inhibitory task contexts.

Functional MRI and calculation processing: considerations on preliminary experience about intra-operative validation by electro-stimulation

We recently reported our experience on functional mapping for calculation processing [1–3]. The numerical processing is a crucial function in daily life and its preservation can be achieved in patients undergoing neurosurgery. Indeed, it is well known the role of functional magnetic resonance imaging (fMRI) in surgical planning in patients affected by a brain tumor located in an eloquent area [4, 5] as well as in the detection of structural and functional brain changes in patients with Parkinson’s disease [6]. However, the fMRI reliability to detect functional sites for calculation in these patients is unclear because we are currently lacking of data on the correspondence between preoperative fMRI and intra-operative findings. A 47-year-old male patient affected by a small right parietal brain tumor recently came to our attention (Fig. 1a, b). Preoperatively, the patient underwent fMRI (3T Ingenia Philips scanner) with 16-s blocks of single-digit additions or multiplications and a control counting task. We focused on both one-digit addition and multiplication because they are the most basic of calculation tasks and their sparing is intuitively essential to perform higher order calculation. The fMRI showed some functional sites for calculation in the right superior lobule of the parietal cortex: three sites involved in addition (Fig. 1c, d) were shown just anteriorly [1, 2] and laterally [3] to the tumor; 1 site involved in multiplication (Fig. 1e) was shown just medially to the tumor. The patient then underwent the surgical resection of the parietal tumor. The approach and intra-operative mapping were performed as previously described [1, 2]. The same calculation tasks used for fMRI were administered during surgery. Remarkably, we intra-operatively noted that the parietal cortical areas of the superior lobule involved in both multiplications and additions detected with electro-stimulation perfectly corresponded to those preoperatively shown by fMRI (Fig. 1f). The correspondence was both for sites and involved functions. Two considerations arise from our report: first, the potential capacity of fMRI to predict sites functional for calculation then detectable with intra-operative electro-stimulation. This concordance between preoperative and intra-operative findings has never reported in literature so far. Even if we must keep in mind that calculation processing is a complex function not completely understood yet, our present experience, and previous studies [1, 2] suggest that some cortical sites can be identified as ‘‘critical’’. Now, we present the first report showing that the same ‘‘critical’’ cortical sites are both activated at fMRI and localized by intraoperative mapping. It is still unclear whether these ‘‘critical’’ sites are also ‘‘essential’’ for involved function. The capacity of interfering with function by electro-stimulation of these sites theoretically supports the hypothesis of a ‘‘crucial’’ role in calculation processing. However, further studies on this key topic are needed. Second, functional mapping has proved a powerful tool to validate fMRI findings of calculation. This issue implies that intra-operative electro-stimulation can be helpful in improving our & Alessandro Della Puppa alessandro.dellapuppa@sanita.padova.it