Clinical, neuroimaging and prognostic study of 127 cases with infarction of the corpus callosum

Clinical characteristics of post-stroke basal ganglia aphasia and the study of language-related white matter tracts based on diffusion spectrum imaging

BACKGROUND

Stroke often damages the basal ganglia, leading to atypical and transient aphasia, indicating that post-stroke basal ganglia aphasia (PSBGA) may be related to different anatomical structural damage and functional remodeling rehabilitation mechanisms. The basal ganglia contain dense white matter tracts (WMTs). Hence, damage to the functional tract may be an essential anatomical structural basis for the development of PSBGA.

METHODS

We first analyzed the clinical characteristics of PSBGA in 28 patients and 15 healthy controls (HCs) using the Western Aphasia Battery and neuropsychological test batteries. Moreover, we investigated white matter injury during the acute stage using diffusion magnetic resonance imaging scans for differential tractography. Finally, we used multiple regression models in correlation tractography to analyze the relationship between various language functions and quantitative anisotropy (QA) of WMTs.

RESULTS

Compared with HCs, patients with PSBGA showed lower scores for fluency, comprehension (auditory word recognition and sequential commands), naming (object naming and word fluency), reading comprehension of sentences, Mini-Mental State Examination, and Montreal Cognitive Assessment, along with increased scores in Hamilton Anxiety Scale-17 and Hamilton Depression Scale-17 within 7 days after stroke onset (P < 0.05). Differential tractography revealed that patients with PSBGA had damaged fibers, including in the body fibers of the corpus callosum, left cingulum bundles, left parietal aslant tracts, bilateral superior longitudinal fasciculus II, bilateral thalamic radiation tracts, left fornix, corpus callosum tapetum, and forceps major, compared with HCs (FDR < 0.02). Correlation tractography highlighted that better comprehension was correlated with a higher QA of the left inferior fronto-occipital fasciculus (IFOF), corpus callosum forceps minor, and left extreme capsule (FDR < 0.0083). Naming was positively associated with the QA of the left IFOF, forceps minor, left arcuate fasciculus, and uncinate fasciculus (UF) (FDR < 0.0083). Word fluency of naming was also positively associated with the QA of the forceps minor, left IFOF, and thalamic radiation tracts (FDR < 0.0083). Furthermore, reading was positively correlated with the QA of the forceps minor, left IFOF, and UF (FDR < 0.0083).

CONCLUSION

PSBGA is primarily characterized by significantly impaired word fluency of naming and preserved repetition abilities, as well as emotional and cognitive dysfunction. Damaged limbic pathways, dorsally located tracts in the left hemisphere, and left basal ganglia pathways are involved in PSBGA pathogenesis. The results of connectometry analysis further refine the current functional localization model of higher-order neural networks associated with language functions.

Case report: Symmetrical and increased lateral sway-based walking training for patients with corpus callosum infarction: a case series

Introduction

Corpus callosum injury is a rare type of injury that occurs after a stroke and can cause lower limb dysfunction and a decrease in activities of daily living ability. Furthermore, there are no studies that focus on the progress in rehabilitation of the lower limb dysfunction caused by infarction in the corpus callosum and the effective treatment plans for this condition. We aimed to present a report of two patients with lower limb dysfunction caused by corpus callosum infarction after a stroke and a walking training method.

Methods

We implemented a walking training method that prioritizes bilateral symmetry and increases lateral swaying before the patients established sitting/standing balance. The plan is a rapid and effective method for improving walking dysfunction caused by corpus callosum infarction.

Case characteristics

Following sudden corpus callosum infarction, both patients experienced a significant reduction in lower limb motor function scores and exhibited evident gait disorders. Scale evaluations confirmed that walking training based on symmetrical and increased lateral sway for patients with lower limb motor dysfunction after corpus callosum infarction led to significant symptom improvement.

Conclusion

We report two cases of sudden motor dysfunction in patients with corpus callosum infarction. Symmetrical and increased lateral sway-based walking training resulted in substantial symptom improvement, as confirmed by scale assessments.

Alien hand syndrome, a rare presentation of corpus callosum and cingulate infarction

Alien hand syndrome (AHS) is a rare apraxia syndrome, characterized by involuntary and uncontrollable movements of one upper limb, often accompanied by intermanual conflict. Damage to the corpus callosum, acute infarction and neurodegenerative disease may result in AHS. Based on the presentation and impairment region, AHS has three variants: frontal, callosal and posterior. Each type may have a different clinical presentation. A total of 157 patients admitted to hospital with corpus callosum infarction between 2012 and 2022 were included for this study, of whom a number of 5 presented with AHS. 4 of them had significant symptoms of intermanual conflict and 1 had strong grip symptoms in the affected upper limb. Moreover, new infarcts involving the corpus callosum and cingulate gyrus were found on MRI in all five patients. We simultaneously performed a retrospective study on all reported AHS cases caused by infarction of the corpus callosum. Case reports and literature reviews were conducted in order to provide clinicians with a better understanding of AHS, its etiology, clinical presentation, diagnosis, and treatment.

Prediction of subjective cognitive decline after corpus callosum infarction by an interpretable machine learning-derived early warning strategy

Background and purpose

Corpus callosum (CC) infarction is an extremely rare subtype of cerebral ischemic stroke, however, the symptoms of cognitive impairment often fail to attract early attention of patients, which seriously affects the long-term prognosis, such as high mortality, personality changes, mood disorders, psychotic reactions, financial burden and so on. This study seeks to develop and validate models for early predicting the risk of subjective cognitive decline (SCD) after CC infarction by machine learning (ML) algorithms.

Methods

This is a prospective study that enrolled 213 (only 3.7%) CC infarction patients from a nine-year cohort comprising 8,555 patients with acute ischemic stroke. Telephone follow-up surveys were carried out for the patients with definite diagnosis of CC infarction one-year after disease onset, and SCD was identified by Behavioral Risk Factor Surveillance System (BRFSS) questionnaire. Based on the significant features selected by the least absolute shrinkage and selection operator (LASSO), seven ML models including Extreme Gradient Boosting (XGBoost), Logistic Regression (LR), Light Gradient Boosting Machine (LightGBM), Adaptive Boosting (AdaBoost), Gaussian Naïve Bayes (GNB), Complement Naïve Bayes (CNB), and Support vector machine (SVM) were established and their predictive performances were compared by different metrics. Importantly, the SHapley Additive exPlanations (SHAP) was also utilized to examine internal behavior of the highest-performance ML classifier.

Results

The Logistic Regression (LR)-model performed better than other six ML-models in SCD predictability after the CC infarction, with the area under the receiver characteristic operator curve (AUC) of 77.1% in the validation set. Using LASSO and SHAP analysis, we found that infarction subregions of CC infarction, female, 3-month modified Rankin Scale (mRS) score, age, homocysteine, location of angiostenosis, neutrophil to lymphocyte ratio, pure CC infarction, and number of angiostenosis were the top-nine significant predictors in the order of importance for the output of LR-model. Meanwhile, we identified that infarction subregion of CC, female, 3-month mRS score and pure CC infarction were the factors which independently associated with the cognitive outcome.

Conclusion

Our study firstly demonstrated that the LR-model with 9 common variables has the best-performance to predict the risk of post-stroke SCD due to CC infarcton. Particularly, the combination of LR-model and SHAP-explainer could aid in achieving personalized risk prediction and be served as a decision-making tool for early intervention since its poor long-term outcome.

Non-severe COVID-19 complicated by cytotoxic lesions of the corpus callosum (mild encephalitis/encephalopathy with a reversible splenial lesion): a case report and literature review

BACKGROUND

Coronavirus disease 2019- (COVID-19-) associated cytotoxic lesions of the corpus callosum (CLOCCs) have been reported as a rare neurological abnormality in severe cases. Here, a case of CLOCCs in the early stages of mild COVID-19 infection during the Omicron BA.1 epidemic is reported along with a literature review.

CASE REPORT

A Japanese woman with COVID-19 presented to the emergency department with altered consciousness and cerebellar symptoms a day after fever onset. Magnetic resonance imaging (MRI) revealed a lesion with restricted diffusion in the corpus callosum. She exhibited no complications of pneumonia, her neurological symptoms resolved after two days, and after 10 days, the brain lesion was not detected on MRI.

LITERATURE REVIEW

The PubMed database was searched for case reports that met the CLOCC definition proposed by Starkey et al. The search yielded 15 COVID-19-associated cases reported as CLOCCs and 13 cases described under former terms, including mild encephalitis/encephalopathy with a reversible splenial lesion. Adult cases with a documented course were accompanied by pneumonia or hypoxemia, whereas pediatric cases were mostly accompanied by a multisystem inflammatory syndrome.

CONCLUSION

COVID-19-associated CLOCCs can occur, even at an early, non-severe stage. Therefore, this condition may be underdiagnosed if MRI is not performed.

Interlimb Transfer of Reach Adaptation Does Not Require an Intact Corpus Callosum: Evidence from Patients with Callosal Lesions and Agenesis

Generalization of sensorimotor adaptation across limbs, known as interlimb transfer, is a well-demonstrated phenomenon in humans, yet the underlying neural mechanisms remain unclear. Theoretical models suggest that interlimb transfer is mediated by interhemispheric transfer of information via the corpus callosum. We thus hypothesized that lesions of the corpus callosum, especially to its midbody connecting motor, supplementary motor, and premotor areas of the two cerebral hemispheres, would impair interlimb transfer of sensorimotor adaptation. To test this hypothesis, we recruited three patients: two rare stroke patients with recent, extensive callosal lesions including the midbody and one patient with complete agenesis. A prismatic adaptation paradigm involving unconstrained arm reaching movements was designed to assess interlimb transfer from the prism-exposed dominant arm (DA) to the unexposed non-dominant arm (NDA) for each participant. Baseline results showed that spatial performance of each patient did not significantly differ from controls, for both limbs. Further, each patient adapted to the prismatic perturbation, with no significant difference in error reduction compared with controls. Crucially, interlimb transfer was found in each patient. The absolute magnitude of each patient’s transfer did not significantly differ from controls. These findings show that sensorimotor adaptation can transfer across limbs despite extensive lesions or complete absence of the corpus callosum. Therefore, callosal pathways connecting homologous motor, premotor, and supplementary motor areas are not necessary for interlimb transfer of prismatic reach adaptation. Such interlimb transfer could be mediated by transcallosal splenium pathways (connecting parietal, temporal and visual areas), ipsilateral cortico-spinal pathways or subcortical structures such as the cerebellum.

Nonconvulsive status epilepticus manifesting as rapidly progressive dementia and infarction in the splenium of the corpus callosum: A case report

RATIONALE

Nonconvulsive status epilepticus (NCSE) is a heterogeneous disease with multiple subtypes. NCSE poses great diagnostic and therapeutic challenges due to the lack of typical symptoms. Here, we report a case of NCSE manifesting as rapidly progressive dementia (RPD) and infarction in the splenium of the corpus callosum. Additionally, the relevant literature was reviewed.

PATIENT CONCERNS

A 63-year-old man presented with RPD. Electroencephalogram (EEG) revealed NCSE, and brain magnetic resonance imaging (MRI) showed an isolated infarction in the splenium of the corpus callosum. Mini-mental state examination showed moderate cognitive impairment (14/30 points).

DIAGNOSIS

A diagnosis of NCSE with RPD and infarction in the splenium of the corpus callosum was made.

INTERVENTIONS

The patient was treated with intravenous diazepam (10 mg), oral levetiracetam (1.0g twice daily), oral sodium valproate (0.2g twice daily), and intramuscular phenobarbital sodium (0.2g once daily).

OUTCOMES

After the treatment, the symptoms were improved. The patient could answer questions. Repeated EEG showed that the background a rhythm was slightly overdeveloped, and no clinical or electrical seizures were observed. After discharge, the patient was treated with oral levetiracetam (1.0g twice daily) and oral sodium valproate (0.2g twice daily) for 6 months. At the last follow-up, the patient had clear consciousness, sensitive response, and fluent answering ability. Repeated mini-mental state examination showed that his cognitive function was significantly improved (28/30 points); nevertheless, the lesion in the splenium of corpus callosum remained unchanged on MRI.

LESSONS

NCSE manifesting as RPD and infarction in the splenium of the corpus callosum is extremely rare. Epileptic events and focal infarction are usually overlooked in patients with dementia, and the diagnostic value of MRI and EEG should be highlighted.