Cerebral asymmetry is a defining feature of the human brain, but some controversy exists with respect to the relationship between structural brain asymmetry and the dimensions of the corpus callosum, the brain\'s major inter-hemispheric commissure. On the one hand, more asymmetric brains might house a proportionally smaller corpus callosum (negative link), potentially due to intra-hemispheric connections dominating over inter-hemispheric connections. On the other hand, asymmetric brains may contain a proportionately larger corpus callosum (positive link), to facilitate a possibly enhanced demand of interhemispheric communication, either through excitatory or inhibitory channels. The scientific literature on this topic is relatively sparse, but we have identified 13 studies that directly assess the relationship between structural asymmetries and callosal morphology. The studies suggest a multitude of effects on the global, regional, and local levels, where findings range from negative links, to positive links, to no links whatsoever. These links are systematically summarized, detailed, and discussed in the present review. Discrepancies between study outcomes might arise from the application of different morphometric approaches, the differential treatment of possible confounds, as well as the size and characteristics of the study sample.

BACKGROUND: Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) is a clinical-radiological syndrome characterized by transient central nervous system symptoms and a reversible lesion in the splenium of the corpus callosum (SCC) on magnetic resonance (MR). We reported a case of adult-onset MERS with uncommon presentation and reviewed the existing literature.
METHODS: We described a case of adult-onset MERS with uncommon symptoms and signs and performed a systematic review of case series including more than four patients of adult-onset (> 14 years old) MERS, from January 2000 to December 2022. We summarized the clinical, laboratory, imaging and therapy data.
RESULTS: We included seven eligible studies for a total of 51 adult-onset MERS patients. Neurological manifestations were preceded by prodromal symptoms in most of the patients (88%), mainly with fever (78%). Headache was the most common symptom (50%), followed by seizures (22%) and disturbance of consciousness (22%). Inflammatory changes on cerebrospinal fluid were present in a half of patient, so defining encephalitis cases. Clinal recovery, was achieved in all patients but two with severe disturbance of consciousness who required ventilator support in the acute phase. MR showed isolated lesion in the SCC in 92% of patients, while 8% of patients showed also extracallosal lesions, all the lesions resolved or improved on follow-up imaging.
CONCLUSIONS: MERS is a form of encephalitis/encephalopathy with a broad range of central nervous system manifestation, often with mild symptoms, such as headache alone, that can lead to overlooked some cases, with an excellent prognosis in most patient.

Seizure disorders have often been found to be associated with corpus callosum injuries, but in most cases, they remain undiagnosed. Understanding the clinical, electrographic, and neuroradiological alternations can be crucial in delineating this entity.
This systematic review aims to analyze the effects of corpus callosum injuries on seizure semiology, providing insights into the neuroscientific and clinical implications of such injuries.
Adhering to the PRISMA guidelines, a comprehensive search across multiple databases, including PubMed/Medline, NIH, Embase, Cochrane Library, and Cross-ref, was conducted until September 25, 2023. Studies on seizures associated with corpus callosum injuries, excluding other cortical or sub-cortical involvements, were included. Machine learning (Random Forest) and deep learning (1D-CNN) algorithms were employed for data classification.
Initially, 1250 articles were identified from the mentioned databases, and additional 350 were found through other relevant sources. Out of all these articles, 41 studies met the inclusion criteria, collectively encompassing 56 patients The most frequent clinical manifestations included generalized tonic-clonic seizures, complex partial seizures, and focal seizures. The most common callosal injuries were related to reversible splenial lesion syndrome and cytotoxic lesions. Machine learning and deep learning analyses revealed significant correlations between seizure types, semiological parameters, and callosal injury locations. Complete recovery was reported in the majority of patients post-treatment.
Corpus callosum injuries have diverse impacts on seizure semiology. This review highlights the importance of understanding the role of the corpus callosum in seizure propagation and manifestation. The findings emphasize the need for targeted diagnostic and therapeutic strategies in managing seizures associated with callosal injuries. Future research should focus on expanding the data pool and exploring the underlying mechanisms in greater detail.

UNASSIGNED: Intracranial lipomas are a rare clinical entity. These lesions are frequently asymptomatic and originate in the pericallosal area. As they are fat-containing lesions which are intimately attached to the surrounding structures, surgery is not recommended. In some individual reports, subtotal resection is recommended to lessen complications. There have been no previous reports of corpus callosum lipoma (CCL) associated with limited dorsal myeloschizis (LDM).
UNASSIGNED: We describe the case of a combination of CCL and bilateral choroid plexus lipoma discovered incidentally during the investigation of LDM in a 3-month-old male child. Given the asymptomatic behavior of the lipoma and the vascular elements of the pericallosal area, it was decided to monitor it regularly. Thus, the patient underwent surgery only for LDM. Histological examination confirmed the diagnosis, and postoperative follow-up 1 year after showed good evolution. To the best of our knowledge, this association has never been described in the literature.
UNASSIGNED: This case suggests a possible developmental relationship between CCL and spinal dysraphism.

The right-ear advantage (REA) for recalling dichotically presented auditory-verbal stimuli has been traditionally linked to the dominance of the left cerebral hemisphere for speech processing. Early studies on patients with callosotomy additionally found that the removal of the corpus callosum leads to a complete extinction of the left ear, and consequently the today widely used models to explain the REA assume a central role of callosal axons for recalling the left-ear stimulus in dichotic listening. However, later dichotic-listening studies on callosotomy patients challenge this interpretation, as many patients appear to be able to recall left-ear stimuli well above chance level, albeit with reduced accuracy. The aim of the present systematic review was to identify possible experimental and patient variables that explain the inconsistences found regarding the effect of split-brain surgery on dichotic listening. For this purpose, a systematic literature search was conducted (databases: Pubmed, Web of Knowledge, EBSChost, and Ovid) to identify all empirical studies on patients with surgical section of the corpus callosum (complete or partial) that used a verbal dichotic-listening paradigm. This search yielded ks = 32 publications reporting patient data either on case or group level, and the data was analysed by comparing the case-level incidence of left-ear suppression, left-ear extinction, and right-ear enhancement narratively or statistically considering possible moderator variables (i.a., extent of the callosal surgery, stimulus material, response format, selective attention). The main finding was an increased incidence of left-ear suppression (odds ratio = 7.47, CI95%: [1.21; 83.49], exact p = .02) and right-ear enhancement (odds ratio = 21.61, CI95%: [4.40; 154.11], p < .01) when rhyming as compared with non-rhyming stimuli were used. Also, an increase in left-ear reports was apparent when a response by the right hemisphere was allowed (i.e., response with the left hand). While the present review is limited by the overall small number of cases and a lack of an appropriate control sample in most of the original studies, the findings nevertheless suggest an adjustment of the classical dichotic-listening models incorporating right-hemispheric processing abilities as well as the perceptual competition of the left- and right-ear stimuli for attention.

Alien hand syndrome (AHS) is an uncommon neurological condition characterized by involuntary, yet seemingly purposeful, movements of a limb, typically an upper extremity, with variable awareness and control by the affected individual. It is associated with a range of peculiar sensations, such as the feeling of limb estrangement, alien control and involuntary mirroring or restraining of movements. AHS indicates a profound disruption in volitional motor control and personal agency. The aetiology of AHS is the dysfunction of critical brain regions secondary to diverse neurological insults, such as tumours, vascular disorders, infarction or neurodegenerative diseases. It is clinically categorized into the parietal and callosal types, depending on the affected region, with manifestations often linked to the specific brain region affected. The callosal type is particularly challenging to diagnose due to its rarity and potential for nonspecific or concealed symptoms amid concurrent brain injuries. Distinguishing AHS from psychiatric disorders is crucial for accurate diagnosis and improved patient outcomes. Further research is imperative for a deeper understanding of the pathophysiology of AHS and the development of effective treatments. AHS predominantly affects adults and is frequently associated with multiple comorbidities. The syndrome is also exemplified by three distinct motor behaviours: Involuntary grasping, inter-manual conflict and limb levitation accompanied by the sensation of an alien limb or the perception of external control over one\'s movements. It has a generally good prognosis with partial or total recovery following appropriate rehabilitation techniques, including pharmacological and psychological measures.

BACKGROUND: Wilson\'s disease (WD) is an inherited disorder of copper metabolism. Agenesis of the corpus callosum is the complete or partial absence of the major united fiber bundles connecting the cerebral hemispheres. Intracranial lipoma is an adipose tissue tumor resulting from an abnormal embryonic development of the central nervous system. The simultaneous occurrence of these three disorders is rare and has not been reported. This report focuses on the pathogenesis and association between the three disorders and highlights the importance of recognizing and effectively managing their coexistence.
METHODS: The purpose of this study was to present a patient with coexisting WD, intracranial lipoma, and corpus callosum dysplasia. We reviewed a female patient hospitalized in 2023 with clinical manifestations of elevated aminotransferases and decreased ceruloplasmin, as well as genetic testing for an initial diagnosis of Wilson\'s disease. Subsequently, a cranial MRI showed corpus callosum dysplasia with short T1 signal changes in the cerebral falx, leading to a final diagnosis of Wilson\'s disease combined with intracranial lipoma and corpus callosum dysplasia. The patient\'s WD is currently stable after treatment with sodium dimercaptosulfonamide (DMPS) and penicillamine, and the patient\'s abnormal copper metabolism may promote the growth of intracranial lipoma.
CONCLUSIONS: The pathogenesis of WD combined with intracranial lipoma and corpus callosum dysplasia is complex and clinically rare. The growth of intracranial lipomas may be associated with abnormal copper metabolism in WD. Abnormal copper metabolism affects lipid metabolism and triggers inflammatory responses. Therefore, early diagnosis and treatment are beneficial for improvement. Each new case of this rare co-morbidity is important as it allows for a better assessment and understanding of these cases\' more characteristic clinical manifestations, which can help estimate the course of the disease and possible therapeutic options.

OBJECTIVE: Cytotoxic lesions of the corpus callosum (CLOCC) are a common magnetic resonance imaging (MRI) finding associated with various systemic diseases including COVID-19. Although an increasing number of such cases is reported in the literature, there is a lack of systematic evidence summarizing the etiology and neuroimaging findings of these lesions. Thus, the aim of this systematic review was to synthesize the applied nomenclature, neuroimaging and clinical features, and differential diagnoses as well as associated disease entities of CLOCC.
METHODS: A comprehensive literature search in three biomedical databases identified 441 references, out of which 324 were eligible for a narrative summary including a total of 1353 patients.
RESULTS: Our PRISMA-conform systematic review identifies a broad panel of disease entities which are associated with CLOCC, among them toxic/drug-treatment-associated, infectious (viral, bacterial), vascular, metabolic, traumatic, and neoplastic entities in both adult and pediatric individuals. On MRI, CLOCC show typical high T2 signal, low T1 signal, restricted diffusion, and lack of contrast enhancement. The majority of the lesions were reversible within the follow-up period (median follow-up 3 weeks). Interestingly, even though CLOCC were mostly associated with symptoms of the underlying disease, in exceptional cases, CLOCC were associated with callosal neurological symptoms. Of note, employed nomenclature for CLOCC was highly inconsistent.
CONCLUSIONS: Our study provides high-level evidence for clinical and imaging features of CLOCC as well as associated disease entities.
CONCLUSIONS: Our study provides high-level evidence on MRI features of CLOCC as well as a comprehensive list of disease entities potentially associated with CLOCC. Together, this will facilitate rigorous diagnostic workup of suspected CLOCC cases.
CONCLUSIONS: • Cytotoxic lesions of the corpus callosum (CLOCC) are a frequent MRI feature associated with various systemic diseases. • Cytotoxic lesions of the corpus callosum show a highly homogenous MRI presentation and temporal dynamics. • This comprehensive overview will benefit (neuro)radiologists during diagnostic workup.

Diffuse midline glioma (DMG), H3 K27-altered, is a newly defined \"pediatric-type,\" diffuse, high-grade glioma under current WHO classifications (updated in 2021). An essential diagnostic criteria of DMG is its occurrence in the midline structures; most intracranial DMG occurs in the brainstem or thalamus but can also occur in other midline structures. We experienced 2 adult cases of intracranial DMGs in areas other than the brainstem and thalamus that were initially difficult to diagnose. Case 1 was a 49-year-old man with extensive T2 high-signal lesions in the bilateral frontal lobes and corpus callosum on brain MRI. A Gd-based contrast medium partially enhanced the lesion and showed marked diffusion restriction, mimicking malignant lymphoma. Case 2 was a 24-year-old man who presented with paroxysmal olfactory abnormalities. The tumor extended mainly to the right temporal lobe, the right basal forebrain, and the bilateral hypothalamus, showing a T2/FLAIR mismatch sign suggestive of IDH-mutant astrocytoma without 1p/19q co-deletion. After a biopsy, both cases were properly diagnosed as DMG, H3 K27-altered (K27M-mutant). Diagnosing adult cases involving atypical midline structures is sometimes challenging before surgery; we discuss this phenomenon with both case details and a literature review.

OBJECTIVE: The goal of this systematic review and meta-analysis was to provide an updated analysis of studies investigating outcomes, morbidity, and mortality associated with MR-guided laser interstitial thermal therapy (MRgLITT) corpus callosum ablation (CCA).
METHODS: Study inclusion criteria for screening required that studies report on human subjects only, including patients aged 1-52 years diagnosed with drug-resistant epilepsy who underwent CCA. Sixteen articles published between 2016 and 2023 were included for the systematic review and analysis, including 4 case reports, 11 case series, and 1 case-control study. Altogether, 85 pediatric and adult patients undergoing CCA were included in the systematic review (46 patients younger and 39 patients older than 21 years). The main outcome of seizure freedom was measured using the decrease in the frequency of atonic seizures following surgery, percentage of atonic seizure freedom following surgery, and percentage of overall seizure freedom following surgery. These measurements were made using data from the last follow-up for patients with at least 6 months of follow-up post-CCA.
RESULTS: The extent of CCA differed across the pooled cohorts, including anterior two-thirds CCA (38.89%, n = 35) and posterior one-third CCA for completion of a prior partial CCA (22.22%, n = 20), complete CCA (27.78%, n = 25), or CCA of residual white matter in the case of subtotal initial ablation (5.56%, n = 5). Overall, 12.94% of the patients undergoing CCA experienced operational complications. The most common operative complications across 90 CCA operations were probe malpositioning (n = 6), hemorrhage (n = 5), off-target extension of splenium ablation to the thalamus (n = 1), infection (n = 1), and postoperative CSF leak (n = 1). Neurological deficits following CCA were reported as transient in 18.82% and permanent in 4.71% of patients across all studies. The most common neurological deficits were disconnection syndrome (n = 4) or transient hemiplegia (supplementary motor area-like syndrome; n = 4). The 6-month overall seizure freedom rate was 18.87% of 53 patients, and the atonic seizure freedom rate was 46.28% of 52 patients postoperatively. CCA resulted in an average decrease in atonic seizure rate from 8.30 to 1.65 atonic seizures per day (average decrease 80.12%).
CONCLUSIONS: CCA is associated with an acceptable complication profile, and most patients experience a meaningful reduction in target seizure semiologies. Accurate MRgLITT probe placement is likely important for maximizing CCA while avoiding collateral damage. Avoidable complications of CCA include off-target ablation (and associated deficits), hemorrhage, and future surgery for residual CCA to palliate continued seizures.