Classification of acquired lesions of the corpus callosum with MRI

Association between the Anatomical Location of Glioblastoma and Its Evaluation with Clinical Considerations: A Systematic Review and Meta-Analysis

Background: Glioblastoma is a primary malignant brain tumor; it is aggressive with a high degree of malignancy and unfavorable prognosis and is the most common type of malignant brain tumor. Glioblastomas can be located in the brain, cerebellum, brainstem, and spinal cord, originating from glial cells, particularly astrocytes. Methods: The databases MEDLINE, Scopus, Web of Science, Google Scholar, and CINAHL were researched up to January 2024. Two authors independently performed the search, study selection, and data extraction. Methodological quality was evaluated with an assurance tool for anatomical studies (AQUA). The statistical mean, standard deviation, and difference of means calculated with the Student's t-test for presence between hemispheres and presence in the frontal and temporal lobes were analyzed. Results: A total of 123 studies met the established selection criteria, with a total of 6224 patients. In relation to the mean, GBM between hemispheres had a mean of 33.36 (SD 58.00) in the right hemisphere and a mean of 34.70 (SD 65.07) in the left hemisphere, due to the difference in averages between hemispheres. There were no statistically significant differences, p = 0.35. For the comparison between the presence of GBM in the frontal lobe and the temporal lobe, there was a mean in the frontal lobe of 23.23 (SD 40.03), while in the temporal lobe, the mean was 22.05 (SD 43.50), and for the difference in means between the frontal lobe and the temporal lobe, there was no statistically significant difference for the presence of GBM, p = 0.178. Conclusions: We believe that before a treatment, it will always be correct to know where the GBM is located and how it behaves clinically, in order to generate correct conservative or surgical treatment guidelines for each patient. We believe that more detailed studies are also needed to show why GBM is associated more with some regions than others, despite the brain structure being homologous to other regions in which GMB occurs less frequently, which is why knowing its predominant presence in brain regions is very important.

Clinico-radiologic subtypes and therapeutic observation of acute Marchiafava-Bignami disease

We aimed to investigate the clinico-radiologic features of acute Marchiafava-Bignami disease (MBD) and its evolutionary process after effective treatment through subgroup comparison. The clinical and MRI data of 23 patients with acute MBD were retrospectively analyzed and divided into type A (12 cases, with entire callosal involvement) and type B (11 cases, with focal callosal involvement). The clinical assessments and MRI findings (before and after treatment) were compared between the two subtypes. Compared with type B, type A had lower MoCA (Montreal Cognitive Assessment) scores at admission (16.50 ± 1.73 vs 18.27 ± 1.68, P = 0.021) and were more common with extracallosal involvement (66.67% vs 18.18%, P = 0.036) and longer illness duration (18.3 ± 2.1 days vs 15.6 ± 2.4 days, P = 0.012). During the treatment, the residual lesion in the splenium was more common in type A (58.33% vs 9.09%, P = 0.027). After treatment, the MoCa scores of both subtypes gradually increased (P < 0.001), and the callosal and extracallasal lesions disappeared completely. Clinico-radiologic typing of acute MBD is related to the severity of early symptoms, but not to the prognosis. Complete clinico-radiologic recovery is possible for both subtypes with combined treatment. The clinico-radiologic reversibility is helpful for accurate diagnosis and therapeutic evaluation.

Secondary neurodegeneration following Stroke: what can blood biomarkers tell us?

Stroke is one of the leading causes of death and the primary source of disability in adults, resulting in neuronal necrosis of ischemic areas, and in possible secondary degeneration of regions surrounding or distant to the initial damaged area. Secondary neurodegeneration (SNDG) following stroke has been shown to have different pathogenetic origins including inflammation, neurovascular response and cytotoxicity, but can be associated also to regenerative processes. Aside from focal neuronal loss, ipsilateral and contralateral effects distal to the lesion site, disruptions of global functional connectivity and a transcallosal diaschisis have been reported in the chronic stages after stroke. Furthermore, SNDG can be observed in different areas not directly connected to the primary lesion, such as thalamus, hippocampus, amygdala, substantia nigra, corpus callosum, bilateral inferior fronto-occipital fasciculus and superior longitudinal fasciculus, which can be highlighted by neuroimaging techniques. Although the clinical relevance of SNDG following stroke has not been well understood, the identification of specific biomarkers that reflect the brain response to the damage, is of paramount importance to investigate in vivo the different phases of stroke. Actually, brain-derived markers, particularly neurofilament light chain, tau protein, S100b, in post-stroke patients have yielded promising results. This review focuses on cerebral morphological modifications occurring after a stroke, on associated cellular and molecular changes and on state-of-the-art of biomarkers in acute and chronic phase. Finally, we discuss new perspectives regarding the implementation of blood-based biomarkers in clinical practice to improve the rehabilitation approaches and post stroke recovery.

Marchiafava-Bignami Disease: A Rare Association With Dysdiadochokinesia and Ataxic Gait

Marchiafava-Bignami disease (MBD) is a rare neurological disorder characterized by demyelination and necrosis of the corpus callosum. The non-specific signs and symptoms associated with MBD including dysarthria, impaired walking, pyramidal signs, primitive reflexes, seizures, incontinence, sensory symptoms, gaze palsies, and altered mental state result in a challenging diagnosis. Here, we report the case of a 64-year-old female presenting with dizziness, gait ataxia, and a history of recurrent falls for several months. Initial blood tests indicated anaemia, hypokalemia, hypomagnesemia, and mildly elevated inflammatory markers. Her presentation was initially attributed to a multifactorial aetiology, including a urinary tract infection, orthostatic hypotension, and electrolyte imbalances; however, on correction of reversible causes, her symptoms persisted. Moreover, further examination revealed right-hand dysdiadochokinesia. Subsequent brain MRI revealed fluid-attenuated inversion recovery hyperintensity within the corpus callosum and a right-sided pericallosal white matter hyperintensity. Neuro-radiology multidisciplinary team reported these findings consistent with MBD. Management with vitamin B supplementation was promptly initiated alongside alcohol cessation advice. She was also reviewed by physiotherapy teams. This case adds to the paucity of literature on MBD.

Atypical case of mild encephalopathy/encephalitis with reversible splenial lesion of the corpus callosum (MERS) associated with Mycoplasma pneumoniae infection in a paediatric patient

Mild encephalopathy with reversible splenial lesion (MERS) is a disorder characterised by prodromal symptoms such as fever, cough, vomiting or diarrhoea, followed by mild encephalopathy 1-7 days later with a documented reversible corpus callosum splenial lesion. MERS is mostly reported in children in the region of East Asia. To the best of our knowledge, this is the first reported case of MERS associated with mycoplasma infection in a child in North America. A brief review of literature is also a part of this report.

Diverse MRI findings and clinical outcomes of acute Marchiafava-Bignami disease

BACKGROUND

The acute onset of Marchiafava-Bignami disease (MBD) is difficult to capture, and its clinical manifestations are overlapped. Magnetic resonance imaging (MRI) is very useful in the diagnosis of acute MBD.

PURPOSE

To investigate the MRI features and clinical outcomes of acute MBD.

MATERIALS AND METHODS

Sagittal T2-weighted (T2W) or T1-weighted (T1W) imaging, axial T1W and T2W imaging, and axial FLAIR and diffusion-weighted imaging (DWI) sequences were performed in 17 patients with acute MBD on 1.5-T MR. According to the different ranges of callosal restricted diffusion, MBD was divided into Type I (n = 7, the completely involved), Type II (n = 5, the mostly involved), and Type III (n = 5, the partly involved). The MRI findings and outcomes of each type were retrospectively analyzed.

RESULTS

With the reduced range of the callosal restricted diffusion, the callosal atrophy or cavitation was more common: no case of Type I; 1 (20%) case of Type II; and 3 (60%) cases of Type III. With the increased range of callosal restricted diffusion, the extracallosal involvement was more common: 6 (86%) cases of Type I; 3 (60%) cases of Type II; and 1 (20%) case of Type III. During the follow-up, five cases had neuropsychiatric sequelae: 1 (14%) case of type I; 1 (20%) case of Type II; 3 (60%) cases of Type III.

CONCLUSION

The MRI findings and clinical outcomes of acute MBD are regular. The extensive restricted diffusion of acute MBD may present the curable condition. Callosal heterogeneity may affect the outcome of acute MBD.

Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) in adults-a case report and literature review

Background

Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) is a rare clinico-radiological entity characterized by the magnetic resonance imaging (MRI) finding of a reversible lesion in the corpus callosum, sometimes involved the symmetrical white matters. Many cases of child-onset MERS with various causes have been reported. However, adult-onset MERS is relatively rare. The clinical characteristics and pathophysiologiccal mechanisms of adult-onset MERS are not well understood. We reviewed the literature on adult-onset MERS in order to describe the characteristics of MERS in adults and to provide experiences for clinician.

Methods

We reported a case of adult-onset MERS with acute urinary retension and performed literature search from PubMed and web of science databases to identify other adult-onset MERS reports from Januarary 2004 to March 2016. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed on selection process. And then we summarized the clinico-radiological features of adult-onset MERS.

Results

Twenty-nine adult-onset MERS cases were reviewed from available literature including the case we have. 86.2% of the cases (25/29) were reported in Asia, especially in Japan. Ages varied between 18 and 59 years old with a 12:17 female-to-male ratio. The major cause was infection by virus or bacteria. Fever and headache were the most common clinical manifestation, and acute urinary retention was observed in 6 patients. All patients recovered completely within a month.

Conclusion

Adult-onset MERS is an entity with a broad clinico-radiological spectrum because of the various diseases and conditions. There are similar characteristics between MERS in adults and children, also some differences.

Marchiafava-Bignami disease in chronic alcoholic patient

Marchiafava–Bignami disease is a rare toxic encephalopathy seen mostly in chronic alcoholics due to progressive demyelination and necrosis of the corpus callosum. It may involve adjacent white matter and subcortical regions. We present here the magnetic resonance imaging findings of Machiafava–Bignami disease in a chronic alcoholic patient. In 1903, Italian pathologists Marchiafava and Bignami described 3 alcoholic men who died after having seizures and coma. All 3 patients were chronic alcoholics and had consumed considerable amounts of red wine.

The Corpus Callosum and Forensic Issues-An Overview

The corpus callosum is a large central white matter tract that connects the right and left cerebral hemispheres. It permits placental mammals to have a more sophisticated interhemispheric integration of sensory cortices and allows communication between cortical and subcortical neurons. Search of the literature and the pathology archives at The University of Adelaide was undertaken to identify lesions and injuries within the corpus callosum that may have forensic significance. These include developmental/congenital lesions with agenesis/dysgenesis, vascular malformations, and lipomas; inherited syndromes such as neurofibromatosis; and acquired lesions involving trauma, neoplasia, demyelination, vascular conditions, infections, fat embolism, aging/dementia, and the effects of toxins. The finding of lesions within the corpus callosum should initiate careful examination of the adjacent brain and other organ systems for related phenomena as this may shed some light on the nature of the underlying condition, and also help to determine whether there are any forensic implications.

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion caused by methicillin-sensitive Staphylococcus aureus bacteremia with toxic shock syndrome: a case report

Background

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a mild encephalopathy caused by various pathological processes, but encephalopathy due to bacteria is rare.

Case presentation

We report the case of a 45-year-old Japanese woman who on receiving chemotherapy for advanced breast cancer developed an altered mental status and dysarthria soon after fever from infection of a subcutaneous implantable port. Staphylococcus aureus was detected in her blood cultures. Magnetic resonance imaging (MRI) revealed an ovoid lesion in the central portion of the splenium of the corpus callosum (SCC). Although hypotension was not observed, we diagnosed probable toxic shock syndrome (TSS) based on fever (temperature: >38.9 °C), altered mental status, erythema, desquamation, thrombocytopenia, liver dysfunction, and creatine phosphokinase elevation. We administered antimicrobial therapy and her neurological symptoms improved gradually. The lesion in the SCC completely disappeared on MRI 7 days after disease onset.

Conclusions

We diagnosed this case as MERS caused by S. aureus bacteremia with TSS. This is the first report of such a case, and we suggest that when a TSS patient presents with neurological symptoms, the possibility of MERS should be considered.

Marchiafava: Bignami Disease Treated with Parenteral Thiamine

Marchiafava - Bignami disease is rare sequelae of chronic alcohol use. We present a case with transient ischemic attack like presentation and its management with parenteral thiamine. A 53 year old male with history of country liquor use since 32 years was brought to hospital with acute onset of delirium & mild weakness involving motor functions of left side of the body, non-reactive planters and exaggerated tendon reflexes on left side. The MRI showed bilateral hyper intense signal on T2W and FLAIR images & Hypo intense lesion on T1W images involving body, genu and splenium of corpus callosum. The features are suggestive of Marchiafava - Bignami Disease. There have been few guidelines for management of MBD and literature supports use of parenteral thiamine 500mg leading to remission of symptoms and symptomatic improvement. It is advisable to use parenteral thiamine in all cases as it overlaps management of other co-morbidities of chronic alcoholism.

[A case of Marchiafava-Bignami disease suggesting vasogenic edema]

A 61-year-old alcoholic man was admitted to our hospital because of disturbance of consciousness. He also exhibited external ophthalmoplegia, diplopia and mild rigidity, but tendon reflex was normal. On brain MRI, diffusion weighted images (DWI) and apparent diffusion coefficient (ADC) map depicted high intensity in the splenium of the corpus callosum. DWI showed high intensity, but ADC map depicted iso-intensity in bilateral precentral gyri. Marchiafava-Bignami disease (MBD) was diagnosed. After intravenous drip of vitamin, his symptoms improved rapidly and the abnormal MRI findings in the splenium of the corpus callosum and bilateral precentral gyri disappeared gradually. MBD is pathologically characterized by demyelination and necrosis in the corpus callosum, which are generally caused by cytotoxic edema. Our case suggests that vasogenic edema may occur at the early stage of the MBD.

Diagnosis and management of Marchiafava-Bignami disease: a review of CT/MRI confirmed cases

OBJECTIVE

Marchiafava-Bignami disease (MBD) is a rare condition mainly associated with alcoholism, although it may be mimicked by several other disorders that cause corpus callosum lesions. Our objective was to identify helpful features for differential diagnosis and assess whether any treatment can be recommended.

METHODS

We reviewed 122 reports containing data on 153 subjects with confirmed MBD that was associated with either alcoholism or malnutrition, and 20 reports with data on 53 subjects with conditions mimicking MBD. All the cases had been verified antemortem by brain imaging. Unconditional logistic regression was used to demonstrate factors that were associated with the outcome of MBD.

RESULTS

The mimicking conditions were differentiated from MBD by the occurrence of solitary and rapidly disappearing splenial lesions; fewer signs and symptoms with exception of seizures, hemiparesis and tetraparesis; nystagmus; and rapid and complete recovery. MBD occurred most frequently among alcoholics, but it was also reported in 11 non-alcoholics (7.2% of all the MBD cases). A better outcome was observed among those who were treated within 2 weeks after onset of symptoms with parenteral thiamine (p=0.033).

CONCLUSIONS

As thiamine deficiency is frequently associated with alcoholism, malnutrition and prolonged vomiting; we recommend prompt treatment of MBD with parenteral thiamine in such subjects. Recovery should be followed by repeated neuropsychological and MRI examinations, preferably using diffusion tensor imaging.

Acute Marchiafava-Bignami disease with extensive diffusion restriction and early recovery: case report and review of the literature

Marchiafava-Bignami disease (MBD) is a neurological disorder that has been found to be associated with chronic alcoholism and malnutrition. MBD classically results in acute edema and demyelination of the corpus callosum. Edema of the complete corpus callosum has been described to be an unfavorable prognostic factor. We present an acute onset of MBD with diffusion restriction of the complete corpus callosum and symmetric bilateral extension into the semioval center, that almost completely resolved clinically as well as in MRI only 3 days later. With early detection and treatment, the prognosis of MBD may be good even in cases with severe diffusion restriction of the complete corpus callosum.

Mild Encephalopathy with Reversible Splenial Lesion in Children

Mild encephalopathy with reversible splenial lesion (MERS) is a recently described clinico-radiological syndrome. It is characterised by acute mild encephalopathy and changes in the splenium of the corpus callosum on brain magnetic resonance imaging (MRI). MERS has been described mainly in East Asian populations. Infection, particularly influenza, is the most common association. The prognosis is generally favourable with spontaneous resolution of clinical and radiological abnormalities. We report two cases of non-influenza MERS in children, one associated with varicella, and discuss their differing clinical presentations.

Diffuse and heterogeneous T2-hyperintense lesions in the splenium are characteristic of neuromyelitis optica

Background:

Callosal lesions in multiple sclerosis (MS) are usually focal, involving the inferior aspect of the corpus callosum on brain magnetic resonance imaging (MRI), but little is known about callosal lesions in neuromyelitis optica (NMO).

Objective:

To clarify MRI abnormalities in callosal lesions of NMO.

Methods:

Japanese patients with NMO ( n=28) or MS ( n=22) were assessed. The distributions and appearances of callosal lesions were evaluated on a brain mid-sagittal T2-weighted image (T2WI) or a fluid-attenuated inversion recovery image with a 1.5T MRI scanner. Logistic regression analysis identified which characteristics of the callosal lesions were useful for discriminating NMO from MS.

Results:

Callosal lesions were present in 79% of NMO and 82% of MS patients. Callosal abnormalities of NMO, including splenial lesions (57% in NMO versus 27% in MS, odds ratio (OR)=4.23, p=0.04), diffusely spreading lesions from the lower to upper edges of the corpus callosum (71% versus 23%, OR=7.18, p=0.0024), and heterogeneous T2 hyperintense lesions (71% versus 9%, OR=44.3, p=0.0006), were feasible for discriminating NMO from MS.

Conclusion:

Diffuse and heterogeneous T2 hyperintense splenial lesions were characteristic of NMO. These findings could help distinguish NMO from MS on MRI.

Acute encephalopathy with a lesion of the splenium of the corpus callosum--a report of two cases

We report two cases of encephalopathy following a short febrile illness. Case one was a five year old child whose magnetic resonance imaging (MRI) of the brain showed a reversible discrete lesion in the splenium of the corpus callosum (SCC) and a ten year old boy who had extensive hyperintensity of the SCC. As these children have presented while there was an outbreak of influenza in our locality and since the second child tested positive for H1N1 antigen on PCR test, we feel that as previous authors have pointed out, these cases are cases of possible influenza encephalopathy. This awareness needs to be disseminated as this specific MRI finding should prompt one to test for H1N1 antigen and offer specific antiviral agent. Case one showed signs that support the existence of a splenial syndrome.

Abnormal corpus callosum in neonates after hypoxic-ischemic injury

BACKGROUND

Literature regarding callosal injury after hypoxic-ischemic injury (HII) is scant.

OBJECTIVE

To present the MRI and US findings of callosal injury after HII.

MATERIALS AND METHODS

MRI and US studies of 76 neonates were evaluated for HII and 53 were considered positive.

RESULTS

Of the 53 neonates with HII, 40 demonstrated restricted diffusion on DWI; of these, 30 revealed callosal involvement. Nine of the 13 neonates with normal DWI, whose routine MRI images were compatible with HII, were imaged after 1 week of age. Five out of ten neonates imaged during the 1st week of life who did not show callosal restriction on DWI had predominantly basal ganglia injury. Callosal US images were regarded as abnormal in 16 out of the 53 neonates with HII, 15 of which revealed concomitant restricted diffusion on DWI.

CONCLUSION

Callosal injuries are common after HII. DWI is effective in confirming these injuries and easily demonstrates injury if performed prior to 1 week of age. The restricted diffusion demonstrated after this time could be attributed to continued injury. US is not a sensitive modality for callosal injury detection; however, abnormally increased callosal echogenicity might be a specific marker of injury in this setting.

[Transient splenial lesion in influenza A H1N1 2009 infection]

Severe neurologic complications have been rarely reported during novel pandemic influenza A(H1N1) virus infections. We describe the case of an 10-year-old boy with new onset seizures and proven influenza A(H1N1) 2009 infection showing a reversible hyperintense lesion in the splenium of the corpus callosum on T2-weighted and FLAIR magnetic resonance images without contrast enhancement. Transient splenial lesions have been described in the context of virus encephalopathy and do not require specific treatment.

Grade II oligodendroglioma localized to the corpus callosum

The presence of a primary central nervous system (CNS) neoplasm within the corpus callosum generally portends a grave prognosis. Common pathologies encountered include glioblastomas and primary CNS lymphomas. In contrast, World Health Organization grade II oligodendroglial tumors demonstrating loss of heterozygosity at 1p and 19q are generally less aggressive, often responding favorably to chemotherapy. The authors present a case of a primary brain tumor isolated to the corpus callosum diagnosed as a grade II oligodendroglioma. A 52-year-old woman presented with new-onset generalized seizure. Magnetic resonance imaging (MRI) revealed a non-contrast-enhancing lesion with associated edema and regional mass effect. The patient underwent a craniotomy and subtotal resection of the lesion using an endoscopic port. Pathological examination revealed a grade II oligodendroglioma. Molecular analysis identified 1p and 19q deletion as well as MGMT promoter methylation. The patient subsequently underwent adjuvant radiation therapy with an excellent response. We present, to our knowledge, the first report of a grade II oligodendroglioma isolated within the corpus callosum with the characteristic molecular features of this tumor type. Histopathologic diagnosis is essential to appropriately guide therapy of callosal tumors.

Isolated reversible splenial lesion in tick-borne encephalitis: a case report and literature review

Here, we demonstrate a first case of tick-borne encephalitis (TBE) associated with an isolated reversible splenial corpus callosum lesion (IRSL) and highlight the wide range of different clinical entities in which such alterations have been observed. A 42-year-old man showed fever, cephalgia and mild disturbance of coordination and gait. Diagnosis was ascertained by slight CSF-pleiocytosis and positive TBE-IgG as well as by positive intrathekal specific antibody index on follow-up. MRI demonstrated a single ovoid hyperintensity in T2 and DWI with reduction in ADC in the splenium of corpus callosum which was abrogated in follow-up after 6 weeks. Most entities of IRSL presented with excellent prognosis, including our novel case of TBE. We discuss different possible pathomechanisms and the so far unexplained propensity of the splenium for such alterations. Clinicians should be familiar with this phenomenon to avoid unnecessary diagnostic or therapeutic efforts.

Neuroimaging findings in alcohol-related encephalopathies

OBJECTIVE

Our aim was to review the emergent neuroimaging findings of alcohol-related CNS nontraumatic disorders. Alcohol (ethanol) promotes inflammatory processes, increases DNA damage, and creates oxidative stress. In addition, the accompanying thiamine deficiency may lead to Wernicke encephalopathy. Associated changes in serum osmolarity may lead to acute demyelination.

CONCLUSION

Alcohol-related encephalopathies can be life-threatening conditions but can be prevented or treated, if recognized.

[Transient lesion in the splenium of the corpus callosum and a sudden antiepileptic drugs withdrawal: a case with focal epilepsy in presurgical evaluation]

INTRODUCTION

A sudden withdrawal of antiepileptic drugs gives higher rate of epileptic seizures in the settings of video electroencephalography (vEEG), monitoring that is a subject to further registration and analysis. A very rare complication of this method is transient lesion of the splenium of corpus callosum (SCC) detected with brain MRI.

CASE REPORT

We presented a patient with a 5-year history of pharmacoresistant epilepsy admitted to the Institute of Neurology (August, 2008) for vEEG monitoring. Interictal epileptic discharges but none seizure were recorded after the sudden withdrawal of antiepileptic medications, during 5 days of vEEG monitoring Initial brain MRI three days after vEEG monitoring revealed focal lesion in SCC, hyperintense on T2 and FLAIR sequence. A longitudinal radiological follow-up (7 and 49 days after initial acquisition) confirmed transient nature of the lesion without diffusion coefficient changes.

CONCLUSION

SCC lesion, reversible and harmless, may occur after a sudden antiepileptic withdrawal. Its early detection makes further extensive neuroradiological and clinical examinations unnecessary.

Occurrence of acute large and edematous callosal lesions in neuromyelitis optica

BACKGROUND

The corpus callosum is commonly involved in multiple sclerosis (MS), but the characteristics of callosal lesions in neuromyelitis optica (NMO) are unknown.ObjectiveTo reveal the features of callosal lesions in NMO in comparison to MS.

METHODS

We retrospectively reviewed the medical records and the brain magnetic resonance imaging films of 56 patients with MS and 22 patients with NMO.

RESULTS

In MS, 36 (64.3%) of 56 patients had callosal lesions, but only four patients had acute lesions. All such acute lesions were small, isolated and non-edematous, and the intensity was homotonic. Chronic lesions were observed in 34 patients with MS, and 32 (94%) of them presented small lesions located at the callosal lower margin ("hemi-oval pattern"). Meanwhile, four (18.2%) patients with NMO had callosal lesions, and three of them had acute lesions. Those acute lesions were multiple, large edematous ones with heterogeneous intensity ("marbled pattern"). In the chronic stage, the lesions shrank or disappeared.

CONCLUSIONS

Acute large, edematous callosal lesions occasionally occur in NMO. Similar to longitudinally extensive transverse myelitis, such callosal lesions may reflect severe edematous inflammation in NMO, and may provide additional evidence that the pathogenesis in NMO is different from that in MS.

Rotavirus-associated encephalopathy with a reversible splenial lesion

The case is reported of a 2-year-old boy with a rotavirus-induced mild encephalopathy that presented as transient intensified signal on the splenium of the corpus callosum. The boy also experienced persistent diarrhea, vomiting, fever, and sudden disturbance of consciousness. Although cerebrospinal fluid analysis did not manifest pleocytosis, electroencephalography demonstrated global diffuse slow waves and cranial magnetic resonance imaging demonstrated intensified signal on the splenium of the corpus callosum. Methylprednisolone was infused for 3 days. The disturbance of consciousness disappeared within 24 hours without any other complications, and the splenial signal and electroencephalogram returned to normal within 6 days.

Restricted diffusion in the splenium of the corpus callosum after cardiac arrest

The value of MRI findings for coma prognostication is a question of great clinical and pathological relevance. We describe MRI evidence of restricted diffusion in the splenium in 5 patients with coma after cardiopulmonary resuscitation following cardiac arrest. The most common clinical presentation of corpus callosum lesions (of any cause) is altered mental status, consistent with the global importance of these extensive inter-hemispheric fibers. In our four cases with bilateral splenium restricted diffusion, none of the patients recovered consciousness. One patient with a unilateral (likely embolic) restricted diffusion lesion had excellent recovery. In contrast to unilateral ischemic callosal lesions, we believe that generalized, midline splenium restricted diffusion occurring after cardiopulmonary arrest represents Wallerian degeneration of interhemispheric neurons rather than direct ischemic damage to the white matter or axons of the callosum and thus will likely portend a poor prognosis.

Extensive callosal infarction showing difficulty in knitting as an initial symptom

A 66-year-old right-handed woman with type 2 diabetes mellitus was admitted to our hospital with progressive dysarthria and gait disturbance preceded by difficulty in knitting. Brain magnetic resonance imaging (MRI) showed a lesion involving the entire corpus callosum. Although tumor was considered in the differential diagnosis because of the atypical imaging findings, she was diagnosed with infarction based on clinical improvement after admission and sequential changes in MRI. We suggest that difficulty in knitting may be an important early manifestation of a callosal disconnection syndrome and that follow-up clinical and imaging examinations would contribute to confirmation of the diagnosis.

[Isolated infarct of the corpus callosum: a misleading appearance]

We report here the case of an isolated corpus callosum infarct in a 48-year-old woman. Characteristics of this unusual condition are illustrated by multiple imaging modalities on follow-up. We discuss the pathophysiology of this rare entity and the more important differential diagnoses.

Acute Marchiafava-Bignami disease with widespread callosal and cortical lesions

Marchiafava-Bignami disease (MBD) is a rare alcohol-related disorder that results in progressive demyelination and necrosis of the corpus callosum. The process may extend to the optic chiasm and tracts, cerebellar peduncle, subcortical resion, neighboring white matter, and rarely, cortical gray matter. We report a case of MBD in which fluid-attenuated inversion recovery and diffusion magnetic resonance imaging studies revealed symmetrical hyperintense lesions in the cerebral cortex in addition to the callosal lesions.