Transient focal lesion in the splenium of the corpus callosum: MR imaging with an attempt to clinical-physiopathological explanation and review of the literature

Cytotoxic corpus callosum lesion and mild CSF pleocytosis during hantavirus infection: a case report

A middle-aged, previously healthy male patient presented with high fever, headache, and aching limbs for 3 days. Laboratory results showed signs of acute kidney injury, elevated procalcitonin, and mild thrombocytopenia. On neurological examination, he had no focal neurological deficits, especially no meningism or visual disturbances. Cerebrospinal fluid (CSF) examination showed mild lymphocytic pleocytosis, and magnetic resonance imaging (MRI) revealed a lesion of the splenium corporis callosum. The patient received anti-infective treatment with acyclovir and ceftriaxone until laboratory results returned positive hantavirus IgM and IgG antibodies in the serum indicating an active hantavirus infection. The renal retention parameters and thrombocytopenia receded following treatment with intravenous fluids, analgesic, and antipyretic agents. MRI follow-up 10 days later showed a residual small FLAIR-positive lesion without any persistent callosal diffusion abnormality. The patient was discharged symptom-free after 8 days and had recovered fully 2 months later. The source of infection in this patient remained unclear. Cytotoxic lesions of the corpus callosum (CLCC) are secondary lesions usually with a good prognosis but require further investigation regarding their underlying etiology and should not be confounded with primary callosal lesions, such as ischemia or lymphoma.

Sequential MR imaging (with diffusion-weighted imaging) changes in metronidazole-induced encephalopathy

Metronidazole-induced neuro-toxicity, though rare, is known. A characteristic spatial distribution of lesions in cerebellar dentate nuclei and dorsal pons is known. However, temporal progression of lesions on magnetic resonance imaging (MRI) has not been described previously. We describe two such cases which presented initially with splenial hyperintesity and showed progression to characterstic lesions. Both cases improved with stoppage of metronidazole.

Miller Fisher Syndrome and Boomerang Sign: A Rare Presentation of Typhoid Fever

Miller Fischer syndrome (MFS) is a variant of Guillain-Barré syndrome which is characterized by a triad of ataxia, ophthalmoplegia, and areflexia. It is uncommonly associated with systemic illnesses. We present the case of a young boy who came back after a trip to New Delhi in India, who developed MFS. MRI showed a callosal splenial hyperintensity which is called the boomerang sign. The evaluation revealed typhoid fever. This is probably the first such report of MFS associated with this infection.

Treatment-related transient splenial lesion of the Corpus Callosum in patients with neuropsychiatric disorders: a literature overview with a case report

Introduction: Transient-localized lesions of the splenium of the corpus callosum (SCC) have been described in various clinical conditions, some of them being attributed to the withdrawal of psychotropic drugs. The pathophysiology of the lesion reflects cytotoxic edema and reversible demyelination.Areas covered: The present article aimed at reviewing cases of transient SCC lesion exclusively related to changes in pharmacotherapy. It also reports the original case of a patient receiving a complex psychopharmacological therapy who developed a transient SCC lesion investigated by magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and pharmacogenetic profiling.Expert opinion: To date, only one review on the subject has been published, analyzing 22 cases of transient SCC lesion arising in epileptic patients on antiepileptic therapy. It hypothesized that the nature of the lesion is a cytotoxic edema and the cases described in the subsequent 14 years seem to support this hypothesis. The authors reported the case of an Italian-Egyptian patient who developed a transient SCC lesion after the rapid withdrawal of Carbamazepine and Lurasidone. The lesion completely disappeared from the MRI performed after 1 month. Patient's ethnic group and its pharmacogenetic profile were considered as possible causes of altered drug metabolism and, likely, of the SCC lesion.

The splenium of the corpus callosum: embryology, anatomy, function and imaging with pathophysiological hypothesis

BACKGROUND AND PURPOSE

The splenium of the corpus callosum is the most posterior part of the corpus callosum. Its embryological development, anatomy, vascularization, function, imaging of pathology, possible pathophysiological mechanisms by which pathology may develop and the clinical consequences are discussed.

METHODS

A literature-based description is provided on development, anatomy and function. MR and CT images are used to demonstrate pathology. The majority of pathology, known to affect the splenium, and the clinical effects are described in three subsections: (A) limited to the splenium, with elaboration on pathophysiology of reversible splenial lesions, (B) pathology in the cerebral white matter extending into or deriving from the splenium, with special emphasis on tumors, and (C) splenial involvement in generalized conditions affecting the entire brain, with a hypothesis for pathophysiological mechanisms for the different diseases.

RESULTS

The development of the splenium is preceded by the formation of the hippocampal commissure. It is bordered by the falx and the tentorium and is perfused by the anterior and posterior circulation. It contains different caliber axonal fibers and the most compact area of callosal glial cells. These findings may explain the affinity of specific forms of pathology for this region. The fibers interconnect the temporal and occipital regions of both hemispheres reciprocally and are important in language, visuospatial information transfer and behavior. Acquired pathology may lead to changes in consciousness.

CONCLUSION

The development, location, fiber composition and vascularization of the splenium make it vulnerable to specific pathological processes. It appears to play an important role in consciousness.

Reversible splenial lesion syndrome due to oxcarbazepine withdrawal: case report and literature review

Background

Reversible splenial lesion syndrome is a distinct entity radiologically characterized by a reversible lesion in the splenium of the corpus callosum. According to previous reports, this condition may be associated with antiepileptic drug use or withdrawal. We herein report a case of reversible splenial lesion syndrome associated with oxcarbazepine withdrawal.

Case Report

A 39-year-old man presented with an 8-year history of epileptic seizures. During the previous 3 years, he had taken oxcarbazepine irregularly. One week prior to admission, he withdrew the oxcarbazepine on his own, and the epilepsy became aggravated. Magnetic resonance imaging (MRI) revealed an isolated lesion in the splenium of the corpus callosum with slight hypointensity on T1-weighted imaging and slight hyperintensity on T2-weighted imaging. Regular oxcarbazepine was prescribed. Over a 5-month follow-up period, repeat MRI showed that the abnormal signals in the splenium of the corpus callosum had completely disappeared.

Conclusion

Reversible splenial lesion syndrome is a rare clinicoradiological disorder that can resolve spontaneously with a favorable outcome. Clinicians should be aware of this condition and that oxcarbazepine withdrawal is a possible etiological factor.

Splenial Lesions of the Corpus Callosum: Disease Spectrum and MRI Findings

The corpus callosum (CC) is the largest white matter structure in the brain, consisting of more than 200–250 million axons that provide a large connection mainly between homologous cerebral cortical areas in mirror image sites. The posterior end of the CC is the thickest part, which is called the splenium. Various diseases including congenital to acquired lesions including congenital anomalies, traumatic lesions, ischemic diseases, tumors, metabolic, toxic, degenerative, and demyelinating diseases, can involve the splenium of the CC and their clinical symptoms and signs are also variable. Therefore, knowledge of the disease entities and the imaging findings of lesions involving the splenium is valuable in clinical practice. MR imaging is useful for the detection and differential diagnosis of splenial lesions of the CC. In this study, we classify the disease entities and describe imaging findings of lesions involving the splenium of the CC based on our experiences and a review of the literature.

Cytotoxic Lesions of the Corpus Callosum That Show Restricted Diffusion: Mechanisms, Causes, and Manifestations

Cytotoxic lesions of the corpus callosum (CLOCCs) are secondary lesions associated with various entities. CLOCCs have been found in association with drug therapy, malignancy, infection, subarachnoid hemorrhage, metabolic disorders, trauma, and other entities. In all of these conditions, cell-cytokine interactions lead to markedly increased levels of cytokines and extracellular glutamate. Ultimately, this cascade can lead to dysfunction of the callosal neurons and microglia. Cytotoxic edema develops as water becomes trapped in these cells. On diffusion-weighted magnetic resonance (MR) images, CLOCCs manifest as areas of low diffusion. CLOCCs lack enhancement on contrast material-enhanced images, tend to be midline, and are relatively symmetric. The involvement of the corpus callosum typically shows one of three patterns: (a) a small round or oval lesion located in the center of the splenium, (b) a lesion centered in the splenium but extending through the callosal fibers laterally into the adjacent white matter, or (c) a lesion centered posteriorly but extending into the anterior corpus callosum. CLOCCs are frequently but not invariably reversible. Their pathologic mechanisms are discussed, the typical MR imaging findings are described, and typical cases of CLOCCs are presented. Although CLOCCs are nonspecific with regard to the underlying cause, additional imaging findings and the clinical findings can aid in making a specific diagnosis. Radiologists should be familiar with the imaging appearance of CLOCCs to avoid a misdiagnosis of ischemia. When CLOCCs are found, the underlying cause of the lesion should be sought and addressed. ^©RSNA, 2017 An earlier incorrect version of this article appeared online. This article was corrected on February 13, 2017.

Chikungunya infection presenting as mild encephalitis with a reversible lesion in the splenium: a case report

Chikungunya fever is an Aedes mosquito-transmitted infection caused by chikungunya virus, an RNA virus in the family Togaviridae. The disease is characteristically manifested as fever, arthralgia, and/or rash. Various neurological manifestations like meningoencephalitis, myelitis, and myeloneuropathy have been mentioned in various reports. We present a rare case of chikungunya fever presenting with mild encephalitis with a reversible lesion of the splenium (MERS), which showed complete clinical and radiological recovery.

Clinical and Neuroimaging Profile of Children with Lesions in the Corpus Callosum

PURPOSE

T2-hyperintense signal changes in corpus callosum (CC) have been described in epilepsy and encephalitis/encephalopathy. Little is known about their pathophysiology. The aim of this study was to examine the clinical presentation and evolution of CC lesions and relationship to seizures.

METHODS

We identified 12 children among 29,634 patients from Radiology Database. We evaluated following characteristics: seizures and accompanying medical history, antiepileptic drug usage, presenting symptoms, and radiological evolution of lesions.

RESULTS

CC lesions were seen in patients with prior diagnosis of epilepsy (n = 5) or in those with new onset seizures (n = 3), or with encephalitis/encephalopathy without history of seizures (n = 4). Seizure clustering or disturbances of consciousness were the main presenting symptoms. No relationship was observed between CC lesion and AEDs. On imaging, ovoid lesions at presentation resolved on follow up imaging and linear lesions persisted. DTI showed that the fibers passing through splenial lesions originated from the posterior parietal cortex and occipital cortex bilaterally.

CONCLUSION

In patients with seizures, no clear relationship was demonstrated between seizure characteristics or AED use with CC lesions. Ovoid lesions resolved and may have different pathophysiologic mechanism when compared to linear lesions that persisted.

Cerebellar mutism in acute disseminating encephalomyelitis

BACKGROUND

Cerebellar mutism in children occurs after posterior fossa tumor resection and can have lasting effects on cognition, language, and behavior. Cerebellar mutism in acute disseminated encephalomyelitis is rare.

PATIENT

A 7-year-old boy with a 3-day history of fever, vomiting, and diarrhea presented with altered mental status and expressive aphasia. Magnetic resonance imaging showed new diffusion restriction in the bilateral dentate nuclei and right cerebellum. With treatment, he began to verbalize again but had long-term cognitive and language difficulties.

CONCLUSION

Acute disseminated encephalomyelitis is commonly a benign process, but its effect on the cerebellum can be long-lasting.

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.

Transient interhemispheric disconnection in a case of insulinoma-induced hypoglycemic encephalopathy

We report a case of a 22-year-old male who was transferred to our hospital in a comatose state following successive seizures. Low blood glucose had been detected upon his arrival at the previous hospital. He became responsive 12 days after the onset of coma. Upon regaining consciousness he exhibited severe dysarthria and several interhemispheric disconnection signs such as intermanual conflict, left-hand dysgraphia, left hemispatial neglect confined to the right hand, impaired interhemispheric transfer, and unilateral constructional apraxia of the right hand. Brain MRI disclosed T2-weighted and diffusion-weighted hyperintense lesions with reduced apparent diffusion coefficients in the bilateral centrum semiovale, splenium of the corpus callosum, right posterior limb of the internal capsule, and bilateral middle cerebellar peduncles. As the MRI findings vanished, his interhemispheric disconnection signs gradually resolved. Abdominal imaging studies revealed a pancreatic tumor, which was later endocrinologically diagnosed as an insulinoma. This is an extremely rare report of interhemispheric disconnection signs due to hypoglycemic encephalopathy. The lesions in the bilateral centrum semiovale likely contributed to the interhemispheric disconnection signs.

MRI evaluation of pathologies affecting the corpus callosum: A pictorial essay

The corpus callosum is a midline cerebral structure and has a unique embryological development pattern. In this article, we describe the pathophysiology and present imaging findings of various typical/atypical conditions affecting the corpus callosum. Since many of these pathologies have characteristic appearances on magnetic resonance imaging (MRI) and their therapeutic approaches are poles apart, ranging from medical to surgical, the neuroradiologist should be well aware of them.

Boomerang sign: Clinical significance of transient lesion in splenium of corpus callosum

Transient signal abnormality in the splenium of corpus callosum on magnetic resonance imaging (MRI) is occasionally encountered in clinical practice. It has been reported in various clinical conditions apart from patients with epilepsy. We describe 4 patients with different etiologies presenting with signal changes in the splenium of corpus callosum. They were diagnosed as having progressive myoclonic epilepsy (case 1), localization-related epilepsy (case 2), hemicrania continua (case 3), and postinfectious parkinsonism (case 4). While three patients had complete involvement of the splenium on diffusion-weighted image (“boomerang sign”), the patient having hemicrania continua showed semilunar involvement (“mini-boomerang”) on T2-weighted and FLAIR image. All the cases had noncontiguous involvement of the splenium. We herein, discuss these cases with transient splenial involvement and stress that such patients do not need aggressive diagnostic and therapeutic interventions. An attempt has been made to review the literature regarding the pathophysiology, etiology, and outcome of such lesions.

Restricted diffusion in the corpus callosum in hypoxic-ischemic encephalopathy

Restricted diffusion within the splenium of the corpus callosum was described in various conditions, but is not a prominent finding in magnetic resonance imaging after neonatal hypoxic-ischemic encephalopathy. Perinatal characteristics were reviewed in 42 term neonates with hypoxic-ischemic encephalopathy treated with selective head cooling. Neonatal images of 34 infants were reviewed. Ten of 34 (29%) infants demonstrated restricted diffusion changes within the splenium of the corpus callosum, with a significantly higher incidence of death or severe developmental delay, compared with infants without changes in the splenium of the corpus callosum (n = 24) (P = 0.002). The positive predictive value of changes in the splenium of the corpus callosum regarding poor outcomes or death was 90%. Changes in the splenium of the corpus callosum were also associated with lower birth weights, larger base deficits in cord arterial gas, and more severe encephalopathy during enrollment in selective head cooling. Restricted diffusion within the splenium of the corpus callosum of term infants with hypoxic-ischemic encephalopathy is often associated with extensive brain injury, and in these circumstances appears to be an early neuroradiologic marker of adverse neurologic outcomes.

Brain regional lesion burden and impaired mobility in the elderly

This study investigated the relationship of brain white matter (WM) lesions affecting specific neural networks with decreased mobility in ninety-nine healthy community-dwelling subjects ≥75 years old prospectively enrolled by age and mobility status. We assessed lesion burden in the genu, body and splenium of corpus callosum; anterior, superior and posterior corona radiata; anterior and posterior limbs of internal capsule; corticospinal tract; and superior longitudinal fasciculus. Burden in the splenium of corpus callosum (SCC) demonstrated the highest correlation particularly with walking speed (r=0.4, p<10(-4)), and in logistic regression it was the best regional predictor of low mobility performance. We also found that independent of mobility, corona radiata has the largest lesion burden with anterior (ACR) and posterior (PCR) aspects being the most frequently affected. The results suggest that compromised inter-hemispheric integration of visuospatial information through the SCC plays an important role in mobility impairment in the elderly. The relatively high lesion susceptibility of ACR and PCR in all subjects may obscure the importance of these lesions in mobility impairment.