Reversible Splenial Lesion Syndrome (RESLES): What's in a Name?

Mild encephalopathy with reversible splenial lesion in a patient with influenza A infection--first report in an adult patient in the USA

We present a case of a 51-year-old man with panhypopituarism who developed clinically mild encephalopathy with a lesion in the splenium of the corpus callosum, in the setting of acute influenza A infection. The patient's initial presentation included hypernatraemia due to pre-existing iatrogenic central diabetes insipidus. Despite adequate treatment of hypernatraemia, his course was complicated by otherwise unexplained mild encephalopathy. Brain MRI revealed a diffusion restricted lesion in the splenium of the corpus callosum. This presentation was consistent with mild encephalopathy with reversible splenial lesion (MERS). The patient subsequently tested positive for influenza A. This is the first reported case of MERS syndrome due to influenza A infection in an adult patient in the USA. Mild encephalopathy associated with influenza A infection and a reversible splenial lesion of the corpus callosum has a favourable prognosis and resolves spontaneously.

Mild encephalopathy with reversible splenial lesion: an important differential of encephalitis

Mild encephalopathy with a reversible splenial lesion (MERS) is a clinico-radiological syndrome characterized by a transient mild encephalopathy and a reversible lesion in the splenium of the corpus callosum on MRI. This syndrome has almost universally been described in children from Japan and East Asia. Here we describe seven cases of MERS occurring in Caucasian Australian children from one centre seen over a 3 year period. All patients had a fever-associated encephalopathy (n = 7), which presented with confusion (n = 4), irritability (n = 3), lethargy (n = 3), slurred speech (n = 3), drowsiness (n = 2) and hallucinations (n = 2). Other neurological symptoms included ataxia (n = 5) and seizures (n = 1). These symptoms resolved rapidly over 4-6 days followed by complete neurological recovery. In all patients, MRI performed within 1-3 days of onset of encephalopathy demonstrated a symmetrical diffusion-restricted lesion in the splenium of the corpus callosum. Three patients had additional lesions involving other parts of the corpus callosum and adjacent periventricular white matter. These same three patients had mild persisting white matter changes evident at followup MRI, while the other patients had complete resolution of radiological changes. A potential trigger was present in five of the seven cases: Kawasaki disease, Salmonella, cytomegalovirus, influenza B and adenovirus (all n = 1). Elevated white cell count (n = 4), elevated C reactive protein (n = 5) and hyponatremia (n = 6) were commonly observed. CSF was performed in four patients, which showed no pleocytosis. This case series of MERS demonstrates this condition occurs outside of East Asia and is an important differential to consider in children presenting with acute encephalopathy.

Reversible Splenial Lesion Syndrome (RESLES) Following Glufosinate Ammonium Poisoning

Isolated and reversible lesion restricted to the splenium of the corpus callosum, known as reversible splenial lesion syndrome, have been reported in patients with infection, high-altitude cerebral edema, seizures, antiepileptic drug withdrawal, or metabolic disturbances. Here, we report a 39-year-old female patient with glufosinate ammonium (GLA) poisoning who presented with confusion and amnesia. Diffusion-weighted magnetic resonance imaging of the brain revealed cytotoxic edema of the splenium of the corpus callosum. The lesion was not present on follow-up MR imaging performed 9 months later. We postulate that a GLA-induced excitotoxic mechanism was the cause of this reversible splenial lesion.

Clinicoradiological spectrum of reversible splenial lesion syndrome (RESLES) in adults: a retrospective study of a rare entity

The presence of reversible lesions that involve the splenium of the corpus callosum (SCC) has been reported in patients with a broad spectrum of diseases and conditions and is referred to as reversible splenial lesion syndrome (RESLES).To describe the clinicoradiological features and establish a clinical position for this disease, we retrospectively examined the clinicoradiological features of adult RESLES patients, as well as discuss the potential pathophysiological mechanisms of this disease.The clinical and MRI findings of patients who presented with RESLES accompanied by symptoms of neurological disorders were retrospectively reviewed. The patients were classified into 2 subgroups (favorable and poor outcome subgroups), which corresponded to the severity of the disability using the Modified Oxford Handicap Scale. In addition, we compared the clinical and neuroimaging features between the 2 outcome subgroups.Eight patients with RESLES associated with various diseases and conditions were included. The clinical presentation was nonspecific; however, MRI exhibited consistent lesions in the SCC with a hypointensity on apparent diffusion coefficient maps and a hyperintensity via diffusion-weighted imaging, which disappeared after a variable lapse. The number of patients with a severe disturbance of consciousness, extracallosal lesions, or diffuse slow waves in the poor outcome subgroup was significantly increased compared with the favorable outcome subgroup (P < 0.05). Thus, the clinicoradiological spectrum of RESLES could be classified into 2 principal categories according to differential outcomes.RESLES is a rare entity with a broad clinicoradiological spectrum because of the various diseases and conditions. Although the overall symptoms of RESLES patients tend to be alleviated, the prognosis of patients with a severe disturbance of consciousness, extracallosal lesions, or diffuse slow waves is likely unfavorable.

Encephalitis with Prolonged but Reversible Splenial Lesion

INTRODUCTION

The splenium of the corpus callosum has a specific structure of blood supply with a tendency towards blood-brain barrier breakdown, intramyelinic edema, and damage due to hypoxia or toxins. Signs and symptoms of reversible syndrome of the splenium of the corpus callosum typically include disorientation, confusion, impaired consciousness, and epileptic seizures.

CASE REPORT

A previously healthy 32-year-old man suffered from weakness, headache, and fever. Subsequently, he developed apathy, ataxia, and inability to walk, and therefore was admitted to the hospital. Cerebrospinal fluid showed protein elevation (0.9 g/l) and pleocytosis (232/1 ul). A brain MRI showed hyperintense lesions in the middle of the corpus callosum. The patient was treated with antibiotics, and subsequently, in combination with steroids. Two months later, the hyperintense lesions in the splenium and the basal ganglia had disappeared. Almost seven months since his hospitalization in the Department of Neurology, the patient has returned to his previous employment. He now does not exhibit any mental changes, an optic edema and urological problems have improved. In addition, he is now actively engaged in sports.

CONCLUSION

We have described a case of a 32-year-old man with confusion, ataxia, and inability to stand and walk. The man developed a febrile meningeal syndrome and a hyperintense lesion of the splenium, which lasted for two months. Neurological changes, optic nerve edema, and urinary retention have resolved over the course of seven months. We think that the prolonged but transient lesion of the splenium may have been caused by encephalitis of viral origin.

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.

Toxic leukoencephalopathies, including drug, medication, environmental, and radiation-induced encephalopathic syndromes

Toxic leukoencephalopathies can be secondary to the exposure to a wide variety of exogenous agents, including cranial irradiation, chemotherapy, antiepileptic agents, drugs of abuse, and environmental toxins. There is no typical clinical picture, and patients can present with a wide array of signs and symptoms. Involvement of white matter is a key finding in this scenario, although in some circumstances other high metabolic areas of the central nervous system can also be affected. Magnetic resonance (MR) imaging usually discloses bilateral and symmetric white matter areas of hyperintense signal on T2-weighted and fluid-attenuated inversion recovery images, and signs of restricted diffusion are associated in the acute stage. In most cases, the changes are reversible, especially with prompt recognition of the disease and discontinuation of the noxious agent. Either the MR or clinical features may be similar to several nontoxic entities, such as demyelinating diseases, leukodystrophies, hepatic encephalopathy, vascular disease, hypoxic-ischemic states, and others. A high index of suspicion should be maintained whenever a patient presents recent onset of neurologic deficit, searching the risk of exposure to a neurotoxic agent. Getting to know the most frequent MR appearances and mechanisms of action of causative agents may help to make an early diagnosis and begin therapy, improving outcome. In this review, some of the most important causes of leukoencephalopathies are presented; as well as other 2 related conditions: strokelike migraine attacks after radiation therapy syndrome and reversible splenial lesions.

Reversible abnormality of the splenium in a bipolar patient with neuroleptic malignant syndrome

OBJECTIVE

To report reversible abnormality of the splenium in a bipolar patient with neuroleptic malignant syndrome (NMS).

METHODS

We studied a 23-year-old male who received oral and parenteral neuroleptics, atypical antipsychotic agents, and mood stabilizers, as well as a course of six electroconvulsive therapy treatments, for an episode of mania. He improved. Five days after discharge on maintenance atypical antipsychotic agents and mood stabilizers, he returned with symptoms suggestive of NMS. Laboratory investigations revealed leucopenia, thrombocytopenia, and elevated creatine phosphokinase levels. Brain magnetic resonance imaging showed swelling of the splenium with centrally restricted diffusion; there was no other abnormality. He was defensively treated with antimicrobials, methylprednisolone, and bromocriptine.

RESULTS

Clinical recovery was complete after nine days, and the splenium lesion resolved after four further days; there were no neuropsychiatric sequelae. Nine months later, the patient remains well on maintenance lithium therapy.

CONCLUSIONS

This is the first report of an isolated splenial lesion reversing within days of resolution of NMS. The outcome supports the recent literature which suggests that an isolated splenial lesion does not need investigation, and that prognosis depends on the underlying disorder, and not on the presence or absence of the splenial lesion.

Neurologic complications of influenza

We report on a child with mild encephalopathy with reversible splenial lesion (MERS) associated with influenza infection and present a case series of neurological complications associated with influenza infections in children who presented to a tertiary children's hospital in Australia over a period of one year.

Reversible corpus callosum splenial lesion due to steroid therapy

Reversible corpus callosum splenial (CCS) lesions are rare findings and usually detected incidentally. We presented a case of 15-year-old boy with a diagnoses of nephrotic syndrome. He was referred for neuropsychiatric symptoms following dose reduction on steroid treatment. Brain magnetic resonance imaging (MRI) revealed a focal lesion in the CCS, hyperintense on T2 and FLAIR and hypointense on T1 images with diffusion restriction on apparent diffusion coefficient map. Follow-up MRI 3 weeks later showed complete resolution of the lesion. It was probably result of focal intramyelinic edema due to excytotoxic mechanisms and/or arginine-vasopressin release.

Clinico-radiological spectrum of reversible splenial lesions in children

Recently, many cases of children presenting reversible splenial lesions during febrile illness (RESLEF) have been reported; however, their overall clinico-radiological features are unclear. To describe the clinico-radiological features, we retrospectively reviewed the etiology (pathogen), clinical course, laboratory data, magnetic resonance imaging and electroencephalography (EEG) findings, therapy, and prognosis of 23 episodes in 22 children (1 child recurred) who presented neurological symptoms, with RESLEF. The etiologies (pathogens) varied. Seizure occurred in 7 episodes, disturbance of consciousness (DC) in 13, and delirious behavior in 18. Serum sodium levels <136 mEq/L were observed in 18 episodes. Lesions outside the splenium were found in 4 cases. Slow waves were observed on EEG in 10 episodes. Methylprednisolone pulse therapy was given in 7 cases. No case resulted in neurological sequelae. Among 23 episodes, clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) was diagnosed in 6 episodes, whereas non-MERS was observed in 17 episodes. No difference was observed in almost all the clinico-radiological features' data between the 2 groups. The largest differences were observed in the rate of purposeless movement, DC, extension of the abnormal lesions outside the splenium, and marked slowing of background activity on EEG. RESLEF exhibit a spectrum of clinico-radiological features. These results suggest that non-MERS and MERS both are a part of a larger pathological condition, which we have termed as RESLEF spectrum syndrome. Given the view that such a syndrome exists, the clinical characteristics and position of non-MERS and MERS become clear.

Delirious behavior or mild reduction of consciousness mimicking influenza-associated encephalopathy

BACKGROUND

During the A/H1N1 pandemic, patients suffered from impaired consciousness. They were suspected of or diagnosed as having influenza-associated encephalopathy (IAE) in an emergency situation. Their symptoms resembled those of a recently described 'unique clinical group', which were reported to have a favorable prognosis.

METHODS

We retrospectively examined 46 patients and divided them into two groups. Group IC contained the 26 patients with persisting impaired consciousness. The remainder of the patients were categorized into group R, consisting of patients with only neurological symptoms without impaired consciousness.

RESULTS

Male predominance (22 male/four female) was noted in group IC. Patient age ranged from 5 to 12 years old (mean ± SD, 7.7 ± 2.3 years). Impaired consciousness such as delirious behavior or mild reduction of consciousness lasted continuously or intermittently from 5 min to 2.5 days. On electroencephalogram, semi-rhythmic high-voltage slow waves in the parieto-occipital regions and diffuse high-voltage slow waves were observed in eight and in two patients, respectively. In group R, there was no gender predominance. Patient age ranged from 1 to 9 years old (mean ± SD, 4.1 ± 2.5 years). All group R patients were clinically diagnosed with febrile seizure.

CONCLUSIONS

Some of the characteristics in group IC resembled those of the unique clinical group, and are part of a continuous clinical spectrum. Some patients may have favorable outcome without specific treatment.

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.

Neurologic complications of electrolyte disturbances and acid-base balance

Electrolyte and acid-base disturbances are common occurrences in daily clinical practice. Although these abnormalities can be readily ascertained from routine laboratory findings, only specific clinical correlates may attest as to their significance. Among a wide phenotypic spectrum, acute electrolyte and acid-base disturbances may affect the peripheral nervous system as arreflexic weakness (hypermagnesemia, hyperkalemia, and hypophosphatemia), the central nervous system as epileptic encephalopathies (hypomagnesemia, dysnatremias, and hypocalcemia), or both as a mixture of encephalopathy and weakness or paresthesias (hypocalcemia, alkalosis). Disabling complications may develop not only when these derangements are overlooked and left untreated (e.g., visual loss from intracranial hypertension in respiratory or metabolic acidosis; quadriplegia with respiratory insufficiency in hypermagnesemia) but also when they are inappropriately managed (e.g., central pontine myelinolisis when rapidly correcting hyponatremia; cardiac arrhythmias when aggressively correcting hypo- or hyperkalemia). Therefore prompt identification of the specific neurometabolic syndromes is critical to correct the causative electrolyte or acid-base disturbances and prevent permanent central or peripheral nervous system injury. This chapter reviews the pathophysiology, clinical investigations, clinical phenotypes, and current management strategies in disorders resulting from alterations in the plasma concentration of sodium, potassium, calcium, magnesium, and phosphorus as well as from acidemia and alkalemia.

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.

Cerebellar mutism and reversible cytotoxic edema in influenza B-associated encephalopathy

BACKGROUND

Influenza virus-associated neurological complications are rare, though well-documented, especially in children. Encephalopathy and seizures are the most common complications and are typically associated with influenza A infection. Cerebellar mutism has been rarely reported in association with influenza B infection.

PATIENT

We describe a 3-year-old boy who presented with cough, fever, altered mental status, seizure, hypotonia, and mutism. He tested positive for influenza B virus. His brain magnetic resonance imaging showed reversible cytotoxic edema limited to the middle cerebellar peduncles and the dentate nuclei. Other viral, vascular, toxic, and metabolic causes were ruled out.

CONCLUSION

Our patient represents a case of cerebellar mutism associated with influenza B encephalopathy in which the brain magnetic resonance imaging scan showed reversible cytotoxic edema limited to the middle cerebellar peduncles and the dentate nuclei. This clinicoradiological correlation supports other reports in which the dentate nuclei play a major rule in the pathogenesis of cerebellar mutism.

Cerebral magnetic resonance imaging findings in adults with haemolytic uraemic syndrome following an infection with Escherichia coli, subtype O104:H4

PURPOSE

Infections with Enterohaemorrhagic Escherichia coli typically occur in children causing haemolytic uraemic syndrome (HUS) and neurological symptoms in 20-50 %. Little information is available on the morphology of brain manifestations in adults. The purpose of this study was to identify a characteristic magnetic resonance imaging (MRI) pattern during the outbreak of a novel mutation of Escherichia coli O104:H4.

METHODS

Patients were recruited from two hospitals between May and July 2011. The MRI protocol included standard anatomical, diffusion-weighted, and susceptibility-sensitive sequences.

RESULTS

A total of 104 MRIs of 57 (32 female, 25 male) patients (mean 45.5 ± 18.4 years) showed abnormal signal intensity on 51 MRIs (49 %). Bilateral thalamus (39 %), bilateral pons (35 %), centrum semiovale and splenium of corpus callosum (33 %) were most often involved. Acute lesions were reversible in 81 % of cases. There was no statistically significant association between symptom onset and the MRI findings (P = 0.2).

CONCLUSIONS

Neuroimaging findings in this adult patient cohort were non-specific and similar to previous findings in children. A characteristic neuroimaging pattern of an infection with Escherichia coli O104:H4 was not identified. However, bilateral symmetric T2 hyperintense lesions of the thalami and dorsal pons characterized by restricted diffusion suggest a metabolic toxic effect of the disease on the brain.

Neuroimaging in patients with abnormal blood glucose levels

SUMMARY

Smooth neuronal functioning requires an uninterrupted supply of energy that is provided by glucose under normal physiologic conditions. Significant variations in plasma glucose levels, be it hypoglycemia or hyperglycemia, can present with myriad clinical manifestations and may mimic stroke. At times, the diagnosis is either not apparent or not clinically suspected. Imaging can suggest the diagnosis in unsuspected cases and can help in the assessment of the extent of neuronal damage in known cases, making it vital for the neuroradiologist to be aware of both common and atypical neuroimaging findings in hypoglycemia and hyperglycemia.

Legionella pneumophila infection presenting as headache, confusion and dysarthria in a human immunodeficiency virus-1 (HIV-1) positive patient: case report

Background

Legionella pneumophila is a common cause of community-acquired pneumonia. Central nervous system dysfunction is common, and diagnosis in the absence of pulmonary symptoms can be challenging. Here we describe an atypical clinical presentation of Legionella infection in a patient with HIV who was found to have an unusual neuroradiologic lesion that further served to obscure the diagnosis. This is the first such description in a patient with Legionellosis and HIV coinfection.

Case presentation

A 43 year-old HIV positive man presented to our hospital with dysarthria, fevers, headache, and altered mental status. Initial work-up revealed pneumonia and a lesion of the splenium of the corpus callosum on magnetic resonance imaging. He was subsequently diagnosed with Legionella pneumonia and treated with complete symptom resolution.

Conclusions

Neurologic abnormalities are frequent in Legionellosis, but the diagnosis may be difficult in the absence of overt respiratory symptoms and in the presence of HIV coinfection. A high index of suspicion and early initiation of empiric antibiotics is imperative since early treatment may help prevent long-term sequelae. Neuroimaging abnormalities, though rare, can help the physician narrow down the diagnosis and avoid unnecessary invasive testing. Future studies should aim to elucidate the as yet unknown role of neuroimaging in the diagnoses and prognostication of Legionellosis, as well as the interaction between Legionella infection and HIV.

Dysfunction of default-mode network in encephalopathy with a reversible corpus callosum lesion

Increasing attention has been paid recently to the study of spontaneous brain activity; moreover, particular attention has been paid to the concept of a default-mode network of brain function. Although the functional significance of the default-mode network remains a matter of debate, it has been suggested to be a candidate for the network subserving basic functions related to consciousness. We report the case of a 29-year-old man with encephalopathy and a reversible lesion of the entire corpus callosum. Despite resolution of corpus callosum lesion on magnetic resonance imaging (MRI) within 1 week, the patient persistently presented disturbance of consciousness. Resting-state functional MRI revealed that the posterior cingulate cortex/precuneus was functionally disconnected from other brain regions within the default-mode network. Our case report suggests that assessment of the functional connectivity in the resting-state default-mode network could be a useful marker of consciousness disturbance even in the presence of a reversible brain lesion.

Callosal warning syndrome

OBJECTIVE

To report the clinical and imaging findings in a patient with an initial fluctuating disconnection syndrome due to corpus callosal ischemia that ultimately culminated in infarction with persistent symptoms.

CASE REPORT

A 40-year-old, hypertensive, right-handed man presented with transient, stereotyped symptoms of corpus callosal disconnection (intermanual conflict, apraxia, dysgraphia and construction difficulties in his left hand). Serial magnetic resonance imaging scans demonstrated the ischemic nature of the initial fluctuating symptoms and later showed callosal infarction when the symptoms were persistent. Magnetic resonance angiogram did not reveal significant stenosis or occlusion of the internal carotid or proximal portion of anterior cerebral arteries. Patient received standard treatment for ischemic stroke and at follow-up 1 month later, had mild left hand apraxia, dysgraphia and construction difficulties.

CONCLUSION

The case highlights the unusual occurrence of crescendo transient ischemic attacks culminating in infarction in the location of corpus callosum. We have termed this novel stroke syndrome as 'callosal warning syndrome' as the temporal profile was quite indistinguishable from that of relatively well-known stroke warning syndromes in the location of internal capsule and pontine tegmentum.