MRI Findings in Osmotic Myelinolysis

Adaptation of the Brain to Hyponatremia and Its Clinical Implications

Hyponatremia is the most common electrolyte disorder, occurring in up to 25% of hospitalized patients. Hypo-osmotic hyponatremia when severe and left untreated invariably results in cell swelling, which can lead to fatal consequences, especially in the central nervous system. The brain is particularly vulnerable to the consequences of decreased extracellular osmolarity; because of being encased in the rigid skull, it cannot withstand persistent swelling. Moreover, serum sodium is the major determinant of extracellular ionic balance, which in turn governs crucial brain functions such as the excitability of neurons. For these reasons, the human brain has developed specific ways to adapt to hyponatremia and prevent brain edema. On the other hand, it is well known that rapid correction of chronic and severe hyponatremia can lead to brain demyelination, a condition known as osmotic demyelination syndrome. In this paper, we will discuss the mechanisms of brain adaptation to acute and chronic hyponatremia and the neurological symptoms of these conditions as well as the pathophysiology and prevention of osmotic demyelination syndrome.

Central pontine myelinolysis during treatment of hyperglycemic hyperosmolar syndrome: a case report

Background

Central pontine myelinolysis (CPM) is a non-inflammatory demyelinating lesion of the pons. CPM and extrapontine demyelination (EPM) are together termed osmotic demyelination syndrome (ODS), a known and serious complication of acute correction of hyponatremia. Conversely, hyperglycemic hyperosmolarity syndrome (HHS) develops in patients with type 2 diabetes who still have some insulin secretory ability due to infection, non-compliance with treatment, drugs, and coexisting diseases, and is often accompanied by ketosis. HHS represents a life-threatening endocrine emergency (mortality rate, 10–50%) associated with marked hyperglycemia and severe dehydration. HHS may develop ODS, and some cases have been associated with hypernatremia.

Case presentation

The patient was an 87-year-old woman with hyperglycemia, dehydration, malnutrition, and potential thrombus formation during long-term bed rest. HHS was suspected to have developed due to progression of hyperglycemia and dehydration caused by pneumonia. Furthermore, ketoacidosis developed from ketosis and prerenal renal failure associated with circulating hypovolemia shock, which was also associated with disseminated intravascular coagulation. Treatment was started with continuous intravenous injection of fast-acting insulin and low-sodium replacement fluid. In addition, ceftriaxone sodium hydrate, heparin sodium, thrombomodulin α, human serum albumin, and dopamine hydrochloride were administered. Blood glucose, serum sodium, serum osmolality, and general condition (including vital, infection/inflammatory findings, and disseminated intravascular coagulation) improved promptly, but improvements in disturbance of consciousness were poor. Diffusion-weighted imaging of the brain 72 h after starting treatment showed no obvious abnormalities, but high-intensity signals in the midline of the pons became apparent 30 days later, leading to definitive diagnosis of CPM.

Conclusions

Fluctuation of osmotic pressure by treatment from hyperosmolarity due to hyperglycemia and hypernatremia in the presence of risk factors such as malnutrition, severe illness, and metabolic disorders may be a cause of CPM onset. When treating HHS with risk factors, the possibility of progression to ODS needs to be kept in mind.

A highly unusual case of osmotic demyelination syndrome and extrapontine myelinolysis in a 3-month-old infant with Bartter syndrome

Bartter syndrome (BS) is a rare autosomal recessive renal tubular disorder characterized by acute electrolyte imbalance, and similarly, osmotic demyelination syndrome (ODS) is a rather rare complication occurring during electrolyte imbalance. The pathological features of ODS include central pontine myelinolysis and extrapontine myelinolysis (EPM), which consist of severe damage to the myelin sheath of neurons. ODS is very rare in children. We describe a case of a 3-month-old infant with ODS and EPM associated with undiagnosed BS. ODS developed because of a sudden change in electrolyte levels and osmolality caused by acute dehydration during a gastrointestinal infection episode. Undiagnosed, untreated, and non-balanced BS was the cause of the neurological complication. Our patient represents the first case of ODS in BS, the ninth case of ODS in an infant less than one year old, and the third case of isolated EPM in such a young patient. This case report reminds us that in rare diseases, young patients tend to have genetic components.

Central Pontine Myelinosis and Osmotic Demyelination Syndrome

BACKGROUND

Osmotic demyelination syndrome (ODS), which embraces central pontine myelinolysis (CPM) and extrapontine myelinosis (EPM), is often underdiagnosed in clinical practice, but can be fatal. In this article, we review the etiology, patho- physiology, clinical features, diagnosis, treatment, and prognosis of ODS.

METHODS

Pertinent publications from the years 1959 to 2018 were retrieved by a selective search in PubMed.

RESULTS

The most common cause of ODS is hyponatremia; particular groups of patients, e.g., liver transplant recipients, are also at risk of developing ODS. The pathophysiology of ODS consists of cerebral apoptosis and loss of myelin due to osmotic stress. Accordingly, brain areas that are rich in oligodendrocytes and myelin tend to be the most frequently affected. Patients with ODS often have a biphasic course, the first phase reflecting the underlying predisposing illness and the second phase reflecting ODS itself, with pontine dysfunction, impaired vigilance, and movement disorders, among other neurological abnormalities. The diagnostic modality of choice is magnetic resonance imaging (MRI) of the brain, which can also be used to detect oligosymptomatic ODS. The current mainstay of management is prevention; treatment strategies for manifest ODS are still experimental. The prognosis has improved as a result of MRI-based diagnosis, but ODS can still be fatal (33% to 55% of patients either die or remain permanently dependent on nursing care).

CONCLUSION

ODS is a secondary neurological illness resulting from a foregoing primary disease. Though rare overall, it occurs with greater frequency in certain groups of patients. Clinicians of all specialties should therefore be familiar with the risk constellations, clinical presentation, and prevention of ODS. The treatment of ODS is still experimental at present, as no evidence-based treatment is yet available.

Mimickers of neuropsychiatric manifestations in systemic lupus erythematosus

Systemic lupus erythematosus (SLE), presenting with new onset or worsening neuropsychiatric (NP) symptoms, is a challenge in clinical practice. Mimickers such as infections, drug-induced side effects, metabolic abnormalities, malignancies, and alcohol-related disorders have to be excluded, before attributing the manifestations to disease activity. Proper diagnosis is essential to guide adequate management and reduce morbidity and mortality. In this review article, we will highlight clinical, laboratorial, and neuroradiological features that are helpful to assist in the differential diagnosis.

[A case report of central pontine and extrapontine myelinolysis in the combination with spinal cord damage in a patient with tuberculosis in the lung]

A case report of central pontine and extrapontine myelinolysis in the combination with spinal cord damage is presented. The authors analyze literature data on this problem and discuss the pathogenesis and diagnostic issues of myelinolysis.

Treatable Leukoencephalopathy in a Patient with Hypophosphatemia

We report the first patient with pathologically proven leukoencephalopathy associated with hypophosphatemia. A 61-year-old woman had repetitive episodes of decreased consciousness with pontine and pallidal lesions and extensive leukoencephalopathy on MRI, later found to be associated with hypophosphatemia. Although hypophosphatemia has been linked to central pontine and extrapontine myelinolysis (osmotic myelinolysis), lesions in the deep white matter have not been reported. Brain biopsy performed during the first diagnosis process revealed nonspecific demyelination with gliosis, a finding similar to that of chronic osmotic myelinolysis. After normalization of phosphate levels, her consciousness completely improved and MRI abnormalities partly resolved. We should consider that leukoencephalopathy can be associated with hypophosphatemia, which is often treatable.

Temporal evolution of the trident and piglet signs of osmotic demyelination syndrome

Central pontine myelinolysis (CPM) is a potentially-devastating complication of rapid osmolar shifts, classically attributed to overlyaggressive correction of chronic hyponatremia. Magnetic resonance imaging (MRI) allowed earlier diagnosis of CPM, but most importantly, it has revealed that the odds of good functional recovery are surprisingly high. A trident shaped pontine lesion is a typical finding in CPM (the trident sign). The "piglet sign" is a much less well-known radiologic finding in CPM. Due to the rarity of CPM, very little has been published on the evolution of these MRI findings. We present a case of CPM in an alcoholic young man, and describe the temporal evolution of both the trident and piglet signs on MRI in CPM.

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.

Magnetic Resonance Imaging Findings in Bilateral Basal Ganglia Lesions

Introduction: Radiologists may encounter bilaterally symmetrical abnormalities of the basal ganglia on magnetic resonance imaging (MRI), typically in the context of diffuse systemic, toxic or metabolic diseases. A systematic approach and broad knowledge of pathology causing this uncommon group of conditions would be useful. Materials and Methods: This review uses illustrative images to highlight metabolic conditions, such as Leigh’s syndrome, citrullinaemia, hypoglycaemia or carbon monoxide poisoning, as well as other causes of bilateral basal ganglia lesions such as osmotic myelinolysis, deep cerebral venous thrombosis and Creutzfeldt-Jakob disease. Results: Careful assessment of radiological findings outside the basal ganglia, such as involvement of the cortex, white matter, thalamus and pons, together with clinical correlation, may be helpful in narrowing the differential diagnosis, and directing further radiological, biochemical or genetic investigations. Recent advances in MR technology have resulted in newer techniques including diffusion-weighted (DW) MR imaging and MR spectroscopy (MRS); these may be helpful if appropriately used. Conclusions: Abnormal MRI findings in the basal ganglia should not be interpreted in isolation. A systematic approach including DW MR imaging, MRS, and a broad knowledge of diffuse systemic, toxic or metabolic diseases is helpful. Key Words: Basal ganglia, Metabolic disorders

Extrapontine Myelinolysis in a Child: a Rare Case with MRI, DWI and MRS Follow-up

We describe a case of extrapontine myelinolysis in a child presenting with chorea and parkinsonian symptoms after treatment for hyponatremic dehydration. Although both extrapontine myelinolysis (EPM) in childhood and extrapyramidal presentation of EPM are very rare in children, the patient presented with pure extrapyramidal symptoms. Besides basal ganglia involvement and sparing brain stem, MRI demonstrated involvement of the amygdala bilaterally hitherto never reported in EPM patients. While single voxel proton spectroscopy (MRS) of the basal ganglia at the beginning was normal, the follow-up MRS showed moderate to severe NAA and mI decrease. Diffusion-weighted imaging abnormalities appeared relatively late during the disease course, also an unexpected finding. In addition, there were apparent increases in apparent diffusion coefficient (ADC) values of the affected basal ganglia instead of diffusion restriction.

Osmotic demyelination syndrome (central pontine and extrapontine myelinolysis with coagulative necrosis of the putamina and cortical laminar necrosis). A case report and review of the literature

Central pontine myelinolysis (CPM) and extrapontine myelinolysis (EPM) are disorders frequently associated with serum osmotic imbalance. The prognosis is very variable from complete regression of clinical symptomatology to signs of significant quadruparesis, a vegetative state and death. We report the case of a 25-year-old man with a diagnosis of osmotic demyelination syndrome. The patient was young healthy man with no history of chronic alcoholism or malnutrition. He underwent head trauma associated with consumption of alcohol, being diagnosed with cerebral commotion. Four days later he presented with generalised epileptic convulsions with unconsciousness. Laboratory findings showed significant hyponatremia and hypochlorinemia. Following the rapid correction of osmotic conditions of serum, spastic quadruparesis and coma developed. MRI of the brain showed finding of CPM and EPM, cortical laminar necrosis (CLN) and coagulative necrosis in the putamina. Our case is suggestive in the rare MRI appearance of myelinolysis in addition to CLN and coagulative necrosis in the basal ganglia following the rapid correction of serum osmolarity. We suggest that this finding is prognostically very unfavourable. In the reported patient clinically initial neurological deficit progressed to a vegetative state within one month.

Differential diagnostic approach to MR imaging of white matter diseases

OBJECTIVES

The purpose of this article is to explore the magnetic resonance (MR) imaging features and the advanced MR techniques for differential diagnosis of white matter diseases of the brain.

RESULTS

Magnetic resonance imaging is exquisitely sensitive for detecting brain abnormalities. Particularly in the evaluation of white matter diseases, MR far outperforms any other imaging technique. Lesions that may be quite subtle or even invisible on computed tomography are often clearly seen on the MR scan. The MR signal characteristics of white matter lesions are similar and relatively nonspecific, but other distinguishing features are often present to assist in diagnosis, such as the pattern of the abnormality, location, signal intensities, and enhancement features. Advanced MR techniques, such as diffusion-weighted imaging, MR spectroscopy, and perfusion imaging, provide additional specificity to the diagnosis of demyelinating diseases.

CONCLUSIONS

Conventional MR images and advanced MR techniques are very helpful in distinguishing various types of white matter disease, for assessing disease burden, and for separating acute and chronic lesions.

Osmotic Demyelination Syndrome in End-Stage Renal Disease After Recent Hemodialysis:MRI of the Brain

OBJECTIVE

Osmotic demyelination syndrome has been reported in patients with end-stage renal disease, but the specific MRI findings in this patient group have not been documented in detail. Our aims were to present the brain MRI findings during an episode after hemodialysis and at follow-up, and to identify possible factors that may contribute to lesion development.

MATERIALS AND METHODS

Seventeen patients with osmotic demyelination syndrome who had undergone hemodialysis at least once and had brain MRI examinations were retrospectively reviewed. Neurologic and MRI examinations were performed during a clinical episode. Serum levels of sodium, creatinine, blood urea nitrogen, and glucose were assessed, and serum osmolality and the ratio of blood urea nitrogen to creatinine (BUN:Cr) were calculated. Follow-up MRI was performed in nine cases. Laboratory and imaging findings were evaluated.

RESULTS

An altered level of consciousness and convulsions were the most common neurologic symptoms. The pons was involved in 11 patients (65%) and extrapontine sites in 12 (71%). Four patients had dysequilibrium syndrome. Follow-up MRI showed complete resolution in six patients and lesion reduction in three within a short time. The most common biochemical changes at the time of MRI were hyponatremia and low BUN:Cr in the blood. Only one patient showed rapid correction of hyponatremia and a rapid change in osmolality during the acute stage.

CONCLUSION

In patients who develop osmotic demyelination syndrome after hemodialysis, the lesions may involve the pons or the pons and extrapontine sites. Most lesions that were followed up resolved rapidly and almost completely, favoring transient edema rather than demyelination. Blood chemistries suggested underlying changes in osmolality, particularly as a result of urea shift from the extracellular fluid.

Functional MRI study of semantic and phonological language processing in bilingual subjects: preliminary findings

The objective of the study was to explore differences in regional fMRI activation topography and lateralization between semantic and phonological tasks performed in English and Spanish in bilingual individuals. Eight bilingual (primary Spanish and secondary English-speaking) individuals performed fMRI noun-verb association and rhyming tasks in both Spanish and English. Functional dataset analysis within Statistical Parametric Mapping (SPM99) with overlay on T1-weighted anatomic images was performed. Significantly higher laterality indices were noted in the semantic tasks as compared with the phonological tasks in the anterior regions of interest comprising the frontal and superior temporal lobes. A task subtraction analysis demonstrated right hemispheric (inferior frontal gyrus and supramarginal gyrus) foci of significantly increased activation in the combined language phonological tasks compared to the combined language semantic tasks; similarly prominent right hemispheric activation was seen in the English phonological-English semantic subtraction, but the analogous Spanish task subtraction revealed no task-related differences. This divergence in activation topography between semantic and phonological tasks performed in the nonnative language, but not in the primary language, suggests that neural networks utilized for phonological and semantic language processing in the nonnative language may not be as similar as those in the primary language.