Centropontine myelinolysis after correction of hyponatremia: role of associated hypokalemia

A novel association of osmotic demyelination in Sjögren's syndrome prompts revisiting role of aquaporins in CNS demyelinating diseases: A literature review

BACKGROUND

Primary Sjögren's syndrome (SS) is a chronic systemic autoimmune disease with varied neurological manifestations. SS is associated with anti-aquaporin-4 antibody (AQP4-IgG)-positive neuromyelitis optica spectrum disorder (NMOSD), a demyelinating autoimmune disorder of the central nervous system (CNS). Intriguingly, there are reports of osmotic demyelinating syndrome (ODS), a supposedly non-inflammatory disorder, in the context of SS and renal tubular acidosis (RTA), both of which are not yet established risk factors for ODS.

METHODS

A literature search was undertaken to identify case reports of ODS in patients with SS. Details of the clinical and laboratory features of these patients were compiled. Additionally, we searched for NMOSD in patients with SS. We looked for co-existing RTA in patients with SS-ODS as well as SS-NMOSD. We also screened for reports of ODS in RTA without underlying SS.

RESULTS & DISCUSSION

We identified 15 patients (all women, median age 40 years) with ODS in SS, and all of these patients had comorbid RTA. There were only three reported cases of ODS in RTA without underlying SS. We identified a total of 67 patients with SS-NMOSD, of whom only 3 (4.5%) had RTA. Hence, unlike NMOSD, the development of ODS in SS requires a prolonged osmotic or electrolyte abnormality caused by the comorbid RTA. The 15 patients with ODS and SS -RTA, showed heterogeneous clinical manifestations and outcomes. The most common symptom was quadriparesis, seen in 14 of the 15 patients. Eleven of the 15 patients had one of the following features, either alone or in combination: worsening of the sensorium, extensor plantar response, dysphagia/dysarthria, and facial palsy. The latter four manifestations were present at the onset in 7 patients and later in the course of the illness in the remaining 4 patients. Ocular palsy was seen in only four of the 15 patients and was a late manifestation. One patient who had extensive long-segment myelitis and subsequent ODS died, but most patients recovered without significant sequelae. None had hyponatremia, while all patients had hypokalemia and/or hypernatremia. Hypokalemia causing nephrogenic diabetes insipidus (NDI) followed by rapid rise in sodium and the resultant osmotic stress could potentially explain the occurrence of ODS in SS-RTA. Aquaporin (AQP) in astrocytes is implicated in ODS, and renal AQP is downregulated in NDI. Antibodies against AQPs are present in some patients with SS. Defective AQP is therefore a common link underlying all the connected diseases, namely SS, NDI, and ODS, raising the possibility of immune-mediated AQP dysfunction in the pathogenesis.

CONCLUSION

The hitherto unreported association between SS-RTA and ODS may implicate SS and/or RTA in the development of ODS. In the setting of SS-RTA, ODS must be suspected when a patient with flaccid quadriparesis does not respond to the correction of potassium or develops additional neurological features along with a rise in sodium. Defective functions of AQPs may be a possible mechanism linking demyelinating CNS lesions, SS, and RTA. Studies evaluating AQP functions and serum antibodies against AQPs in these conditions are warranted.

A Survey of Hospital Pharmacy Guidelines for the Administration of 3% Sodium Chloride in Children

Three percent sodium chloride (3% NaCl) is the treatment of choice for symptomatic hyponatremia. A barrier to the use of 3% NaCl is the perceived risk of both local infusion reactions and neurologic complications from overcorrection. We examine whether children’s hospital pharmacies have policies or practice guidelines for the administration of 3% NaCl and whether these pharmacies have restrictions on the administration of 3% NaCl in terms of rate, route, volume and setting. An Internet survey was distributed to the pharmacy directors of 43 children’s hospitals participating in the Children’s Hospital Association (CHA) network. The response rate was 65% (28/43). Ninety-three percent (26/28) of pharmacy directors reported a restriction for the administration of 3% NaCl, with 57% restricting its use through a peripheral vein or in a non-intensive care unit setting, 68% restricting the rate of administration and 54% restricting the volume of administration. Seventy-one percent (20/28) reported having written policy or practice guidelines. Only 32% of hospital pharmacies allowed 3% NaCl to be administered through a peripheral IV in a non-intensive care unit setting. The majority of children’s hospital pharmacies have restrictions on the administration of 3% NaCl. These restrictions could prevent the timely administration of 3% NaCl in children with symptomatic hyponatremia.

An Unusual Cause of Bulbar Palsy in the Emergency Department

BACKGROUND

Osmotic demyelination syndrome commonly occurs after rapid correction of hyponatremia. But it has also been reported after graded correction of hyponatremia in the presence of other risk factors like chronic alcoholism, malnutrition, liver disease, and hypokalemia.

CASE REPORT

We report a case of a 67-year-old man who presented with dysphagia and nasal regurgitation and had features suggestive of bulbar palsy on neurological examination. He had spontaneous rapid correction of hyponatremia from a serum sodium level of 122 mEq/L to 132 mEq/L after discharge from our hospital. Neuroimaging was suggestive of extrapontine myelinolysis involving the basal ganglia. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: An emergency physician should be aware of this because osmotic demyelination syndrome should also be considered in the differential diagnosis of patients presenting with bulbar palsy to the emergency department.

Syndrome de démyélinisation osmotique compliquant la correction rapide d’une hyponatrémie sévère associée à une hypokaliémie

Le syndrome de démyélinisation osmotique correspond à une démyélinisation du centre de la protubérance ou d'autres parties du cerveau. Nous rapportons un cas de syndrome de démyélinisation osmotique chez une patiente âgée de 55 ans, connue hypertendue, suivie pour cervicarthrose étagée, hospitalisée pour coma non fébrile d'installation brutale compliquant un tableau de gastroentérite aigue. L'évolution a été marquée par l'aggravation neurologique avec confusion, aphasie, tétraplégie et aréflexie ostéotendineuse. Le diagnostic de myélinolyse centropontine et extrapontine a été confirmé par une imagerie par résonance magnétique cérébrale faite 20 jours après une première qui n’a pas montré d'anomalies spécifiques. La correction rapide de l'hyponatrémie était la cause principale de ce syndrome, sans négliger le rôle favorisant très probable de l'hypokaliémie associée. L'évolution de la myélinolyse centropontine (MCP) et myélinolyse extrapontine (MEP) est variable. Le traitement est principalement préventif basé sur la correction prudente des hyponatrémies sévères et des facteurs favorisants.

Osmotic Demyelination Syndrome - Evolution of Extrapontine Before Pontine Myelinolysis on Magnetic Resonance Imaging

Osmotic demyelination syndrome is a rare entity characterized by noninflammatory demyelination afflicting the central pons, basal ganglia, thalami, peripheral cortex, and hippocampi. Histopathologically, there is a destruction of myelin sheaths sparing the underlying neuronal axons due to the susceptibility of oligodendrocytes to rapid osmotic shifts often encountered in chronically debilitated patients. We present the temporal progression of signal abnormalities on sequential magnetic resonance imaging (MRI) scans in a middle-aged male initially presenting with altered mental status due to severe hyponatremia and subsequently developing rigidity, diagnosed as osmotic demyelination syndrome based on typical imaging findings and supportive laboratory parameters. This case demonstrates the importance of diffusion signal abnormalities as the first indicator of osmotic demyelination, evolution of extrapontine before pontine signal changes and the relative lack of correlation between patient's clinical profile and the extent of MRI signal abnormalities.

Risk Factors and Outcomes of Rapid Correction of Severe Hyponatremia

BACKGROUND AND OBJECTIVES

Rapid correction of severe hyponatremia can result in serious neurologic complications, including osmotic demyelination. Few data exist on incidence and risk factors of rapid correction or osmotic demyelination.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a retrospective cohort of 1490 patients admitted with serum sodium <120 mEq/L to seven hospitals in the Geisinger Health System from 2001 to 2017, we examined the incidence and risk factors of rapid correction and osmotic demyelination. Rapid correction was defined as serum sodium increase of >8 mEq/L at 24 hours. Osmotic demyelination was determined by manual chart review of all available brain magnetic resonance imaging reports.

RESULTS

Mean age was 66 years old (SD=15), 55% were women, and 67% had prior hyponatremia (last outpatient sodium <135 mEq/L). Median change in serum sodium at 24 hours was 6.8 mEq/L (interquartile range, 3.4-10.2), and 606 patients (41%) had rapid correction at 24 hours. Younger age, being a woman, schizophrenia, lower Charlson comorbidity index, lower presentation serum sodium, and urine sodium <30 mEq/L were associated with greater risk of rapid correction. Prior hyponatremia, outpatient aldosterone antagonist use, and treatment at an academic center were associated with lower risk of rapid correction. A total of 295 (20%) patients underwent brain magnetic resonance imaging on or after admission, with nine (0.6%) patients showing radiologic evidence of osmotic demyelination. Eight (0.5%) patients had incident osmotic demyelination, of whom five (63%) had beer potomania, five (63%) had hypokalemia, and seven (88%) had sodium increase >8 mEq/L over a 24-hour period before magnetic resonance imaging. Five patients with osmotic demyelination had apparent neurologic recovery.

CONCLUSIONS

Among patients presenting with severe hyponatremia, rapid correction occurred in 41%; nearly all patients with incident osmotic demyelination had a documented episode of rapid correction.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_06_05_CJASNPodcast_18_7_G.mp3.

Clinical Evolution of Central Pontine Myelinolysis in a Patient with Alcohol Withdrawal: A Blurred Clinical Horizon

Central pontine myelinolysis (CPM), a potentially fatal and debilitating neurological condition, was first described in 1959 in a study on alcoholic and malnourished patients. It is a condition most frequently related to rapid correction of hyponatremia. Chronic alcoholism associated CPM tends to be benign with a favorable prognosis compared to CPM secondary to rapid correction of hyponatremia. We describe a normonatremic, alcoholic patient who presented with CPM after a rapid rise in his sodium levels. Our case illustrates the fact that CPM can manifest even in patients who are normonatremic at baseline. Rapid rises in sodium levels should be promptly reversed before clinical symptoms manifest in patient with risk factors for CPM irrespective of their baseline sodium levels. Furthermore, clinical evolution of CPM can be difficult to discern from the natural course of alcohol withdrawal delirium, requiring astuteness and maintenance of a high degree of clinical suspicion on the part of the physician.

Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremia is a common electrolyte derangement in the setting of the intensive care unit. Life-threatening neurological complications may arise not only in case of a severe (<120 mmol/L) and acute fall of plasma sodium levels, but may also stem from overly rapid correction of hyponatremia. Additionally, even mild hyponatremia carries a poor short-term and long-term prognosis across a wide range of conditions. Its multifaceted and intricate physiopathology may seem deterring at first glance, yet a careful multi-step diagnostic approach may easily unravel the underlying mechanisms and enable physicians to adopt the adequate measures at the patient’s bedside. Unless hyponatremia is associated with obvious extracellular fluid volume increase such as in heart failure or cirrhosis, hypertonic saline therapy is the cornerstone of the therapeutic of profound or severely symptomatic hyponatremia. When overcorrection of hyponatremia occurs, recent data indicate that re-lowering of plasma sodium levels through the infusion of hypotonic fluids and the cautious use of desmopressin acetate represent a reasonable strategy. New therapeutic options have recently emerged, foremost among these being vaptans, but their use in the setting of the intensive care unit remains to be clarified.

Extra pontine osmotic demyelination syndrome

The osmotic demyelination syndrome (ODS) has been identified as a complication of the rapid correction of hyponatremia for decades. However, in recent years, a variety of other medical conditions have been associated with the development of ODS, independent of changes in serum sodium which cause a rapid changes in osmolality of the interstitial (extracellular) compartment of the brain leading to dehydration of energy-depleted cells with subsequent axonal damage that occurs in characteristic areas. Slow correction of the serum sodium concentration and additional administration of corticosteroids seems to be a major prevention step in ODS patients. In the current report we aimed to share a rare case which we observed in our hospital. A 65 year old female admitted as altered sensorium with history of vomiting, diarrhea was managed with intravenous fluids for 2 days at a peripheral health centre. Patient was referred to our centre with encephalopathy, evaluated and found to have hyponatremia and hypokalemia rest of biochemical parameters and septic profile were normal. Patient’s electrolyte disturbances were managed as per guidelines but encephalopathy persisted. Supportive treatment was continued and patient was discharged after 2 wks of stay in hospital after gaining full sensorium and neurological functions.

Central pontine myelinolysis: electrolytes and beyond

Central pontine myelinolysis (CPM), which is a component of the osmotic demyelination syndrome (ODS), is a frequent neurological complication that follows rapid correction of hyponatraemia. However, there are other predisposing risk factors (chronic alcoholism, hypokalaemia) that perpetuate the development of ODS. We report a case of a 39-year-old woman with a history of chronic alcoholism who presented to us with progressive neurological deficits (paraparesis, paresthesias). She was initially detected to have coexisting hypokalaemia which was eventually rectified with potassium supplementation. However, she continued to experience progressive worsening of her neurological symptoms despite adequate potassium supplementation. Therefore, a neurological opinion was sought for and she was diagnosed with CPM based on a background of chronic alcoholism and malnutrition; an MRI of the brain showed a hyperintense signal in the central pontine region. Following the diagnosis of CPM, she was rehabilitated with occupational and physiotherapy.

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.

Osmotic demyelination syndrome following slow correction of hyponatremia: Possible role of hypokalemia

A 47-year-old male presented with hyponatremia that was corrected slowly as per the recommended guidelines. The patient improved initially but went on to develop a quadriparesis with a locked-in state due to a central as well as extrapontine myelinolysis and subsequently succumbed to an intercurrent infective illness. The patient had associated hypokalemia. Hyponatremia can result in central pontine myelinolysis even when the electrolyte disorder is treated slowly, and the concomitant hypokalemia seems to play a contributory role in the pathogenesis of the neurological disorder.

Central pontine myelinolysis: historical and mechanistic considerations

Central pontine myelinolysis (CPM) is a demyelinating condition affecting not only the pontine base, but also involving other brain areas. It usually occurs on a background of chronic systemic illness, and is commonly observed in individuals with alcoholism, malnutrition and liver disease. Studies carried out 25-30 years ago established that the principal etiological factor was the rapid correction of hyponatremia resulting in osmotic stress. This article reviews progress achieved since that time on its pathogenesis, focusing on the role of organic osmolytes, the blood-brain, barrier, endothelial cells, myelinotoxic factors triggered by osmotic stress, and the role of various factors that predispose to the development of CPM. These advances show great promise in providing novel therapeutic options for the management of patients afflicted with CPM.

Central pontine myelinolysis secondary to hypokalaemic nephrogenic diabetes insipidus

Central pontine myelinolysis (CPM) has been described in alcoholic patients and in the aftermath of rapid correction of chronic hyponatraemia. We describe a case of CPM occurring secondary to nephrogenic diabetes insipidus (DI), which developed as a consequence of severe hypokalaemia. A 63-year-old man with alcohol dependence was admitted to hospital with severe pulmonary sepsis and type 1 respiratory failure. On admission, he had euvolaemic hyponatraemia of 127 mmol/L, consistent with a syndrome of inappropriate antidiuretic hormone secondary to his pneumonia. Following admission, his plasma potassium dropped from 3.2 to a nadir of 2.3 mmol/L. Mineralocorticoid excess, ectopic adrenocorticotrophic hormone production and other causes of hypokalaemia were excluded. The hypokalaemia provoked significant hypotonic polyuria and a slow rise in plasma sodium to 161 mmol/L over several days. Plasma glucose, calcium and creatinine were normal. The polyuria did not respond to desmopressin, and subsequent correction of his polyuria and hypernatraemia after normalization of plasma potassium confirmed the diagnosis of nephrogenic DI due to hypokalaemia. The patient remained obtunded, and the clinical suspicion of osmotic demyelination was confirmed on magnetic resonance imaging. The patient remained comatose and passed away 10 days later. This is the first reported case of nephrogenic DI resulting in the development of CPM, despite a relatively slow rise in plasma sodium of less than 12 mmol/L/24 h. Coexisting alcohol abuse, hypoxaemia and hypokalaemia may have contributed significantly to the development of CPM in this patient.