Central pontine myelinolysis secondary to hypokalaemic nephrogenic diabetes insipidus

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.

The cascade to a serendipitous discovery of lithium-induced nephrogenic diabetes insipidus

Lithium therapy is a common treatment for affective disorders and is widely regarded as a lifesaving drug. However, because its elimination is almost wholly unchanged via the kidneys, both acute and long-term adverse effects relating to toxicity may occur, including declining renal function and nephrogenic diabetes insipidus (DI). DI may be difficult to detect and is frequently preceded by dehydration and which, in our patient, was discovered by chance. We describe a case of an elderly woman on chronic lithium therapy for bipolar affective disorder who initially presented with dehydration from vomiting but possibly developed extra-pontine myelinolysis (EPM) after over-zealous correction of hyponatraemia. Steroids administered appeared to have prevented further progression but a persisting hyperosmolar state then alerted us to the presence of nephrogenic DI. Although both conditions were later successfully reversed with no obvious chronic sequelae, the recovery of the patient was protracted. Clinicians should be vigilant for complications of managing dehydration states in people prescribed with lithium.

Central pontine myelinolysis secondary to glycemic variability in type 1 diabetes: a case report and a systematic review of the literature

Central pontine myelinolysis (CPM) is a rare manifestation of osmotic demyelination syndrome (ODS) which involves the pons and causes significant morbidity and mortality. CPM usually occurs in the setting of rapid correction of severe chronic hyponatremia. A rare case of CPM due to hyperglycemia in a 27-year-old man with type 1 diabetes is reported. During the patient’s hospitalization, his plasma glucose level showed a wide variability ranging from 38 mg/dL to 530 mg/dL, while plasma sodium level was constantly normal. At computed tomography (CT) scans, areas of hypodensity with a hyperdense ring were identified in the anterior part of the pons. At magnetic resonance imaging (MRI) scan, pontine abnormalities compatible with CPM were observed. According to laboratory tests, we concluded that CPM resulted from rapid and wide shifts in osmolar gradient owing to variability in plasma glucose levels. While universally recognized in several clinical settings, CPM is rarely observed in diabetic patients. Our report supports the notion that hyperosmolarity per se plays a key role in the pathogenesis of CPM, which may occur independently of sodium abnormalities.

Osmotic Demyelination Syndrome following Correction of Hyponatremia by ≤10 mEq/L per Day

Background

Overly rapid correction of chronic hyponatremia may lead to osmotic demyelination syndrome. European guidelines recommend a correction to ≤10 mEq/L in 24 hours to prevent this complication. However, osmotic demyelination syndrome may occur despite adherence to these guidelines.

Methods

We searched the literature for reports of osmotic demyelination syndrome with rates of correction of hyponatremia ≤10 mEq/L in 24 hours. The reports were reviewed to identify specific risk factors for this complication.

Results

We identified 19 publications with a total of 21 patients that were included in our analysis. The mean age was 52 years, of which 67% were male. All of the patients had community-acquired chronic hyponatremia. Twelve patients had an initial serum sodium <115 mEq/L, of which seven had an initial serum sodium ≤105 mEq/L. Other risk factors identified included alcohol use disorder (n=11), hypokalemia (n=5), liver disease (n=6), and malnutrition (n=11). The maximum rate of correction in patients with serum sodium <115 mEq/L was at least 8 mEq/L in all but one patient. In contrast, correction was <8 mEq/L in all but two patients with serum sodium ≥115 mEq/L. Among the latter group, osmotic demyelination syndrome developed before hospital admission or was unrelated to hyponatremia overcorrection. Four patients died (19%), five had full recovery (24%), and nine (42%) had varying degrees of residual neurologic deficits.

Conclusion

Osmotic demyelination syndrome can occur in patients with chronic hyponatremia with a serum sodium <115 mEq/L, despite rates of serum sodium correction ≤10 mEq/L in 24 hours. In patients with severe hyponatremia and high-risk features, especially those with serum sodium <115 mEq/L, we recommend limiting serum sodium correction to <8 mEq/L. Thiamine supplementation is advisable for any patient with hyponatremia whose dietary intake has been poor.

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.

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.

Desmopressin to Prevent Rapid Sodium Correction in Severe Hyponatremia: A Systematic Review

BACKGROUND

Hyponatremia is common among inpatients and is associated with severe adverse outcomes such as osmotic demyelination syndrome. Current guidelines recommend serum sodium concentration correction targets of no more than 8 mEq/L per day in patients at high risk of osmotic demyelination syndrome. Desmopressin is recommended to control high rates of serum sodium concentration correction in severe hyponatremia. However, recommendations are based on limited data. The objective of this study is to review current strategies for DDAVP use in severe hyponatremia.

METHODS

Systematic literature search of 4 databases of peer-reviewed studies was performed and study quality was appraised.

RESULTS

The literature search identified 17 observational studies with 80 patients. We found 3 strategies for desmopressin administration in hyponatremia: 1) proactive, where desmopressin is administered early based on initial serum sodium concentration; 2) reactive, where desmopressin is administered based on changes in serum sodium concentration or urine output; 3) rescue, where desmopressin is administered after serum sodium correction targets are exceeded or when osmotic demyelination appears imminent. A proactive strategy of desmopressin administration with hypertonic saline was associated with lower incidence of exceeding serum sodium concentration correction targets, although this evidence is derived from a small case series.

CONCLUSIONS

Three distinct strategies for desmopressin administration are described in the literature. Limitations in study design and sample size prevent definitive conclusions about the optimal strategy for desmopressin administration to correct hyponatremia. There is a pressing need for better quality research to guide clinicians in managing severe hyponatremia.

Desmopression is an effective adjunct treatment for reversing excessive hyponatremia overcorrection

We report a case of a 50-year-old malnourished African American male with hiccups, nausea and vomiting who was brought to the Emergency Department after repeated seizures at home. Laboratory evaluations revealed sodium (Na⁺) 107 mmol/L, unmeasurably low potassium, chloride < 60 mmol/L, bicarbonate of 38 mmol/L and serum osmolality 217 mOsm/kg. Seizures were controlled with 3% saline IV. Once nausea was controlled with iv antiemetics, he developed large volume free water diuresis with 6 L of dilute urine in 8 h (urine osmolality 40-60 mOsm/kg) and serum sodium rapidly rose to 126 mmol/L in 12 h. Both intravenous desmopressin and 5% dextrose in water was given to achieve a concentrated urine and to temporarily reverse the acute rise of sodium, respectively. Serum Na⁺ was gradually re-corrected in 2-3 mmol/L daily increments from 118 mmol/L until 130 mmol/L. Hypokalemia was slowly corrected with resultant auto-correction of metabolic alkalosis. The patient discharged home with no neurologic sequaele on the 11^th hospital day. In euvolemic hyponatremic patients, controlling nausea may contribute to unpredictable free water diuresis. The addition of an antidiuretic hormone analog, such as desmopressin can limit urine output and prevent an unpredictable rise of the serum sodium.

Clinical semiology and neuroradiologic correlates of acute hypernatremic osmotic challenge in adults: a literature review

The complex interplay between hypernatremic osmotic disturbances and cerebral lesions is yet to be clarified. In this review, we discuss, on the basis of the reported data of hypernatremic CNS challenge in the adult population, the clinical and radiologic features of the condition. Our search captured 20 case studies and 1 case series with 30 patients in total who acquired acute hypernatremia due to different etiologies and developed CNS lesions. We explored the associations between premorbid conditions, clinical presentation, hypernatremic state, correction rate, and radiologic appearance, including the localization of brain lesions and the outcomes. The results revealed that altered mental status was the most commonly reported symptom and osmotic demyelination syndrome in the form of extrapontine myelinolysis was the prevailing radiologic pattern. Finally, we contrasted, when appropriate, clinical and experimental data related to hypernatremic and hyponatremic osmotic insults to aid the understanding of the pathophysiology of CNS osmotic brain injury.

Syndrome of inappropriate antidiuretic hormone secretion: Revisiting a classical endocrine disorder

Hyponatremia occurs in about 30% of hospitalized patients and syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common cause of hyponatremia. SIADH should be differentiated from other causes of hyponatremia like diuretic therapy, hypothyroidism and hypocortisolism. Where possible, all attempts should be made to identify and rectify the cause of SIADH. The main problem in SIADH is fluid excess, and hyponatremia is dilutional in nature. Fluid restriction is the main stay in the treatment of SIADH; however, cerebral salt wasting should be excluded in the clinical setting of brain surgeries, subarachnoid hemorrhage, etc. Fluid restriction in cerebral salt wasting can be hazardous. Sodium correction in chronic hyponatremia (onset >48 hours) should be done slowly to avoid deleterious effects in brain.