IMAGES IN CLINICAL MEDICINE. Central Pontine Myelinolysis

Locked-in syndrome after central pontine myelinolysis, an outstanding outcome of two patients

OBJECTIVE

Central pontine myelinolysis (CPM) is a rare demyelinating disease that affects the pons and which can cause extreme disabilities such as locked-in syndrome (LIS) in the initial phase. The aim of the study was to describe the evolution over a 12-month period of two patients with CPM causing an initial LIS.

METHOD

We retrospectively report the unexpected clinical outcome of these two patients in relation with the anatomical damages documented by brain MRI, associated with diffusion tensor imaging and reconstruction of corticospinal tracts in tractography. The following clinical parameters systematically assessed at 3, 6, 9, and 12 months: muscle testing on 12 key muscles (Medical Research Council), prehension metrics (box and block test and purdue pegboard), and independence for acts of daily living (functional independence measure).

RESULTS

Both patients showed a progressive recovery beginning between 2 and 3 months after the onset of symptoms, leading to almost complete autonomy at 12 months (FIM > 110), with motor strength greater than 4/5 in all joint segments (MRC > 50/60). On brain MRI with tractography, CST appeared partially preserved at pons level.

INTERPRETATION

The possibility of a near-complete functional recovery at 12 months is important to consider given the ethical issues at stake and the discussions about limiting care that may take place initially. It seems to be the consequence of reversible myelin damage combined with partially preserved neurons. Development of collateral pathways or resolution of conduction block may explain this recovery. MRI comprising DTI and tractography could play a key role in the prognosis of motor recovery.

Possible Option for Treatment of Severe Congestive Heart Failure Under Mechanical Ventilation Using Tolvaptan via Nasogastric Tube: A Single-Center Analysis

Background: The oral vasopressin-2 receptor antagonist tolvaptan causes aquaresis, and its effect on heart failure is proven. However, it is not recommended in patients who are unable to appropriately respond to thirst because of possible severe hypernatremia. Aim: To assess the safety and efficacy of tolvaptan treatment via nasogastric tube in patients who are unable to respond to thirst by fluid ingestion. Methods: We analyzed 70 consecutive patients with severe congestive heart failure (CHF) who were resistant to loop diuretics and treated with tolvaptan. From the 70 patients, 12 required endotracheal intubation under sedation (Group Tube; GT) and 58 did not (Group Oral; GO). We administered tolvaptan orally in GO; however, in GT, we had to administer tolvaptan via nasogastric tube to achieve pulmonary decongestion quickly. In GT, serum sodium level was monitored closely, and intravenous fluid infusion volume was controlled in the intensive care unit (ICU). Outcomes, including safety and efficacy parameters, were evaluated. Results: In both groups, tolvaptan treatment did not develop a significant rise in serum sodium level compared with baseline, and the incidence of worsening renal failure was comparable, despite greater net fluid loss and higher doses of loop diuretics used in patients of GT compared to GO. In GT, all patients achieved pulmonary decongestion and were weaned from mechanical ventilation. Conclusions: In sedated patients with severe CHF who are unable to respond to thirst by fluid ingestion, tolvaptan can be used without clinically significant hypernatremia under close monitoring in the ICU.

Occult central pontine myelinolysis post liver transplant: A consequence of pre-transplant hyponatremia

Rapid overcorrection of chronic hyponatremia can lead to osmotic demyelination syndrome or central pontine myelinolysis (CPM), a diagnosis often triggered by observing the characteristics of neurological abnormalities developed as a result of CPM. However, anyone with chronic hyponatremia and overcorrection of serum sodium is at risk of physiological CPM despite the lack of clinical symptoms. We report an adult patient who presented as post-op delirium, had incidental finding of CPM by magnetic resonance imaging (MRI) of the head after a liver transplant. Despite his non-typical presentation, the patient had the typical risk factors of CPM such as chronic hyponatremia, rapid overcorrection of serum sodium and cirrhosis undergoing a transplant. As hyponatremia and neurological disorder such encephalopathy simultaneously affect patients with cirrhosis, CPM may be more common than once thought in the chronic liver disease population and inappropriate hyponatremia management has important medical consequences that can go unnoticed.

Pontine Neoplasm or Myelinolysis Despite Normal Sodium Levels

An elderly woman was transferred for biopsy of a pontine lesion. Her condition, including gait disturbances, truncal ataxia, and dysarthria-presumed to be due to severe alcohol abuse-had deteriorated during treatment of ambulatory-acquired pneumonia. No electrolyte abnormalities were noted during hospitalization. However, the neuroimaging findings were in line with central pontine myelinolysis, typically sparing the peripheral pontine fibers. Although extremely rare, pontine myelinolysis can occur in the presence of normal electrolyte levels. Thus, imaging findings should not be misinterpreted as pontine neoplasms, and patients should not undergo stereotactic biopsy-a procedure that could result in disastrous morbidity.

Osmotic Demyelination Syndrome in a Patient with Hypokalemia but No Hyponatremia

Osmotic demyelination syndrome (ODS) is characterized by loss of myelin in various parts of the central nervous system. It is mainly caused by a rapid correction of hyponatremia, although other factors that may cause rapid rise in serum osmolality can also be associated with its development. Its prognosis is poor and the recovery rate is unknown. The authors report a rare case of a patient with multiple risk factors for ODS, without hyponatremia, who developed ODS and surprisingly recovered. This case report highlights the importance of recognizing risk factors for the development of ODS, even if the main one is not present.

Hyponatremia in the elderly: challenges and solutions

Decreased serum sodium concentration is a rather frequent electrolyte disorder in the elderly population because of the presence of factors contributing to increased antidiuretic hormone, the frequent prescription of drugs associated with hyponatremia and also because of other mechanisms such as the “tea and toast” syndrome. The aim of this review is to present certain challenges in the evaluation and treatment of hyponatremia in the elderly population and provide practical solutions. Hyponatremia in elderly subjects is mainly caused by drugs (more frequently thiazides and antidepressants), the syndrome of inappropriate antidiuretic hormone secretion (SIAD) or endocrinopathies; however, hyponatremia is multifactorial in a significant proportion of patients. Special attention is needed in the elderly population to exclude endocrinopathies as a cause of hyponatremia before establishing the diagnosis of SIAD, which then requires a stepped diagnostic approach to reveal its underlying cause. The treatment of hyponatremia depends on the type of hyponatremia. Special attention is also needed to correct serum sodium levels at the appropriate rate, especially in chronic hyponatremia, in order to avoid the osmotic demyelination syndrome. In conclusion, both the evaluation and the treatment of hyponatremia pose many challenges in the elderly population.