Medical Image of the Week: Osmotic Demyelination

Figure 1. MRI of the brain with FLAIR hyperintensity within the pons (see arrow), no stroke or watershed infarction.

A 59 year-old woman with past medical history of diabetes mellitus type II and end stage renal disease (ESRD) on hemodialysis (HD) presented with a right ankle fracture. She missed two days of HD. Fifteen minutes into HD, she became confused, hypotensive, bradycardic and then unresponsive with generalized body stiffness for approximately one minute. She never lost her pulse. Her vital signs returned to normal spontaneously after this episode. Patient was intubated for airway protection because she was obtunded.

On examination, while she was off sedation, her eyes were open but she did not track or follow commands. She had a positive cough, gag and corneal reflex but oculocephalic reflex was absent with dysconjugate gaze. She had intact brainstem reflexes but absence of deep tendon reflexes. She had no movements of her upper extremities and did not withdraw to painful stimulus. MRI of the brain was obtained to rule out acute stroke and showed FLAIR hyperintensity within the pons, no stroke or watershed infarction (Figure 1). Laboratory showed no acute changes of sodium levels or glucose level.

After 7 days of hospitalization, she started to track with her eyes and follows commands. She was extubated on day 15 of hospital stay and was discharged to a rehabilitation center after a total of 25 days of hospital stay. She was awake, alert and oriented to time, place, and person and able to talk and move all four of her extremities.

The rapid deterioration of mental status with acute neurological changes in this case is typical for osmotic demyelination syndrome (ODS). The exact mechanism behind the demyelination remains not well understood but involves the inability of brain cells to respond to rapid changes in osmolality, and hence destruction of myelin and neurons. It can also occur in chronically debilitated patients without osmolality shift and ESRD may be a risk factor (1,2). MRI images may show large symmetrical lesions in the basis pontis, usually sparing the ventral pons, or there may be smaller “butterfly” or trident-shaped lesions in the base of the pons. The initial MRI images may reveal nothing abnormal especially in the acute phase (3).

ODS should be considered in ESRD patients who present with any neurological symptoms, unexplained behavioral disorder or neurologic signs related to the pons or brainstem region. ODS secondary to dialysis has favorable prognosis.

Jennifer J. Huang, DO¹

Judy Dawod, MD²

¹Sarver Heart Center and ²Neurology Department

University of Arizona

Tucson, AZ USA

References

1. Miller MG, Baker HL, Okazaki H, Whistant J. Central pontine myelinolysis and its imitators: MR findings. Radiology. 1988;168:795-802. [CrossRef] [PubMed]
2. Tarhan NC, Agildere AM, Benli US, Ozdemir FN, Aytekin C, Can U. Osmotic demyelination syndrome in end-stage renal disease after recent hemodialysis: MRI of the brain. AJR Am J Roentgenol. 2004 Mar;182(3):809-16. [CrossRef] [PubMed]
3. Moriwaka F, Tashiro K, Maruo Y, Nomura M. Hamada K, Kashiwaba. MR imaging of pontine and extrapontine myeliolysis. J. Computer Assist. Tomogr. 1988;12(3):446-9. [CrossRef] [PubMed] 

Cite as: Huang JJ, Dawod J. Medical image of the week: osmotic demyelination. Southwest J Pulm Crit Care. 2016;13(6):303-4. doi: https://doi.org/10.13175/swjpcc111-16 PDF

December 2016 Imaging Case of the Month

Eric A. Jensen, MD

Michael B. Gotway, MD 

Department of Radiology

Mayo Clinic Arizona

Scottsdale, AZ USA

Imaging Case of the Month CME Information  

Members of the Arizona, New Mexico, Colorado and California Thoracic Societies and the Mayo Clinic are able to receive  0.25 AMA PRA Category 1 Credits™. Completion of an evaluation form is required to receive credit and a link is provided on the last panel of the activity.

0.25 AMA PRA Category 1 Credit(s)™

Estimated time to complete this activity: 0.25 hours

Lead Author(s): Eric A. Jensen, MD. All Faculty, CME Planning Committee Members, and the CME Office Reviewers have disclosed that they do not have any relevant financial relationships with commercial interests that would constitute a conflict of interest concerning this CME activity. 

Learning Objectives:
As a result of this activity I will be better able to:    

1. Correctly interpret and identify clinical practices supported by the highest quality available evidence.
2. Will be better able to establsh the optimal evaluation leading to a correct diagnosis for patients with pulmonary, critical care and sleep disorders.
3. Will improve the translation of the most current clinical information into the delivery of high quality care for patients.
4. Will integrate new treatment options in discussing available treatment alternatives for patients with pulmonary, critical care and sleep related disorders.

Learning Format: Case-based, interactive online course, including mandatory assessment questions (number of questions varies by case). Please also read the Technical Requirements.

CME Sponsor: University of Arizona College of Medicine at the Arizona Health Sciences Center.

Current Approval Period: January 1, 2015-December 31, 2016

Clinical History: A 47-year-old woman presented for medical evaluation prior to trans-sphenoid hypophysectomy for pituitary adenoma for Cushing syndrome. The patient had an extensive past medical history, including kidney minimal change disease treated with corticosteroids between 5-7 years previously (no longer on corticosteroid therapy), type II diabetes mellitus, focal segmental glomeruloscleroosis on renal biopsy, morbid obesity, gout, obstructive sleep apnea on continuous positive airway pressure (CPAP) supplemented with oxygen for the previous 8 years, hypertension, and recent-onset atrial fibrillation, as well as a history of several pneumonias, perhaps related to chronic immunosuppression. Her past surgical history included bilateral partial knee replacement, lower extremity vein ablation, and breast reduction. Her medication list was extensive, including allopurinol, anti-hypertensives, anti-depressants, colchicine, oxygen, and Tacrolimus, among others, including over-the-counter medications.

Laboratory data, include white blood cell count, coagulation profile, and serum chemistries were within normal limits. Oxygen saturation on room air was 95%.

Frontal and lateral chest radiographs (Figure 1) were performed. A previous chest radiograph performed 2 years earlier is presented for comparison (Figure 2).

Figure 1. Frontal (A) and lateral (B) chest radiography.

Figure 2.  Frontal chest radiography performed 2 years prior to presentation.

Which of the following statements regarding the chest radiograph is most accurate? (Click on the correct answer to proceed to the second of seven pages)

1. Frontal and lateral chest radiography appears normal
2. Frontal and lateral chest radiography shows a mass projected over the right paratracheal region
3. Frontal and lateral chest radiography shows asymmetric hyperlucency affecting the right thorax
4. Frontal and lateral chest radiography shows basal reticulation suggesting possible fibrotic disease
5. Frontal and lateral chest radiography shows cardiomegaly only, but is unchanged from prior

Cite as: Jensen EA, Gotway MB. December 2016 imaging case of the month. Southwest J Pulm Crit Care. 2016;13(6):290-301. doi: https://doi.org/10.13175/swjpcc135-16 PDF