1. Case Study 7 Craig Horbinski, M.D, Ph.D.

2. History 63-year-old male with generalized progressive weakness especially in his lower extremities with difficulty ambulating. The patient states that he was ill for approximately three weeks prior to this admission, with 20 pound weight loss and anorexia during the past two to three weeks. He denies any pain. He has no neuropathy or paresthesias that he admits to. He denies similar symptoms in the past. He states that the weakness seems to be symmetrical. He has no known history of recent infection and he states that his upper extremity weakness is not nearly as severe as lower extremity weakness. He states that he had one episode of night sweats prior to his admission. During his present hospitalization, he has had intermittent temperature elevations as high as 38.9. No medications on a regular basis except for intermittent inhaler for COPD.

3. Question 1 What are the main test results you want to make sure was done before proceeding (this goes for any neuromuscular pathology case)?

4. Answer Electromyograph (EMG) and nerve conduction studies. Creatine kinase might also be helpful, particularly if the clinical impression is of a predominantly muscle (rather than nerve) etiology.

5. Question 2 EMG and nerve conduction studies revealed a significant polyneuropathy. A nerve biopsy was requested. What is the #1 most popular nerve for biopsy? Are there any long-term deficits as a result of biopsy?

6. Answer The sural nerve in the leg because it is easily accessed. The only permanent deficit is numbness in the posterior leg and lateral foot.

7. Question 3 Describe what you see. Click here to view slide.here

8. Answer There are 5 fascicles within the sural nerve cross section. There is no vasculitis or substantial perivascular inflammation.

9. Question 4 What do you see in this toluidine blue plastic section? (Don’t feel bad if you aren’t sure, this is tough.) Click here to view slide.here

10. Answer Patchy loss of myelinated axons, occasional myelin ovoids (acutely degenerating axons), and possible vesicular demyelination of some of the axons.

11. Question 5 What additional histologic preparation might help us confirm whether there is true demyelination?

12. Answer Teased nerve fibers

13. Question 6 What is the predominant finding in this teased nerve fiber preparation? Click here to view slide.here

14. Answer Demyelination and remyelination. Note the abrupt and multifocal loss of strongly osmiophilic myelin on many of the teased axons (demyelination) and weak osmiophilic thin myelination on many axons (remyelination).

15. Question 7 Given the patient’s history and the nerve biopsy results, what is the most likely diagnosis (i.e. what’s the first demyelinating disorder that comes to mind)?

16. Answer Guillain-Barré