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CASE 30


Sam is a 44-year-old, previously healthy man who has been suffering from blurred vision and intermittent numbness in the left leg and right arm for 7 months. Over the past 4 weeks he has been incontinent of urine twice. His male companion is convinced he has a brain tumor or some other sinister disorder. All of his routine blood work is normal, as is his urinalysis, antinuclear antibody (ANA) titers, and complement C3 levels. His last HIV test (6 years ago) was negative, and he has lived with his current partner for more than 5 years. A repeat HIV test is negative.



QUESTIONS FOR GROUP DISCUSSION



1. Review the types of infection that cause chronic infection of the central nervous system (CNS) or encephalitis. What single piece of evidence would reduce the likelihood that Sam has an infection or a multifocal brain tumor?

2. Systemic lupus erythematosus (SLE) cerebritis might present in this manner. Review Case 18 and explain why this disorder might lead to cerebritis. How would you rule out SLE?

3. What disorders are associated with urine incontinence in males?

4. Multiple sclerosis (MS) is a waxing/waning disease that manifests at different sites, and so this disorder should be the focus of investigation. Explain how magnetic resonance imaging (MRI) and magnetic resonance spectroscopy could help in the diagnosis of MS. What would a biopsy show?

5. Oral feeding of antigen (bovine myelin) has been used as a therapeutic intervention in some clinical trials of patients with MS. Explain the rationale for this approach.

6. Explain why chemokine antagonists are being considered as therapeutic agents in MS. (Hint: review Case 23.)

7. Explain tolerance induction and how this might be achieved in patients with MS.

8. Discuss the pros/cons of targeting specific Vβ T cells as therapy for patients with MS.

9. What antibody isotype(s) is (are) found in the CSF of patients with MS? In the serum?

10. Review the steps of delayed-type hypersensitivity (DTH). Note, in particular, the role of interferon gamma (IFNγ). Explain why IFNγ would exacerbate MS.


RECOMMENDED APPROACH



Implications/Analysis of Family History


Although we are not provided with any family history, there is a genetic susceptibility for MS. However, risk for this autoimmune disorder involves more than gene inheritance. For example, living in a temperate zone (both north and south of the equator) has been shown to be a risk factor for MS. However, even within the same temperate climate the prevalence of MS is higher in whites.



Implications/Analysis of Clinical History


The altered vision and intermittent numbness in Sam’s arm and leg are indicative of multiple, distinct sites in the nervous system and lead one to consider a multifocal brain tumor. However, the fact that the altered vision and changes in sensation are also occurring at different points in time suggests we are dealing with a waxing/waning disease entity, which is not characteristic of tumors but should make you think of other causes, especially immunologic ones.



Infection


Toxoplasmosis (and other chronic CNS infections [e.g., Cryptococcus neoformans]) could present as a multifocal disease. One might expect viral encephalopathies (e.g., herpes simplex virus, also referred to as human herpesvirus 1) to present more acutely than over months. Again, infection is unlikely to be intermittent. Immune complex deposition disease (lupus cerebritis) such as occurs in systemic lupus erythematosus (SLE), is a possibility because it is associated with intermittent inflammation in the CNS (see Case 31).



Urine Incontinence


The urine incontinence is puzzling in that Sam does not appear to have an infection and is not taking medications known to affect continence. In men, diabetic neuropathy, MS, and Parkinson’s disease are known to be causes of incontinence. There is no evidence of diabetes or Parkinson’s disease, but the symptoms of blurred vision and changes in sensation are consistent with a diagnosis of MS.

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Jun 18, 2016 | Posted by in IMMUNOLOGY | Comments Off on 30

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