Alexa is a 25 year old graduate student who arranged an urgentappointment with her primary care provider because her ‘vision isblurry’ in her left eye. She states that two days ago her visionchanged. She compares her visual field to looking through a foggedup window. Her provider interprets this to mean she has a decreasein contrast and brightness. Eye examination reveals a markedreduction of visual acuity of her left eye. A swinging flashlighttest reveals an afferent pupillary defect (Marcus Gunn pupil) ofher left eye (i.e., paradoxical papillary dilatation in response toincreased light). Visual acuity and pupillary responses in herright eye are normal. Assessment of the retina and retinal vesselsin both eyes is normal. Additional findings show patchy butconsistent hypoesthesia (decreased feeling) to pin and light touchover her right limbs. On questioning, Alexia states that sheexperienced a self-limiting episode of numbness and tingling a fewmonths ago. She also states that she has been experiencing fatigue,particularly at the end of the day. She denies depression, and herfamily history is unrevealing. The remainder of the physical examin normal. Alexa is referred to an ophthalmologist who diagnosesoptic neuritis (inflammation of the optic nerve). She beginscorticosteroid treatment, and is referred to a neurologist whoschedules a cranial MRI with gadolinium. The MRI reveals thepresence of multiple deep white matter lesions scattered throughoutthe brain, suggesting multiple sclerosis. A subsequent lumbarpuncture and analysis of Alexia’s cerebral spinal fluid (CSF) isconsistent with possible multiple sclerosis. Further work-up rulesout other possible causes. Ultimately, the neurologist diagnosesAlexia with relapsing-remitting multiple sclerosis.
- Multiple sclerosis is an autoimmune disease, in which theimmune system reacts to self-antigen (i.e., loss ofself-tolerance). What is self-tolerance? Describe the processes(central and peripheral) that allow the immune system to developself-tolerance, and how self-tolerance might be compromised.
