A 70 year old man presents with difficulty moving. When you ask further, he says he noticed a slow progressive onset of weakness. He has trouble getting up from a chair or climbing stairs. He gets muscle fatigue, cramping, stiffness, and aching. On review of systems, he notes dry mouth, blurred vision, constipation, and erectile dysfunction.
Challenge: Here, you can suggest two associated diagnoses. What are they?
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On exam, you note a bit of ptosis but sustained upgaze leads to excessive eyelid elevation. Neuro exam shows symmetric muscle weakness in the proximal but not distal muscles. There is no muscle atrophy. You get no deep tendon reflexes. A routine CXR shows a lung nodule so a follow-up CT was taken.
Challenge: Here, you can suggest two associated diagnoses. What are they?
The muscle-associated symptoms and anticholinergic effects suggest Myasthenia Gravis. It is associated with thymoma. The lung nodule shown could be an invasive form of the thymoma
ReplyDeleteLambert eaton
ReplyDeleteBoth MG and Lambert-Eaton are on the DDX; here, the exam (sustained upgaze leads to excessive eyelid elevation) is more consistent with L-E.
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Two in One
This is Lambert-Eaton myasthenic syndrome which is strongly associated with small cell lung cancer. The pathogenesis involves paraneoplastic autoantibodies directed towards the voltage-gated calcium channel, clinically manifesting as proximal weakness and autonomic dysfunction. The differential diagnosis includes myathenia gravis. The CT supports the likelihood of a small cell lung cancer.
Sources: UpToDate; Wikipedia.
ummm.. i agree that both are valid differentials.. though dont you think 77 is a little late for myaesthenia to present?
ReplyDeleteyeah...so lambert eaton is much higher on the ddx
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