Time again for #NeuromuscularQandA? RT. #neurology #medtwitter#MedEd #medstudent#neurologyresident Join me in discussing/learning/educating with #passion and #humor@WNGtweets @MonicaDhakar @MadSattinJ @NinaRiggins @AaronLBerkowitz @RachelSalasMD
@Tracey1milligan @DxRxEdu
@Tracey1milligan @DxRxEdu
Q: Doc, doc. The limb girdle muscular dystrophies (LGMDs) are giving me a headache. Too many, too many, can’t you simplify them pretty please?
A: Your wish is my command. Let’s think about common presentations. Are there early contractures? Is there calf hypertrophy? Is there calf atrophy? Is there cardiomyopathy? Is there scapular winging? Is there facial weakness?
Q: Alrighty then. This Spanish lady in her 20s comes in with scapular winging and calf atrophy. No cardiomyopathy.
A: Calpainopathy is common especially in Mediterranean ethnicity and presents in with scapular winging. Of course have in the back of your mind other inherited causes of scapular winging - FSHD, sarcoglycanopathy.
Q: This Danish woman in her 20s comes in with calf hypertrophy and cardiac and respiratory failure.
A: Early cardiac and respiratory failure and calf hypertrophy in a young person of Northern European ancestry occurs in FKRP mutations.
Q: This teenager presents with medial calf atrophy. No cardiomyopathy.
A: That’s typical for dysferlinopathy or ano5 mutation.
Q: How about a young boy with calf hypertrophy? With cardiomyopathy.
A: That’s Duchenne’s or Becker’s.
Q: What about early contractures of the elbows, neck, knees, ankles?
A: If there’s cardiomyopathy, think Emerin Dreifuss muscular Dystrophy - that’s emerin, laminA/C, FHL1 mutations. If no cardiomyopathy, think Col6 mutations - Ullrich or Bethlam myopathy. These patients with Col6 mutations have early contractures and also laxity of finger joints.
Q: What about early foot drop?
A: Think about the myofibrillar myopathies - myotillin, desmin, filamin C, BAG3, ZASP, are some genes affected - those may also present with cardiomyopathy. GNE myopathy, Udd (titinopathy) and Laing distal myopathy (MYH7) are also considerations.
Q: How about late onset finger extensor weakness?
A: Typical for TIA mutations in Finnish/Swedish population - that’s Welander distal myopathy.
Q: What about muscular dystrophies with cardiomyopathy?
A: Let’s recap - think EDMD, FKRP mutation, Duchennes and Becker’s, sarcoglycanopathy, myofibrillar myopathy, Laing myopathy. These patients may have sudden cardiac death so it’s important to consider ICD.
Q: Asymmetrical facial weakness?
A: Think FSHD.
Q: Alrighty doc, now if you got an inkling then how would you investigate?
A: So we be new school. Genetic testing based on phenotype, then muscle biopsy with immunohistochemistry and western blot.
Q: Any treatment? Precision medicine perchance?
A: Only conservative at this time, I’m afraid. Low impact exercise training like swimming and cycling, avoid eccentric muscle contractions, maintain function. That’s all the bare bones for now, neuromuscular out.
