@DrNeuro123 @AaronLBerkowitz In muscular dystrophies with leg involvement, the calf muscles and leg muscles are affected first. Ext dig profundus (EDB) overcompensates for the foot drop caused by atrophy of the tibialis anterior (TA) so it hypertrophies as it tries desperately to lift the toes. (1)
@DrNeuro123 @AaronLBerkowitz In generalized neuropathies like CMT, the nerve dies backwards so by the time the nerve to the TA is affected, the nerve to the EDB has already been affected, so the EDB is atrophied just like the TA. So it’s a useful way to determine whether it’s a nerve or muscle problem. (2)
@DrNeuro123 @AaronLBerkowitz Peroneal neuropathies and L5/S1 radiculopathies are common causes of foot drop. When you examine foot drop, check foot inversion because that’s done by the tibialis posterior which is innervated by the tibial nerve. If that’s involved, it can’t be just the peroneal nerve (3)
@DrNeuro123 @AaronLBerkowitz If the tibialis and peroneal nerve are both involved, then it could be (1) both nerves are separately involved (2) sciatic nerve which gives rise to both nerves is involved (3) L5/S1 nerve roots which send fibers through these nerves to these muscles (TA, TP) are involved (4)
@DrNeuro123 @AaronLBerkowitz So you go for the big money. Now if you examine the hamstrings, that is innervated by both sciatic nerve and L5/S1. What to do? How about a muscle that’s innervated by L5/S1 but not the sciatic nerve? So if that’s affected you know it’s L5/S1 radiculopathy and not sciatic (5)
@DrNeuro123 @AaronLBerkowitz So then you examine hip abduction as that’s innervated by gluteus medius via the superior gluteal nerve through L5/S1. Now if that’s affected you know (1) it’s not sciatic (2) it’s L5/S1 radiculopathy since other L5/S1 innervated muscles (TA, TP) are affected thru diff nerves (6)
@DrNeuro123 @AaronLBerkowitz So there you have it by a process of deduction akin to #SherlockHolmes who, incidentally, wished he could be a neurologist n.neurology.org/content/37/5/8… For a more comprehensive review - checkout @AaronLBerkowitz #neuroanatomy #Tweetorial - it’s Ab Fab!
@threadreaderapp pls unroll
