Extensor vs Flexor Weakness

The question that I had was the following:  What type of deficit and at what neuroanatomical location is it possible to suffer a deficit in biceps and hamstrings strength with simultaneous normal strength in the triceps and quadriceps.  That is what leads to flexor weakness with preserved extensor strength?  One possibility that I thought of was MS; however are there other explanations that could produce this bilaterally?

[CCF Neuro[P] MD, RPS]

Dear Bharat Guthikonda:

The lesion would have to be peripheral nerve or muscle problem.  A central lesion would not discriminate between muscle groups.  The lesion may also be due to a bad exam where mild decrease in power was not diagnosed properly.  The make the distinction between triceps and biceps, the nerves would be mucocutaneous and radial.  However, the brachial radalis would also have to be involved.  Since this is not involved, maybe you have a polymyositis.  The hamstring weakness in the face of quadriceps strength may be due to sparing of some L2/3/4 while hitting certain parts.  Again this is usually not seen.  

Spotty neuropathy such as described might occur in CIDP but this is very unusual.  It would not be due to MS as this disease is strictly central.

I would favor a poor neurological exam as the reason for such findings.

Sincerely,

CCF Neuro MD