right foot will not flex loss of balance when step

It started with what I call "waitress foot pain" in as where most of us experience a feeling of bruising on the ball of foot (feet) after a long shift.  But then my gait began to shift.  When I tried walking on the right side of my right foot to relieve the discomfort, my entire leg gave out on me.  Not so with my left foot, as I experimented with both sides.  Then one morning I woke up not being able to flex my right foot at all.  I could point but not flex unless I did this manually.  I had an MRI on brain and back which showed no signs of nerve issues. Only results that came back negatively were that I have vitamin deficiencies mainly the b's. Three days into tests no one can figure out what is wrong.  Funny thing is that I have a little discomfort but no pain.  I am obviously missing work because of this freaky condition and I need help to find out what is wrong.

[Sara Khan]

Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.

Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.

From your description it sounds like you may have what we call a " foot drop". Foot drop is caused by weakness or paralysis of the muscles below the knee involved in lifting the front part of the foot. There are numerous causes resulting in a foot drop. It could be due to a nerve, muscle or spinal cord/brain related problem. The fact that you brain and spinal cord MRIs are normal is very good news, and rules out the last possibility.

The most common cause usually is nerve injury. The muscles that are responsible for flexing at the ankle are supplied by a nerve called the Common peroneal nerve. This nerve is a branch of the Sciatic Nerve, which you may have heard of. The Peroneal nerve runs right along the outer edge of your knee, and therefore in that position is highly susceptible to compression in people who for example keep their legs crossed for long periods of time. It can also be damaged with direct trauma to the nerve, hyperextension of the knees, or from other causes of nerve damage including diabetes, vitamin deficiencies ( most commonly Vitamin B12) etc. Genetic and hereditary causes of nerve damage are also possible though rare.

The damage could be higher up, in the nerve roots as they come out of the spinal cord, right before they join to form the Sciatic nerve. However they would probably have seen this on an MRI.

The next step in your evaluation should be an EMG ( or elecromyogram) with Nerve conduction studies. This test directly checks the electrical activity in nerves and muscles, and can therefore determine the location of the damage, whether in the spinal cord, spinal roots, nerve or muscle. Once they have detemined the location, they can run further tests to look for the specific causes.

I recommend that you see a neurologist, who can better assess you and recommend tests based on your neurological exam.

I hope this helps. Good luck!