Lumbar puncture test and foot drop

I have developed foot drop about a year ago. I have seen only one specialist, but so  far all the tests were inconclusive.  
Now the specialist want to do a lumbar puncture test and I am not so sure if it's a necessary procedure which can help with my foot drop. Any one had this procedure before? Are there any risks involved? And is there any benefit of this test?
Thanks for all help.

[Neuro Forum]

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.

I can not comment on the potential benefit of lumbar puncture (which I will abbreviate LP) in assessing your foot drop without knowing your full history and physical examination. LP could potentially be helpful in general in assessing a foot drop if it is of a specific type or a specific distribution, caused by affectation of specific areas of the peripheral nervous system. However, I will provide you with information regarding the potential risks and benefits of this test.

During an LP, after you are positioned (usually in fetal position but sometimes sitting up), the area is cleaned, then an anesthetic is injected into the lower back area. This may burn very briefly, then the sensation of pain is reduced though you will still feel pressure. A larger needle is then inserted and spinal fluid is drained. Then the needle is removed and a bandage placed over the area. You are asked to lay flat afterwards for 30-60 minutes. A small amount of spinal fluid is removed (usually 12-20 cc), and your body makes a lot of spinal fluid every day (about 600 cc) so it won't really be missed too much. However, the most common side effect experienced after an LP is headache. This is usually transient and is related to your brain adjusting to the removal of the fluid, until it replaces it. This can be prevented by hydrating yourself very well the days prior to the procedure and by specific technique used by the person doing the LP. A more protracted headache that lasts hours to days occurs if there is persistent leakage of CSF from the tiny hole made by the needle, and this is treatable if it occurs. Much less common (occuring in <1% of patients) is what is called herniation, or a pulling down of the brain due to the void created by removing CSF. This would typically only occur in someone who has a large brain tumor or another cause for elevated pressure within the brain. Other potential causes include bleeding around the spinal cord, but this would be unlikely unless you have a bleeding tendency of some sort. Infection is another potential complication, but extensive measures are usually taken to clean the area of LP well and prevent infection. If there already is an infection in the lower back area, LP should not be done. Risk of spinal cord damage is minimal because LPs are done below where the spinal cord ends, but temporary or much less commonly permanent nerve root damage may occur. There are of course other risks that are very uncommon but have been reported.

I recommend you discuss the potential risks and benefits of LP with your physician.

Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.