Botox is a drug which blocks the nerve impulse to muscles. Therefore the muscles get weak. This usually lasts 2-3 months. After that it will need to be repeated. However over time the effects of the botox may last longer.
It is hard to say where the botox would be needed without seeing your leg and foot.
There is no indication for botox int the foot below the ankle. Depending on where there is muscle spasm if above the ankle, botox could be needed. Again, it is used to treat the muscle spasm that is causing the pain. Other than stopping the spasm, which may reduce the pain, it has no action to stop pain and is never used just to treat pain from Neuropathy.
The side effect would be muscle weakness. So if the botox is injected below the Knee
you would have weakness in your leg and what is called foot drop. If it was given in your thigh, you would have leg weakness being unable to get up out of a chair and walk because you would lose control of the overall leg weakness. These would be temporary for 1-2 months and then slowly improve. If it helped with the muscle spasm and related pain, it would then need to be repeated.
The cost is extreme. Botox medication costs $650 per vial. In the calf you would probably need 2 vials. Cost with injection fees probably 1500. 6000/year.
The larger the muscle, the more botox is needed. Thigh probably 5 vials. $3500.
Cost per year $15,000.
Because of the extreme expense, it may be difficult to get medical coverage for the injection. There are specific criteria for its use which is covered by insurance. It may be difficult to get approval for injections an in general Botox treatment is only approved when there are conditions for which there is strong medical evidence that it is helpful. There is no medical evidence that it is helpful for treatment of Neuropathy without muscle spasm causing the pain.
I was trained at the National Institute of Health in Washington DC on the use of botox 20 years ago. I have done over 200 patients in 20 years, ans I am currently injecting 20 patients continually ever the year( 4x a year).
I have many patients with muscle spasm pain that would benefit from botox, but it is very difficult to get medical approval for the medication.
Hope this helps, DR S