It would depend on the cause. I am not aware of a specific topical treatment that would 'restore' the sensitivity. If there was a local dermatitis reaction, local steroid creams can be considered.
I would also consider metabolic causes of numbness, such as diabetes, thyroid or vitamin B12 deficiency. These options can be tested via appropriate blood tests.
These options can be discussed with your urologist, or in conjunction with a neurologist.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
kevinmd_