The differential diagnosis of increased leg pain after a microdiscectomy is a recurrent disc herniation, mass effect (hematoma), nerve irritation (the nerve is manipulated during surgery and this could irritate the nerve) and nerve injury (heaver handling of the nerve during surgery).
Since it has been only six days since surgery, an oral steroid would be helpful. If the cause is either irritation of the nerve or hematoma, the nerve symptoms will improve and most likely stay improved with some mild drop off of improvement when the steroid is stopped. The hematoma can resolve (by reabsorption) over time and the nerve irritation will improve over time.
If the pain is from a recurrent disc herniation or from a non-resolving hematoma, the pain will return to the previous level after the steroid is stopped. A new MRI will be necessary and will reveal the compressive mass. If the mass is a hematoma, commonly, an outpatient procedure using aspiration with a needle will resolve the compression. If the mass is a recurrent disc herniation, a new surgery is in order to remove this fragment.
If the pain is from nerve damage, time is needed for some resolution of symptoms.
Dr. Corenman