I have a herniated disc and had an epidural, doctor said it massively herniated, it has been 24 hours since the shot. Should I consider microdiscetomy?
Not necessarily. The decision is not only based on the size of the disc. The following criteria would push you toward surgery: the presence of weakness, duration of symptoms more than 6 weeks, repeated symptoms over years, superimposed spinal stenosis, and spinal cord compression if the disc is cervical. 24 hours is not enough time to decide that the epidural has failed.
May take 7-14 days. Epidural steroid injections sometimes take as long as two wks to work. If you have problems with bladder/bowel control or real leg weakness, consider diskectomy. Disc surgery only trims the disc but does not "fix" it. The disc may even be weaker and herniate again after surgery. The elasticity can't recove. Even the current "replacement discs" are not an adequate substitution for the original cushion.
Consider all. There are two general indications for surgery: intractable pain and progressive neurologic deficit (nerve injury). The size of the herniation and use of the epidural shot do not directly factor in this choice. Work with your doctor (s) and wait and see what develops. Even a 'massive' disk can retreat in time.
Follow up. If it is not improved, and it as herniated as you say, then your surgeon will have to make the call, but it sounds like you will need surgery.