lumbosacral stenosis - say what?

AP Here:
Tonka and I have been to see a Neurologist, Dr. Harris http://www.vetneurochesapeake.com/index.php?page=dr-jeanene-harris at Veterinary Neurology of the Chesapeake www.vetneurochesapeake.com/ . His left hind leg is still not right and he is walking sideways. While he was there he was also seen by Dr.Burgess http://www.cvssvets.com/surgeons.php as an orthopedic consult.  The presumptive results were-

Assessment and Diagnosis

Neuro Localization - Spinal lumbosacral cord (L4-S3): Tonka's neurologic exam is revealing subtle lower motor neuron deficits in his left pelvic limb. Given these findings in association with pain on tail elevation, the most likely location for the problem is at the lumbosacral junction. Possible causes would include lumbosacral stenosis (Type II disk disease, arthritis of the articular facets, and enlargement of associated ligaments and soft tissues). Other possibilities would include neoplasia (primary or metastatic cancer) or infectious/inflammatory diseases; however these are thought less likely.

The best diagnostic test to determine the exact cause for his defecits would be an MRI /- a spinal tap and electrodiagnostics (EMG, MNCV, etc.).

Tonka's mild neurologic deficits are further complicated by concurrent orthopedic disease. An orthopedic exam revealed discomfort on manipulation of both of his hips (left more than right) and radiographs of his pelvis reveal evidence of hip dysplasia and osteoarthitis of the left hip. Tonka also resisted manipulation of his left stifle (knee) and there is concern that there may be a meniscal tear. There is no evidence of cruciate ligament rupture at this time.

Since Tonka had his heart surgery this year and just had the rhinoscopy a month ago we are opting to try medication for a few weeks to see if there is any improvement. If not then we will have the MRI to rule out the Lumbar Sacral problem. I am hesitant to put him back under anesthesia so quickly after the last one and we are just now getting the prednisone out of his system and he is acting more alert and like his old self. We have known about the hip since 2009 and it has never been an issue until now so I am not sure what to think. We will just have to deal with whatever comes our way like we always do. I know he is tired of being poked and prodded and I don't blame him. If you are curious as to what an MRI for your dog costs these days in the Maryland area try $1750.00 and that does not include any additional items like a dye test or spinal tap.