To answer windysan's question, yes. About 30% of the people who take tramadol or Ultram (brand name) experience an effect similar to that of a fast acting anti-depressant, along with the pain relief effects as tramadol acts as an SNRI.
I took it for about a year after it was prescribed to me by my pain management doctor and it was the only thing which worked well on my lower back pain. The dosages the OP referred to are very high as the maximum daily dosage should not exceed 400mg with 300mg+ substantially raising the risk of seizure.
You can build up a tolerance very quickly and many people say the withdrawals are worse than heroin withdrawals. Tramadol is actually a synthetic opiate.
The one good thing it did for me was to change my opinion of anti-depressants so I went to a psychiatrist who prescribed Cymbalta as it is also an SNRI (which helps the back pain as well). I can honestly say I don't get anywhere near the level of anxiety and depression which I experienced before it.
I realize a lot of people are down on medication but, in the right circumstance, the right medication can really help. As you can't take Tramadol with Cymbalta due to the risk of serotonin syndrome, I have to make do with aspirin when I have a spell with my back.
Congratulations again to you and your wife!