I'm going through the diagnosis process for potential idiopathic Parkinson's disease (and it's been a very long road indeed, very similar to many of the stories I've seen described in this forum). As part of the process, I'm taking one and a half Sinemet 25/100 tablets twice a day, and a half tablet at the end of the day. I'm also taking 4 25-mg Lodosyn (carbidopa) tablets at the beginning of the day, to help with severe nausea. I had to ramp up to this level over a couple of weeks to help minimize side-effects, which apparently I'm susceptible to. The MDS I'm working with tells me he wants to judge my response to the medication as a part of the diagnosis.

My main symptoms are strongly asymmetric bradykinesia and stiffness (left side only at this point), with a small amount of resting tremor in my left hand. The doc tells my I exhibit cogwheel rigidity on the left side, but not on the right. I can't type with my left hand, and have trouble with buttons and tying my tie. When I make a conscious effort to try to move my left hand rapidly (clenching and unclenching, for example), it results in an odd quivering, jerking, uncontrolled movement. I also have developed a limp on the left side, and occasionally find myself dragging my left leg when I walk. Based on what I have read and what I've been told, these are classical PD symptoms, and should respond well to levodopa therapy. I also believe I'm experiencing some non-motor symptoms, but it could be that I'm just freaked out and not thinking straight.

Here's the problem - none on the symptoms seem to be improved from the Sinemet I've been taking for the last several weeks, although the side effects (mainly nausea and dizziness) are bad enough that I'm almost unable to work. I'm still experiencing all the symptoms I described earlier, with no noticeable improvements. I've searched this forum pretty extensively to find a discussion on this subject - my apologies to you all if this is well-discussed and I just don't know it.

I've been chasing this for at least three years, thinking it's first one thing and then the next. The diagnosis process has looked at things like rotator cuff tears (MRI says no), carpal tunnel syndrome or cubital tunnel syndrome (nerve conduction study and EMG said probably not, but orthopedist wanted to do surgery anyway), normal sports injuries (I'm 47, and sometimes have the tendency to try to relive past athletic glory), simple advancing age and normal decline (my health up to this point has typically been good), and things like diabetes or other metabolic disorders. Lab tests have recently ruled out Wilson's disease, and I just had a cerebral SPECT scan that I don't have the results for yet.

Can anyone give me insight into the following concerns and questions?

1. How long should it take Sinemet to have an effect on symptoms? I've read that it's an almost immediate effect if it's going to work, and doesn't require a "build-up" period of days to weeks. Is this true? What's your experience with Sinemet? How fast and how well does it work (discounting longer-term effects like diskinesias, which are not yet an issue for me)?

2. How much improvement should I really be expecting? Return to full function or only subtle improvements?

3. What could this be if I have classical PD symptoms that don't respond to levodopa therapy? I've read about "Parkinson's plus" syndromes and things like corticobasal degeneration (the doc mentioned this last as an unlikely possibility), but I don't show any signs of autonomic system dysfunction (blood pressure problems, incontinence, sexual dysfunction, etc).

4. Is there reason to have hope that this is just one of those odd misdiagnoses, and that PD or parkinsonism isn't the culprit here?

5. How much value have any of you seen in using SPECT scans to clarify your diagnosis? The literature I've read seems to be somewhat inconclusive.

I realize this is a long post, but as I mentioned before, I'm frankly a bit freaked out and am reaching out to this community for some clarity. I'm grateful for any insights you can provide.