From what you've previously said about motor control, I suspected it was brain tumour Kev.
Well you've more than doubled your chance of recovery by opting for surgery, so fair play to you for that
. I tend to be quite interested in medical stuff like this, and fairly recently saw some amazing ops where tumours were removed with millimetre-accuracy, often with the patient awake and undergoing little mental tests to make sure healthy tissue wasn't being affected.
Best of luck for a good recovery chap, and if you do I reckon your libido will be going through the roof
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