Age: 47. Had ct: bladder distended, cyto: no blockage. Chronic retention. Urologist wants to 'ream uro-prostate channel.' could problem be neuro?

Maybe. It can be neurological in origin but that would be rare without other symptoms. Are you on any medication? Most urologists would try medical therapy for this problem before jumping straight to surgery. I would recommend a second opinion.
Absolutely. Significant prostate obstruction at age 47 is unusual. Poor bladder emptying in the face of no visible obstruction often suggests a neurological basis for retention of urine. Not always required for cases of bladder outlet obstruction, but at your age one should consider having cystometrogram urodynamic studies prior to undertaking any surgical procedures.