I've had a nerve root compressed w/pain for 15 months. i've exhausted conservative options. if i delay surgery could it cause more nerve damage?

It's possible: If you have clinical(or EMG/NCS - muscle/nerve testing) findings of weakness, muscle atrophy(decreasing muscle mass), or sensory problems that can be attributable to anatomic problems with your spine, it's possible that the damage could progress if not already be irreversible. Please review this with your neurologist, and/or neurosurgeon and/or orthopedic spine surgeon.

Not usually: Nerve root compression that causes pain rarely results in permanent nerve damage. Likewise, numbness is rarely permanent. However, if there is actual weakness in the muscles controlled by that nerve, then surgery becomes a real option. Also, if the symptoms have been constant for 15 months, it may be time for surgery. In most cases, this problem can be expected to come and go for your whole life.

Nerve root: compression can cause loss of function if the electrical impulses from the brain and spinal cord cannot reach the the muscles or glands that are anatomically and physiologically connected. Surgery may not restore muscle strength but it can potentially prevent further loss of muscle fibers that rely on their respective paired nerve stimulation to remain viable.