Pain long after lumbar puncture, dr. listed "lumbosacral plexopathy", "lumbar puncture reaction". did procedure cause perm damage, can dr be at fault?

Doubtful diagnosis: The lumbar plexus is nowhere near a lumbar puncture needle. This is likely the wrong code. Lumbar pain is rare after a lumbar puncture but not non-existent. Because it is rare, coding might be difficult and he probably just chose one that comes close. This is probably "mal-outcome" (expected potential side effect) rather than malpractice.

LP unlikely cause: It's an error if LS PLEXOPATHY is used to explain SINGULAR pain after an LP. The LS plexus is nowhere near an LP needle's location in the back. It's so well protected in the deep muscles of the pelvis that it's rare for ANY direct trauma to affect the plexus let alone a single needle. Also, plexopathy should ONLY BE DIAGNOSED after doing ELECTRICAL & IMAGING studies. Most pain resolves with time.