See below. A LP involves withdrawing cerebrospinal fluid for study. A myelogram involves injecting a special dye for evaluation of spinal pathology. The placement and location of the needle are the same for both procedures.
The difference is . That a lumbar puncture is a spinal tap to obtain fluid and measurements of the cerebral spinal fluid while a myelogram is the same procedure but then a contrast material or "dye" is then injected to outline the spinal cord for imaging with x-rays or radiographs and usually followed by a ct scan.
Lumbar puncture. The spinal cord has three layers, the dura, arachnoid and the pia. The cerebrospinal fluid is sub arachnoid. A "lumbar puncture" is placing a spinal needle to access the cerebrospinal fluid. A myelogram is a diagnostic procedure usually for spine related pain that requires a lumbar puncture to inject contrast or dye into the cerebrospinal fluid after which an xray and usually ct scan are done. Read more...