TELF — Transforaminal Endoscopic Lumbar Foraminotomy

As the spine ages, the foramen — the doorway where the nerve exits — can be narrowed by several things at once: overgrown bone spurs from the facet joint, a bulging or collapsed disc reducing the height of the tunnel, thickened ligament, and loss of disc height that lets the vertebrae settle closer together. The exiting nerve, already in a tight space, becomes squeezed, producing sharply localised leg pain that can be difficult to pin down on a quick look at a scan. When it does not settle with non-operative care, enlarging the foramen to free the nerve is offered.

A foraminotomy is, quite literally, an enlargement of the foramen — reopening the tunnel so the nerve has room again. The transforaminal endoscopic route reaches the foramen from the side, along the line of the nerve itself, and uses a controlled foraminoplasty — trimming the overgrown front edge of the facet joint and any bone spurs with a fine burr, and addressing any ligament or disc material narrowing the tunnel — until the nerve is decompressed. It does this without the muscle stripping or facet removal an open approach would need, and it can frequently be carried out under local anaesthetic and sedation, so the patient can report sensation as the nerve is freed. Decompression is confirmed when the nerve regains its natural angle and lies free under the endoscope.

The transforaminal foraminotomy fits this problem well for two reasons. First, it approaches the foramen from exactly the direction the narrowing lies, so the compressive bone and tissue are addressed directly. Second, because it is minimally invasive and can be done awake, it is particularly valuable in older patients — who make up many of those with degenerative foraminal stenosis and who may have other medical conditions that make a bigger operation and a general anaesthetic riskier. Being able to relieve a trapped nerve through a few-millimetre corridor, often under local anaesthetic, is one of the reasons I value the endoscopic approach so highly in this group.

The craft of a foraminotomy lies in enlarging the tunnel enough to free the nerve while protecting the exiting nerve and its sensitive ganglion throughout, and in judging how much of the facet edge to remove without thinning the pars and creating instability. Identifying the nerve and the landmarks around it before addressing the compression is essential. These are precisely the judgements that subspecialty experience in endoscopic foraminal surgery is built on, and they are the focus of my practice and teaching.

The evidence supports transforaminal endoscopic foraminotomy for foraminal stenosis. Long-term prospective studies of endoscopic foraminoplasty report durable relief in foraminal stenosis and in some failed-back cases, and cohorts specifically in elderly and octogenarian patients show high rates of improvement with the awake, local-anaesthetic approach. Radiographic studies confirm genuine enlargement of the foramen after the procedure, and classification systems now help match the pattern of foraminal narrowing to the surgical approach. The recognised consideration of temporary nerve irritability after work near the ganglion applies here, underlining the importance of careful technique.

Because the muscles and most of the bone are spared, recovery is usually quick — many people go home the same day or the next, walking, with early relief of the leg pain. Some temporary tingling or nerve sensitivity can occur in the first weeks and generally settles; numbness and long-standing weakness may take longer and do not always resolve fully. Activity is built back up over the following weeks, and the spine is followed up over the longer term.

• —Transforaminal endoscopic lumbar decompression and foraminoplasty: 10-year prospective survivability study. (PMC4325492)
• —Long-term outcomes following endoscopic foraminoplasty for single-level foraminal stenosis. (PMC9519075)
• —Transforaminal endoscopic lumbar foraminotomy for octogenarian patients. (PMC10867165)
• —Percutaneous endoscopic lumbar foraminoplasty for foraminal stenosis in the elderly: radiographic changes. (PMID 30887488)
• —Percutaneous endoscopic lumbar foraminotomy for foraminal stenosis with postlaminectomy syndrome in geriatric patients. (PMID 31323406)
• —Lumbar foraminal stenosis classification guiding surgical treatment. (PMID 35710724)
• —Ruetten S, et al. Full-endoscopic versus microsurgical decompression for lateral recess/foraminal stenosis (RCT). (PMID 19929343)