This section describes safety outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
5.1 A systematic review of transforaminal endoscopic surgery for symptomatic lumbar disc herniation reported that the median percentage of complications in non‑controlled studies was 2.8% (28 studies, n=6,336). There was no significant difference in median complication rates between intradiscal (5.3%; 12 studies, n=1,206) and intracanal techniques (2.1%; 17 studies, n=5,362); or between far lateral herniation (5.1%; 5 studies, n=214); central herniation (2.7%; 1 study, n=71) and all types of herniation (4.9%; 15 studies, n=2,934). The controlled studies found no significant difference in median complication rates between transforaminal endoscopic surgery (1.5%) and open lumbar microdiscectomy (1.0%; 6 studies, n=1,302). Most reported complications were transient dysaesthesia or hypaesthesia.
5.2 Post‑discectomy pseudocysts (defined as cystic lesions of T2W high and T1W low at discectomy site) were detected on postoperative MRI at 2 months in 1% (15/1,503) of procedures in a case series of 1,406 patients. The mean interval from surgery to detection was 53.7 days. The interlaminar approach significantly correlated with pseudocyst formation (3%; 9/298) compared with the transforaminal approach (1%; 6/1,205, p=0.001). Ten pseudocysts were treated conservatively and 5 were treated surgically. There was no difference in treatment outcome between conservative and surgical management at a mean follow‑up of 25 months.
5.3 Symptomatic retroperitoneal haematoma was reported in 1% (4/412) of patients in a retrospective case series of 412 patients treated by transforaminal endoscopic surgery. Two patients with massive diffuse‑type retroperitoneal haematomas compressing their intra‑abdominal structures needed open haematoma evacuation. The other 2 patients had small localised retroperitoneal haematomas that were treated conservatively. Symptoms improved without any neurological sequelae in 3 patients at a median follow‑up of 21 months. One patient had transient hip flexion weakness and mild dysaesthesia on the lateral thigh which improved in 6 months.
5.4 Symptomatic dural tears were reported in 1.1% (9/816) of patients in a case series of 816 patients treated by transforaminal endoscopic lumbar discectomy. In 3 patients, dural tears were detected intraoperatively (patients complained of headache with back pain as the cerebrospinal fluid leak occurred). Six patients had delayed diagnosis (clinical findings or by MRI) after an average symptom‑free interval of 2.5 days and their condition was unresponsive to conservative management. Two of the delayed diagnosis patients had nerve root herniation causing profound leg pain and neurological deficits; 4 had nerve root irritation causing leg pain. All patients had secondary open repair surgery (with a standard microscope‑assisted interlaminar approach) without any neurological sequelae. One had subsequent fusion surgery at the same level. At a mean follow‑up of 30.8 months, the mean visual analogue scale score of leg and back pain and mean Oswestry disability index improved. The final outcome was poor in 2 patients with unrecognised dural tear with nerve root herniation.
5.5 Spondylodiscitis (with or without soft tissue infection) was reported in less than 1% (12/9,821) of patients in a retrospective case series of 9,821 patients treated by transforaminal endoscopic lumbar discectomy. The average time to diagnosis by MRI was 14.6 days. Four patients were treated with antibiotic therapy only; 2 with surgical debridement; the remaining 6 were unresponsive to initial therapies or surgical drainage, and had anterior lumbar interbody fusion with posterior instrumentation surgery. At a mean follow‑up of 31.7 months, the mean Oswestry disability index and visual analogue scale score for leg and back pain improved. Based on the modified MacNab criteria, 58% (7/12) of patients had an excellent or good outcome.
5.6 A sequestered disc post‑procedure was reported in 1 patient who had transforaminal endoscopic surgery in a case series of 55 patients. The patient was treated by open discectomy.
5.7 'Transitory foot drop' was reported in 1 patient and 'transitory sensibility disturbance' of the foot was reported in 3 patients in a retrospective case series of 255 patients who had transforaminal endoscopic lumbar discectomy (no further details were reported).
5.8 In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers listed the following anecdotal adverse event: iliac crest pain during the procedure. They considered that the following were theoretical adverse events: visceral injury, cauda equina syndrome and allergic reactions to local anaesthetic.