Transforaminal Endoscopic Lumbar Discectomy for Left L3–4 Extraforaminal Disc Herniation With Upward Migration Under Local Anesthesia

0:00 Transforaminal Endoscopic Lumbar Discectomy(TELD)

In this video, we discuss a case of lumbar 3 lumbar 4 foraminal disc herniation on the left side that was successfully treated by transforaminal endoscopic lumbar discectomy under local anesthesia.

00:12 Introduction

Percutaneous transforaminal endoscopic discectomy has gained popularity worldwide since Kambin introduced it in 1983 [1]. This technique has the advantages of less soft tissue stripping and paraspinal muscle damage, less postoperative pain, reduced risk of infection, and no risk of spine destabilization [2-4]. This technique has a steep learning curve and lack of experience can lead to serious complications like hypoesthesia, nerve root damage, dural tear, vascular damage and also death [3,5]. Also, in a study by Choi et al. [6], out of 10,228 patients 33.6% cases of incomplete removal of herniated disc were due to inappropriate positioning of working channel. Therefore, meticulous placement of needle and hence the working channel is extremely essential for a successful transforaminal endoscopic lumbar discectomy surgery.

01:03 Case Description

A 50-year-old gentleman man presented to us with chief complaints of low back pain and left lower limb radiculopathy. He is symptomatic since 2 months when he fell down from his bike. On examination, he had notable antalgic gait, dysesthesia, numbness along the left anterolateral thigh and his left hip flexion was Medical Research Council (MRC) grade 4 out of 5, and left knee extension was MRC grade 3 out of 5. His peripheral pulses of lower limb were normal.

01:31 Radiological Imaging

His x-ray lumbar spine revealed normal spine alignment with no gross spondylolisthesis and no fracture from a previous injury. The magnetic resonance imaging (MRI) scan shows L3–4 left side extra-foraminal disc herniation with upward migration. The parasagittal cut of the MRI scan shows no perineural fat around the left L3 nerve root compared to other levels, suggesting compression by upward migrated fragment from L3–4 disc herniation.

01:58 Gait Video

This video shows him limping due to excruciating pain on walking and his visual analogue scale score for left leg pain and back pain were 8 out of 10 and 4 out of 10 respectively. His symptoms have been worsening for the last 2 months. He has not been able to go for his work since then. Patients with foraminal disc herniation exhibit more severe pain and motor dysfunction preoperatively as it directly compresses and irritates the dorsal root ganglion [7].

02:25 Diagnosis and Treatment Options

Diagnosis was made correlating the clinical and radiological findings. Patient’s symptoms were mainly from left L3 nerve root as suggested by numbness and pain along left L3 dermatome distribution and motor deficit in the form of weakness in left knee extension.

All the treatment options were thoroughly discussed with the patient like conservative care, open discectomy surgery, and minimally invasive surgical options like tubular discectomy, endoscopic discectomy and also fusion surgery. Our patient was amenable to surgery and was keen on returning to work as a gym instructor as soon as possible. The goal of the surgery was to decompress the neural elements, halt the progression of further neurological impairment, and to improve the quality of his life. In a patient of lumbar foraminal disc herniation with no accompanying degenerative central stenosis transforaminal endoscopy can be a more minimally invasive route compared to interlaminar route which needs more bony work and extensive detachment of ligamentum flavum.

03:22 Patient Positioning

Patient was positioned prone on a radiolucent operating table with spine, knees and hips flexed to reduce the lumbar lordosis and all the bony prominences were adequately padded with the help of gel rolls. This positioning helps to increase the size of intervertebral foramen and does not stretch the lumbar nerve roots. The care was taken to keep the abdomen free and hence avoid any pressure on the inferior vena cava. He underwent lumbar 3-lumbar 4 fully endoscopic transforaminal discectomy under local anesthesia and conscious sedation.

03:53 Planning the Skin Incision

The approximate distance of skin entry point was calculated on preoperative MRI scan axial view. The intended landing point on the disc should be as close as possible to the annular tear point [8]. We always ensure to get perfect anteroposterior (AP) and lateral views of C-arm fluoroscopy before starting the procedure. With the help of radiopaque metal rod vertical midline and L3–4 transverse disc space line is drawn on the skin with the help of sterile marker. The success of transforaminal endoscopic surgery depends entirely on the meticulousness of docking the endoscope which in turn depends on starting skin entry point. This can be deemed as the rate limiting step of the entire procedure.

04:34 Needle Insertion

An 18-gauge spinal needle was inserted approximately 7 cm for midline under continuous fluoroscopy guidance. With the help of the needle skin puncture is made and it is then inserted towards L3–4 disc space. The care is taken not to cross medial pedicle line in AP view at all the times. Ideal target for the position of tip of the needle in this case was lateral pedicle line, just above left L4 pedicle and at the posterior edge of superior end plate of lower vertebra (L4) in lateral views.

05:05 Performing Discography

The needle is further advanced along the planned trajectory and it is inside the disc space we perform discogram with the help of indigo carmine which stains the degenerated disc material. This helps us to identify the disc space level and also determines the leakage pattern through the annular fissure.

05:22 Nerve Root Block

The needle was withdrawn a bit so as to locate its tip inside the foramen and a nerve root block was given for left L3 nerve root with a mixture of local anesthetic and radio-opaque dye. This helps us to trace the left L3 exiting nerve root.

05:36 Endoscope Insertion

Following this, a staged dilation technique from the guide wire, obturator, and final working cannula is performed. The beveled working cannula is targeted into the lower third of foramen as the nerve root is located in the upper third of the foramen. Care is taken to keep the bevel of the cannula open towards the exiting nerve root which helps to avoid inadvertent nerve injury. We use an endoscope with an outer diameter of 7.00 mm, a working channel diameter of 4.3 mm and which has a viewing angle of 30°. This can be finally inserted through the working cannula after switching on the irrigation system.

06:15 Tissue Exposure

Once the endoscope is inserted, anatomical landmarks such as left L4 superior articular process (SAP), pedicle, transverse process are identified by palpation with the help of curved tip of radiofrequency forceps. It is recommended to use the flexible curved tip of the radiofrequency probe as a smooth dissector, but limiting the continuous vaporization of the tissues to no more than 2 seconds at a time to avoid injury to the anterior ramus of lumbar spinal nerve which is anterior to transverse process of the inferior vertebra [9].

06:39 Removing the Foraminal Ligament

With the help of an endoscopic cutter the foraminal ligament is taken down.

06:45 Removal of Ligamentum Flavum and Root Exposure

Following this, the endoscopic Penfield is used to detach ligamentum flavum from the lateral aspect of SAP. Then endoscopic Kerrison punch is used to remove ligamentum flavum piece meal and expose the exiting nerve (left L3). Thus, the Kambin triangle is exposed.

07:06 Adequate Hemostasis

Once the ligamentum flavum is removed, we can also see the perineural fat tissue and there is some bleeding from branches of epidural vessels. Adequate hemostasis is achieved with the help of radiofrequency probe.

07:20 Rotating Maneuver of Working Cannula

After controlling the bleeding, the endoscopic Penfield is used to retract the nerve away from disc space (more laterally) and simultaneously under vision the working cannula is rotated clockwise so that the opening of the bevel faces the SAP-transverse process junction. This way the exiting nerve root is behind the longer edge of working cannula and becomes safe while performing discectomy. Similarly, counter-clockwise rotation of working cannula is needed for right sided surgery.

07:43 Discectomy

This is followed by annulotomy with the assistance of endoscopic knife. The degenerated disc is easily identified as it is stained by blue indigo carmine dye. Gentle rotation of the cannula helps to squeeze out the disc fragment. The discectomy is performed piecemeal under vision and while removing the largest fragment of disc the scope needs to be pulled out of the working cannula as the working channel diameter is small for it. A radiofrequency electrode was then utilized for meticulous hemostasis and to perform annuloplasty. A flexible curved probe can track the trajectory of disc migration and can help to hunt for any remaining disc fragment. Also, specialized semiflexible forceps can help reach upward or downward migrated disc fragment in transforaminal endoscopy.

08:29 Skin Closure

Subcutaneous suturing was done for the surgical incision. Estimated blood loss was around 10 mL.

08:36 Surgical Summary

The surgical duration was 35 minutes and there were no intraoperative complications.

08:40 Postoperative Mobilization

He was mobilized on the same day of surgery in the evening and he could walk comfortably without any leg pain. He was discharged on the next day.

08:51 Postoperative Imaging and Outcome

Postoperative MRI scans showed removal of herniated fragment of L3–4 disc from left foramen and well decompressed left L3 nerve root.

09:01 Follow-up

At 1 year follow-up the patient is completely symptom free and has achieved excellent outcome according to MacNab criteria. There is no development of secondary instability at L3–4 level due to surgical procedure done.

09:13 Advantages

Thereby we conclude, that transforaminal endoscopic lumbar discectomy can be performed as daycare surgery under local anesthesia. The patient is awake during the entire procedure and can act as a neuromonitor guiding the surgeon about neural structures. This procedure has less postoperative pain, minimal scarring and a faster return to daily activities for the patient. Transforaminal endoscopic lumbar discectomy can achieve effective neural decompression equivalent to microscopic discectomy.