The herniated lumbar disc (HLD) in young patients is increasing. The endoscopic discectomy has been used as a treatment option, but it is limited in the management of large extruded or migrated disc herniations. Recently, with an application of extreme lateral endoscopic lumbar discectomy (ELELD), it is possible to obtain access to epidural space directly and to remove herniated disc. In this study, result of ELELD based on the direction of disc protrusion, degree of protrusion and migration of the protrude disc in young patients were assessed.
Retrospective study of 135 patients with HLD underwent ELELD was conducted. The patients were classified according to size, type and degree of disc herniation. Axial locations of those herniations were divided central, posterolateral and foraminal. Migrated herniations were classified into low or high grade according to the extent of migration.
The average visual analogue scale (VAS) pain score was reduced from 8.92±1.20 to 2.38±1.55 (p<0.05). High-grade migration group showed lower success rate compared with other group. The failures were considered to result from a free fragment having migrated too far from disc level in the lateral recess to be effectively removed. The patient with the poor result underwent open surgery subsequently.
The ELELD has expanded capabilities of previous endoscopic procedures including posterolateral approach and can be surgical alternative to conventional microdiscectomy. However, open surgery is more advisable rather than endoscopic discectomy in the lumbar disc herniation with high-grade migration.
The number of herniated lumbar disc (HLD) in people under 25 years of age, 5.5 per 100,000, is relatively lower than 128.3 per 100,000 for people of 40 to 45 years of age; but the frequency of the condition is increasing due to the change in body position, lifestyle, and diagnostic techniques
The discectomy through laminectomy, which was considered traditional method, showed relatively satisfactory result, and could be applied to patients with degenerative bony spur, far lateral disc herniation, migrated and sequestrated disc. However, the surgery requires avulsion of the lumbar spine muscles, elimination of ligamentum flavum, incision of annulus fibrosus and posterior longitudinal ligament. The surgery can be complicated with postoperative damage on soft tissue, joint, nervous tissue, nerve root compression, adhesion due to scar tissue, and hemorrhage due to blood vessel damage
To avoid such complications of this surgery, various minimally invasive surgeries were developed
Recently, to overcome such limitations, extreme lateral endoscopic lumbar discectomy (ELELD) has been performed. In this study, result of ELELD based on the direction of disc protrusion, degree of protrusion and migration of the protrude disc in young patients were assessed. Additionally this study identifies indications, limitations and shortcomings of endoscopy and provides solutions.
One hundred thirty-five patients out of 156 who were diagnosed with HLD underwent ELELD between December of 2007 and September of 2014 in Bundang Medical Center. All patients were male, with average age of 22 (20–25 years old). Average follow up period were 16 months. Magnetic resonance imaging (MRI) and computed tomography (CT) were done to all the patients. Surgery was done on patients who had conservative therapy for at least 3 months without improvement on lower back pain, radiating pain and radiological findings matched with clinical symptoms. Additionally, plain radiography was taken to check if iliac crest is higher than the space between L5 and S1 and enlarged transverse process prevents the working channel to get inserted to spinal epidural space. We excluded the patient who underwent laminectomy, discectomy, or endoscopic transforaminal lumbar discectomy.
The herniation was categorized as central, postero-lateral and foraminal based on the radiological findings, whether the herniated disc was migrated or not; and if migrated, severity was measured based on the posterior disc space; and if not migrated, severity was measured based on the 50% of area of lumbar spinal canal.
The surgery was done on prone position with slight flexion and local anesthesia at the site of the herniation. C-arm was placed to observe anterior-posterior plane perpendicular to lateral plane of the upper and lower vertebrates of the target disc. Basal line was set with posterior facet line (
Skin incision (0.5–1 cm) was made to the injection site after local anesthesia was applied. 18 gauge needle was injected with c-arm image to inject the needle to the posterior facet by extreme lateral approach. The angle of approach was 5 to 20 degrees to the ground (
The postoperative follow up study was carried out by means of outpatient clinic and telephone interview, the clinical result was evaluated through MacNab’s criteria and visual analogue scale where the ‘excellent’ and ‘good’ score was considered as successful result. The statistical testing was carried out by analysis of variance (ANOVA) using SPSS for windows (Release 7.5.1; SPSS Inc., Chicago, IL, USA).
Sixty seven percent of patients complained about lower back pain and radicular pain, and 33% only complained about the radicular pain. Sixty five point seven percent of patients had sensory dysfunction and motor weakness was observed in 40.3%. Eighty seven percent were positive in the straight leg raising test. Patents with osteophyte due to the apophyseal ring fracture were excluded from this study. Average period of lower back pain until surgery was 2.3 years and 4.5 months for radicular pain. Seventy four point one percent of patients had surgery between L4 and L5, 19.3% had surgery on the disc between L5 and the S1, and 6.7% had surgery on the disc between L3 and L4 (
The surgery was evaluated using MacNab method and excellent or good scores were considered as successful surgery. Overall, the average visual analogue scale (VAS) of all patients before surgery was 8.92±1.20 and VAS at the final follow up was 2.38±1.55 (p<0.05) (
HLD is a disease which must be considered for patients with lower back and lower limb pain under 25 years of age, despite the fact that the frequency of onset is lower than that of patients over 40 years of age
To overcome the shortcomings of traditional method, the discectomy by laminectomy, such as damage of soft tissue and nerve tissue, and nerve adhesion, development and improvement of the minimally invasive surgeries allowed identification and removal of the protruded nucleus pulposus via endoscopy
Newly introduced extreme lateral approach was thought to be applicable to wide variety of indications of lumbar disc herniation, which approach the lesion more parallelly to epidural space, which allowed increase mobility in the epidural space than inside of the disc. Compared to posterior lateral approach, extreme lateral approach has following strength. First, as the method approach the epidural space directly, removal of normal annulus fibrosus is not necessary. The unnecessary removal of annulus fibrosus induces severe pain during the surgery and persistent pain after the surgery. Additionally this is one of the major reasons to increase possibility of reoperation. Second, this method allows removal of central herniated disc by approaching in parallel with posterior longitudinal ligament. Third, it minimizes the nerve root damage by identifying the nerve root from the early stage of the surgery. To inject the needle safely, posterolateral approach uses triangular working zone, but the average distance between the incision point of annulus fibrosus and the exiting nerve root was 3.4±2.7mm(0.0–10.8mm) and 17.2% were 0mm
For the surgery on L5-S1 herniated disc, conventional posterolateral approach was performed instead of extreme lateral approach as iliac crest and large transverse process of L5 blocked access to L5-S1 disc space by trajectory of extreme lateral approach. Usually iliac crest is considered a major obstacle. Therefore, during L5-S1 level endoscopic discectomy, interlaminar approach instead of the posterolateral approach has been used for the endoscopic lumbar discectomy
Based on this study, complete removal of herniated disc was difficult, which decrease success rate of removal of severely migrated herniated disc. Lower limit of the endoscope is less than the half of the height of the lower vertebrae of the lesion, and when the herniated disc migrated to lateral recess, removal of the herniated disc was difficult due to the angle of approach was limited. When the herniated disc migrated to lateral recess, it could be approached from the different side, so this method should be considered. Or by making skin incision point more dorsal than usual and reach upper intervertebral foramen (intervertebral foramen consist of the upper vertebrae of the lesion) to increase the lower range of the endoscope, but increases nerve root damage as the exiting nerve root comes out of the upper intervertebral foramen. Limitations of this study are that the subject was specialized group of people and the long-term follow up was impossible. In addition, the result of the surgery is largely dependent on the proficiency of surgeon, but this research used data from three different surgeons’ cases. Despite all the limitations, this research provided insights for usability, stability, and limitation of the extreme lateral endoscopy compared to the previous endoscopic approach.
As young patients have soft intervertebral disc protrusion and less degenerative change, ELELD would replace the discectomy through laminectomy, but if the herniated disc migrates higher than the lower vertebral height in either upward or downward, or sequestrated, the removal of the herniated disc is extremely difficult, so the discectomy through laminectomy may be considered. As osteophyte due to the apophyseal ring fracture occurs frequently to the young patients, pre-operational CT scan must be performed and the discectomy through laminectomy or posterior lumbar interbody fusion is recommended.
This work was supported by a grant of the Korea Health Technology Research and Development Project, Ministry for Health and Welfare Affairs (H114C3270).
This work was supported by a grant of the Korea Health Technology Research and Development Project, Ministry for Health and Welfare Affairs (HR16C0002).
Skin window. Skin window should be over the posterior facet line in the lateral projection for prevention of peritoneal perforation.
Abdomen computed tomography. Computed tomography shows needle trajectory from the skin window. The distance from the midline to skin window is approximately 8 to 10cm in posterolateral approach (
Location of needle. The needle is positioned at inner pedicular line on the anteroposterior view (
Location of needle. The needle is replaced by a guide wire followed by an obturator and a final working cannula in that sequence.
Visual analogue scale (VAS). The average VAS pain score was reduced from 8.92±1.20 to 2.38±1.55 (p<0.05).
Skin entry and trajectory for L5-S1 endoscopic discectomy. At L5-S1 percutaneous endoscopic lumbar discectomy, skin entry is located above iliac crest, trajectory line is angled inferiorly.
Level of disc herniation
Number (%) | |
---|---|
L3/4 | 9 (6.7) |
L4/5 | 100 (74.1) |
L5/S1 | 26 (19.3) |
Total | 135 (100) |
Type of disc herniation
Number (%) | |
---|---|
Central | 33 (24.4) |
Posterolateral | 85 (63.0) |
Foraminal | 17 (12.6) |
Total | 135 (100) |
Type and degree of disc herniation
Number (%) | |
---|---|
Non-migration | |
<50% canal compromise | 75 (55.1) |
>50% canal compromise | 24 (17.6) |
Migration | |
Low grade | 28 (20.6) |
High grade | 9 (6.6) |
Total | 136 (100) |
Operative results
Excellent | Good | Fair | Poor | % | |
---|---|---|---|---|---|
Non-migration | |||||
<50% canal compromise | 33 | 38 | 3 | 1 | 94.6 |
>50% canal compromise | 2 | 18 | 3 | 1 | 87 |
Migration | |||||
Low grade | 11 | 15 | 1 | 1 | 92.9 |
High grade | 0 | 5 | 2 | 2 | 55.6 |
Total | 69 | 8 | 6 |
%: success rate.
Complication
Number (%) | |
---|---|
Discitis | 1 (0.7) |
Dural laceration & CSF leakage | 2 (1.5) |
Root injury | 2 (1.5) |
Dysesthesia | 27 (19.7) |
Incomplete removal | 3 (2.2) |
Disc space collapse | 2 (1.5) |
Recurrent | 0 (0.0) |
None | 100 (73.0) |
Total | 137 (100) |
CSF: cerebrospinal fluid.