ORIGINAL ARTICLE |
https://doi.org/10.5005/jojs-10079-1141 |
Effect of Intradiscal Methylene Blue Injection in Endoscopic Transforaminal Lumbar Discectomy
1–3Department of Orthopaedics, Tirunelveli Medical College, Tirunelveli, Tamil Nadu, India
Corresponding Author: Babu Aloy, Department of Orthopaedics, Tirunelveli Medical College, Tirunelveli, Tamil Nadu, India, Phone: +91 9489373767, e-mail: sankar836@gmail.com
Received: 27 November 2023; Accepted: 06 January 2024; Published on: 14 June 2024
ABSTRACT
Background: Low back pain reduces the quality of life. The most common cause is lumbar disc prolapse. Endoscopic discectomy is a minimally invasive procedure used to treat lumbar disc prolapse. The use of intradiscal methylene blue injection in endoscopic lumbar discectomy improves patient’s functional outcomes.
Aim and objective: To evaluate the functional outcome of methylene blue injection in the endoscopic transforaminal lumbar discectomy in lumbar disc disease patients and clinical improvement in the form of postoperative (postop) radicular pain relief, early return to daily activities, and occupation.
Materials and methods: A mixture of 1 mL 1% methylene blue and 1 mL 2% lidocaine. A 30° spinal endoscope with a working channel of 4.1 mm was used in this study. Study design prospective cohort study. A total of 20 patients with lumbar disc prolapse operated with transforaminal endoscopic lumbar discectomy with methylene blue injection. According to pain improvement, functioning abilities, and clinical symptoms, results were done based on the modified Oswestry disability index.
Results: In our study, 90% of patients have postop radicular pain relief within 1 week. Around 85% of patients returned to their normal daily day-to-day activities within 3 weeks. Around 80% of patients returned to their work within 4 weeks. Around 75% of patients had neurological recovery in between 3 and 5 weeks. The modified Oswestry disability index in preop and postop patients were studied. The mean value significantly decreased from 69.5% in preop to 31.5% in postop conditions. The p-value is 0.00 (p-value < 0.05) and significant. In Macnab’s criteria, our study shows an excellent to good outcome of 75%.
Conclusion: This study showed that the use of intradiscal methylene blue injection in endoscopic transforaminal lumbar discectomy gives good radicular pain relief. It improves the accuracy and efficacy of endoscopic spine surgery.
How to cite this article: Pirabakaran S, Aloy B, Pavanasam M. Effect of Intradiscal Methylene Blue Injection in Endoscopic Transforaminal Lumbar Discectomy. J Orth Joint Surg 2024;6(2):87–92.
Source of support: Nil
Conflict of interest: None
Keywords: Endoscopic discectomy, Methylene blue, Lumbar disc disease.
INTRODUCTION
Low back pain reduces the quality of life. The most common cause is lumbar disc prolapse. In developed nations, the lifetime prevalence of nonspecific low back pain was believed to be 60–70%.
Between the ages of 35 and 55, the prevalence rises to a high. Endoscopic discectomy is a minimally invasive procedure used to treat lumbar disc prolapse. The use of intradiscal methylene blue injection in endoscopic lumbar discectomy improves patient’s functional outcomes.1,2
Between the ages of 35 and 55, the prevalence rises to a high. Endoscopic discectomy is a minimally invasive procedure used to treat lumbar disc prolapse. The use of intradiscal methylene blue injection in endoscopic lumbar discectomy improves patient’s functional outcomes.1,2
MATERIALS AND METHODS
Our study is a cohort study done in the Department of Orthopaedics, Tirunelveli Medical College, Tirunelveli, Tamil Nadu, India, from December 2020 to 2022.
Our study includes a total of 20 cases. All the patients were treated with transforaminal endoscopic lumbar discectomy with methylene blue injection.
All patients were followed up on a regular basis. According to pain improvement, functioning abilities, clinical symptoms, and treatment results were done based on the modified Oswestry disability index, 3 which has four categories—excellent, good, fair, bad, and Macnab criteria. After institutional board approval, the patients were enrolled prospectively.
Materials
A mixture of 1 mL 1% methylene blue and 1 mL 2% lidocaine had been used. A 30°spinal endoscope and 4.1 mm working channel were used.
Inclusion Criteria
Age >18 years.
Clinically proven lumbar disc confirmed by magnetic resonance imaging (MRI).
Exclusion Criteria
Prior lumbar spine surgery at the afflicted level.
Spinal infection, malignancy, and neurological illness.
Lumbar disc patients with instability.
Sequestrated disc.
METHYLENE BLUE MECHANISM
Methylene blue is a liposoluble dye. Direct inhibitor of nitric oxide (NO) synthase inhibits NO production and inhibits the inflammatory process of disc degeneration and discogenic pain (Fig. 1).3,4
Fig. 1: Methylene blue dye
It spreads into radial fissures of the nucleus pulposus and destroys the free nociceptive nerve endings for relief of pain. It is acidophilic and stains the nucleic acids of any dead cells. This helps distinguish viable and nonviable tissues, particularly those inside a disc.
During surgery, if the tissue is blue, it is nonviable and probably should be removed. MB prevents postop perineural fibrosis, which may be responsible for the recurrent pain after discectomy.3,5
Side Effects
It has a strong neurotoxic impact when delivered intrathecally or epidurally in high dosages. Excessive injection may cause nerve root discoloration and toxic effects.4
Operative Technique
True anteroposterior (AP), lateral fluoroscopy is mandatory. The adjacent vertebral body’s endplates should be parallel. A vertical line is drawn using the spinous process. A horizontal line is drawn on the disc level in AP view. Two lines should intersect onto the affected disc (Fig. 2).
Fig. 2: Image intensifier—horizontal and vertical line
Marking the Entry Point
A 17G spinal needle is presented until it comes to the border between a cranial portion of the caudal pedicle and superior articular process (SAP) (Figs 3 and 4).
Fig. 3: Marking entry point
Fig. 4: 17 G spinal needle position
For access to L4–5: 12 cm from the midline.
For L5–S1: 10 cm from the midline.
For L3–4: 10 cm from the midline.
For L2–3: 10 cm from the midline.
For L1–2: 8 cm from the midline.
A 1.5 mm guidewire was introduced through the spinal needle across the superior articulate process on the lateral view up to the medial pedicular line on the AP view.
Discography done with Iohexol radiopaque dye—confirmed the presence of a needle inside the disc (Fig. 5). Around 1 mL of 1% methylene blue and 1 mL of 2% lignocaine mixer were introduced through a spinal needle. It will stain the degenerated disc a blue color (Fig. 6).
Fig. 5: Discography
Fig. 6: Methylene blue injection and bluish discolorations of disc
A 30°spinal endoscope with a 4.1 mm working channel is inserted through the working portal.6
We can visualize the exiting nerve root by turning the working tube cranially. Epidural venous bleeding can be controlled by a radiofrequency ablation (RFA) probe.3
OBSERVATIONS
The observations and results from the study are as follows:
The age of patients in this study ranges from 40 to 65. The mean is 52 years (Table 1).
Out of a total of 20 patients, males were 14 in number and females 6 in number (Table 2).
Duration is >1 year in 4 cases and 6 months to 1 year in 12 cases. Less than 6 months in 4 cases (Table 3).
Radicular pain in lower limbs was experienced by 20 individuals (Table 4).
Sciatic scoliosis affected one of the individuals in this study.7,8
All 20 patients in this study were found to be straight leg-rising test (SLRT) positive (+ve).
| Age | <50 years | 50–60 years | >60 years |
|---|---|---|---|
| No. of patients | 7 | 7 | 6 |
| Percentage | 35% | 35% | 30% |
| Sex | Male | Female |
|---|---|---|
| No. of patients | 14 | 6 |
| Percentage | 70% | 30% |
| Duration of symptoms | <6 m | 6 months to 1 year | >1 year |
|---|---|---|---|
| No. of patients | 4 | 12 | 4 |
| Percentage | 20% | 20% | 60% |
| Symptoms | Low back pain | Radiculopathy | Neurological deficit |
|---|---|---|---|
| No. of patients | 20 | 20 | 8 |
Well-leg-raising Test
In five individuals, the well-leg-lifting test was positive and was pathognomonic of disc prolapse. Neurological signs were seen in 8 patients. A total of 17 patients had limitations in spinal movements (Table 5).
| Signs | Sciatic scoliosis | SLRT + ve | Well-leg-raising test+++ | Neurological signs | Limitation of spinal movements |
|---|---|---|---|---|---|
| 1 | 20 | 5 | 8 | 17 |
SLRT, straight leg rising test
Level of Disc Involvement
The most prevalent level of disc herniation was L4–5, which accounted for 19 cases. L5–S1 is the next most frequent lesion, accounting for 4 cases. L3–L4 level in one case.
POSTOPERATIVE OUTCOME ANALYSIS
Postoperative Radicular Pain Relief
Out of 20 patients, radicular pain disappeared in <7 days for 18 patients (Fig. 7).
Fig. 7: Postoperative radicular pain relief
Return to Daily Activities
Out of 20 patients, 8 patients returned to daily activities in 3 weeks. A total of 12 patients returned to daily activities in >3 weeks.
Out of 20 patients, 7 patients returned to their work within 4–6 weeks; patients returned to their work in >6 weeks (Fig. 8).
Fig. 8: Return to daily activities
Neurological Recovery
Out of 8 neurological deficit patients, 5 had sensory deficits, which improved in 3 months. Out of 3 motor deficit patients, 1 patient recovered in 3 months, and 2 patients recovered after 3 months.
Complications
Superficial infection of the surgical site was identified in one patient and was managed successfully with antibiotics. No deep-seated infection was experienced. One patient ended up with failed back syndrome due to incomplete removal and was treated with open discectomy (Table 6).
| Complications | Superficial infection | Failed back syndrome |
|---|---|---|
| No. of patients | 1 | 1 |
RESULTS
There was a significant decrease in disability in postop compared to preop among subjects. In crippled and pain impinges conditions showed a decrease from 55% in preop to 5% in postop. Patients with severe disability in preop was 30% and in postop 10%. The modified Oswestry disability index for preop and postop were studied among subjects. The mean value significantly decreased from 69.5% in preop to 31.5% in postop conditions. The p-value is 0.00 (p-value < 0.05) and statistically significant (Tables 7 to 9) and (Fig. 9).
| Preop | Frequency | Percentage |
|---|---|---|
| Severe disability | 6 | 30.0 |
| Cripple pain impinges on all aspects of patient’s life | 11 | 55.0 |
| Patients are bedbound or exaggerating their symptoms | 3 | 15.0 |
| Total | 20 | 100.0 |
| Modified Oswestry disability index | Mean | N | Standard deviation | t-value | p-value |
|---|---|---|---|---|---|
| Pre | 69.9500% | 20 | 12.36921% | 11.560 | 0.000 S |
| Post | 31.3500% | 20 | 19.84221% |
| Outcome | Excellent | Good | Fair | Poor |
|---|---|---|---|---|
| No. of patients | 7 | 8 | 3 | 2 |
| Percentage | 35% | 40% | 15% | 10% |
Fig. 9: Results
DISCUSSION
Major patients are between the ages of 40 and 60. Subjective sensory abnormalities in the form of numbness or paresthesia were observed in the majority of individuals. The most common disc involvement was L4–L5. The majority of patients’ symptoms appear as gradual onset.
As per the assessment of the modified Oswestry disability index, the postop disability score was drastically reduced with the use of methylene blue in our procedure. Preop, 55% of the patients were found to be moderately disabled (Table 7), and postop, it was reduced to 5% (Table 10), which was statistically proved by the p-value (0.000).
| Postop | Frequency | Percentage |
|---|---|---|
| Minimal disability | 7 | 35.0 |
| Moderate disability | 9 | 45.0 |
| Severe disability | 2 | 10.0 |
| Cripple pain impinges on all aspects of patient’s life | 1 | 5.0 |
| Patients are bedbound or exaggerating their symptoms | 1 | 5.0 |
| Total | 20 | 100.0 |
Around 95% of the patients were discharged home in <1 week, and the remaining 5% in 1–2-week duration.
All patients who underwent endoscopic transforaminal lumbar discectomy showed great results in terms of pain relief, return to regular activities, and disability reduction. Almost two-thirds of the patients got pain relief within 1 week after surgery.
A direct correlation was observed between the age of the patient and pain relief in days in our study.
Concerning neurological recovery, all patients with sensory deficits recovered within 3 months after surgery, and one-third of the patients with motor deficits recovered within 3 months. More than half of the patients returned back to normal activity within 4 weeks. Female patients show early recovery than male patients.
According to another study, endoscopic discectomy has clear advantages over open surgery in terms of hospital stay, blood loss, postop pain, and epidural fibrosis. Methylene blue is associated with fewer intraoperative and postop complications.8 Our study shows an excellent to good outcome of 75% when compared to the previous study conducted by Jhala and Mistry’s by transforaminal endoscopic lumbar discectomy without using methylene blue.
When compared with the Tang et al. study,5 which yielded 70–80% excellent to good outcomes with methylene blue use, our study also positively correlated with the above study.
A few randomized control studies have shown that endoscopic discectomy produces better results than other procedures. The advantages of endoscopic surgery include a short hospital stay, low morbidity, and quick recovery.
According to our findings, using methylene blue in this procedure provides additional benefits such as faster pain relief and improved accuracy. Around 90% of our study subjects were free from postop complications. Patients ended up with failed back syndrome due to incomplete removal and were treated with open discectomy.8
Our study observes that the use of methylene blue improves the accuracy of surgery by coloring the degenerated disc. So that the surgeon could easily identify and remove the degenerated disc.
According to Butkraemer et al., the adverse effect of methylene blue due to dye extravasation results in headache, vomiting, nausea, confusion, shortness of breath, high blood pressure, and blue-green discoloration of urine, sweat, and stool.8
CONCLUSION
Helped fully with the removal of the disc.
Good pain relief and curative effect for the patients.
Makes the surgery faster and safer.
Improves the accuracy and efficacy of the endoscopic spine surgery.
Lower postop morbidity, shorter hospital stay, and lower expenditures.
Observance of ethical guidelines.
Tirunelveli Medical College’s Institutional Ethics Committee (tirec)-refno-1889 has approved the study. Before inclusion, all patients provided written informed consent.
ORCID
Sankarnath Pirabakaran https://orcid.org/0009-0001-7747-420X
Babu Aloy https://orcid.org/0009-0006-6496-8274
Manikandan P https://orcid.org/0009-0000-0814-9385
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