Low back ache and lumbar radiculopathy are common problems that affect most individuals at sometime during their lives. The estimated prevalence of lumbar radiculopathy has been described as 9.8 per 1,000 cases of low back pain. ^[1] Intervertebral disk herniation and degenerative lumbar spinal stenosis are the two most common causes of lumbar radiculopathy. ^[2] While lumbar radiculopathy secondary to disc herniation resolves spontaneously in 23% to 48% of patients, 5% to 15% of patients undergo surgery, resulting in a strain on the health care system and subsequently, the economy. ^[3] Various conservative, nonsurgical modalities for treating lumbar disc herniation or radicular pain exist, including epidural injections. Data from the Spine Patient Outcomes Research Trial (SPORT) evaluation reported the clinical and cost effectiveness of lumbar disc herniation surgery. ^[4] Surgery is associated with failure in approximately 25% of patients in well selected cases. Due to comorbid factors, not everyone who is symptomatic is a surgical candidate; some disc protrusions and small disc herniations are not amenable to surgical interventions. ^[5]

Noninvasive methods include pharmacologic and non-pharmacologic approaches. Pharmacologic therapy includes use of various drugs such as Acetaminophen, NSAIDs, Opioid analgesics, Skeletal muscle relaxants, Tricyclic antidepressants, Gabapentin and others. ^[6] Non pharmacologic therapy includes acupuncture, exercise therapy, massage, yoga, physical therapy etc. Invasive methods include administration of epidural steroid injection and surgical intervention. ^[7]

Epidural injection is one of the most common nonsurgical treatments for lumbar disc herniation. ^[8] Epidural injection of corticosteroids is one of the most commonly used interventions in managing chronic low back pain. Steroids presumably exert their effects by limiting inflammatory response, inhibiting leukocyte aggregation, preventing degranulation of inflammatory mediators, stabilizing lysosomal and other membranes, and reducing the synthesis and release of proinflammatory factors. ^[9]

Epidural injections are administered by accessing the lumbar epidural space by multiple routes including interlaminar, caudal, and transforaminal. While significant differences have been described between these 3 approaches, interlaminar entry is considered to deliver the medication closely to the assumed site of pathology, even though the transforaminal approach is considered the target specific modality requiring the smallest volume to reach the primary site of pathology. ^[10] Caudal epidural is considered as the safest and easiest with minimal risk of inadvertent dural puncture, and preferred modality in post-surgery syndrome, even though requiring relatively high volumes. Increasing emphasis is placed on fluoroscopically guided, target specific injections to improve treatment outcomes. ^[11]

The present study was designed to compare the efficacy of Transforaminal Versus Interlaminar Approaches to Epidural Steroid Injections for Symptomatic Lumbar Intervertebral Disc Herniation.

AIMS

To evaluate and compare clinical outcome of TFESI versus ILESI for symptomatic lumbar disc prolapse in a prospective outcome study.

This is prospective study consist of 60 patients of 18 to 60 years of age are enrolled suffering with symptomatic lumbar Intervertebral disc herniation at BGS Global Institute of Medical Sciences, Bangalore. over a period of 1 year. Each participant underwent a thorough standard evaluation by a single orthopedician which included an evaluation of their clinical history, physical examination, x-rays, magnetic resonance imaging (MRI).

 Inclusion Criteria

• Chief complaint of low back pain radiating to one lower extremity
• Failed analgesic and nonpharmacologic therapy trial of at least one Month
• Duration of current back and leg pain for greater than one month and less than a year
• Symptoms due to acute disc disease with prolapse
• Correlation between the clinically determined level(s) of radiculopathy and the findings on MRI.
• Inability to tolerate physical therapy or no benefited from ongoing physical therapy

 Exclusion Criteria

• Previous lumbar spine surgeries or epidural steroid injections in the previous 6 months
• Multilevel degenerative spine disease, unstable spine, spondylolisthesis (> grade 1), spondylolysis
• Cauda equina syndrome, arachnoiditis, progressive neurologic deficit
• Central spinal canal stenosis (congenital or acquired) from other origins, vertebral compression fracture(s)
• Active cancer diagnosis, history of substance abuse, current psychiatric co- morbidity, pregnancy
• Myelographic contrast allergy, steroid allergy, local anesthetic allergy

METHODS OF COLLECTION OF DATA –

During the above said period 60 patients with low back pain satisfying the inclusion criteria are selected. The Patients are randomly allocated to one of the two groups of 30 patients each. Group IL – For interlaminar approach, Group TF- For transforaminal approach Patients are explained about the procedure and informed and written consent obtained. Routine NPO protocols are followed. Intravenous line is secured. Following monitors are connected – NIBP, SpO2, ECG.

Place the patient prone on a pain management table. Aseptically prepare the skin area with isopropyl alcohol and povidone- iodine several segments above and below the laminar interspace to be injected. Drape the area in a sterile fashion

TECHNIQUE FOR INTER LAMINAR LUMBAR EPIDURAL INJECTION

Under anteroposterior fluoroscopy guidance, identify the target laminar interspace. using a 27 gauge, 1/4 –inch needle, anaesthetize the skin over the target interspace on the side of the patients pain with 1 to 2ml of 1% preservative – free lidocaine without epinephrine.

Insert a 23-guage, 3 ½ - inch spinal needle vertically until contact is made with upper edge of the inferior lamina at the target interspace, 1 to 2 cm lateral to the caudal tip of the inferior spinous process under fluoroscopy.

 Anaesthetize the lamina with 2 ml of 1% preservative- free lidocaine without epinephrine. Anaesthetize the soft tissue with 2ml of 1% lidocaine as the spinal needle is withdrawn.

Insert a 18 gauge 3 ½ - inch Tuohy epidural needle and advance it vertically with in the anesthetized soft tissue track until contact with the lamina has been made under fluoroscopy.

 “Walk off” the lamina with the Tuohy needle onto the ligamentum flavum. Remove the stylet from the tuohy needle, and attach a 10 – ml syringe filled halfway with air and sterile saline to the Tuohy needle. Advance the Tuohy needle into the epidural space using loss of resistance technique remove the stylet when loss resistance has been achieved. Aspirate to check for blood or CSF. If nether blood nor CSF is present, remove the syringe from the Tuohy needle and attached 5ml syringe containing 2ml of Iohexol dye. Conform epidural placement by producing an epidurogran with the dye. Inject 80 mg (2 mL) of methylprednisolone with 2 mL of normal saline.

TECHNIQUE FOR TRANSFORAMINAL LUMBAR EPIDURAL INJECTION

Under anteroposterior fluoroscopy guidance, identify the target interspace. Anaesthetize the soft tissues over the lateral border and midway between two adjacent transverse process at the target interspace.

 Insert a 23 gauge, 3 ^1/2 –inch spinal needle and advance it with in the anaesthetize soft tissue track under fluoroscopy until contact is made with the lower adge of the superior transverse process near its junction with superior articular process. Retract the spinal needle 2 to 3 mm, redirect it toward the base of appropriate pedicle, and advance its slowly to the 6 0’clock position of the pedicle under fluoroscopy. Adjust the C – arm to a lateral projection tobconform the position and then return the C – arm to the AP view. Remove the stylet, inject 1ml iohexol (Non ionic contrast agent) slowly to produce a perineurosheathogram

After an adequate dye pattern is observed, inject slowly 80 mg (2 mL) of methylprednisolone with 2 mL of normal saline is injected.

 Patient monitored for 15 mins after the procedure and observed for immediate side effects, if any Primary outcome: pain relief at the end of 2nd and 3rd week after the epidural steroid injection using Numerical Rating Scale (NRS) and Verbal Rating Scale (VRS) Secondary outcome: Pain relief immediately after the epidural steroid injection by NRS, VRS, Straight leg raising test (SLRT) Improvement in walking tolerance, Reduction in analgesic use, reversal of paranesthesia.

Table no. 01: Comparison of age group distribution between the two groups

 Table no. 02: Comparison of sex distribution between the two groups

The mean age of the patients in this study in Group TF was 39.4±10.7 years and in Group IL was 41.4±12.0 years. The sex distribution in the 2 groups were similar with 19 males and 11 females in each group.

Table no. 03: Comparison of laterality of radicular pain between the two groups

In Group IL, 19 patient suffered from left lower limb radicular pain and 11 patients had right lower limb radicular pain. In Group TF, 20 patients presented with left lower limb radicular pain and 10 patients had right lower limb radicular pain.

 Table no. 04: Comparison of Level of approach between the two groups

Among the sixty patients, most patients had herniation at the level of L4-L5 i.e 20 patients in Group IL and 21 patients in Group TF.

Table no.05: Comparison of Numerical Rating scale for pain between the two groups

NRS 15 mins after epidural steroid injection reduced from 7.77±1.2 (pre- procedure) to 6.93±1.1 in Group IL and from 7.8±1.3(pre-procedure) to 6.7±0.8 in Group TF. The difference among the 2 groups was not significant (P value-0.354) In Group IL, NRS decreased from 7.77±1.2 (pre-procedure) to 4.73±1.1 and 4.27±1.5 at the end of 2^nd and 3^rd week respectively. In Group TF, NRS decreased from 7.8±1.3 (pre- procedure) to 2.77±1.7 and 2.63±1.7 at the end of 2^nd and 3^rd week respectively. This difference in NRS was statistically significant both at the end of 2^nd week and 3^rd week with a P value of 0.001 with Group TF having better pain relief.

Table no. 06: Comparison of Verbal Rating Scale for pain between the two groups

VRS 15 mins after epidural steroid injection reduced from 2.3±0.5(pre- procedure) to 2.37±0.6 in Group IL and from 2.47±0.7(pre-procedure) to 2.3±0.8 in Group TF. This difference was not found to be significant (P value- 0.909). In Group IL, VRS improved from 2.3±0.5 (pre-procedure) to 1.1±0.8 and 1.13±0.8 at the end of 2^nd and 3^rd week respectively. In Group TF, it improved from 2.47±0.7 (pre-procedure) to1.33±0.6 and 1±0.7 at the end of 2^nd and 3^rd week respectively. This difference in VRS was not statistically significant with a P value of 0.224 and 0.465 respectively. Among the 2 groups, the difference in VRS was not statistically significant.

Table no. 07: Comparison of improvement in Straight leg raising test between the two group

TL group (n=30) TF group (n=30) Mean SD Mean SD P value

In Group IL, Straight leg raising test (SLRT) pre-procedure, at fifteen minutes, at the end of 2^nd and 3^rd week after epidural steroid injection was 68.67±14.5, 70±12.5, 80±8.9 and 80±8.9 degrees respectively. In Group TF, it was 63.33±14.5, 67±11.5, 79.67±8.9 and 80.83±8.8 degrees.This difference was not found to be significant (P value>0.05).Among the 2 groups, the difference in the improvement in SLRT was not significant at 15 mins, end of 2^nd week or 3^rd week.

Table no. 08: Comparison of improvement in walking tolerance between the two groups

Table no.09: Comparison of Reduction of analgesic use between the two groups

Table no.10: Comparison of Reversal of paraesthesia between the two groups

 There was no statistically significant difference among the 2 groups with respect to improvement in walking tolerance, reduction in analgesic use and reversal of paraesthesia at the end of 3^rd week.

Table no.11: Comparison of Complication between the two groups

One patient in the IL group had a vasovagal reaction, 10 mins following the procedure which was treated with Inj.Atropine 0.6mg and i.v fluids. We did not encounter any other complication during the study.

show any significant difference in symptom duration between the two groups. There was also no significant difference in MRI findings, VRS, NRS indicating comparable baseline data in both groups. Of note, the interlaminar group had a lower VRS score compared to the transforaminal group prior to the procedure, but the difference did not reach statistical significance. Therefore, the patients in this trial were matched for pre-injection VNRS scores, MRI finding and symptom duration.

Watts and Silagy (2015) ^[12] in a meta- analysis of efficacy of epidural corticosteroids in the treatment of sciatica, utilized 11 studies considered of good quality, including a total of 907 patients, and concluded that quantitative evidence from meta- analysis of pooled data from randomised trials illustrated that epidural administration of corticosteroids was effective in the management of lumbosacral radicular pain. Similarly, we used methylprednisolone (80 mg) made upto 4ml with saline in both the groups

Williamson A & Hoggart B (2015) ^[13] compared three commonly used pain rating scales-NRS, VRS and VAS. They concluded that all three pain-rating scales are valid, reliable and appropriate for use in clinical practice, although the Visual Analogue Scale has more practical difficulties than the Verbal Rating Scale or the Numerical Rating Scale. For general purposes, the Thomas et al (2013) ^[14] conducted a randomized, controlled trial on thirty- one patients with discal radicular pain of less than 3 months duration. Patients were consecutively randomized to receive either radio-guided transforaminal or blindly performed interspinous epidural corticosteroid injections. Post- treatment outcome was evaluated clinically at 6 , 30 days, and 6 months. Outcome measures consisted of pain, functional status assessment. At day 30 and 6 months, pain relief, daily activities, work, leisure activities, anxiety, and depression, were better in transforaminal group. ^[15] They concluded that transforaminal epidural steroid injection was more effective.

In our study, the primary outcome was to assess pain relief between the two groups-IL and TF at the end of 2^nd and 3^rd week by using numerical rating scale and verbal rating scale.In Group IL, NRS decreased from 7.77±1.2 (pre-procedure) to 4.73±1.1 and 4.27±1.5 at the end of 2^nd and 3^rd week respectively. In Group TF, it decreased from 7.8±1.3 (pre- procedure) to 2.77±1.7 and 2.63±1.7 at the end of 2^nd and 3^rd week respectively. This difference in NRS was statistically significant both at the end of 2^nd week and 3^rd week with a P value of 0.001 with Group TF having better pain relief.

In Group IL, VRS improved from 2.3±0.5 (pre-procedure) to 1.1±0.8 and 1.13±0.8 at the end of 2^nd and 3^rd week respectively. In Group TF, it improved from 2.47±0.7 (pre-procedure) to1.33±0.6 and 1±0.7 at the end of 2^nd and 3^rd week respectively. This difference in VRS was not statistically significant with a P value of 0.224 and 0.465 respectively.

Michael K. Schaufele et al(2006) ^[16] conducted a case control study - Interlaminar versus Transforaminal epidural injections for the treatment of symptomatic lumbar vertebral disc herniations. In the transforaminal group, there was a statistically significant improvement in the NRS scores from before the injection (NRS mean 5.9) to immediately i.e 1 hour after the injection (NRS mean 2.9, p<0.01). In the interlaminar group, there was a statistically significant improvement in the NRS scores from before the injection (NRS mean 7.3) to immediately after the injection (NRS mean 3.1, p<0.01).

The post-injection VRS scores showed no statistical difference between the groups at post-injection, i.e. immediately after the injection. However, at follow-up there was a statistically significant difference between the two groups in the improvement in the VRS scores (p<0.01) in favor of the transforaminal group and these results are comparable with the present study. We agree with others that the more targeted delivery of the injectate along the inflamed spinal nerve is the most likely explanation for these better outcomes

In our study, most patients showed a improvement in SLRT of about 20⁰ in both the groups by the end of 3^rd week. The improvement in SLRT was almost equal in the 2 groups and hence, the difference in the improvement of SLRT between the 2 groups was not statistically significant. There are no studies available in literature so far, comparing the 2 routes with respect to SLRT.

As far as short term benefit is considered, 80% of patients in IL group in our study had improved walking tolerance as compared to 66.67% of patients in TF group. 33.3% patients reported reduction in analgesic use in Group IL as compared to 23.3% in Group TF. 10 patients out of 14 in Group IL and 11 patients out of 17 in Group TF had reversal of paresthesia. The difference between the 2 groups, with respect to the above parameters were not statistically significant.

Patients who received a transforaminal epidural steroid injection for the treatment of symptomatic lumbar disc herniation had significantly better short-term pain improvement and equal functional improvement when compared to Interlaminar epidural steroid. After evaluation, it can be concluded that, Epidural steroid injection by transforaminal technique provides better subjective pain relief in the short term

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