The aim of this study is to investigate the efficacy of adjuvant hypertonic saline to lumbosacral transforaminal epidural block in patients with lumbosacral radicular pain screened for neuropathic pain using DN4 questionnaire. 
Neuropathic pain cannot be clearly diagnosed but is presumed according to clinical symptoms since there are no biochemical markers for this condition. It has been found that neuropathic pain is distinguished from other chronic pain that has a combination of several characteristics.(burning pain, electrical pain, abnormal sensations, allodynia, etc.) Based on this, a number of simple symptom-based questionnaires have been developed to help select and screen patients with neuropathic pain. Douleur neuropathique en 4 questions (DN4) is a questionnaire that is most commonly used for screening and diagnosing neuropathic pain. It consists of a total of 10 items, 7 items related to the quality of pain and 3 items based on patient interviews. The DN4 questionnaire is easy to score and has proven to have excellent sensitivity (74-85%) and specificity (76-90%) in distinguishing between neuropathic and non-neuropathic (nociceptive) pain in many feasibility studies. This questionnaire has spread rapidly worldwide and is currently being translated and used in more than 90 languages, and its validity has been confirmed in many other languages ​​including Korea.
Meanwhile, in patients with chronic neuropathic pain, interventional treatments such as epidural nerve block and neuroplasty including epidural adhesiolysis may be performed as conservative treatments for pain control. In these epidural procedures, adjuvant hypertonic saline is sometimes added. In several studies, injection of hypertonic saline in epidural procedures has reduced the degree of pain, prolonged the pain reduction period, increased satisfaction, and decreased the frequency of additional procedures. The mechanism of pain reduction caused by hypertonic saline is speculated to cause blockage of nerves that transmit nociceptive stimuli by high concentration of chloride ions, and to reduce nerve swelling by osmosis. Still, the mechanism of hypertonic saline is not clearly identified, and data are insufficient.
Also, in many previous studies on epidural hypertonic saline, the subject was not clearly limited to neuropathic pain. This is because the researcher conducted a study on patients who judged neuropathic pain based on the patient's clinical symptoms such as radiating pain in which lesions were confirmed in the cervical and lumbar spine. Patients with cervical or lumbar disease may have some characteristics of neuropathic pain, but because nociceptive pain and neuropathic pain may be mixed, in some cases, patients who cannot be diagnosed as neuropathic pain may be included. Therefore, it remains a limitation that previous studies did not target patients identified as neuropathic pain using diagnostic tools whose validity had proven. In other words, there is no study on the effect of epidural hypertonic saline in patients with neuropathic pain screened by a validated questionnaire, such as DN4.
Therefore, we will investigate the effectiveness of adjuvant hypertonic saline in lumbosacral transforaminal epidural block in patients with chronic lumbosacral radicular pain screened for neuropathic pain using the DN4 questionnaire.

Treatment

After obtaining informed consent, the patient's condition is evaluated before the procedure, and the site lumbosacral spine to be performed is marked. After applying general monitoring device such as a pulse oximeter and a blood pressure cuff to the patient, the patient is placed in a prone position with a pillow under the lower abdomen in order to minimize lumbar lordosis and provide an easy approach to the intervertebral foramen. After sterile preparation and draping of the insertion area, the skin is infiltrated with 1% lidocaine and a 25-gauge, 3.5-inch spinal needle is gently advanced under fluoroscopic guidance. The oblique radiographic view is obtained to ensure proper positioning. Anatomic landmarks are identified, the needle is advanced and positioned in the upper quadrant of the target foramen located under the pedicle of the upper vertebral body. Anteroposterior and lateral views is obtained to confirm correct needle positioning, and special care is taken to prevent undesirable injection. After aspiration for blood or cerebrospinal fluid, a realtime fluoroscopically guided injection of 0.5–2.0 mL contrast dye is injected to confirm adequate flow to the epidural space and prevent further possible intravascular or intrathecal injection. After confirmation of correct needle positioning and adequate radiographic imaging, 3 mL of 1% lidocaine with 1,500 units of hyaluronidase was administered. Five minutes after the administration of local anesthetics and hyaluronidase, the patient is asked about any motor or sensory change in the ipsilateral and contralateral lower extremity. The study drugs is not administered to any patient presenting severe paresthesia or pain during injection and possible signs of intrathecal or intravascular local anesthetic administration. The hypertonic group received 3 mL of 5% sodium chloride solution mixed with 5 mg dexamethasone; the control group received 3 mL of 0.9% saline mixed with 5 mg of dexamethasone. The attending physician and the participating patient are unaware of the concealed study drug throughout the procedure. The patients are then sent to the outpatient post-anesthesia care unit for recovery, and additional post-procedure sensory testing and motor function evaluations are performed by a nurse or an anesthesiologist blind to the study group.

Arm Label

Target Number of Participant

Arm Type

Arm Description

In the hypertonic saline group (HS group), 3 mL of 5% hypertonic saline including 5 mg of dexamethasone is injected.

Arm Label

Target Number of Participant

Arm Type

Arm Description

In the normal saline group (NS group), 3 mL of 5% normal saline including 5 mg of dexamethasone is injected.

Gender

Age

Description

1) Patients with chronic lumbosacral unilateral radiating pain over 3 months
2) Patients with symptom-related unilateral 1-2 level lesions of the lumbosacral spine in radiologic examination (CT or MRI)
3) Patients screened for neuropathic pain by obtaining 4 points or more in DN4 questionnaire
4) Patients whose symptoms have not improved even after conservative treatment for more than 3 months
5) Patients with pain intensity of NRS 4 or higher
6) 20 ≤ age <80
7) Patients who voluntarily agreed in writing to participate in this clinical trial

1) Patients in acute phase with pain period less than 3 months
2) Patients whose pain intensity is less than 4 points or 10 points in NRS
3) When the axial pain is more severe than the radiating pain
4) Patients with progressive motor weakness or neurological findings
5) Those who are contraindicated in nerve block procedure, such as coagulopathy or infection
6) Patients with uncontrolled medical or psychiatric problems
7) Patients with side effects from local anesthetics, steroids, or contrast agents
8) Pregnant or lactating patients
9) Patients diagnosed with cancer and undergoing treatment
10) Patients with a history of surgery on the cervical spine
11) If the patient does not agree to participate in the study

NRS (Numerical rating scale, 0 = no pain, 10 = unbearable pain)

3 months after procedure

NRS (Numerical rating scale, 0 = no pain, 10 = unbearable pain)

1,6 months after procedure

ODI(0 – 50; 0 = no disability, 50 = complete disability)

1, 3 and 6 months after procedure

MQS (Medication quantification scale)

1, 3 and 6 months after procedure

PHQ-9 (patient health questionnaire-9)

1, 3 and 6 months after procedure

GPE (Global perceived effect, 1-7)

1, 3 and 6 months after procedure

Responder rate (0 – 100% of patients)

1, 3 and 6 months after procedure