Introduction: Use of Selective Nerve Root Block (SNRB) in lumbar region to relieve radicular pain along the course of a particular nerve is being practiced in the recent past. We observed and tabulated therapeutic outcomes of this procedure in management of radiculopathy induced by a prolapsed disc affecting a particular lumbar nerve root.

Methods: 40 patients with various grades of disc prolapse affecting a particular lumbar nerve root presenting with chronic radicular pain were identified irrespective of age and sex. All were injected with a combination of 40 mg of Methylprednisolone based suspension with local anaesthetic over the affected nerve root and results were analyzed.

Results: Those graded mild had 4.3 months relief and those graded moderate had 2.5 months relief. Those with severe disc prolapse had no relief except for the immediate postprocedural relief. Only 20% patients had relief up to 6 months.

Conclusion: Effect of SNRB is typically short acting in majority of patients and recurrence is expected. It creates a window period with reduced pain but of varied intervals depending on the pathology. It did not alter the prognosis in those with severe disease where surgery is well indicated.

Level of Evidence–Level 4

Keywords: Selective Nerve Root Block, Disc prolapse, Radicular Pain, Lumbar Radiculopathy

Introduction

Lumbar radiculopathy can be defined as pain from lower back radiating until the leg or further beyond along the course of a particular lumbar nerve. Selective Nerve Root Block (SNRB) is practiced as a part of the management of radicular pain due to a particular affected nerve root in both cervical and lumbar regions 1-3. Although its specificity as a diagnostic tool is said to be low, Therapeutic efficacy needs to be debated 4, 5. It is used invariably for those with or without significant surgical spinal lesions 6. Mechanical lesions include various stages of disc prolapse, ligamentum flavum hypertrophy, facet hypertrophy and degenerative osteophytes causing foraminal stenosis, all leading to nerve root irritation 7. Inflammatory response to exposed nucleus pulposus is also said to contribute to the nerve root pain 7. The principle behind this technique is to reduce inflammation of the nerve root by injecting a steroid and thus reducing the intensity of pain. But the actual pathology causing the nerve root irritation remains and hence recurrence is expected. Our aim is to study the prognosis after single dose of SNRB over affected lumbar nerve roots and find out whether a window period of reduced pain be achieved before proceeding to next line of management.

Materials and Methods

Selection criteria of our patients were irrespective of age and sex. Those patients with complaints of lumbar radiculopathy for more than 3 months demonstrating a positive unilateral Straight Leg Raising test (SLRT) within 30-60 degrees were selected. MRI was done in all patients as a standard protocol to look for mechanical lesions. Only those patients with intervertebral disc lesions affecting a particular lumbar nerve root were selected for the study. Those with more of back pain component than radiating pain were excluded. Those with bilateral symptoms, multiple nerve root involvement and neurological weakness were excluded. We used the MSU Classification for herniated lumbar discs on MRI to grade our patients (Table I) 8.