Radicular Pain Simplified

On March 10 2026, I posted an article in response to Quora Question about radicular pain and the value of physiotherapy. I have expanded the text somewhat for this Blog. The reference list I provide is selective and incomplete, but does give a brief idea of the spread of published information on the subject, going back to the mid-1980s.

“Radicular pain” is the term used to describe the pain experienced when a spinal nerve is compressed or irritated - usually by a prolapsed or herniated disc. Most cases involve the lumbar spinal nerves, and a smaller proportion involves the cervical spinal nerves.  Lumbar radicular pain is usually dominant in the buttock and/or lower limb and is aggravated by tension being applied to the nerve, such as in the straight leg raise or slump test. Cervical radicular pain is typically dominant in the scapula and upper limb. The median nerve upper limb tension test usually provokes the dominant pain, and sometimes the radial nerve test hurts more.

Figure 1 is the pain drawing from a patient with acute lumbar radicular pain with MRI showing the L4/5 disc (Figure 2).

Figure 1. Acute right mid-lumbar radicular pain

Figure 2. MRI of the patient with the pain drawing in Figure 1.

Figure 3. Acute right C6/7 radicular pain.

Figure 4. MRI of the patient with cervical radicular pain and pain drawing of Figure 3.

Sometimes, pressure on the nerve is sufficient to produce radiculopathy, which is the term used to designate clinical evidence of pressure on the spinal nerve, such as key muscle weakness, a clear loss of sensory capacity in the distribution of the spinal nerve or an absent tendon reflex.

Radicular pain can occur in the absence of radiculopathy. This is usually caused by an inflammatory response around the spinal nerve, without significant or sustained pressure on the nerve. Most physiotherapists can examine the patient to determine if the diagnosis is radicular pain alone or radicular pain with radiculopathy. Suitably trained physiotherapists can carry out a repeated movements assessment to see if the pain may be centralised from the lower leg to closer to the spine, or not. If pain centralisation[1-5] can be achieved, the therapist can teach the patient which movements and postures can continue the process. Sometimes, manipulative therapy techniques such as the lateral shift correction or other mobilisations are needed to assist the centralisation of symptoms. If centralisation of symptoms is achievable within a week or so, the prognosis is very good, and physiotherapy interventions guided by the direction of movement that achieved the centralisation will likely be rapidly successful. No other treatment would be required.

If centralisation of symptoms is not rapidly achievable, other interventions such as epidural injection and use of various medications can help with the pain[6-8]. About 75% of patients with acute radicular pain recover spontaneously in 3–6 months, with or without any treatment. In other words, the natural history is rather good[9]. For 10–15% of cases, surgical removal of the prolapsed disc is the best way forward. Which mix of treatments to use is a matter of patient choice and availability of suitably trained clinicians.

If the pain of acute severe radicular syndrome cannot be centralised, guided epidural injection at the level of the affected spinal nerve is highly successful in over 40% of cases. Just under 40% have the source of symptoms confirmed by a positive local anaesthetic effect, but the corticosteroid is not effective. Those responding to epidural corticosteroid are conveniently labelled “Inflammatory” radicular syndrome. Those reporting no benefit from corticosteroid epidural injection are conveniently diagnosed as having “Mechanical” radicular syndrome, meaning that the pain is largely due to direct pressure and tension on the nerve root from the herniated disc[8]. The line graph of inflammatory and mechanical type radicular pain responses to epidural injection is in the published paper[8], and is reproduced here in Figure 5.

Figure 5. from Laslett, Kennedy, Shackel, Johnson, Boet & McDonald 2025

References

1.            Kopp JR, Alexander AH, Turocy RH, Levrini MG, Lichtman DM: The use of lumbar extension in the evaluation and treatment of patients with acute herniated nucleus pulposis. Clin Orthop 1986, 202(January):211-218.

2.            Alexander AH, Jones AM, Rosenbaum MC: Nonoperative Management of Herniated Nucleus Pulposis. Patient selection by the extension sign- long-term followup.  . In: Annual meeting of ISSLS,. Boston, MA, USA; 1990.

3.            Peul WC, van Houwelingen HC, van den Hout WB, Brand R, Eekhof JA, Tans JT, Thomeer RT, Koes BW: Surgery versus prolonged conservative treatment for sciatica. N Engl J Med 2007, 356(22):2245-2256.

4.            Donelson R, Silva G, Murphy K: Centralisation phenomenon - Its usefulness in evaluating and treating referred pain. Spine 1990, 15:3, 211-213.

5.            Long A: The centralization phenomenon: Its usefulness as a predictor of outcome in conservative treatment of low back pain: A pilot study. Spine 1995, 20:2513-2521.

6.            van Helvoirt H, Apeldoorn AT, Knol DL, Arts MP, Kamper SJ, van Tulder MW, Ostelo RW: Transforaminal epidural steroid injections influence Mechanical Diagnosis and Therapy (MDT) pain response classification in candidates for lumbar herniated disc surgery. J Back Musculoskelet Rehabil 2016, 29(2):351-359.

7.            van HH, Apeldoorn AT, Knol DL, Arts MP, Kamper SJ, van Tulder MW, Ostelo RW: Transforaminal epidural steroid injections influence Mechanical Diagnosis and Therapy (MDT) pain response classification in candidates for lumbar herniated disc surgery. J Back Musculoskelet Rehabil 2016.

8.            Laslett M, Kennedy J, Shackel D, Johnson A, Boet R, McDonald B: Anaesthetic and corticosteroid response immediately following epidural injection in patients with MRI confirmed lumbar disc herniation. Musculoskelet Sci Pract 2025, 75.

9.            Weber H, Holme I, Amlie E: The natural course of acute sciatica with nerve root symptoms in a double-blind placebo-controlled trial evaluating the effect of piroxicam. Spine 1993, 18(11):1433-1438.