Radicular Pain

Definition

Pain evoked by ectopic discharges emanating from a dorsal root or its ganglion (Bogduk, 2009).

Cause

Herniation of a lumbar disc is the most common cause, with inflammation of the affected nerve (Bogduk, 2009).

Presentation

• Lancinating, electric shock like pain
• Travelling along the length of the lower limb (Bogduk, 2009)

Radiculopathy

Definition

Radiculopathy is a neurological state in which conduction is blocked along a spinal nerve or its roots. When sensory fibres are blocked, numbness is the symptom and sign. When motor fibres are blocked weakness ensues.

Diminished reflexes occur as a result of either sensory or motor block. The numbness is dermatomal in distribution and the weakness is myotomal.

Radiculopathy can occur in the absence of pain and radicular pain can occur in the absence of radiculopathy (Bogduk, 2009) therefore radiculopathy is not defined by pain. It is defined by objective neurological signs.

Cause

Usually due to compression or injury to a nerve root in the lumbar spine. The axons of these nerves are either compressed directly or are rendered ischaemic by compression of their blood supply.

The 3 most common ways that compress or irritate an exiting nerve root include

• Herniation of a disc posterolaterally
• Degeneration of disc causing decreased height causing narrowing of neural foramen
• Both formation of osteophytes and hypertrophied joints, can contribute to narrowing of the neural foramen

The exact pathogenesis of Lumbar radiculopathy is unclear.

Prevalence

Less than 5%

Presentation

Back pain associated with radiculopathy is often unilateral. Pain radiation depends on the involved nerve root, although some distributional overlap may exist.

Sensory or motor dysfunction may be present without significant pain (Eubanks, 2010; Yoon, 2011).

Signs of lumbar radiculopathy may include postural changes (e.g. antalgic posture, fixed flexion) restricted and painful back movements, muscle wasting and neurological signs (CKS NICE, 2015).

Frequent signs and symptoms include varying degrees of sensory loss, reduction of muscle power with or without evidence of muscle wasting and reduction or absence of reflexes as well as anaesthesias, dysesthesias and paraesthesia's related to nerve roots (NASS).

In subjects with confirmed radiculopathy (from nerve conduction studies), as many as 31% will have no weakness and as many as 45% will have no sensory abnormalities detected on physical examination.  This is due to significant overlap of dermatomes which results in each segment of skin receiving sensory information from more than one spinal nerve.

Weakness requires degeneration or conduction block of a relatively large proportion of axons contributing to a particular muscle. Nearly all muscles receive innervations from more than one spinal nerve (De Luigi, 2011).

Lumbar x-ray and other imaging studies and investigations are not routinely required to diagnose or assess back pain with or without radiculopathy (CKS NICE, 2015).

MRI is the diagnostic choice if further investigation is required to determine the presence of lumbar radiculopathy (Yoon, 2011).

See general conservative treatment advice

Progressing as expected (up to 3 Rxs) before discharge or onward referral.

Consider general progression/escalation advice.

Expect:

• 80% better at 6/52
• 90% better at 12/52
• 93% better at 24/52

Consider early referral to APP Lumbar for review if:

• 6/52 of significant or progressive neuro changes and pain, or
• 12/52 of persistent pain with or without loss of power or sensation . [Info on GGC Back pain service and referral??]

Bogduk N. On the definitions and physiology of back pain, referred pain, and radicular pain. Pain 2009 Dec 15;147(1-3):17-19 (link correct as at 15/2/22)

De Luigi AJ, Fitzpatrick KF. Physical examination in radiculopathy. Phys Med Rehabil Clin N Am 2011 Feb;22(1):7-40 (link correct as at 15/2/22)

Eubanks JD. Cervical radiculopathy: nonoperative management of neck pain and radicular symptoms. Am Fam Physician 2010 Jan 1;81(1):33-40 (link correct as at 15/2/22)

National Institute for Health and Care Excellence. Back pain - low (without radiculopathy). 2015; Available at: http://cks.nice.org.uk/back-pain-low-without-radiculopathy Accessed 15/2/22

National Institute for Health and Care Excellence. Sciatica (lumbar radiculopathy). 2015; Available at: http://cks.nice.org.uk/sciatica-lumbar-radiculopathy. Accessed 15/2/22

NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE, Clinical Knowledge Summaries [Homepage of NICE], [Online]. Available: http://cks.nice.org.uk/ [15/2/22].

North American Spine Society. Clinical guidelines for diagnosis and treatment of lumbar disc herniation with radiculopathy. 2012; Available at: https://www.spine.org/Portals/0/Documents/ResearchClinicalCare/Guidelines/LumbarDiscHerniation.pdf. Accessed 03/12/20

Yoon SH. Cervical radiculopathy. Phys Med Rehabil Clin N Am 2011 Aug;22(3):439-46, viii (link here - link correct as at 15/2/22)