Approach to sciatica

Shekar RoopanKing Dinuzulu Hospital

Introduction

• Lower back pain - 84% lifetime incidence

• Sciatica

• 13-40% lifetime incidence

• 1-5% annual incidence

• 90% don’t seek help after 3 months

Osseous anatomy

Neuroanatomy

Neuroanatomy

Intervertebral disc• Crucial biomechanical role

• Distributes compressive forces across bodies

• Permits a small degree of movement

• Shock absorption

• Composed of annulus fibrosis and nucleus pulpous

Annulus fibrosis• Concentric laminae of type

1 collagen (15-20)

• Alternative layers are at 30-60 degree angles

• Provides resistance to forces in any direction and hoop stresses

Nucleus pulposus• Hydrophilic proteoglycans with

type 2 collagen

• High water content (90-70%)

• Deforms like fluid when compressive forces applied spreading hydraulically to equalise the forces

• Reduced ability to deform with age as water content decreases

Definitions

• Sciatica - radicular pain in the distribution of the sciatic nerve

• Radicular pain - pain perceived as arising in a limb or the trunk caused by ectopic activation of nociceptive afferent fibres in the spinal nerves or roots

Aetiology• Discogenic - Lumbar disc

herniation

• Non discogenic:• Extraspinal:

• Muscular compression - piriformis syndrome

• Bony - sacroilitis, hip disorders

• Vascular - aneurysms

• Gynaecological - MFU, pelvic endometriosis

• Intraspinal:

• Bony compression - spinal stenosis, spondylolistheisis, osteophytes, facet syndrome

• Infection - caseating disease, abscess, discitis

• Malignancy - schwannomas, metastasis

MA Stafford; Sciatica: review of history, epidemiology and pathogenesis; BJA 2007

Aeitology• Discogenic - Lumbar disc

herniation

• Non discogenic:• Extraspinal:

• Muscular compression - piriformis syndrome

• Bony - sacroilitis, hip disorders

• Vascular - aneurysms

• Gynaecological - MFU, pelvic endometriosis

• Intraspinal:

• Bony compression - spinal stenosis, spondylolistheisis, osteophytes, facet syndrome

• Infection - caseating disease, abscess, discitis

• Malignancy - schwannomas, metastasis

MA Stafford; Sciatica: review of history, epidemiology and pathogenesis; BJA 2007

Pathophysiology

MA Stafford; Sciatica: review of history, epidemiology and pathogenesis; BJA 2007

Failure of disc• Classic teaching - rupture of annulus fibrosis

results in disc herniation

• Rajasakeran et al:

• Avulsion of the end plate together with annulus in majority of patients (65%) - Type 1 (End plate junction failure)

• Disruption of annulus only (35%) - Type 2

Rajasekaran S et al; The anatomy of failure in lumbar disc herniation: an in vivo, multimodal, prospective study of 181 subjects. Spine 2013

Type of herniations

Clinical presentations

Far lateral disc herniations

• Affect nerve roots at more than one level

• Affect nerve roots that have already exited the canal

Cauda equina syndrome

• Usually due to central herniation

• Emergency

• Features:

• Bladder and bowel incontinence

• Perineal numbness

• Bilateral sciatica

• Lower limb weakness

• Crossed straight leg raise

History• Pain

• Site

• Onset

• Character

• Radiation

• Associations

• Time course

• Exacerbating/relieving factors

• Severity

History

• Neurology - bowel and bladder, lower limb weakness, paraesthesia

• ADLS

• Constitutional symptoms

• Psychosocial

Examination• General

• Gait

• Spinal

• Neurological

• PR

• Systemic

Clinical tests• Straight leg raise test

• Lasegue’s test

• Bowstring test

Waddell’s signsPsychological distress amplifying symptoms resulting in anatomically inappropriate signs

• Superficial non anatomic tenderness

• Stimulation sign - exaggerated response to axial compression or rotation

• Distraction sign - SLR varies in sitting and lying down

• Regional sensory or motor disturbance - non anatomical distribution of symptoms e.g. glove and stocking

• Overreaction - theatrical reaction to gentle examination

Radiology

• MRI

• X-rays - disc space, osteophytes

• CT scan

• Myelography - side effects

Modic changes• Signal intensity changes in vertebral body

marrow adjacent to the endplates of degenerative discs

Oedema Fatty Sclerosis

Knutsons phenomenon

• Collection of gas within the disk space, the vertebral body, the apophyseal joint or the spinal canal

• observed in degenerative disk disease

Natural history• 90% improvement by 12 weeks

• Reduction in herniation size due to enzymatic digestion

• Large herniation and sequestered fragments more likely to reabsorb

• Nucleus pulposus more readily absorbed than annulus or end plate

Management• Usually non operative

• Reassurance

• Short period of rest (no more than 2 days)

• Anti-inflammatory medication

• Analgesics

• Physiotherapy

• Exercise

• Weight loss

Non steroidal anti inflammatories

• Most frequently prescribed medications for LBP

• 51 trials (6057 patients)

• Outcomes:

NSAIDs better than placebo

conflicting evidence that NSAID’s better than

paracetomol

• Conclusion:

NSAID’s effective for short term treatment of acute LBP

insufficient evidence on long term useVan Tulder, Scholten, Koes. The Cochrane Library, Issue 2, 2003

NASS Guidelines• TNF Alpha inhibitors - no benefit

• IV glucocorticosteroids - insufficient evidence

• 5HT receptor inhibitors - insufficient evidence

• Amitriptilline - insufficient evidence

• Physical therapy alone - insufficient evidence but recommended for limited period for mild to moderate symptoms

• Spinal manipulation - option for symptomatic relief

• Traction - insufficient evidence

NASS Evidence-Based Clinical Guidelines for Multidisciplinary Spine Care

Injections• Transforaminal epidural - steroid injection is

recommended to provide short-term (2-4 weeks) pain relief

• Is there an optimal frequency or quantity of injections for the treatment of lumbar disc herniations with radiculopathy? - No evidence to answer question

• Approach (?caudal, transforaminal, interlaminar) - No evidence

NASS Evidence-Based Clinical Guidelines for Multidisciplinary Spine Care

Ancillary treatments

• bracing, electrical stimulation, acupuncture and transcutaneous electrical stimulation (TENS) - insufficient evidence

NASS Evidence-Based Clinical Guidelines for Multidisciplinary Spine Care

Operative• Immediate surgery:

• Cauda equina syndrome

• Marked motor loss <48hrs

• Elective surgery - failure of medical treatment

(persistent pain after combined treatment with

NSAIDs, morphine and 3 epidural steroid

injections)

Sciatica from disk herniation: Medical treatment or surgery?;E. Legrand et al. ;Joint Bone Spine (2007)

Operative

• Conventional discectomy

• Micro-discectomy

Similar results with success rate >80%

• Percutaneous discectomy - endoscopic/automated - recommended in carefully selected patients

Sciatica from disk herniation: Medical treatment or surgery?;E. Legrand et al. ;Joint Bone Spine (2007)

Conclusion

• 80% have good prognosis

• Other causes to consider

• Good history and clinical examination

• Mostly non operative management with indications for surgery