👹 Radiculopathy, cauda equina syndrome & neurogenic claudication

👹 Radiculopathy, cauda equina syndrome & neurogenic claudication

August 3, 2024
Neurosurgery, Pain
Claudication, Foot Drop

Radiculopathy, cauda equina syndrome & neurogenic claudication #

Introduction #

  • Radiculopathy is a symptom generated by pathology affecting the nerve roots.
  • Peripheral neuropathy is differentiated from radiculopathy by the distribution of the symptoms.

Anatomy #

  • The nerve roots ‘radiate’ from the spinal cord = radiculopathy.
  • The root traverses four zones:
  1. the central canal (intrathecal);
  2. the lateral recess (within the root sleeve);
  3. the foramen; and
  4. the extraforaminal space .

Pathology #

  • Due to both compression and inflammation - ‘chemical neuroradiculitis’.
  • nucleus pulposis herniation = Slipped disc
    • Due both compression and inflammation
    • Causes 90% of radiculopathy.
  • Most intervertebral disc prolapses are paracentral - zones 1 and 2.
    • Irritation here can cause symptoms in the transiting root

Assessment #

The goals:

  • localize the level of the lesion
  • identify the nature of the lesion
    • UMN vs LMN pathology
  • screen for emergency conditions
    • Cauda equina syndrome
    • Acute painful foot drop
  • screen for anaesthetic risk factors.
    • Fitness for surgery

History #

  • Pain - Electric shock like severe pain increase when limb extended.
  • altered perianal sensation
  • urogenital symptoms - ‘autonomic dysfunction’
    • insensate urinary incontinence
    • i.e. retention and has overflow incontinence.

Examination #

  • Root tension manoeuvres (Lasegue and Braggard’s)
  • Tone and reflexes should be normal or reduced.
  • If hyperreflexia and hypertonia -> assess cervicothoracic spine.
  • Perianal sensory loss -> strong predictor of cauda equina compression
Feature Bragard Test Lasegue Test
Purpose To evaluate nerve root compression and differentiate between a genuine and pseudo-Lasegue sign To evaluate sciatic nerve irritation or lumbar nerve root irritation
Patient Position Supine Supine
Initial Movement Examiner raises the patient’s leg while extended at the knee until pain is felt (Lasegue sign) Examiner raises the patient’s leg while extended at the knee until pain is felt
Subsequent Movement Examiner lowers the leg just until the pain subsides, then dorsiflexes the foot None
Positive Test Indication Pain reproduced upon dorsiflexion of the foot indicates nerve root compression Pain in the back or along the sciatic nerve distribution indicates sciatic nerve irritation
Area of Concern Nerve root compression, typically between L4 and S1 levels Sciatic nerve or lumbar nerve roots
Mechanism of Pain Elicitation Stretching of the sciatic nerve through dorsiflexion Stretching of the sciatic nerve during leg raise

Red flags of cauda equina syndrome #

  • Bilateral leg neurological deficit
    • major motor weakness
      • knee extension,
      • ankle eversion,
      • or foot dorsiflexion
  • Recent-onset urinary retention +/- incontinence
  • Recent-onset faecal incontinence
  • Perianal or perineal sensory loss
  • lax anal sphincter

Imaging #

  • MRI imaging T2 within 6 months of onset of symptoms
  • CT myelogram - If patient with a old implantable devices.

Treatments #

Non-surgical #

  • The majority (90%) of radiculopathy are treated non-surgically.
  • 1st line - Antineuropathics
    • Eg: duloxetine
    • first-line treatment in radiculopathy without motor symptoms
  • 2nd line pregabalin and gabapentin.
    • Mechanism of action: works at the root and spinal cord level to reduce ascending pain fibre neuronal discharge.

Steroid injection #

  • Peri-root steroid injection is an effective treatment.
  • reduces the production of inflammatory mediators.
  • Efficacy rates are high, with 66% of patients with good relief at a year.

Surgery #

  • Microdiscectomy - remove the compressive disc extrusion

    • 80% - 90% have relief of pain in the immediate postoperative period
    • often motor and sensory symptoms respond less reliably and less immediately.

  • A small laminotomy allows for fenestration of the ligamentum flavum.

  • Medial facetectomy allows lateral recess and proximal foraminal decompression of the nerve root.

  • Common complications:

    • infection 3%
    • recurrent disc prolapse 5%
    • inadvertent durotomy (‘CSF leak’) 7%
    • continuing radicular symptoms 10%.

  • Rare complications:

    • 1% nerve injury resulting in urogenital, motor or sensory deficits
    • 1:4000 of iliac vessel injury during discectomy
    • very rare risk of visual deficit from prone positioning.

Warning

  • The outcome is that 75% of patients at 3 months and 95% of patients at 1 year will have recovered with conservative management.
  • the timing of the intervention is controversial, as many patients will improve without intervention. offer surgery or injection therapy after 3-6 months of failed conservative management.

Specific conditions #

Cauda equina syndrome #

  • Triad of symptoms - Cauda equina syndrome (CESR) is defined as a triad of symptoms including:
  1. bilateral lower limb radicular pain
  2. perianal sensory loss
  3. insensate urinary retention and subsequent incontinence.

  • Often the first symptom is the radiculopathy. Urogenital symptoms last.

  • Terms

    • Cauda equina syndrome (CESR)
    • Cauda equina in evolution (CESE) = A patient progressing through these symptoms.
    • Impending cauda equina syndrome (CESI ) = A clinical picture with the absence of the urinary dysfunction.

  • Investigation: CESI, CESE and CESR represent a neurosurgical emergency and when seen mandate an urgent MRI scan

  • Management:

    • surgical decompression within 24-48 hours.
    • Delays leads to devastating urogenital dysfunction

Acute foot drop #

  • An acute painful foot drop suggests compression and may need surgical treatment.

  • Painless foot drop is likely a ‘medical’ aetiology such as diabetes.

  • Ankle dorsiflexion

    • Muscles
      • tibialis anterior,
      • extensor hallucis longus and
      • extensor digitorum longus.
    • Nerve supply mostly L5, with a few from L4.

  • L5 outflow is through common peroneal nerve.

  • How to differentiate between a foot drop of L5 root aetiology and a foot drop from a common peroneal nerve aetiology?

    • The L5 root weakness associated with
      • back pain,
      • gluteal weakness,
      • radicular pain and paraesthesia in a dermatomal distribution,
      • relative preservation of peroneus muscle group (L4-S1) - i.e normal foot eversion.
    • The common peroneal nerve aetiology will have
      • no gluteal weakness,
      • no back pain,
      • pain and paraesthesia limited to the first webspace
      • impaired foot eversion.

  • Management

    • early decompression
    • foot drop splints

  • Good prognosis, with two-thirds improving by 6 months.

Lumbar canal stenosis #

  • Neurogenic claudication
  • older patients
  • Clinical features
    • Spine extension - Classical feature: walking and standing results in U/L or B/L leg pain/numbness/pins and needles
    • Spine flexion: improves symptoms ‘shopping trolley sign’
    • often vague symptoms - legs feel dead
    • symptoms usually slowly alleviated with rest
    • significant limitation to walking distance
  • Differential diagnosis: vascular claudication.
  • Pathology
    • often insidiously progresses
    • The compression is mainly from hypertrophy and liagmentum flavum degeneration facet joint to narrow the neural canal and lateral recess.
    • symptomatic when walking due to relative ischaemia of the roots.
  • Management
    • antineuropathics are unhelpful.
    • Due to the non-inflammatory nature, steroid injections also unhelpful.
    • Posterior decompression can improve the claudicant symptoms greatly