Lumbrosacral Radiculopathy

Related Subjects: |Inclusion Body Myositis |Inflammatory Myopathies |Peripheral neuropathy |Proximal myopathy |Foot Drop |Friedreich's Ataxia |HTLV-1 Associated myelopathy (Tropical Spastic Paraparesis) |Hereditary Spastic Paraparesis |Lumbrosacral Radiculopathy

ℹ️ About

• Lumbrosacral Radiculopathy refers to pathology affecting nerve roots in the lumbar and sacral spine, causing sensory or motor symptoms in corresponding myotomal or dermatomal distributions.

🧬 Aetiology

• Damage to nerve roots caused by disc herniation, osteophytes, tumours, infection, or diabetes.
• May result in demyelinating or axonal damage to affected nerve roots.
• Diagnosis is primarily clinical, supported by findings from nerve conduction studies (NCS) and electromyography (EMG).

🩺 Clinical Features

• Symptoms of motor or sensory involvement restricted to the distribution of an isolated nerve root, such as C5 or L5.
• Motor Symptoms: Weakness, atrophy, or (rarely) fasciculations within a specific myotome distribution.
• Sensory Symptoms: Numbness, diminished pin-prick sensation, or loss of temperature sensation in a specific dermatome.
• Pain: Often follows a dermatomal distribution, though less useful for localization due to potential referred or non-dermatomal pain patterns.
• Reflexes: Reduced or absent in the affected dermatome.

Localization of Radiculopathy by Nerve Root Level

• L1 Radiculopathy:
  • Motor: None
  • Sensory: Inguinal area
  • Pain: Inguinal region
  • Reflex: None
• L2 Radiculopathy:
  • Motor: Hip flexion
  • Sensory: Anterior upper/middle/lateral thigh
  • Pain: Anterior thigh and leg
  • Reflex: None
• L3 Radiculopathy:
  • Motor: Hip flexion, hip adduction, knee extension
  • Sensory: Medial thigh and knee
  • Pain: Anterior thigh, groin, and leg
  • Reflex: Loss of adductor reflex
• L4 Radiculopathy:
  • Motor: Knee extension, hip adduction, mild ankle dorsiflexion
  • Sensory: Medial calf and medial foot
  • Pain: Anterior thigh and medial leg
  • Reflex: Loss of knee reflex
• L5 Radiculopathy:
  • Motor: Large toe extension, hip abduction, ankle inversion
  • Sensory: Dorsum of the foot, large toe, lateral calf
  • Pain: Posterior/lateral thigh and calf, large toe, dorsum of the foot
  • Reflex: Internal hamstring reflex
• S1 Radiculopathy:
  • Motor: Ankle plantar flexion, toe curling
  • Sensory: Sole of foot, lateral foot, posterior calf
  • Pain: Posterior/lateral thigh and calf, lateral toes, heel
  • Reflex: Loss of ankle reflex & lateral hamstring reflex
• S2-S4 Radiculopathy:
  • Motor: None
  • Sensory: Posterior thigh (S2), behind knee (S2), medial buttocks (S3), perineum (S3-4), perianal area (S4)
  • Pain: Medial buttocks
  • Reflex: Bulbocavernosus, anal wink
• Cauda Equina Syndrome:
  • Motor & Sensory: Multiple roots (L1-S4) affected, leading to a mix of symptoms based on affected levels.
  • Reflex: May affect multiple reflex arcs depending on level of compression.

🔎 Investigations

• Blood Tests: Usually normal, but elevated calcium, ESR, or CRP may indicate red flags for alternative causes.
• Plain Films: X-rays may reveal degenerative changes in spine.
• MRI: Highly sensitive for nerve root impingement, showing potential causes such as disc herniation, tumours, or osteophytes.
• EMG & Nerve Conduction Studies: Useful after three weeks of symptoms to confirm radiculopathy and differentiate between axonal and demyelinating damage.

💊 Management

• Physiotherapy: Encourage mobility as pain allows; avoid prolonged bed rest.
• Pain Management: NSAIDs and appropriate analgesia to manage symptoms.
• Surgical Intervention: Considered for persistent symptoms, weakness, or significant functional impairment despite conservative treatment.

Further Reading

• Lumbrosacral Radiculopathy - NCBI

Cases - Lumbosacral Radiculopathy

• Case 1 - L5 Radiculopathy 💥: A 42-year-old warehouse worker develops acute low back pain radiating down the lateral thigh to the dorsum of the foot after lifting a heavy box. Exam: weakness of ankle dorsiflexion (foot drop), reduced sensation over dorsum of foot, reflexes preserved. Straight leg raise positive. MRI: left L4/L5 disc prolapse. Diagnosis: Left L5 radiculopathy. Management: Analgesia, physiotherapy, activity modification; neurosurgical review if severe/persistent.
• Case 2 - S1 Radiculopathy 🦶: A 50-year-old man presents with sciatica radiating down the posterior thigh to the lateral foot. Exam: weakness of ankle plantarflexion, absent ankle jerk, sensory loss over lateral foot. MRI: right L5/S1 disc herniation compressing S1 root. Diagnosis: Right S1 radiculopathy. Management: Conservative (NSAIDs, physio); consider epidural steroid injection or surgery if deficit progresses.
• Case 3 - L4 Radiculopathy ⚡: A 62-year-old woman complains of back pain radiating to the anterior thigh and knee. Exam: quadriceps weakness, diminished knee jerk, sensory loss over medial shin. MRI: foraminal stenosis at L3/L4 due to degenerative spondylosis. Diagnosis: Left L4 radiculopathy from spinal stenosis. Management: Analgesia, physio, epidural steroid injection; surgical decompression if severe or functionally limiting.

Teaching Commentary 🧠

Lumbosacral radiculopathy = nerve root compression, most often from disc herniation or foraminal stenosis. - L4: weak knee extension, ↓ knee reflex, anterior thigh pain. - L5: foot drop, sensory loss dorsum of foot, pain lateral thigh/calf. - S1: weak plantarflexion, ↓ ankle reflex, sensory loss lateral foot, pain posterior thigh. Diagnosis = clinical + MRI. Management: start conservative (analgesia, physio, avoid prolonged bed rest). Surgery if red flags (cauda equina, severe/progressive deficit, intractable pain).