Anatomy Msk · Year 1 · from Anatomy Msk
Case 1: Lumbar Disc Herniation with Radiculopathy
Clinical Image
Source: Wikimedia Commons - Lumbar Disc Herniation MRI - CC BY-SA 3.0
Case Presentation
A 42-year-old warehouse worker presents with 3 weeks of severe lower back pain radiating down his right leg to the foot. The pain started suddenly while lifting a heavy box and has progressively worsened. He describes the leg pain as sharp and burning, traveling along the back of his thigh, lateral calf, and into the top of his foot and great toe. Pain is exacerbated by sitting, coughing, and bending forward. He reports numbness along the same distribution and weakness when trying to lift his big toe. Physical examination reveals antalgic gait with listing to the left. Straight leg raise is positive at 30 degrees on the right with reproduction of radicular symptoms. Neurological examination demonstrates weakness of right great toe dorsiflexion (EHL - 4/5), decreased sensation over the dorsum of the foot, and diminished Achilles reflex. MRI of the lumbar spine reveals a large posterolateral disc herniation at L4-L5 compressing the traversing L5 nerve root. After failing 6 weeks of conservative management with physical therapy, NSAIDs, and epidural steroid injection, he undergoes L4-L5 microdiscectomy with complete resolution of radicular symptoms.
Key Learning Points
- Intervertebral discs consist of a central nucleus pulposus (type II collagen, proteoglycans) and outer annulus fibrosus (type I collagen)
- Disc herniation typically occurs posterolaterally where the annulus is weakest (posterior longitudinal ligament is narrow)
- At L4-L5, a posterolateral herniation compresses the traversing L5 root (not the exiting L4 root)
- L5 radiculopathy causes weakness of ankle/toe dorsiflexion (tibialis anterior, EHL) and sensory loss over dorsal foot
- The straight leg raise test stretches the sciatic nerve and L4-S1 nerve roots