Lower Back Syndromes

Sciatica is the clinical description of pain in the leg that occurs due to lumbrosacral nerve root compression usually secondary to lumbar disc prolapse or extrusion. L5/S1 disc level is the most common site of disc herniation. The following are the characteristic "lower back syndromes" associated with nerve root compression. Note that disc herniations are mostly in the posterolateral direction, thus compression of the nerve root exiting from the vertebral foramen at one level below is affected. (The nerve root at the same level of the herniation is already within the vertebral foramen and therefore not compressed)
L5/S1 Disc Prolapse

• Pain along posterior thigh with radiation to the heel
• Weakness on plantar flexion (may be absent)
• Sensory loss in the lateral foot
• Absent ankle jerk reflex

L4/L5 Disc Prolapse

• Pain along the posterior or posterolateral thigh with radiation ot
• the top of the foot
• Weakness of dorsiflexion of the great toe and foot
• Paraesthesia and numbness of top of foot and great toe
• No reflex changes noted

L3/L4 Disc Prolapse

• Pain in front of thigh
• Wasting of quadriceps muscles may be present
• Diminished sensation on the front of the thigh and medial lower leg
• Reduced knee jerk reflex