Posteriorly Protruding Disc: Definition, Symptoms, and Treatment

A posteriorly protruding disc (disc bulge/protrusion) occurs when the nucleus pulposus pushes posteriorly through a weakened annulus fibrosus toward the spinal canal, potentially compressing the thecal sac or nerve roots.

Key Features

• Location: Most common at L4-L5, L5-S1 (lumbar); also cervical (C5-C6, C6-C7).
• Mechanism: Degenerative annular tears + axial loading.
• Distinction: Protrusion = base wider than apex; Extrusion = apex wider than base; Sequestration = fragment detached.

Symptoms

• Axial back/neck pain
• Radiculopathy: radiating pain, numbness, weakness in dermatomal/myotomal distribution
• Neurogenic claudication (lumbar): leg pain with walking, relieved by sitting
• Myelopathy (cervical/thoracic): gait imbalance, hand clumsiness, UMN signs

Treatment

• Conservative (6–12 weeks): NSAIDs, activity modification, PT (McKenzie, core stabilization), epidural steroid injection.
• Surgical: Microdiscectomy, laminectomy, or endoscopic decompression for refractory radiculopathy, progressive deficit, cauda equina syndrome.

Most improve without surgery. Imaging (MRI) correlates poorly with symptoms; treat the patient, not the image.