Sequestrated Disc Pathophysiology and Clinical Implications

Introduction to Sequestrated Discs

A sequestrated disc occurs when a fragment of the nucleus pulposus herniates through the annulus fibrosus and becomes completely separated from the parent disc, migrating into the epidural space as a free fragment, according to the American College of Physicians 1

The pathophysiological cascade begins with herniation of the nucleus pulposus through a defect in the fibrous outer covering (annulus fibrosus) of the intervertebral disc, as reported by the American College of Physicians 1

Sequestrated fragments cause neural compression through both mechanical mass effect and chemical irritation of nerve roots, resulting in radiculopathy with pain, sensory impairment, weakness, or diminished deep tendon reflexes in the affected nerve root distribution, according to the American College of Physicians 1
The free fragment can compress nerve roots from the lower cord segments, potentially causing cauda equina syndrome with urinary retention, bilateral motor weakness, and saddle anesthesia, as noted by the British Journal of Neurosurgery and the American College of Physicians 1, 2

The most dangerous pitfall is delayed recognition of cauda equina syndrome, which requires emergency surgical decompression to prevent permanent neurological deficits including bladder/bowel dysfunction and lower extremity paralysis, as emphasized by the British Journal of Neurosurgery 2

Cauda equina syndrome (CES) associated with sequestered disc fragments commonly presents with urinary retention or incontinence, bilateral lower‑extremity motor weakness, saddle anesthesia, and bowel dysfunction. Early recognition is critical because delayed decompression can lead to permanent bladder/bowel dysfunction and paralysis. 3

Magnetic resonance imaging (MRI) without contrast is the preferred initial modality for evaluating suspected lumbar disc pathology. When a sequestered fragment mimics a tumor or infection, additional contrast‑enhanced sequences should be obtained. This approach balances diagnostic accuracy with efficiency. 3, 4

Re‑operative discectomy without spinal fusion provides satisfactory clinical outcomes in 69 %–85 % of patients with recurrent or sequestered lumbar disc herniations. Fusion is reserved only for cases with documented lumbar instability, spondylolisthesis, or chronic mechanical low‑back pain, as routine fusion adds morbidity, cost, and complications without proven benefit. 5