What is the difference between a herniated disc and lumbosacral (lower back) radiculopathy?

Understanding Herniated Disc vs. Lumbosacral Radiculopathy

A herniated disc is an anatomical condition (the structural problem), while lumbosacral radiculopathy is a clinical syndrome (the resulting symptoms) that can be caused by a herniated disc or other pathologies. These terms describe different aspects of the same disease process and are not mutually exclusive.

Key Conceptual Differences

Herniated Disc (Anatomical Diagnosis)

• Structural abnormality where the intervertebral disc material protrudes beyond its normal boundaries 1
• Represents the underlying pathology that can be visualized on imaging studies 2
• May exist without causing symptoms—not all herniated discs produce radiculopathy 3
• The herniation causes both mechanical compression and chemical irritation of adjacent nerve roots 3

Lumbosacral Radiculopathy (Clinical Syndrome)

• Symptom complex characterized by radiating pain in one or more lumbar or sacral dermatomes 4
• Represents the clinical manifestation of nerve root irritation or compression 5
• Defined by pain distribution, sensory changes, motor weakness, and reflex abnormalities in a specific nerve root pattern 6
• Annual prevalence ranges from 9.9% to 25% in the general population, making it the most common form of neuropathic pain 4

Clinical Relationship

The herniated disc is the cause; radiculopathy is the effect. 1

• A patient can have a herniated disc on MRI without radiculopathy if the disc doesn't compress or irritate a nerve root 2
• Conversely, radiculopathy can occur from causes other than disc herniation, including spinal stenosis, tumors, or lumbosacral plexopathy 6
• Most lumbar disc herniations with radiculopathy improve within the first 4 weeks with conservative management 2

Important Diagnostic Distinctions

When Disc Level and Symptoms Don't Match

• Disc herniations typically affect the nerve root exiting under the pedicle at the adjacent inferior level 7
• Atypical presentations exist: An L2/3 disc herniation can occasionally cause L5 radiculopathy through non-adjacent compression 7
• Lateral disc herniations may cause plexopathy rather than simple radiculopathy and may not be detected on standard lumbar spine MRI 6

Radiculopathy vs. Plexopathy

• Radiculopathy follows a single dermatome distribution, while plexopathy crosses multiple dermatomes 6
• Failure to distinguish between these conditions is a common diagnostic pitfall 6
• Lumbosacral plexopathy requires dedicated MRI of the plexus, not just standard lumbar spine imaging 6

Treatment Implications

Surgery targets the herniated disc (the structural problem), while conservative treatment addresses radiculopathy symptoms (the clinical syndrome). 1

• Routine fusion is not recommended for primary herniated disc with radiculopathy, as discectomy alone produces excellent outcomes 1
• Fusion may be considered in manual laborers or patients with significant axial low-back pain, though this adds recovery time (25 weeks vs. 12 weeks) 1
• Conservative management including physical therapy, McKenzie method, mobilization, exercise therapy, and neural mobilization have moderate evidence (Level B) for treating disc herniation-related radiculopathy 5

Red Flags Requiring Urgent Intervention

• Cauda equina syndrome: saddle anesthesia, neurogenic bowel/bladder dysfunction, and abnormal lower extremity reflexes 3
• Progressive neurological deficits such as foot drop or extremity weakness 2
• These presentations warrant immediate surgical evaluation regardless of imaging findings 2, 3