Can L4–L5 bulging discs cause right-sided neck, shoulder, thoracic, and lower back pain?

L4-L5 Bulging Discs Cannot Directly Cause Neck, Shoulder, or Thoracic Pain

L4-L5 disc pathology is anatomically limited to causing lower back pain and lower extremity radiculopathy—it cannot directly cause neck, shoulder, or thoracic pain due to the segmental innervation of the spine.

Anatomical Explanation

The L4-L5 disc sits in the lower lumbar spine and can only affect neural structures at or below that level:

• L4 nerve root (compressed by L3-L4 disc or far lateral L4-L5 herniation): Causes anterior thigh pain, knee weakness, and diminished patellar reflex
• L5 nerve root (most commonly compressed by L4-L5 disc): Causes posterolateral leg pain radiating to the dorsum of the foot, weakness of great toe extension, and foot drop 1

The thoracic spine (T1-T12), shoulder region (C5-T1), and neck (C1-C7) are innervated by completely separate nerve roots that originate far above the L4-L5 level. There is no anatomical pathway for L4-L5 pathology to directly cause symptoms in these upper body regions 1.

What L4-L5 Pathology Actually Causes

Based on established guidelines, L4-L5 disc bulging or herniation produces:

• Lower back pain: Localized to the lumbar region 2
• Radiculopathy/sciatica: Pain radiating down the leg below the knee in the L5 distribution (posterolateral leg, dorsum of foot) 1
• Neurogenic symptoms: Weakness, sensory changes, or reflex abnormalities in L5 distribution 1

Important caveat: While disc bulges are common findings on imaging, they are frequently seen in asymptomatic individuals and do not always correlate with symptoms 1, 3. Up to 43% of asymptomatic 80-year-olds have disc protrusions on MRI 3.

Alternative Explanations for Your Symptom Pattern

If you have right-sided pain spanning neck, shoulder, thoracic, and lower back regions, consider:

• Separate pathology at multiple spinal levels: Cervical disc disease (C5-C7) for neck/shoulder pain, thoracic pathology for mid-back pain, and L4-L5 for lower back pain
• Myofascial pain syndrome: Can cause referred pain patterns across multiple regions
• Postural dysfunction: Chronic poor posture causing muscular strain from neck to lower back
• Systemic inflammatory conditions: Ankylosing spondylitis or other spondyloarthropathies affecting multiple spinal segments

Clinical Approach

Do not attribute upper body symptoms to L4-L5 pathology. If imaging shows L4-L5 disc bulging but you have neck/shoulder/thoracic pain:

1. Obtain appropriate imaging of the symptomatic regions (cervical and thoracic spine) if red flags present or symptoms persist beyond 4-6 weeks despite conservative management 3

2. Red flags requiring urgent evaluation include: fever, unexplained weight loss, history of cancer, progressive neurologic deficit, bowel/bladder dysfunction, or saddle anesthesia 1

3. Initial conservative management for 6 weeks includes remaining active, physical therapy, and appropriate analgesia for all spinal regions 1, 3

The presence of L4-L5 disc bulging on imaging is likely incidental to your upper body symptoms and should not drive treatment decisions for neck, shoulder, or thoracic complaints 1, 3.