Is the patient with degenerative disc disease at L5/S1 and a right central disc protrusion likely to experience right S1 radiculopathy?

S1 Radiculopathy from L5-S1 Disc Protrusion

Yes, this patient is highly likely to experience right S1 radiculopathy given the imaging findings of a right central disc protrusion with an inferiorly migrating extruded component that directly impinges the right S1 nerve root at L5-S1.

Anatomical Correlation

The imaging description provides clear evidence of nerve root compression that would produce radiculopathy:

• The right central disc protrusion with inferior migration at L5-S1 directly compresses the S1 nerve root, which is the anatomical pathway for this nerve as it exits the spinal canal 1
• L5-S1 disc lesions most commonly affect the S1 nerve root when there is central or paracentral herniation, as opposed to far lateral herniations which would affect L5 2
• The presence of an extruded component with inferior migration increases the likelihood of significant nerve root compression and subsequent radiculopathy 1

Expected Clinical Manifestations

If S1 radiculopathy is present, look for these specific findings:

• Weakness of plantar flexion (inability to stand on toes), as S1 primarily controls this motor function 3
• Diminished or absent ankle jerk reflex on the right side, which is the hallmark reflex finding for S1 radiculopathy 2
• Sensory loss along the lateral aspect of the foot and heel, following the S1 dermatome distribution 3
• Radicular pain radiating down the posterior thigh and lateral leg to the foot, though atypical presentations can occur 3

Diagnostic Confirmation

The imaging findings strongly suggest radiculopathy, but clinical correlation is essential:

• MRI findings of nerve root compression must correlate with clinical signs and symptoms to confirm the diagnosis and establish medical necessity for intervention 4
• The presence of disc protrusion with nerve root impingement on imaging has high clinical significance in symptomatic patients, with L5-S1 being the most common level for symptomatic disc protrusions (52.3% in weight-bearing positions) 5
• Electrodiagnostic studies can help differentiate true radiculopathy from plexopathy if the clinical picture is unclear 2

Clinical Pitfalls to Avoid

• S1 radiculopathy can present atypically - one case report documented isolated hamstring weakness and posterior knee pain as the sole initial manifestation, leading to delayed diagnosis 3
• Do not confuse this with L5 radiculopathy, which would present with foot dorsiflexion weakness and sensory loss in the big toe and dorsal foot, not plantar flexion weakness 2
• The mild disc bulges at L2/3 and L3/4 without nerve root impingement are unlikely to be clinically significant and should not distract from the L5-S1 pathology 6

Management Implications

• Conservative management should be attempted first unless there are signs of cauda equina syndrome (urinary retention, saddle anesthesia, bilateral lower extremity weakness) 7
• If conservative therapy fails and clinical findings correlate with the imaging evidence of nerve root compression, surgical decompression may be indicated 4
• Urgent surgical evaluation is warranted if the patient develops cauda equina syndrome features, as outcomes are significantly better when treated early (CESI stage) rather than after complete retention develops (CESR stage) 7