Lumbar Disc Herniation — ABOS Oral Boards Preparation
What examiners expect and how to prepare
Clinical Scenario
A 38-year-old right-hand-dominant male high school football coach presents to your office with a 6-week history of progressive left lower extremity radiculopathy. He reports sharp, burning pain radiating from his left buttock down the posterolateral thigh and calf to the dorsum of his foot. The pain is worse with sitting and Valsalva maneuvers. He initially managed the symptoms with NSAIDs and activity modification. He received an epidural steroid injection 3 weeks ago with temporary improvement lasting about 10 days. He denies bowel or bladder dysfunction, saddle anesthesia, or bilateral symptoms. He has no medical comorbidities. On exam, he has a positive straight leg raise at 35 degrees on the left (negative on the right). Cross-over straight leg raise is negative. EHL (extensor hallucis longus) strength is 4/5 on the left and 5/5 on the right. Ankle dorsiflexion is 4+/5 on the left. Ankle jerk is diminished on the left. Sensation is diminished to light touch over the left lateral calf and dorsum of the foot. Femoral nerve stretch test is negative.
MRI of the lumbar spine shows a large left paracentral disc herniation at L4-L5 with caudal migration, compressing the traversing left L5 nerve root. There is no central canal stenosis. The remaining lumbar levels are unremarkable. No cauda equina compression.
After 6 total weeks of failed conservative management with persistent motor weakness, you performed a left-sided L4-L5 microdiscectomy through a standard midline posterior approach using an operating microscope. The herniated disc fragment was identified compressing the L5 nerve root, which appeared edematous but in continuity. The fragment was removed, the nerve root was decompressed, and the annular defect was inspected. No loose fragments were found in the canal. Post-operatively, the patient reported immediate resolution of leg pain and was discharged home the same day with activity restrictions for 6 weeks.
What Examiners Look For
- Data gathering: Correlate the history and physical exam to a single nerve root — L5 radiculopathy produces specific motor, sensory, and reflex findings.
- Diagnosis: Which nerve root does an L4-L5 disc herniation compress? Describe the difference between a paracentral herniation (traversing root) and a foraminal herniation (exiting root).
- Treatment plan: What constitutes adequate conservative management before surgery? What are the absolute and relative indications for discectomy?
- Technical skill: Describe the microdiscectomy technique — positioning, level localization, laminotomy extent, nerve root retraction, and fragment removal.
- Complications: Recurrent disc herniation — what is the incidence and how do you manage it? What about incidental durotomy?
- Applied knowledge: What is cauda equina syndrome and how does its presence change the urgency of intervention? What are the time-sensitive criteria?
Common Pitfalls
- Operating on the wrong level — describe your intraoperative localization technique (fluoroscopy, counting from sacrum).
- Not being able to differentiate L4, L5, and S1 radiculopathy by exam — this is a core competency tested repeatedly.
- Recommending surgery before adequate conservative treatment unless a progressive motor deficit or cauda equina syndrome is present.
- Forgetting to ask about bowel and bladder function and saddle anesthesia — missing cauda equina syndrome is a liability.
- Citing randomized trial names instead of discussing the evidence broadly — describe the outcomes data without the bibliography.
Key Classifications
Related Scenarios
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