What is the most likely diagnosis for a 48-year-old male with right buttocks and lateral hip pain radiating down the anterior lateral thigh into the right lower leg, with diminished sensation to light touch along the medial aspect of the right lower leg?

Lumbar Radiculopathy (L3 or L4 Nerve Root)

This patient most likely has lumbar radiculopathy affecting the L3 or L4 nerve root, based on the characteristic anterior-lateral thigh and medial lower leg pain distribution with corresponding sensory deficits and asymmetric patellar reflex.

Clinical Reasoning

Pain Distribution Pattern

• The radiation from buttock/lateral hip down the anterior-lateral thigh into the lower leg is classic for upper lumbar radiculopathy 1, 2
• Diminished sensation along the medial aspect of the right lower leg just inferior to the knee is highly specific for L3 or L4 nerve root involvement 3
• L3 radiculopathy typically presents with symptoms at the ventral surface of the thigh, knee, and upper ventral leg, while L4 affects the ventro-lateral surfaces with the lateral shin being distinctive 3

Neurological Examination Findings

• Asymmetric patellar reflexes (1+ right vs 3+ left) indicates L4 nerve root dysfunction, as the patellar reflex is mediated by the L4 nerve root 1, 4
• Normal strength in lower extremities does not exclude radiculopathy, as motor weakness may be absent in early or mild cases 2
• Preserved Achilles reflexes (2+ bilaterally) effectively rules out S1 radiculopathy 1

Key Negative Findings That Support This Diagnosis

• Negative straight leg raise test is expected with upper lumbar radiculopathy (L3/L4), as this test is primarily sensitive for lower lumbar disc herniations (L5-S1) 1, 4
• The straight leg raise has 91% sensitivity for herniated discs but is most useful for L5-S1 pathology; upper lumbar radiculopathy often presents with negative SLR 4, 2
• Negative FABER and FADIR tests effectively exclude hip pathology as the primary source 1

What This Is NOT

Not Sciatica (L5 or S1 Radiculopathy)

• True sciatica involves pain radiating below the knee in the posterior or lateral leg, not the anterior-medial distribution seen here 2, 5
• L5 radiculopathy would show lateral thigh/leg symptoms with dorsiflexion weakness, not medial leg sensory changes 1, 3
• S1 radiculopathy would present with lower buttock, dorso-lateral leg pain, diminished Achilles reflex, and plantarflexion weakness 1, 3

Not Hip Pathology

• Negative FABER and FADIR tests have substantial ability to rule out femoroacetabular impingement syndrome and other intra-articular hip pathology 1
• No lateral hip tenderness and ability to sleep on the affected side argues against trochanteric bursitis or gluteal tendinopathy 1
• Hip pathology typically does not cause dermatomal sensory changes or reflex asymmetry 1

Not Meralgia Paresthetica

• This would affect only the lateral thigh (lateral femoral cutaneous nerve) without medial leg involvement, reflex changes, or buttock pain 6

Recommended Next Steps

Imaging Strategy

• Obtain lumbar spine MRI without contrast to identify disc herniation, foraminal stenosis, or other compressive pathology at L3-L4 or L4-L5 levels 1, 7
• The American College of Physicians recommends imaging for radiculopathy when symptoms persist beyond 4-6 weeks or when considering interventional treatment 1, 4
• MRI is preferred over CT for evaluating nerve root compression and disc pathology 7, 4

Management Approach

• Continue NSAIDs (ibuprofen 600mg) for symptomatic relief, though current partial response suggests need for additional interventions 1
• Consider physical therapy focused on nerve mobilization and core stabilization 8
• If conservative management fails after 6-12 weeks, transforaminal epidural steroid injection at the affected level can provide significant relief 5, 8
• Surgical consultation (discectomy) is appropriate if progressive neurological deficits develop or severe pain persists despite 6-12 weeks of conservative treatment 7, 6

Critical Pitfalls to Avoid

• Do not dismiss this as mechanical low back pain simply because the straight leg raise is negative; upper lumbar radiculopathy frequently has negative SLR 4, 2
• Do not delay imaging beyond 6 weeks in a patient with objective neurological findings (reflex asymmetry, sensory deficit) and functional impairment affecting work 1, 7
• Do not pursue hip imaging given the negative hip examination and classic radicular pattern 1
• Monitor for red flags: progressive weakness, bowel/bladder dysfunction, or saddle anesthesia would require urgent MRI and surgical evaluation 1, 6