Right foraminal disk protrusion at L3-L4.

Vincent M. Arlet, MD, and Andrew H. Milby, MD: The provided history, examination findings, and imaging studies are all consistent with the diagnosis of acute radiculopathy due to lumbar disk protrusion. Pain localized to the anterior thigh in combination with quadriceps weakness suggests involvement of the ipsilateral L3 or L4 nerve roots. Relief of pain with hyperflexion is a reverse-tension sign, suggesting nerve root irritation when the L3 or L4 nerve roots are placed under tension with the right hip in the neutral or extended position. In addition to the selected magnetic resonance imaging (MRI) cuts, a complete initial workup should include standing flexion–extension radiographs of the lumbar spine to assess for associated instability, as well as additional MRI sequences, including axial and sagittal T1and T2-weighted images. Lumbar nerve roots may be affected by disk protrusions or spondylosis at multiple sites: central, causing canal stenosis and likely bilateral symptoms; paracentral, most common and affecting the traversing nerve root (ie, L2-L3 paracentral compression affecting the L3 nerve root); or foraminal or far lateral, affecting the exiting nerve root. The MRI in this case shows what appears to be disk material from the L3-L4 disk space that is obscuring the right L3 neural foramen and causing compression of the L3 nerve root. However, these images are not sufficient to exclude possible compression of the right L4 nerve root because it traverses the subarticular recess. One can observe Vincent Arlet, MD, Department of Orthopaedic Surgery, Penn Comprehensive Spine Center, Philadelphia, Pennsylvania.