Central, Lateral Recess, or Foraminal? A Narrative Review of MRI Stenosis Compartments and Lower-Limb Radiculopathy Patterns
Abstract
Background: Degenerative lumbar canal stenosis (LCS) is a leading cause of low-back pain, neurogenic claudication, and lower-limb radiculopathy in older adults. Although magnetic resonance imaging (MRI) is the preferred modality for anatomical assessment, clinical interpretation often remains challenging because stenosis can occur in distinct compartments—central canal, lateral recess (subarticular zone), and neural foramen—each with different neuroanatomical targets. Objective: This narrative review summarizes compartment-based lumbar stenosis anatomy, degenerative mechanisms, MRI evaluation and commonly used grading systems, and the typical symptom patterns associated with central, lateral recess, and foraminal stenosis, with emphasis on how compartment dominance may shape radiculopathy distribution. Methods: A narrative synthesis of key concepts from anatomical, radiological, and clinical literature on degenerative LCS was performed, focusing on mechanisms of narrowing (disc height loss, facet hypertrophy/osteophytes, ligamentum flavum thickening/buckling), MRI-based localization, and compartment-specific clinical manifestations. Results: Central canal stenosis commonly involves multiroot compression and is frequently associated with bilateral symptoms and neurogenic claudication. Lateral recess stenosis typically affects traversing nerve roots and more often produces unilateral dermatomal pain, while foraminal stenosis compromises exiting roots and may present with distal-predominant radiculopathy influenced by posture. MRI grading systems provide standardized morphological descriptors; however, static MRI may not fully capture dynamic compression and vascular/venous contributors to symptoms. Conclusion: A compartment-based approach improves clinical reasoning in degenerative LCS and supports symptom-relevant MRI interpretation. Direct evidence linking dominant stenosis compartment to specific lower-limb radiculopathy patterns remains limited, highlighting a need for targeted clinicoradiological studies. Keywords: Degenerative lumbar canal stenosis; Magnetic resonance imaging; Central canal stenosis; Lateral recess stenosis; Foraminal stenosis