False Localizing Signs in High Lumbar Stenosis: L2/3 Compression Mimicking L5 Radiculopathy

Degenerative lumbar spinal stenosis typically manifests with symptoms that correlate precisely to the anatomical level of compression. However, 'false localising signs' do exist, which can lead to diagnostic conundrums. A foot drop is classically attributed to a pathology at the L4/5 level affecting the L5 nerve root; however, it may rarely result from more proximal lumbar compressive pathologies. We report a rare case of high lumbar stenosis (L2/3) manifesting with typical and atypical symptoms, highlighting the importance of sound clinical decision-making while recognising this confounding clinical entity. A 55-year-old man presented with chronic back pain, neurogenic claudication, and a right-sided foot drop (Medical Research Council grade 1/5). Magnetic resonance imaging (MRI) of the lumbar spine revealed severe stenosis at the L2/3 level but no significant compression at the L4/5 or L5/S1 levels. Interestingly, neurophysiological studies confirmed L5 radiculopathy. The patient subsequently underwent an L2/3 decompression for neurogenic claudication. Post-operatively, the patient reported improvement in claudication and complete resolution of the foot drop, which remained stable at 12 months' follow-up. This case highlights that high lumbar lesions can mimic distal lumbosacral radiculopathy. This case emphasises that the level of the clinical deficit does not always correlate with the level of compression, leading to false localising signs. It is hypothesised that the L5 nerve root is particularly vulnerable at the L2/3 level due to its peripheral position within the thecal sac as it descends the cauda equina. Clinicians should be aware of this phenomenon to avoid unnecessary or incorrect surgical targeting and to aid in counselling and expectation setting.