title: Segmental overlap: foot drop in S1 radiculopathy.
abstract: Knowledge of segmental innervation of skeletal muscles is essential for diagnosing lumbar radiculopathy. Myotomes and dermatomes are traditionally thought to be innervated by a single spinal segment, but experimental studies have shown that this pattern of segmental innervation allows considerable overlap. This implies that muscles (or dermatomes) are innervated not only by axons of one spinal segment, but also partially by axons of adjacent spinal levels. We describe a patient in whom overlap in segmental innervation complicated adequate diagnosis of a recurrent lumbar hernia. Further, we present an outline of electrophysiological and anatomical studies on segmental innervation.
authors.affiliation: Neuromuscular Centre Nijmegen, Department of Neurology, Radboud University Nijmegen Medical Centre, The Netherlands. n.voermans@neuro.umcn.nl
authors.forename: N C
authors.initials: NC
authors.lastname: Voermans
authors.forename: A C
authors.initials: AC
authors.lastname: Koetsveld
authors.forename: M J
authors.initials: MJ
authors.lastname: Zwarts
mesh_terms: D017586:Diskectomy; D005260:Female; D020233:Gait Disorders, Neurologic / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology / Q000503:physiopathology; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000503:physiopathology; D007866:Leg / Q000294:innervation / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000473:pathology / Q000503:physiopathology; D008160:Lumbosacral Plexus / Q000033:anatomy & histology / Q000293:injuries / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation* / Q000503:physiopathology; D010243:Paralysis / Q000209:etiology / Q000503:physiopathology; D011843:Radiculopathy / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D012585:Sciatica / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D013126:Spinal Nerve Roots / Q000293:injuries / Q000473:pathology / Q000503:physiopathology; D016896:Treatment Outcome