• Tommi Kääriäinen, Ville Leinonen, Simo Taimela, Timo Aalto, Heikki Kröger, Arto Herno, Veli Turunen, Sakari Savolainen, Markku Kankaanpää, and Olavi Airaksinen.
• Department of Orthopaedics, Traumatology and Handsurgery, Kuopio University Hospital, 70211 Kuopio, Finland. tommi.kaariainen@kuh.fi
• Eur Spine J. 2013 Apr 1; 22 (4): 788-93.

IntroductionImpaired muscle function and lumbar proprioception have been observed in lumbar spinal stenosis (LSS) but those have not been studied in LSS patients with age-matched controls. We assessed lumbar movement perception and paraspinal and biceps brachii (BB) muscle responses during sudden upper limb loading in age-matched healthy subjects and patients with LSS.MethodsThe study included 30 patients selected for an operation due to LSS and 30 age-matched controls without chronic back pain. The paraspinal and BB muscle responses for upper limb loading during unexpected and expected conditions were measured by surface EMG. The ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in a seated position. Pain, disability and depression scores were recorded.ResultsPatients had poorer lumbar perception (mean difference 2.3 ± 0.6°, P < 0.001) and longer paraspinal muscle response latencies [mean difference 4.6 ± 0.6 ms (P = 0.033)] than age-matched healthy controls. Anticipation increased paraspinal and BB muscle activation prior to the load perturbation (P < 0.001) but less in LSS patients than in controls [9 vs. 30 %, P = 0.016 (paraspinals); 68 vs. 118 %, P = 0.047 (BB)].ConclusionsThe observed impairments in lumbar proprioception and activation of paraspinal and upper limb muscles indicate an extensive loss of both sensory and motor functions in LSS. The main new finding was decreased anticipatory muscle activation during expected upper limb loading reflecting involvement of central movement control mechanisms.

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