Correlation between neurological leg deficits and reaction time of upper limbs among low-back pain patients

The purpose of the study was to examine how neurological deficits of the leg, i.e. sensory deficit, deficient reflexes and muscular weakness, correlate with reaction times of upper limbs in a group with chronic low-back pain. Thirty-two patients were studied. Three sets of measurements of simple reaction time and choice reaction time of upper limbs were conducted at one-week intervals. Neurological deficits of the leg were recorded by a physician and the subjects answered a questionnaire about the severity of their low-back symptoms (Oswestry's index). We also defined a neurological index which reflected the total sum of the three types of leg deficits experienced by each of the subjects. Sensory deficit of the leg and the neurological index correlated strongly with slower reaction times of upper limbs, while the other two neurological deficits did not reach a level of significance. Sensory deficits of the leg seem to be an indicator of much greater motor disability than has been thought so far. The motor disability not only appears distally from the lumbar radicular damage caused for example by an intervertebral herniation, it also seems to relate to psychomotor reaction more generally, even on upper limbs.