title: Deficits in foot skin sensation are related to alterations in balance control in chronic low back patients experiencing clinical signs of lumbar nerve root impingement.
abstract: Chronic low back pain (LBP) patients with radiculopathy, or sciatica, experience pain, tingling or numbness radiating down their leg due to compression of the lumbar nerve root. The resulting reduction in somatosensory information from the foot sole may contribute to deficits in standing balance control. This work was designed to investigate the relationship between foot skin sensitivity and standing balance control in chronic LBP patients with associated radiculopathy. Patients (n=9) and matched healthy controls (n=9) were recruited to the study, and were tested for balance control in both quiet standing as well as during rapid arm raise perturbation trials on a force plate. Foot skin sensitivity was tested bilaterally for vibratory threshold (3, 40 and 250 Hz) and touch (monofilament) threshold. Results demonstrate that patients had reduced sensitivity to 250 Hz vibration in their affected compared to unaffected foot (at the great toe and heel), as well as compared to controls (at the great toe), but there were no differences with lower frequency vibratory testing or with monofilament testing. While there were no significant between-group differences in balance measures, moderate statistically significant correlations between 250 Hz sensitivity and quiet standing balance parameters were uncovered. Thus, patients demonstrate reduced high-frequency vibratory sensitivity at the foot sole, and correlations with quiet standing balance measures indicate a connection between these foot skin sensitivity deficits and alterations in balance control. Clinically, this identifies high frequency vibration testing as an important measure of skin sensitivity in patients with radiculopathy.
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd East, Guelph, Ontario N1G2W1, Canada.
authors.forename: Lydia R
authors.initials: LR
authors.lastname: Frost
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd East, Guelph, Ontario N1G2W1, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Bijman
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd East, Guelph, Ontario N1G2W1, Canada.
authors.forename: Nicholas D J
authors.initials: ND
authors.lastname: Strzalkowski
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd East, Guelph, Ontario N1G2W1, Canada.
authors.forename: Leah R
authors.initials: LR
authors.lastname: Bent
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd East, Guelph, Ontario N1G2W1, Canada. Electronic address: shmbrown@uoguelph.ca.
authors.forename: Stephen H M
authors.initials: SH
authors.lastname: Brown
mesh_terms: D000328:Adult; D002908:Chronic Disease; D005260:Female; D005528:Foot / Q000294:innervation*; D006801:Humans; D017116:Low Back Pain / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000150:complications* / Q000503:physiopathology; D004856:Postural Balance / Q000502:physiology*; D011312:Pressure; D011843:Radiculopathy / Q000150:complications* / Q000503:physiopathology; D012677:Sensation / Q000502:physiology*; D012879:Skin Physiological Phenomena; D014732:Vibration; D055815:Young Adult
keywords: Balance; Chronic low back pain; Foot skin sensitivity; Nerve compression; Sciatica