Near infrared muscle spectroscopy in patients with Friedreich's ataxia.
Friedreich's ataxia is a progressive neurodegenerative disorder of the afferent cerebellar pathways associated with mitochondrial dysfunction at the cellular level. We have used noninvasive continuous near infrared muscle spectroscopy (NIRS) to investigate the delivery and utilization of oxygen in response to exercise in this disorder. Patients performed an incremental treadmill walking protocol in which levels of muscle deoxygenation or oxygenation were continuously measured in the medial calf muscle. The kinetics of recovery from exercise-induced deoxygenation, called the half-time of recovery (t(1/2)) were determined. The t(1/2) was prolonged in patients with Friedreich's ataxia compared with controls, and the degree of prolongation correlated with the length of the shorter GAA repeat, a genetic measure that correlates with the age of onset of disease. The t(1/2) also correlated inversely with patient age and with the maximum treadmill speed attained. Several patients also displayed features consistent with inadequate oxygen utilization by muscle. These results suggest that NIRS may be an effective tool for monitoring the biochemical and functional features of Friedreich's ataxia in parallel.
Lynch
David R
DR
Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.|Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Lech
Gwen
G
Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Farmer
Jennifer M
JM
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Balcer
Laura J
LJ
Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Bank
William
W
Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Chance
Britton
B
Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Wilson
Robert B
RB
Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005621:Friedreich Ataxia / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007700:Kinetics; D007866:Leg; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D012016:Reference Values; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D016138:Walking / Q000502:physiology
D010100:Oxygen