Neurophysiological evaluation in children with Friedreich's ataxia.
BACKGROUND
In children with Friedreich's ataxia (FRDA children), clinical ataxia outcomes are hardly substantiated by underlying neurophysiological parameters. In young FRDA children, some reports (based upon International Cooperative Ataxia Rating Scale scores (ICARS)) mention transient neurological improvement upon idebenone treatment. However, these outcomes are obtained with adult instead of pediatric reference values. It is unknown whether age-related neurophysiological parameters can really substantiate neurologic improvement.


OBJECTIVE
In young FRDA children, we aimed to determine longitudinal neurophysiological parameters during idebenone treatment.


METHODS
During a two-year study period, 6 genetically proven FRDA children with cardiomyopathy (6-18years) were longitudinally assessed for neurophysiological parameters [sensory evoked potentials (SEPs), F response, peripheral nerve conduction and dynamometry] in association with age-matched ICARS-scores.


RESULTS
In all FRDA children, SEPs remained absent during the two-year study period. Peroneal nerve conduction velocity declined (from -1SD to -2SD; p<.05), whereas F responses remained essentially unaltered. Total muscle force and leg muscle force decreased (from -2 to -3SD and -2.5 to -3.5SD; both p<.05) and age-related ICARS-scores deteriorated (median increase +41%; p<.05).


CONCLUSIONS
In FRDA children, age-related neurophysiological and ataxia parameters deteriorate during idebenone treatment. Although we cannot exclude some (subjective) disease stabilization, age-related neurophysiological parameters do not substantiate neurologic improvement.
Sival
D A
DA
Department of Pediatrics, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700RB Groningen, The Netherlands. d.a.sival@bkk.umcg.nl
du Marchie Sarvaas
G J
GJ
Brouwer
O F
OF
Uges
D R
DR
Verschuuren-Bemelmans
C C
CC
Maurits
N M
NM
Brunt
E R
ER
van der Hoeven
J H
JH
D000293:Adolescent; D000367:Age Factors; D000975:Antioxidants / Q000627:therapeutic use*; D002648:Child; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects; D005621:Friedreich Ataxia / Q000188:drug therapy / Q000503:physiopathology*; D006801:Humans; D008137:Longitudinal Studies; D053581:Muscle Strength Dynamometer; D009431:Neural Conduction / Q000187:drug effects; D016896:Treatment Outcome; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000627:therapeutic use
D000975:Antioxidants; D014451:Ubiquinone; C036619:idebenone