Friedreich ataxia (FA) is the most frequent autosomal recessive cerebellar ataxia. Although the phenotype is well known, disease progression has not been evaluated in a prospective manner.
To perform a long-term prospective follow-up of neurological, cardiological, and oculomotor function in patients with FA (FA patients).
In this open-labeled prospective survey, we examined 104 FA patients every 6 months during a median period of 5 years (range, 6 months to 7 years), with a systematic standardized protocol. Data are reported as mean ± SD.
Neurological examinations were performed at the Federation of Neurology and the Department of Genetics of the Salpêtrière Hospital, Paris, France. Cardiological follow-up was performed at the Department of Cardiology; oculomotor examinations were performed at the Institut National de la Santé et de la Récherche Médicale Unit 679, at the same hospital.
We studied 104 FA patients with a confirmed molecular diagnosis. None were receiving antioxidant therapy at baseline; 88 accepted treatment with the coenzyme Q10 analogue idebenone (5 mg/kg per day). Sixteen preferred not to be treated.
Neurological status was evaluated with the International Cooperative Ataxia Rating Scale (ICARS) and a quantitative writing test. Cardiological evaluations included echocardiography, electrocardiography, and Holter monitoring. Oculomotor function was evaluated by electro-oculography to determine the frequency of square wave jerks.
The total ICARS score worsened during follow-up, whether or not the patients were treated with idebenone (1.93 ± 0.25 and 4.43 ± 1.56 points per year, respectively). The total ICARS score increased faster in patients with onset before age 15 years compared with the others (2.6 ± 0.4 [n = 51] vs 1.1 ± 0.3 [n = 37]; P = .05). The posture subscore increased faster in patients able to stand at baseline, who also had shorter disease durations than patients unable to stand (1.25 ± 0.12 vs 0.47 ± 0.22 point per year; P<.001). Neurological progression was underestimated, however, by the ICARS scores, which reached a plateau in patients with long disease durations. Oculomotor function slightly deteriorated (0.09 ± 0.02 Hz per year; P<.001). Left ventricular mass index decreased (−4.1 ± 1.5 g/m2 per year; P = .008), as did ejection fraction (−1.32% ± 0.29% per year; P<.001).
The neurological condition of FA patients deteriorated slowly over time, even with idebenone treatment. Although cardiac hypertrophy decreased under treatment, cardiac function did not improve. The ICARS scale is not appropriate to evaluate the progression of FA in patients with long disease durations. Additional quantitative measures may improve the reliability of this scale.