Objective: we aim to describe the clinical, radiological and electrophysiological features of Friedreich’s ataxia (FA) in our population.

Background: FA is the most common autosomal recessive cerebellar ataxia in the world, with a reported prevalence of 1:50000 in Europe and 1:100000 in USA. Its incidence is not well-known in Africa.

Method: A retrospective descriptive study was conducted at the neurology department of the National Institute of Neurology of Tunis over 41 years (1982-2023), involving 51 genetically confirmed FA cases from 31 different families. A comprehensive neurological and general examination was performed. Biological, electrophysiological, and radiological data were collected and analyzed.

Results: The mean age at onset was 16 years ±6.37 [1-32].  Only 5 patients had a late onset form (>25years). Forty-three percent of our patients were from the central region of the country, and 92% of them were born from consanguineous marriages. The sex ratio was 1.55. Clinically, patients had progressive cerebellar ataxia (100%), dysarthria (94%), deep sensory deficit (85%), progressive lower limb weakness (49%), amyotrophy (43%), areflexia (73%) and Babinski sign (90%). In contrast to Harding’s diagnostic criteria, lower limb reflexes were preserved in 15.63%, knee reflexes were brisk in 11.2% and plantar responses were normal in 10%. Rarely, FA patients developed head tremor (16%), cervical dystonia (2%), bowel dysfunction (13,7%) and swallowing disorders (15,7%). Ophthalmological examination showed decreased visual acuity (6%), ptosis (4%) and strabismus (2%). The fundus exam revealed maculopathy and optic atrophy in 1 case, respectively. Extra-neurological signs were frequent, as 50% had orthopaedic abnormalities, 26% had cardiomyopathy and 8% had hearing loss and diabetes respectively. The mean SARA scale was 21.9 ± 8.18 and the mean age of grabatization was 24.8 years ± 6.36. Electromyogram was abnormal in 97% mainly due sensitive axonal neuropathy (73%). The visual Evoked Potentials showed demyelinating (41%) and axonal (10%) optic neuropathy. Cerebral and medullary imaging were mostly normal (72%). Only 7 patients had cerebellar atrophy and 3 had spinal atrophy.

Conclusion: This study allowed us to highlight the phenotypic variability among our patients, including FA with retained reflexes and late-onset FA forms. However, the Harding criteria remain pertinent, as they continue to be met by the majority of our patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/friedreichs-ataxia-a-descriptive-study-of-a-tunisian-cohort/