Slowly Progressive Cerebellar Ataxia in a 55-Year-Old Female Patient

D. Mitochondrial ataxia

Friedreich ataxia (FRDA; choice A) is one of the most common autosomal recessive cerebellar ataxias, caused by GAA trinucleotide repeat expansions in the frataxin (FXN) gene, with onset typically occurring in the second decade of life. Associated peripheral neuropathy, dorsal root ganglionopathy, and dorsal column involvement lead to areflexia with early loss of distal vibration sense. Oculomotor findings include fixation instability and frequent square-wave jerks, while gaze-evoked nystagmus is less common.¹ Common systemic manifestations include cardiomyopathy, diabetes, and musculoskeletal abnormalities like scoliosis, pes cavus, foot inversion, and hammertoes.² Late-onset cases commonly present with spastic ataxia with preserved or even brisk reflexes, without systemic manifestations.² Brain MRI in patients with FRDA shows spinal cord atrophy with preserved cerebellar volume.¹ This patient had sensory neuronopathy and skeletal deformities in the feet. However, disease onset was in the fourth decade of life with absent reflexes, prominent gaze evoked nystagmus, slow saccades, gaze palsy, and diffuse cerebellar atrophy on MRI. Test results for FRDA genetics were negative.