Section of the spinal cord (at levels Th.6 and Th.12) from a case of Friedreich's ataxia, showing degeneration of the posterior columns and the pyramidal tracts. The dorsal spino-cerebellar tracts are also affected. This disease is a progressive paralysis usually developing about puberty and causing death in a few years. The patient shows a striking ataxia of all limbs, due not only to the degeneration of the posterior column tracts (of Goll and Burdach) but also the involvement of the spino-cerebellar tracts. The ataxia is much more uncontrollable than in tabes (in which only the posterior column tracts are affected) − it is so severe that the patient cannot control it even if he carefully watches the limb which is being moved. There is also a general tremor of the body and head, the speech tends to be slurred and rather staccato in character (a sort of ataxia of speech), and there is also nystagmus.

On the motor side, the degeneration of the pyramidal tracts leads to an extensor response in the plantar reflex. On the other hand, because of the concomitant involvement of the posterior column and spino-cerebellar tracts (and consequent loss of muscular tone), tendon reflexes are weak or absent and the muscles are not spastic.

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