Benign hereditary cerebellar ataxia with extensive thermoanalgesia.

A New Zealand family with 3 members affected by late onset hereditary cerebellar ataxia is reported, distinguished by the development of near global thermoanalgesia. Because proprioception and autonomic function were preserved, and ataxia only slowly worsened, this proved to be a benign syndrome. The pattern of sensory loss indicated a 'length-dependent' neuropathy. Evaluation of sural nerve biopsy revealed a marked loss of axons, especially of those with diameters 1-7 microns and 0.2-1.5 microns. It therefore seemed likely that impairment of pain and temperature in the syndrome resulted from a loss of primary sensory afferents. It is concluded that this family represents a previously unrecognized variant and that the spectrum of hereditary ataxias needs to be widened to include an associated severe but selective loss of pain and temperature sensation.