Distal symmetric polyneuropathy phenotype in patients with sensory neuronopathy at the time of electrodiagnosis

It is unknown how often patients with sensory neuronopathy (SNN) present with a distal symmetric polyneuropathy (DSP) phenotype. In these cases, electrodiagnostic testing may discriminate SNN with a DSP phenotype from DSP.

We reviewed the records of patients who met SNN diagnostic criteria between January 2000 and February 2021 and identified patients with a DSP phenotype at the time of electrodiagnosis.

Sixty-two patients fulfilled SNN diagnostic criteria. At symptom onset, 20 (32.2%) patients presented with distal symmetric sensory symptoms limited to the feet. However, most progressed rapidly over 6 months or developed asymmetric symptoms. At the time of electrodiagnosis, only seven (11.3%) patients had a DSP phenotype. Of these seven patients, four had cerebellar ataxia with neuropathy and vestibular areflexia syndrome, one had vitamin B₆ deficiency, one was thought to be alcohol-induced, and one was idiopathic.

Patients with SNN rarely present with a DSP phenotype at the time of electrodiagnosis. The finding that one third of cases resemble DSP at onset highlights the importance of clinical monitoring. In patients with a DSP phenotype, the presence of ataxia at onset or significant progression within 6 months may suggest the possibility of SNN and should prompt additional investigations, such as electrodiagnosis.