Diagnostic Value of Neurophysiological Evaluation in Patients with ARSACS

Background: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is characterized by early-onset spastic ataxia with congenital deformity of the extremities and retinal striation. Although it has been known that ARSACS is frequently associated with peripheral neuropathy, it has not been described in detail using electrophysiology.

Methods and finding: We report the clinical, electrophysiological, and nerve ultrasonographic findings of three patients with ARSACS. Our patients exhibited electrophysiological signs of both myelinopathy and axonopathy, predominantly affecting the lower limbs, with slow MCV and prolonged F wave latency. These results suggested that the characteristics of neuropathy in ARSACS might arise from primary length-dependent peripheral myelinopathy associated with secondary axonal injury that worsened over a long period. Nerve ultrasonography revealed slight nerve enlargement, also suggestive of peripheral nerve demyelnation. These findings indicated that the peripheral neuropathy observed in patients with ARSACS might predominantly be demyelinating in origin with patchy demyelination.

Conclusion: These electrophysiological and ultrasonographical observations might be helpful for the accurate diagnosis of ARSACS because clinical features of ARSACS are diverse, including atypical cases with a spasticity-lacking phenotype or cases without a family history.