Objectives: To determine A-waves of a family with autosomal recessive form of demyelinatig hereditary motor and sensory neuropathy Lom (HMSNL).
Methods: A-waves were investigated during conventional F-wave study of family members with HMSNL which had genetic testing.
Results: During routine F-wave studies A-waves were observed in all tested nerves. They appeared between M-responses and F-wave. The A-waves were with low amplitude, shorter duration and constant shape and latency than F-waves. They appeared independently of F-waves. A-waves were more often recorded as multiple waves in lower and upper extremities. More than three A-waves per nerve were found mostly in ulnar and facial nerves. In 16 cases A-waves were found in the absence of F-waves.
Conclusion: It is assumed that the A-waves could be seen as additional signs of pathology because they were not observed in unaffected members of the family and in healthy subjects.