Involvement of thin afferents in carpal tunnel syndrome: Evaluated quantitatively by argon laser stimulation

Abstract
The thin afferent nerves were tested quantitatively by determining the thresholds of warmth and pricking pain to argon laser stimulation and by measuring the brain potentials related to pricking pain. In 27 patients with electrophysiologically verified carpal tunnel syndrome these parameters were measured from fingers 3 and 5 on both hands. All patients had had sensory symptoms ranging from 3 months to 25 years. Both the thresholds were elevated (P P P <0.01). No correlations were found between the measured parameters and the clinical electrophysiological investigation. The findings support previous assumptions that chronic low-force compressions cause impairment of intraneural microcirculation, and hence can affect the function of the thin afferents.