Brain, Vol. 115, No. 4, 1081-1092, 1992
© 1992 Guarantors of Brain
research-article |
TEXTURE DISCRIMINATION IN CARPAL TUNNEL SYNDROME
1Department of Clinical Neurophysiology, The Prince Henry Hospital Sydney, Australia 2School of Physiology and Pharmacology, University of New South Wales Sydney, Australia
Correspondence to:
Correspondence to Dr J W. Morley, School of Physiology and Pharmacology, University of New South Wales, PO Box 1, Kensington, NSW 2003, Australia
The ability to discriminate textured surfaces was measured in patients with carpal tunnel syndrome (CTS) Patients were initially diagnosed using clinical and electrophysiological criteria The textured surfaces were gratings of alternating ridges and grooves. The gratings differed in their spatial period only, with the ratio of the ridge width to the groove width remaining constant (1:5) A two-alternative forced-choice paradigm was employed in which subjects, both patients and age-matched controls, rubbed their index finger (D2) or little finger (D5) back and forth across the surfaces. The grating spatial period at which subjects could discriminate a difference between the standard grating (spatial period = 2000 µm) and the comparison grating (spatial period in the range 2000–2900µm) with a probability of 0 75 was taken as the measure of discriminative ability Statistical comparison of the mean 75% values showed that: (i) when patients used D2 their discriminative ability was significantly impaired in comparison with the discriminative ability of controls using either D2 or D5; (ii) there was no significant difference in discriminative ability between patients and controls when patients used D5 to discriminate the textures; (iii) the 75% values for patients using D2 or D5 did not differ significantly. The degree of abnormality of each patient's sensory evoked potential did not allow us to predict their subsequent performance on the discrimination task
Received November 22, 1991. Revised March 17, 1992. Accepted March 31, 1992.