MYOTONIA-CONGENITA - QUANTITATION OF DIFFERENT ASPECTS OF MOTOR-PERFORMANCE

In order to quantitatively assess the motor performance characteristic s of 14 patients with congenital myotonia, the reaction time, speed of movement, synergy of different muscle groups and accuracy were measur ed. The Human Performance Measurement/Basic Elements of Performance de vice was used for recordings. Warned simple and choice reaction times (SRT, CRT) were significantly longer in the myotonic patients than in the controls. SRTs, consisting of one constant visual stimulus followe d by a single movement response of the upper extremities (patients vs. controls) were 218 +/- 48 ms (mean +/- SD) and 172 +/- 12 (p = 0.0038 ). In the lower extremities the corresponding results were 293 +/- 46 and 239 +/- 24 (p = 0.0018). 1-CRTs, consisting of the upper extremiti es response to one randomized light signal (patients vs. controls) wer e 265 +/- 45 and 218 +/- 26 (p = 0.0069), and those of the lower extre mities 337 +/- 73 and 279 +/- 39 (p = 0.0107), respectively. 2-CRTs, c onsisting of two possible visual stimuli in randomized order followed by a movement response of the upper extremities (patients vs. controls ), were 308 +/- 54 and 249 +/- 33 (p = 0.0018), and those of the lower extremities 387 +/- 53 and 323 +/- 46 (p = 0.0028), respectively. We did not find any significant difference between the patient and the co ntrol groups in speed of movement, synergy of different muscle groups or accuracy. Nor was any significant correlation between the motor per formance disability and the disease severity found.