Comparison of spinal myotatic reflexes in human adults investigated with cross-correlation and signal averaging methods.

A cross-correlation method for recording spinal myotatic reflexes has been developed to meet the need for brief test periods in babies and children and subjects with central neurological pathology. In normal adult subjects the method has been validated by comparing excitatory and inhibitory reflexes obtained with cross-correlation with those obtained with conventional signal averaging. In the cross-correlation method a pseudo-random binary sequence of 64 brief tendon taps was delivered in <1.5 s, and in the averaging method 20-150 taps at one per second. The reflexes were expressed as unit impulse responses to enable direct, quantitative comparisons to be made. With cross-correlation the responses were slightly expanded in time, had lower peak amplitudes, and onset latencies advanced by 10 ms, the clock period of the pseudo-random binary sequence. The amplitude of biceps phasic stretch reflex increased with muscle contraction in a similar manner with both methods. In tests for stationarity the amplitude of biceps phasic stretch reflex varied <10% in the first six repeats of the pseudo-random binary sequence. The tap force required at threshold for cross-correlation was approximately half that for averaging, but with both methods the magnitude of biceps phasic stretch reflex varied linearly with tap force over the range of one to two times threshold. The validity of responses obtained with cross-correlation was assessed by a statistical procedure. In conclusion, the cross-correlation method is robust and gives similar results to those obtained with averaging.

Reciprocal and Renshaw (recurrent) inhibition are functional in man at birth.

The aims were (1) to determine when in human postnatal development Group Ia reciprocal and Renshaw inhibition can be demonstrated; (2) to explore the relationship between the expression reciprocal inhibition and the disappearance of Group Ia excitatory reflexes between agonist and antagonist muscles. Studies were performed on 99 subjects, aged 1 day to 31 years, of whom 53 were neonates. A longitudinal study was also performed on 29 subjects recruited at birth and studied 3 monthly until 12 months of age. Reciprocal inhibitory and excitatory reflexes were recorded in the surface EMG of contracting biceps brachii (Bi), evoked by taps applied to the tendon of triceps brachii (Tri). Reciprocal excitatory reflexes were recorded in all but one neonate. Reciprocal inhibition was observed in 25% of neonates; evidence is provided that it was likely to have been masked by low threshold reciprocal excitation in the remaining neonates. Reciprocal inhibition was demonstrated in all subjects after 9 months of age. In four neonates there was depression of inhibition of Bi during co-contraction of Bi and Tri implying that Group Ia interneurones may be under segmental and suprasegmental control at birth. Renshaw cells, identified in human postmortem cervical spinal cord by their morphology, location and calbindin D28K immunoreactivity, were present at 11 weeks post-conceptional age (PCA) and by 35 weeks PCA had mature morphological characteristics. In four neonates reciprocal inhibitory responses in Bi disappeared when the tap to Tri evoked its own homonymous phasic stretch reflex, providing neurophysiological evidence for Renshaw inhibition of Group Ia inhibitory interneurones.

A case report of low intensity laser therapy (LILT) in the management of venous ulceration: potential effects of wound debridement upon efficacy.

OBJECTIVE: This single case report (ABA design) was undertaken as a preliminary investigation into the clinical effects of low intensity laser upon venous ulceration, applied to wound margins only, and the potential relevance of wound debridement and wound measurement techniques to any effects observed. METHODS: Ethical approval was granted by the University of Ulster's Research Ethical Committee and the patient recruited was required to attend 3 times per week for a total of 8 weeks. Treatments were carried out using single source irradiation (830 nm; 9 J/cm2, CB Medico, Copenhagen, Denmark) in conjunction with dry dressings during each visit. Assessment of wound surface area, wound appearance, and current pain were completed by an independent investigator. Planimetry and digitizing were completed for wound tracings and for photographs to quantify surface areas. Video image analysis was also performed on photographs of wounds. RESULTS: The primary findings were changes in wound appearance, and a decrease in wound surface area (range 33.3-46.3%), dependent on the choice of measurement method. Video image analysis was used, but rejected as an accurate method of wound measurement. Treatment intervention produced a statistically significant reduction in wound area using the C statistic on digitizing data for photographs (at Phase one only; Z = 2.412; p < 0.05). Wound debridement emerged as an important procedure to be carried out prior to measuring wounds. Despite fluctuating pain levels recorded throughout the duration of the study, VAS scores showed a decrease of 15% at the end of the study. This hypoalgesic effect was, however, statistically significant (using the C statistic) at Phase one only (Z = 2.554; p < 0.05). CONCLUSIONS: Low intensity laser therapy at this dosage, and using single source irradiation would seem to be an effective treatment for patients suffering venous ulceration. Further group studies are indicated to establish the most effective therapeutic dosage for this and other types of ulceration.