Question

How would you expect the latencies and amplitudes in the skin of the hand and the foot compare? Explain any differences in the latencies.

Answer 1

SYMPATHETIC SKIN RESPONSE (SSR):-
- It is a change in potential recorded from the surface of the skin, and is seen when the eccrine sweat glands are activated by sympathetic nerve activity.
- there are Many different types of stimuli that can activare the SSR.
- this is due to activation of polysynaptic reflex arc.

LATENCY AND AMPLITUDE IN HAND SKIN AND FOOT SKIN:-
(i) LATENCY:-
-The latency of the SSR includes-
a)Afferent conduction (about 20 ms)
b) central processing time (a few ms)
c) Efferent conduction in pre and
slow
postganglionic autonomic nerve fibre.
-SSR latency
of around 1.5 s at the hands and 2 s at the feet.
Therefore, differences in fast afferent conduction
are not relevant for the SSR latency.
- The normal latency is 1.3±
1.5 s when recording from the palm and 1.9±2.1s
when recording from the sole.

(ii) AMPLITUDE:-
- The amplitude is affected by skin temperature and habituation.
-the reproducibility of the electrically evoked SSR is poor.
-The within day variability for 5 consecutive increasing stimuli was
42% for amplitudes in palms and 35% foot.