Page 61 - Psychology of Wounds and Wound Care in Clinical Practice ( PDFDrive )

34 Chapter 2. Pain

Descending control

Large diameter nerve fibres
carry non-painful information

Spinal
cord T-Cells

Small diameter fibres carry
painful impulses
Gate, open or closed:
Open: Extent of injury, anxiety.
Closed: Rubbing, excitement, self-
efficacy

Figure 2.1 Gate control theory of pain (Adapted from Melzack and
Wall ( 1965 ))

Specifically, it investigates the structure of the nervous system
suggesting that the experience of pain is dependent on a
complex interplay of these two systems; central nervous
system and the peripheral nervous system.
Briefly, according to the GTC, when an injury occurs, pain
messages originate within the nerves in the affected tissue and
travel along the peripheral nerves to the spinal cord and then
on up to the brain (see Fig. 2.1 ). However, before reaching the
brain, the pain messages encounter a ‘gate keeper’ (a group of
nerve cells known as the substantia gelatinosa situated within
the spinal cord), which determines whether the pain signals
proceed on to the brain or are blocked. This gate plays an
important role in the pain management of the central nervous
system. The substantia gelatinosa modulates sensory input
through balancing the activity of small- diameter ( A - Delta and
C ) and large-diameter ( A - beta ) fibres (Melzack 1996 ). Whilst
large fibre activity (non-nociceptive) results in the closure of
the spinal gating mechanism and prevention of synaptic
transmission to centrally projecting T cells ( transport cells),