Physical Analgesia: Methods, Mechanisms and Algorithms for Post-Operative Pain

*Ivet B. Koleva, Borislav R. Yoshinov, Teodora A. Asenova and Radoslav R. Yoshinov*

#### **Abstract**

Physical analgesia is the application of physical modalities for pain relief. Our objective is to present the potential of some physical factors and correspondent methods of application; and to explain their mechanisms of action. For pain reduction we use: low and middle frequency electric currents (e.g. TENS, interferential currents), electrostatic field (Deep oscillation), magnetic field, light (including Laser), some mineral waters and peloids, physiotherapy (e.g. analytic exercises, mechanotherapy, post-isometric relaxation, massage), reflexotherapy (e.g. acupuncture, acupressure). In rehabilitation practice, we use reflectory connections between the surface of the body and the internal organs (cutaneous-visceral, subcutaneousvisceral, proprio-visceral, periostal-visceral). The theory of Melzack and Wall for gate-control explains some effects of physical factors. We propose our own theory for explanation of mechanisms of physical analgesia. We propose our concept about rehabilitation algorithms in diseases of the nervous and locomotor systems, accentuating on conditions after surgical intervention (neurosurgical and orthopedic operations, including joint endoprosthesis and limb amputations). We present some of our own results in patients with post-operative pain.

**Keywords:** pain, physical factors, analgesia, electric currents, magnetic field, photo-therapy, physiotherapy

#### **1. Introduction**

According the International Association for the Study of Pain (IASP) pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in term of such damage [1]. Pain is provoked by stimulation of nociceptors (pain receptors), by modifications in sensory roads, or in cerebral zones. Pain perception depends on different physical, chemical or psychological factors [2].

The biological importance of pain is the safeguard of the organism from negative stimuli (external or internal), liberating a defensive reaction. The French philosopher Rene Descartes [3] explains the shielding character of pain and its capacity to unchain a reaction as a self-protective reflex.

In 1959, Willem Noordenbos [4] expressed the hypothesis for the multi-synaptic transmission of pain-signal.

In 1965, the British physiologist Patrick Wall and the Canadian psychologist Ronald Melzack published the article "Pain Mechanisms: A New Theory" [5]. According the theory of gate control, in the spinal medulla exists a controlling mechanism, which is closed in response to the normal stimulation of fast fibers of tactile sense, but is open if the slow fibers of pain perception transport numerous and intensive sensory signals. A subsequent stimulation of the fast fibers can close the gate and interrupt these signals [6, 7].

Pain perception has different levels: receptors, sensory roots, posterior columns of the spinal medulla, thalamus opticus, reticular formation, and cerebral cortex. Actually, we apply three groups of theories for explanation of pain perception: specific, non-specific and combined [8–10]. Specific theories accept the existence of specific pain receptors—nociceptors. According non-specific theories: pain perception depends on decoding (at spinal level) of temporo-spatial organization of patterns—signals, perceived by intensive stimulation of non-specific receptors. The third group of theories accept both theories.

The pathogenesis of pain determines the differentiation of *acute and chronic (persistent) pain; nociceptive and neuropathic pain.* In clinical practice, every pain has elements of nociceptive and neuropathic elements, and this fact is the base of our *therapeutic impotence* behind pain [8, 9].

In rehabilitation practice, we observe different types of pain: *Nociceptive* and *Neuropathic* pain, *Central* pain, *Post-operative pain* (in neurological and neurosurgical conditions); *Degenerative and Inflammatory pain* (in rheumatologic diseases); *Traumatic (Post-traumatic) pain; Post-operative pain; Fibromyalgia or Myofascial pain, pain due to muscle dysbalance; Tendinopathy pain* or *Ligamentar pain* (in orthopedic and traumatic conditions); *Cancer pain (oncological); Phantom pain* [2, 10].

The Declaration of Montréal of the International Pain Summit of the International Association for the Study of Pain (IASP) categorizes chronic pain as a serious health problem and proclaims access to pain management as a fundamental human right [11].
