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

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, subcutaneous-visceral, 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.

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, 9, 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].

2. Physical analgesia: methods

Pain management is very important for the successful rehabilitation. Different members of our multi-disciplinary multi-professional rehabilitation team are included in the pain treatment. The role of the medical doctors—specialists in Physical and Rehabilitation Medicine is crucial in this process [12, 13].

Physical analgesia is the application of physical factors for pain management. The anti-pain effect of physical modalities is significant [2, 10, 14]. Physical analgesia has not side effects and can be combined with other therapies [15].

In physical analgesia, we apply several physical modalities (Table 1).

• Preformed modalities: Electric currents; Magnetic fields; Ultra-sound; Light beams: infra-red, ultra-violet or Laser [2, 10, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25];

• Natural modalities: Kryo-factors; Thermo-agents; Mineral waters; Hydro and balneo-physiotherapy techniques; Peloids; Physiotherapy techniques—analytic exercises or soft-tissue techniques [2, 10, 15, 25, 26, 27, 28, 29, 30, 31, 32, 33];

• Reflectory methods: electrotherapy, thermotherapy and physiotherapy in reflectory points and zones; acupuncture, laserpuncture, acupressure, etc [34].

• Telerehabilitation techniques [35, 36].

Types of physical modalities	Methods	Procedures
Preformed modalities	Electrotherapy	Low frequency currents (galvanic, diadynamic currents); Low frequency modulated middle frequency currents (sinusoidal-modulated, interferential, Kots currents); Trans-cutaneous electroneurostimulation (TENS)
		High frequency currents (diathermy, ultra-high frequency currents, decimeter and centimeter waves)
		Deep Oscillation
	Magnetotherapy	Low frequency pulsed magnetic field
		Ultra-sound and phonophoresis with NSAIDs;
	Phototherapy	infra-red, ultra-violet, visible light; LASER (laser-therapy)
Natural modalities	Cryo-therapy	ice, cold packs, cold compresses
	Thermo-therapy	hot packs, hot compresses
	Hydro- and Balneo-therapy	douches, baths, piscine
	Hydro and balneo-physiotherapy	underwater massage, under water exercises,
	Peloidotherapy	fango therapy, thermal mud, sea lye compresses
	Physiotherapy	Analytic exercises; stretching, post-isometric relaxation
	Manual therapy	Traction (distraction), mobilization, manipulation
	Massage	Manual massage or with devices; periostal, connective tissue massage, etc.
Reflectory methods	Reflexotherapy	Electrotherapy, thermotherapy and physiotherapy in reflectory points and zones
		Acupuncture and Acupressure
		Laserpuncture and Laseracupuncture
Telerehabilitation techniques

Table 1.

Methods of Physical analgesia.

3. Physical analgesia: mechanisms

The gate-control theory [5] is widely applied in physical medicine, especially for explanation of physical analgesia, using the principle of the “contra-stimulation”—final effect reticence by stimulation of inhibiting systems, or else final effect stimulation by embarrassment of inhibiting systems [37, 38]. Investigations of J. Gacheva demonstrated that the selective electrostimulation of tactile Аβ-nerve fibers (with high velocity of conduction) provokes a previous stimulation of suppressive neurons, they inhibit the tardily arrived nociceptive stimuli of А-δ and C-fibers (with slower conduction velocity) [37].

At peripheral level, the direct anti-adaptive electrostimulation of receptors probably provokes a hyperpolarization with a decrease of the sensibility of the nociceptors.

A direct low frequency electrical stimulation of the Aδ and C fibers may cause an analgesic effect.

During last years, the development of the physical medicine proved the existence of some reflectory connections in the human body, based on the theory for the metameric structure of the embryo during intra-uterine development. In physical analgesia, we apply the following groups of reflectory connections (Figure 1).

• cutaneous-visceral—between skin and internal organs (e.g. zones of Head, used in iontophoresis),

• between the subcutaneous connective tissue and visceras (e.g. zones of Leube–Dicke, applied in connective massage),

• proprio-visceral and motor-visceral—between proprio-receptors and internal organs (e.g. zones of Mackenzie, used in the physiotherapeutic method of Mackenzie),

• periostal-visceral—between periostium and internal organs (e.g. zones of Vogler–Krauss, used in periosteal massage).

Figure 1.

Groups of reflectory connections.

We consider that physical modalities may provoke an analgesic effect by different pathogenetic mechanisms (Figure 2, Table 2).

• By influence on the cause for irritation of pain receptors—consequence of stimulation of circulation, metabolism and trophy of tissues;

• By blocking of nociception;

• By inhibition of peripheral senzitization;

• By peripheral sympaticolysis;

• By stopping the neural transmission (by С and Аδ delta—fibers) to the body of the first neuron of the general sensibility;

• By input of the gate-control mechanism;

• By activation of different reflectory connections;

• By influence on the pain-translation at the level of the posterior horn of the spinal medulla—using the root of activation of encephalic blocking system in the central nervous system (increasing the peripheral afferentation) and influence on the descending systems for pain—control;

• By inhibition of central sensitization;

• By influence on the psychic state of the patient—the drug “doctor” and the drug “procedure”.

Figure 2.

Mechanisms of physical analgesia.

Mechanism of physical analgesia	Procedures with physical modalities, using this mechanism
By influence on the cause for irritation of pain receptors	Low and medium frequency electric currents, magnetic field, ultrasound, He-Ne laser; massages; manual techniques
By blocking of nociception	Low frequency currents, including transcutaneous electrical nerve stimulation or TENS; lasertherapy
By inhibition of peripheral senzitization	Low and middle frequency currents, TENS; magnetic field; lasertherapy
By peripheral sympaticolysis	Low frequency currents e.g. dyadinamic currents, peloids
By stopping the neural transmission (by С and Аδ delta—fibers) to the body of the first neuron of the general sensibility	Iontophoresis with Novocain in the receptive zone—the region of neuro-terminals
By input of the gate-control mechanism	TENS with frequency 90–130 Hz and interferential currents with high resulting frequency—90-150 Hz
By activation of the reflectory connections	classic manual, connective tissue and periostal massage, post-isometric relaxation and stretching-techniques
By influence on the pain-translation at the level of posterior horn of the spinal medulla—using the root of activation of encephalic blocking system in the central nervous system (increasing the peripheral afferentation) and influence on the descending systems for pain—control	TENS with frequency 2–5 Hz and interferential currents with low resulting frequency 1–5 Hz, acupuncture and laserpuncture; reflectory and periostal massage, zonotherapy, acupressure, su-dgok massage; preformed factors in reflectory zones /palms of hands, plants of feet, paravertebral points; zones of Head, of Mackenzie, of Leube-Dicke, of Vogler-Krauss/
By inhibition of central sensitization	Lasertherapy; peloidotherapy; physiotherapy
By influence on the psychic state of the patient— the drug «doctor» and the drug «procedure».	Regular procedures with physical modalities

Table 2.

Mechanism of physical analgesia and correspondent procedures.

4. Physical analgesia: systematic mechanisms

Physical modalities influence at different levels: on the cells and the interstitium, especially on the cellular membrane and on mitochondrial membranes; on the neuron and neuroglia; on systematic level; on psychic condition of the patient (psycho-emotional stress of chronic pain).

Low frequency electric currents, Deep oscillation, lasertherapy and active physiotherapy have influence on different mechanisms of cellular alteration, as follows: ischemic, hypoxic, hypo-energetic, oxidative stress.

Some rehabilitation procedures stimulate active hyperemia: electrotherapy, magnetic field, active physiotherapy, hydro- and balneo-therapy, acupuncture.

Other agents reduce passive hyperemia: magnetotherapy, deep oscillation, manual massage, manual lymphatic drainage and lymphopressotherapy, active physiotherapy.

Some procedures influence on the exudative phase of inflammation, reducing exudates: high frequency electric currents, laser, deep oscillation, lymphatic drainage, manual massage, active physiotherapy.

Physical modalities reduce systematic effects of inflammation. Active physiotherapy, manual massage and reflectory techniques reduce toxo-infectious syndrome. Active and passive physiotherapy, lasertherapy and ultra-violet light therapy reduce the asteno-adynamic syndrome. Active physiotherapy and reflectory techniques reduce C-reactive protein, regulate endocrinium, and regulate the balance between sympaticus and parasympathicus.

Active physiotherapeutic procedures reduce hypoxia (hypoxic, circulatory and tissue hypoxia) and stimulate compensatory mechanisms (respiratory, cardio-vascular and tissular).

Physical modalities ameliorate the function of the central and peripheral nervous system. Low frequency electric currents (iontophoresis, functional electrical stimulations) have influence on neuronal dysfunction. Physiotherapy, transcranial electric and magnetic stimulations stimulate the function of neuronal groups, chains and nets. Active physiotherapy and ergotherapy improve the cerebral function, acting on cerebral ischaemia, the brain oedema and the intracranial hypertension.

5. Physical analgesia: pros and contras

Physical analgesia is a cheap treatment, accepted positively by patients. Physical procedures have not significant side effects and contra-indications.

The treatment is not difficult for realization, is relatively cheap.

We can combine different rehabilitation procedures. We can combine physical analgesia with other types of analgesia.

We must admit that actually there is a lack of sufficient evidence in the area of physical analgesia.

An interdisciplinary team (of medical doctors — specialists in Neurology, Neurosurgery, Rheumatology, Orthopedics and Traumatology, Physical and Rehabilitation Medicine) programs rehabilitation. For practical realization of the procedures, we need a staff of physiotherapists, occupational therapists, nurses, etc.

6. General algorithm for pain management

Pain management with physical modalities is based on traditions of physical and rehabilitation medicine (PRM). According the definition of the European Union of Medical Specialists—PRM Section [12] this is an independent medical specialty, oriented to the promotion of physical and cognitive functioning, activities, participation and changes in personal factors and environment.

According the World Report on Disability of the World Health Organization and World Bank [39] rehabilitation is a functional treatment, based on a detailed functional assessment. Goals of rehabilitation are functional amelioration and functional recovery [39].

The White Book on Physical and Rehabilitation Medicine [12, 13] formulates the basic objective of PRM: increase of patients’ quality of life, especially autonomy in everyday activities [40]. Tasks of PRM are oriented to amelioration of functioning and participation in different types of activities [12, 13, 41, 42, 43].

Modern rehabilitation algorithm requires a detailed functional evaluation, based on International Classification of Diseases; International Classification of Functioning, disability and Health (ICF) and on clinical principles [44, 45, 46]. In rehabilitation clinical practice, we apply a complex rehabilitation programme, combination of different physical factors, in some cases—with drugs.

We consider that the complex algorithm for pain management must include: systematic drugs (and vitamins); rehabilitation complex, and patient education.

The complex PRM algorithm includes a detailed functional assessment of the patient and a complex rehabilitation programme. Functional evaluation emphasizes on goniometry, manual muscle test, grasp and gait evaluation, autonomy in everyday activities, ICF evaluation, Visual analogue scale for pain /VAS 0-10/, McGill Pain questionnaire) [47]. The rehabilitation program is established by synergic combination of different natural and preformed physical modalities (kinesiotherapy and ergotherapy, cryo and peloido-procedures, electrotherapy and photo-therapy, magnetic field, etc.). This program must include: one or two pre-formed modalities; one thermo- or kryo-agent; one or two physiotherapeutic procedures (including analytic exercises, soft tissue techniques, manual therapy, etc.).

At the end of every rehabilitation course, it is obligatory to realize a functional assessment—with the goal to evaluate the efficacy and to prescribe the consecutive rehabilitation procedures.

During our modest clinical experience (of 30 years) we received multiple significant results in patients with conditions of the nervous and motor systems [48, 49, 50, 51, 52]. We realized comparative evaluation between the efficacy of pure drug therapy, physical analgesia and combined anti-pain therapy (drug and physical analgesia) on different types of pain: spastic pain; rigidity pain; hemiparetic shoulder pain and hemiplegic hand pain; paravertebral (upper & low back) pain; radicular neuropathic pain; diabetic polyneuropathy pain; arthrosis pain; arthritis pain; scoliotic pain; post-traumatic pain; post-operative pain; phantom pain.

7. Pathogenetic base of PRM-programs for pain management

The influence of physical modalities on the interstitium (milieu intérieur of Claude Bernard) is the theoretical base for combination of drugs and physical modalities [53, 54].

The synergy between different physical modalities is the logical base for prescription of complex rehabilitation program. According the theory of Ferreira (1983) pain is a consequence of the combination of algesic and hyperalgesic stimulation [54]. Natural physical modalities (physiotherapy, hydrotherapy, ergotherapy) provoke a block of the hyperalgesic stimulation. The algesic stimulation is influenced by preformed physical factors (electric currents, magnetic field, light, etc.). The combination of natural and preformed physical modalities can reduce pain, using different paths.

The construction of a complex physical and rehabilitation programme is needed, because the mechanism of action of different procedures is diverse (Figure 3).

Figure 3.

Synergic combination of physical modalities in pain patients.

8. Rehabilitation team for pain patients

The obligatory condition for the staff in Pain management is to have competencies in several thematic fields: Pain theories and the correspondent clinical field.

From the point of view of rehabilitation, the objective must be to assure the quality of life and the dignity of these patients. Our problem is the quality of care of pain patients. For us the most important is to guarantee the quality of life of pain patient.

The multi-disciplinary multi-professional team for pain patients must include:

• Medical doctors: specialists in Pain medicine, Neurology, Neurosurgery, Oncology (Neuro-Oncology), Anesthesiology, Radiology (Neuroradiology), Orthopedics and Traumatology; Physical and Rehabilitation Medicine;

• Medical and para-medical staff: Physiotherapist, Ergotherapist (occupational therapist), Nurse, Dietitian, Psychologist, Sociologist, etc.

9. Functional assessment of pain patients

Functional assessment in PRM-practice is based on ICF (Figure 4).

Figure 4.

ICF.

The holistic approach to the patient must be obligatory—the complex evaluation must include:

• Cognitive capacities (orientation, memory, attention, compliance during rehabilitation, conscience of necessity of preventive measures due to the principal disease);

• Pain (localization, type, intensity /verbal or visual analogue scale/; activities increasing pain);

• Range of motion (active and passive);

• Muscle force or muscle weakness, motor deficiency;

• Coordination (static, locomotor or dynamic ataxia);

• Mobility (necessity of technical aids, gadgets; instruments, etc.);

• Endurance (capacity to support extreme changes, necessity of pauses during investigations and functional activity);

• Independence in activities of daily living (bathing, dressing, eating, hygiene, necessity of assistance in self-care).

We evaluate some problems of the pain patient: Reduced endurance and supportability to physical activity, fatigue; Motor weakness; Coordination problems (posture, locomotion, grasping); Pain; Necessity of preventive measures; Necessity of technical aids; Necessity of assistance; Difficulties in activities of daily living; Reduced performance and Reduced functional mobility.

The final complex evaluation, based on ICF, have to include (Figure 5).

• Body functions (pain, range of motion, motor weakness, dyscoordination syndromes—ataxia);

• Activities (verticalization, mobility, standing up, walking, transport, grasping, activities of daily living—ADL);

• Participation (family life, leisure, social life, participation in political activities);

• Environmental factors (environment at home & at work, family & friends, health insurance, health assurance, social contacts);

• Personal factors (health culture, polimorbidity, age, sex).

Figure 5.

Assessment of pain patient, based on ICF.

10. Algorithms of pain management in post-operative cases

In every case, including post-operative cases, we apply the same algorithm: detailed functional assessment and complex rehabilitation. This complex rehabilitation principle comprises a synergic combination of different physical modalities and techniques, accentuating on physiotherapy, ergotherapy, functional electrical stimulations and pain management with preformed modalities (Figure 6).

Figure 6.

Rehabilitation puzzle in post-operative cases.

We emphasize on strictly analgesic procedures, as follows:

• From the group of preformed modalities: dyadinamic electric currents, transcutaneous electroneurostimulation (TENS), Trabert current, interferential currents, magnetic field, LASER, Deep Oscillation, Shock-Wave therapy;

• From the group of natural physical modalities: soft tissue techniques (post-isometric relaxation, relaxing massage), manual therapy, extension therapies, balneo-physiotherapy, peloidotherapy;

• From the group of reflectory methods: acupuncture, low frequency electric currents in reflectory points.

The choice of the concrete physical factor and of the respective therapeutic method depends on the type of pain and of the principal disease or condition [55, 56, 57, 58, 59], as follows:

• In nociceptive pain—we apply low frequency electric current (galvanic current, Lidocaine-iontophoresis, dyadinamic current, especially diphase fixe—DF); position therapy, infiltration therapy;

• In neuropathic pain—we prefer transcutaneous electroneurostimulation (TENS), Interferential currents, Deep Oscillation; balneotherapy, peloidotherapy;

• Rheumatic pain in degenerative articular diseases: magnetic field, middle frequency electric currents; laser-therapy, Deep Oscillation; isometric exercises; infiltration therapy (in the joint or around it);

• Rheumatic pain in inflammatory joint diseases: in the acute stage—low and middle frequency electric currents, magnetic field, cryotherapy, analytic isometric exercises; in the chronic stage—interferential currents, magnetic field, Deep Oscillation, laser; balneotherapy, peloidotherapy, passive physiotherapy;

• In post-traumatic conditions: cryotherapy, position therapy, active exercises (accentuating on isometric exercises), magnetotherapy, interferential currents;

• In cases with myofascial pain—middle-frequency electric currents, deep oscillation, stretching of the respective fascia; analytic exercises—against gravity and against resistance; underwater exercises, underwater douche massage;

• In ligamentar pain—shock wave therapy, TENS, cryotherapy, underwater exercises;

• In spondylogenic pain (vertebrogenic and discogenic)—low-frequency electric currents, post-isometric relaxation (PIR), stretching, extension therapy (extension vertebrotherapy), manual therapy (tractions, mobilizations, manipulations), in chronic stage—ultrasound (or phonophoresis with a non-steroidal anti-inflammatory gel), LASER (lasertherapy, laserpuncture, laseracupuncture), exercises for muscular belt, paravertebral infiltrations;

• In oncologic pain—infiltration therapy, active physiotherapy.

During the preparation of the rehabilitation complex, we must combine synergically procedures with three or more mechanisms of physical analgesia.

In some cases, we must combine physical analgesia and medications.

Patient’s education is obligatory in cases with chronic pain, especially after surgical intervention.

In the scientific literature, exist some investigations, proving the effectiveness of physical analgesia (with different level of evidence) after surgical interventions. Some of the used combinations are:

• In patients after orthopedic surgery (hip, knee or shoulder arthroplasty; metallic osteosynthesis of long bones of extremities)—mechanotherapy, active exercises for limbs muscles, cryotherapy, interferential currents, Deep Oscillation, functional electrical stimulations, telerehabilitation [10, 24, 25, 30, 31, 33, 34, 35, 49, 51, 52];

• In patients after mini-invasive operation of ruptured ligaments—TENS, Interferential currents, Deep Oscillation, magnetic field, laser, analytic exercises, mechanotherapy [23, 49];

• In patients after neurosurgical intervention for brain tumors—mechanotherapy, active exercises, proprioceptive neuromuscular stimulation, balance and gait training [49];

• In patients after operation of discal hernia—TENS, dyadinamic currents, interferential currents, Deep Oscillation; Magnetic field, lasertherapy; analytic exercises, position therapy, relaxing massage, gait training [10, 17, 22, 31, 33, 49, 50];

• In patients after limb amputation with stump pain and phantom pain—Deep Oscillation, Lasertherapy, analytic exercises [26, 48];

• In patients after abdominal operations: active exercises, electrical stimulations for stimulation of the peristaltic [26].

11. Conclusion

Pain management is an important part of rehabilitation algorithms in clinical practice. PRM-programmes of care is obligatory in pain cases, especially in post-operative patients.

We could recommend our complex pain management program.

The on-time start of rehabilitation procedures in pain management (especially after surgical intervention) has a lot of beneficial consequences: improvement of patient condition and prevention of complications; increase of muscle force and range of motion; regularization of static and balance; normalization of humero-scapular and pelvi-femoral rhythm; functional recovery of the grasp and gait, amelioration of autonomy of patients and of quality of life; acceleration of resocialization and participation in functional activities, positive economic effect.

Conflict of interest

The authors declare no conflicts of interest.