**2. Pain**

According to the last guidelines by the International Association for the Study of Pain (IASP), pain is defined as unpleasant sensory and emotional experience associated with or resembling that of actual or potential tissue damage [5].

The presence of pain in patients at PC is associated with actual or potential tissue damage which has implications on their daily physical activities, produces debilitation and mental destabilization and has social consequences. In general, pain is a special medical condition which pathophysiology is complex and originates from different causes [6].

Many stimulations arising from injuries or destroyed tissues, commonly associated with prime pathological event in the body, produce noxious stimuli. Peripheral painful stimuli are detected by nociceptors, which are free nerve endings located in tissues and organs. Following complex mechanisms, the noxious stimuli are transformed and recognized by the brain as pain [7].

The released neurotransmitters and neuropeptides enable the pain stimuli to ascend to the thalamus and midbrain through two main tracts, the spinothalamic tract and the spinoreticular tract (involved in descending inhibition of the pain) and through the spinomesencephalic tract. They go from the spinal cord, are synapsing in the periaqueductal gray meter in the midbrain and are involved in the modulation of the pain [8]. Descending pathways descend in the dorso-lateral fasciculus and synapse in the dorsal horn inhibitory tracts; they are coming mainly from areas (periaqueductal gray matter, the raphe nuclei, and the locus ceruleus) in the brainstem tracts.

Modulation of the pain is a process of inhibition or amplification of the pain signals [9]. It happens along its ascending pathways on several levels, at segmental level (the primary afferent neuron and dorsal horn), supra-segmental level (midbrain) and cortical, or through the descending pathways. In this process the following excitatory substances are included: excitatory amino acids (EAA), acetylcholine (Ach), glycine, substance P (sP), Oxytocin, central corticotropin releasing hormone (CRH), and the inhibitory substances as serotonin, noradrenalin (NE), and gamma-amino butyric acid (GABA) including endorphins (eg, enkephalin) [10].

Many drugs are acting as modulators of pain. They are acting at segmental level (local anesthetics), supra segmental (opioids, non-opioids, and adjuvants), and central or cortical levels (opioids). The endogens opioids endorphins and enkephalins are acting via the descending system and are responsible for the analgesia induced by stress.

Modulation and perception are the component of the plasticity of the pain. Pain plasticity is a result of the possibility of the nervous system to modify its function under different conditions [9]. For the perception of the noxious stimuli and the formation of the memory of the pain, the middle and higher levels of the brain are responsible. The subconscious pain information's are ended in sub cortical level at hypothalamus, thalamus, amygdale, and hippocampus. They are transferred to the cortical centers where they are recognized as pain in somato sensory cortex, insula, and anterior cingulate cortex [10].

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*Multimodal Pain Management in the Setting of Palliative Care*

In general, pain can be acute (physiological) and chronic (pathological). Some authors make a distinction between physiological and pathological pain, classify it as Nociceptive (somatic, visceral), and Neurophatic (burning along the nerves, dysesthesia, allodynia, Hyperalgesia) [11]. Under certain conditions, acute pain can become maladaptive and non-protective and turn to pathological, dysfunctional

The evidence concerning pain among patients in PC show that during the care phase, pain is present in one moment in approximately 70–90% of the patients [9]. Pain is seen in many end stage diseases. The prevalence of pain is most common in cancer; 70–90% in latter stages of the illness and 33–70% in patients receiving treatment [12]. Comparatively, the prevalence of chronic pain in the general adult population ranges from 2% to 40%. It is known that back pain alone affects "up to

Many conditions in palliative settings could provoke the pain. Mainly they are caused by the primary diseases, disorders, and conditions. An accidental situation such as trauma, blunt trauma, broken bone, burning, electrical injury, eye injury, heart attacks or postoperative state (amputation, removal of a part of an organ) needs corresponding analgesia. In chronic illnesses from circulatory, infectious, or malignant origins, the pain is expressed as neural compression or malignant infiltration, bone metastasis, obstructions, and infiltration of the soft tissues. Many

Resulting from the type of the pain, the feeling pain is different. The pain is reported as dull, achy, stabbing, shooting, burning, severe, or pins-and-needles

The patients on PC fear pain because of its physical, emotional, and psychological components [3]. Unrelieved or undertreated pain with all its effects to the body systems, may transit to chronic pain. The pain experience is unique for each individual and the way everyone perceives pain, and its severity is different, leading to changes in the personality that has social implications. If the pain is with chronic persistence, it disturbs the sleep and appetite, lowers the tolerance to stress and is often the reason for depression. There are evidences that pain contributes to the development of some cognitive dysfunctions. It impairs attention, memory,

The reaction to pain and thresholds to pain are complex and individual and depend to the individual experiences to pain. The intensity of the pain is in the proportion of the extent of the tissue damage, the severity of the illness and the degree of the patients' discomfort [14]. The after-effects of persistent pain are multiple due to stress-reaction with the involvement of the adreno-cortical axis and hyperactivity in many organs and systems. Increased heart rate with low cardiac output, presence of fear, increase respiration rate, cold vasoconstricted skin, neurological dysfunctions and other impairments in homeostasis are often seen as associated symptoms to the pain [15]. Patients with chronic pain may have low

Modifications of the quality of the pain are product of different physiological and psychological phenomena. The protective function of the pain has function to restore the homeostasis at both levels (autonomic and psychological). The intensity of pain can be modulated by psychological factors where emotions have an important role in the perception of pain. The memory of pain episodes, the patients' reactivity to pain, families and friends supports, religion, personal defense skills, and therapeutic strategies are the most frequent reasons for these modifications [8]. The levels of education, culture and tradition have an important part in the formation of the pain experience. Severe pain produces mental and physical torture of the body [17]. The person is exhausted, fatigued and without energy. Fatigue is one

degenerative processes produce inflammation and are reason for pain.

concentration, and content of thought [13].

levels of endorphins in their spinal fluid [16].

*DOI: http://dx.doi.org/10.5772/intechopen.96579*

pain - chronic pain.

84%" of adults.

sensations.

*Suggestions for Addressing Clinical and Non-Clinical Issues in Palliative Care*

Pain is very often present at the end of the life, but unfortunately the presence of pain in palliative care is underestimated. The reasons for that are multi-factorial. One of the reasons is a lack of communication and difficulties between the patients and the palliative care providers; the second is unrecognized and misunderstood presence of pain; the third is the mixture of different symptoms or other reasons [4]. Due to these reasons, it is necessary to improve the knowledge about the pathogenesis of pain and the modern approaches to the management of pain relief.

According to the last guidelines by the International Association for the Study of Pain (IASP), pain is defined as unpleasant sensory and emotional experience associated with or resembling that of actual or potential tissue damage [5]. The presence of pain in patients at PC is associated with actual or potential tissue damage which has implications on their daily physical activities, produces debilitation and mental destabilization and has social consequences. In general, pain is a special medical condition which pathophysiology is complex and originates

Many stimulations arising from injuries or destroyed tissues, commonly associated with prime pathological event in the body, produce noxious stimuli. Peripheral painful stimuli are detected by nociceptors, which are free nerve endings located in tissues and organs. Following complex mechanisms, the noxious stimuli are trans-

The released neurotransmitters and neuropeptides enable the pain stimuli to ascend to the thalamus and midbrain through two main tracts, the spinothalamic tract and the spinoreticular tract (involved in descending inhibition of the pain) and through the spinomesencephalic tract. They go from the spinal cord, are synapsing in the periaqueductal gray meter in the midbrain and are involved in the modulation of the pain [8]. Descending pathways descend in the dorso-lateral fasciculus and synapse in the dorsal horn inhibitory tracts; they are coming mainly from areas (periaqueductal gray matter, the raphe nuclei, and the locus ceruleus) in the brainstem tracts. Modulation of the pain is a process of inhibition or amplification of the pain signals [9]. It happens along its ascending pathways on several levels, at segmental level (the primary afferent neuron and dorsal horn), supra-segmental level (midbrain) and cortical, or through the descending pathways. In this process the following excitatory substances are included: excitatory amino acids (EAA), acetylcholine (Ach), glycine, substance P (sP), Oxytocin, central corticotropin releasing hormone (CRH), and the inhibitory substances as serotonin, noradrenalin (NE), and gamma-amino butyric acid (GABA) including endorphins (eg, enkephalin) [10]. Many drugs are acting as modulators of pain. They are acting at segmental level (local anesthetics), supra segmental (opioids, non-opioids, and adjuvants), and central or cortical levels (opioids). The endogens opioids endorphins and enkephalins are acting via the descending system and are responsible for the analgesia

Modulation and perception are the component of the plasticity of the pain. Pain plasticity is a result of the possibility of the nervous system to modify its function under different conditions [9]. For the perception of the noxious stimuli and the formation of the memory of the pain, the middle and higher levels of the brain are responsible. The subconscious pain information's are ended in sub cortical level at hypothalamus, thalamus, amygdale, and hippocampus. They are transferred to the cortical centers where they are recognized as pain in somato sensory cortex, insula,

**222**

induced by stress.

and anterior cingulate cortex [10].

**2. Pain**

from different causes [6].

formed and recognized by the brain as pain [7].

In general, pain can be acute (physiological) and chronic (pathological). Some authors make a distinction between physiological and pathological pain, classify it as Nociceptive (somatic, visceral), and Neurophatic (burning along the nerves, dysesthesia, allodynia, Hyperalgesia) [11]. Under certain conditions, acute pain can become maladaptive and non-protective and turn to pathological, dysfunctional pain - chronic pain.

The evidence concerning pain among patients in PC show that during the care phase, pain is present in one moment in approximately 70–90% of the patients [9]. Pain is seen in many end stage diseases. The prevalence of pain is most common in cancer; 70–90% in latter stages of the illness and 33–70% in patients receiving treatment [12]. Comparatively, the prevalence of chronic pain in the general adult population ranges from 2% to 40%. It is known that back pain alone affects "up to 84%" of adults.

Many conditions in palliative settings could provoke the pain. Mainly they are caused by the primary diseases, disorders, and conditions. An accidental situation such as trauma, blunt trauma, broken bone, burning, electrical injury, eye injury, heart attacks or postoperative state (amputation, removal of a part of an organ) needs corresponding analgesia. In chronic illnesses from circulatory, infectious, or malignant origins, the pain is expressed as neural compression or malignant infiltration, bone metastasis, obstructions, and infiltration of the soft tissues. Many degenerative processes produce inflammation and are reason for pain.

Resulting from the type of the pain, the feeling pain is different. The pain is reported as dull, achy, stabbing, shooting, burning, severe, or pins-and-needles sensations.

The patients on PC fear pain because of its physical, emotional, and psychological components [3]. Unrelieved or undertreated pain with all its effects to the body systems, may transit to chronic pain. The pain experience is unique for each individual and the way everyone perceives pain, and its severity is different, leading to changes in the personality that has social implications. If the pain is with chronic persistence, it disturbs the sleep and appetite, lowers the tolerance to stress and is often the reason for depression. There are evidences that pain contributes to the development of some cognitive dysfunctions. It impairs attention, memory, concentration, and content of thought [13].

The reaction to pain and thresholds to pain are complex and individual and depend to the individual experiences to pain. The intensity of the pain is in the proportion of the extent of the tissue damage, the severity of the illness and the degree of the patients' discomfort [14]. The after-effects of persistent pain are multiple due to stress-reaction with the involvement of the adreno-cortical axis and hyperactivity in many organs and systems. Increased heart rate with low cardiac output, presence of fear, increase respiration rate, cold vasoconstricted skin, neurological dysfunctions and other impairments in homeostasis are often seen as associated symptoms to the pain [15]. Patients with chronic pain may have low levels of endorphins in their spinal fluid [16].

Modifications of the quality of the pain are product of different physiological and psychological phenomena. The protective function of the pain has function to restore the homeostasis at both levels (autonomic and psychological). The intensity of pain can be modulated by psychological factors where emotions have an important role in the perception of pain. The memory of pain episodes, the patients' reactivity to pain, families and friends supports, religion, personal defense skills, and therapeutic strategies are the most frequent reasons for these modifications [8]. The levels of education, culture and tradition have an important part in the formation of the pain experience. Severe pain produces mental and physical torture of the body [17]. The person is exhausted, fatigued and without energy. Fatigue is one

of the leading symptoms of terminal states and often concomitant symptom of the malignancy, producing a poor quality of life.
