A Review of the Emotional Aspects of Neuropathic Pain: From Comorbidity to Co-Pathogenesis

Pain and Therapy, Nov 2017

Neuropathic pain is characterized by both sensory and affective disturbances, supporting the notion that pain and mood disorders share common pathogenetic mechanisms. Moreover, biological and neuroimaging data show that common brain areas are involved in the modulation of painful and emotional experiences. Improved understanding of the molecular mechanisms underlying the role of neuroinflammation in regulation of affective behavior in neuropathic pain states is important for the development of novel therapeutic strategies. Psychological issues must be considered a factor influencing treatment and outcome in patients with neuropathic pain. Funding: Pfizer, Italy.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://link.springer.com/content/pdf/10.1007%2Fs40122-017-0088-z.pdf

A Review of the Emotional Aspects of Neuropathic Pain: From Comorbidity to Co-Pathogenesis

Pain Ther A Review of the Emotional Aspects of Neuropathic Pain: From Comorbidity to Co-Pathogenesis 0 R. Torta V. Ieraci (&) F. Zizzi Department of Neuroscience ''Rita Levi Montalcini'', University of Turin , Turin , Italy Neuropathic pain is characterized by both sensory and affective disturbances, supporting the notion that pain and mood disorders share common pathogenetic mechanisms. Moreover, biological and neuroimaging data show that common brain areas are involved in the modulation of painful and emotional experiences. Improved understanding of the molecular mechanisms underlying the role of neuroinflammation in regulation of affective behavior in neuropathic pain states is important for the development of novel therapeutic strategies. Psychological issues must be considered a factor influencing treatment and outcome in patients with neuropathic pain. Funding: Pfizer, Italy. Mood disorders; Molecular mechanisms; Neuroinflammation; Neuropathic pain; Therapeutic strategies - Neuropathic pain is associated with a substantial economic burden for both individuals and society [1]. There is strong evidence available to suggest that patients with neuropathic pain experience worse health-related quality of life (QOL) than the general population [2–4], and a negative effect of neuropathic pain has also been reported in other health conditions [5, 6]. Chronic pain with a neuropathic component has been shown to be associated with worse QOL, greater psychological distress, increased interference with sleep, and loss of more workdays than chronic pain without a neuropathic component [ 7 ]. Neuropathic pain is characterized by sensory symptoms such as gain or loss of somatosensory function, burning and evoked pain, as well as abnormal temporal summation [8]. Nerve injury models have shown sensory disturbances to arise from interactions between neurons, immune and immune-like glial cells, and other immune cell-derived inflammatory mediators, including cytokines and chemokines, ATP, histamine, bradykinin and prostaglandins; in this sense, neuropathic pain is a neuro-immune disorder [9]. This report discusses the relationships between mood disorders and neuropathic pain, with a focus on the pathogenetic mechanisms linking these two disorders, and reviews available treatment strategies. Compliance with Ethics Guidelines This article is based on previously conducted studies and does not involve any new studies of human or animal subjects performed by any of the authors. MOOD DISORDERS IN PATIENTS WITH NEUROPATHIC PAIN Clinically, neuropathic pain is characterized by both sensory and affective disturbances, and this frequent comorbidity supports the notion that pain and mood disorders share some common pathogenetic mechanisms [ 10 ]. It is important, therefore, to treat an affective disorder that coexists with pain. The affective disturbances associated with pain include working memory dysfunction, impaired cognition, decreased appetite, depression, anhedonia, disruptions to sleep cycles, and impaired familial and social interactions [ 11 ]. The most common regions of the brain involved with pain in affective disturbances are the nucleus accumbens, the medial prefrontal cortex and the periaqueductal gray [ 12 ]. However, while available research highlights that there are some psychological variables common across different disorders, every pathology is characterized by some specific psychological aspects [ 10 ]. Neurological disorders associated with neuropathic pain are characterized by important associations between psychosocial factors and pain intensity. The importance of emotional aspects of pain is particularly evident for depression and anxiety [ 10 ]. Depression is predictive for pain in many conditions, including chronic musculoskeletal pain, multiple sclerosis, post-stroke pain and Parkinson’s disease [ 13–16 ]. Moreover, the presence of a neuropathic component correlates with higher values for depression and anxiety [ 17–19 ]. Depression can also be associated with alexithymia, with evidence suggesting that if these two factors are present together, they have a combined influence on the affective component of pain [20]. Anxiety is frequently present in patients with chronic pain conditions, and appears to be correlated with pain intensity [ 17, 21 ]. Neuropathic pain is associated with specific psychological factors: fear linked to the painful sensation and perceived danger associated with different activities may cause irritability and social withdrawal [10]. Importantly, an inadequate response of neuropathic pain to various drug therapies constitutes a substantial unmet need [1]. PATHOGENETIC MECHANISMS OF PAIN AND AFFECTIVE DISTURBANCES Supraspinal neuroinflammation has a potential role in the development of affective disorders in patients with neuropathic pain conditions. Evidence suggests sickness behavior, cognitive impairment, depression and other neuropsychiatric disor (...truncated)


This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1007%2Fs40122-017-0088-z.pdf

Riccardo Torta, Valentina Ieraci, Francesca Zizzi. A Review of the Emotional Aspects of Neuropathic Pain: From Comorbidity to Co-Pathogenesis, Pain and Therapy, 2017, pp. 11-17, Volume 6, Issue 1, DOI: 10.1007/s40122-017-0088-z