Pain control
Marta Imamura, Associate Professor at the University of São Paulo School of Medicine, São Paulo, Brasil
Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Pain is a relevant biological phenomenon as it informs an actual or potential tissue damage. In these cases, pain control measures should address the underlying pathology, injury and related health condition. Chronic pain occurs beyond the expected healing time, usually persisting for more than three months of its onset. Neuropathic pain arises as a direct consequence of a lesion or disease affecting the somatosensory system.
Painful peripheral neuropathy, polyneuropathy, radiculopathy, postherpetic neuralgia, trigeminal neuralgia, spinal cord injury, postamputation and central poststroke pain. Nociplastic pain is recently defined as pain that arises from altered nociception despite no clear evidence of actual or threatened tissue damage causing the activation of peripheral nociceptors or evidence for disease or lesion of the somatosensory system causing the pain.
Nociplastic pain derives from augmented pain processing and altered pain modulation in the central nervous system and should be considered in any patient with chronic pain. It is a phenotypic expression of multifactorial processes originating from different inputs, both as a response to a peripheral nociceptive or neuropathic trigger and reduced pain inhibitory mechanisms. Main clinical features of nociplastic pain conditions include combined peripheral and central sensitization, spinal cord reorganization, hyper-responsiveness to painful and non-painful sensory stimuli, associated with fatigue, sleep and cognitive disturbances, hypersensitivity to environmental stimuli, anxiety and depression mood.
Pain control measures include nonopioid analgesics such as nonsteroidal anti-inflammatories (NSAIDs), acetaminophen, and aspirin. Additionally, medications such as tramadol, opioids, antiepileptic drugs (gabapentin or pregabalin) can be used with caution. Antidepressants such as tricyclic antidepressants and serotonin and norepinephrine reuptake inhibitors (SNRI’s), topical analgesics, muscle relaxers, N-methyl-d-aspartate (NMDA) receptor antagonists, and alpha 2 adrenergic agonists are also possible pharmacological therapies. Adjunctive topical agents such as topical lidocaine, NSAIDs and capsaicin cream may also be useful treatments.
Multidisciplinary rehabilitation approaches target sleep hygiene, adequate nutrition, physical fitness as tolerated and in progressive fashion. Nonpharmacological options include heat and cold therapy, cognitive behavioral therapy, relaxation therapy, biofeedback, group counseling, ultrasound stimulation, acupuncture, aerobic exercise, chiropractic, physical therapy, osteopathic manipulative medicine, occupational therapy, TENS units and neuromuscular stimulation.
Interventional techniques can also be utilized for pain control. Spinal cord stimulation, epidural steroid injections, radiofrequency nerve ablations, botulinum toxin injections, nerve blocks, trigger point injections, and intrathecal pain pumps are some of the procedures and techniques commonly used to combat chronic pain. Pain control strategies should be introduced in a stepwise fashion, considering patient’s tolerance and to avoid side effects.
It is crucial to recognize the types of pain, as they respond differently to therapies. Patients diagnosed with nociplastic pain, for example, present with a decreased responsiveness to peripherally directed therapies such as anti-inflammatory drugs, opioids, surgeries and invasive procedures. First line interventions include non-pharmacological treatments, patient education, promotion of self-management control measures, including proper lifetime habits and psychological therapies.
Related references:
Raja, Srinivasa N.a,*; Carr, Daniel B.b; Cohen, Miltonc; Finnerup, Nanna B.d,e; Flor, Hertaf; Gibson, Stepheng; Keefe, Francis J.h; Mogil, Jeffrey S.i; Ringkamp, Matthiasj; Sluka, Kathleen A.k; Song, Xue-Junl; Stevens, Bonniem; Sullivan, Mark D.n; Tutelman, Perri R.o; Ushida, Takahirop; Vader, Kyleq. The revised International Association for the Study of Pain definition of pain: concepts, challenges, and compromises. PAIN: September 2020 – Volume 161 – Issue 9 – p 1976-1982 doi: 10.1097/j.pain.0000000000001939
Breivik H, Collett B, Ventafridda V, Cohen R, Gallacher D. Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment. Eur J Pain. 2006 May;10(4):287-333. doi: 10.1016/j.ejpain.2005.06.009. Epub 2005 Aug 10. PMID: 16095934.
Dydyk AM, Conermann T. Chronic Pain. [Updated 2022 May 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK553030/
Doth AH, Hansson PT, Jensen MP, Taylor RS. The burden of neuropathic pain: a systematic review and meta-analysis of health utilities. Pain. 2010 May;149(2):338-344. doi: 10.1016/j.pain.2010.02.034. Epub 2010 Mar 15. PMID: 20227832.
Treede RD, Jensen TS, Campbell JN, Cruccu G, Dostrovsky JO, Griffin JW, Hansson P, Hughes R, Nurmikko T, Serra J. Neuropathic pain: redefinition and a grading system for clinical and research purposes. Neurology. 2008 Apr 29;70(18):1630-5. doi: 10.1212/01.wnl.0000282763.29778.59. Epub 2007 Nov 14. PMID: 18003941.
Short Bio
Marta Imamura, MD PhD is Associate Professor at the University of São Paulo School of Medicine, Department of Legal Medicine, Bioethics, Labour Medicine, and Physical Medicine and Rehabilitation. Prof Imamura received her medical degree at the University of São Paulo School of Medicine in São Paulo, Brazil in 1987. She specialized in Physical and Rehabilitation Medicine after completing a three-year residency programme at University of São Paulo School of Medicine (1988-1990) in 1990. She received her master and doctorate degree at the same University in 1994 and in 1998 respectively. She coordinates the Pain Laboratory at the Clinical Research Center of the institute of Physical Medicine and Rehabilitation, Hospital das Clinicas, University of Sao Paulo School of Medicine. Her research focuses on functional assessment and rehabilitation management of chronic disabling pain. She is member of the Pan American Health Organization Collaborating Center for Rehabilitation. Prof Imamura coordinates the medical undergraduate Rehabilitation discipline in the core curriculum at the University of Sao Paulo School of Medicine and the post-graduation disciplines entitled “Functional Assessment in Rehabilitation” and “Clinical Trials Designs in Rehabilitation Research”. She is currently the Associate Editor of the Acta Fisiatrica Journal. Prof Imamura has authored and co-authored more than 70 peer-reviewed publications. She has served as President of the Brazilian Association of Physical Medicine and Rehabilitation for two consecutive terms: 2008-2010, 2010-2012. Dr Imamura has also served as President of the International Society of Physical and Rehabilitation Medicine in 2012-2014 and currently serves as member at large of the World Federation for NeuroRehabilitation.
