The concept of pain has been changing over the years. One of the most widely accepted pain definitions today is the one proposed by the International Association for the Study of Pain (IASP), which defines it as an unpleasant sensory and emotional experience with actual or potential tissue damage, or described in terms of such damage .
Neuropathic pain (NeP) is understood as the result of an injury or disease that affects the somatosensory system  and can be classified according to its location (central or peripheral), its distribution (localized or diffuse), its etiology or production mechanisms.
The most characteristic symptom of DN is the painful or burning sensation (dysesthesia), together with hyperalgesia (exaggerated response to pain) or and allodynia (perception of any stimulus as painful), characteristic of an altered hypersensitivity, making the difference between positive sensory symptoms and negative .
The special group on the study of neuropathic pain (NeuPSIG) proposed a classification system to guide decisions about the level of certainty with which NeP can be determined in a patient: possible, probable, and definitive .
In reference to the guidelines for the therapeutic management of NeP, consensus recommendations are followed and complementary treatment algorithms have been developed for use in the Primary Care setting and by non-pain specialists  , as well as those recommended by Special Interest IASP Group on Neuropathic Pain (NeuPSIG) for peripheral and localized neuropathic pain .
The objective of this work is to propose a protocol for the assessment of NeP that allows quantifying its impact in the personal, health, work and social environment and to establish guidelines for its management, evolution and adaptation in the work environment.
Prior to including the variables in the protocol, a review of the existing scientific literature on the global concept of NeP and its relationship with work, social impact and quality of life was carried out. The search was done in Medline through the PubMed platform (https://pubmed.ncbi.nlm.nih.gov/), free access and with wide international coverage. The search period was limited to the 10 years prior to the start of the study (2009-2019) and, especially, to the last 5 years, including classified journal articles (editorials, originals, letters, reviews, clinical notes). The search strategy has been based on relating neuropathic pain with specific aspects of the occupational world. The MeSH headings used were: “neuropathic pain” “neuropathic pain and work” “neuropathic pain and work neurotoxicity” “neuropathic pain and work health”.
Based on the results found in this review, elements to evaluate the impact and repercussion of DN were included in the protocol: personal aspects, with a global assessment of 10 points (age, level of training or education, economic situation, support from the environment—understanding as such the support of family members, cohabiting friends at home or of aid agencies or entities- and employment situation); clinical and care aspects, with a global assessment of 50 points (pain, muscle tone, function or muscle balance based on the modified Medical Research Council Scale , peripheral pulses-associated, vascular alterations, neurological involvement—sensory, motor, reflex alteration, sphincter alteration, gait disorders, complementary examinations-electromyography); therapeutic aspects (effectiveness of the treatment, side effects and comorbidities); labor aspects, with a global score of 30 points, med a self-created preventive labor check-list; and social aspects-quality of life, with a global score of 10 points, for which the use of the HAQ questionnaire is proposed.
Each of these aspects is scored individually to obtain a maximum total score of 100 points. The limitation is stratified in scores according to the final punctuation: 0 - 25 points, mild score; 26 - 50 points, moderate score; 51 - 75 points, severe score and 76 - 100 points, extreme score.
Based on current evidence and taking into account the changes that scientific research is permanently incorporating, different evaluation parameters have been included in this Neuropathic Pain Assessment Protocol, structured in four sections, to reach a final assessment. The aspects to be assessed are summarized in Figure 1 and detailed in Tables 1-4.
This is a proposal that has not been validated at the present time.
Table 1. Personal aspects related to neuropathic pain impact.
Table 2. Clinical and therapeutic aspects related to neuropathic pain impact.
Table 3. Labor aspects related to neuropathic pain impact: CHECK LIST.
Table 4. Social aspects/quality of life related to neuropathic pain impact. HAQ questionnaire.
Figure 1. Protocol for assessment of neuropathic pain in occupational health.
The medical bibliography collected in databases specialized in health sciences (PUBMED) shows studies on NeP that estimate its prevalence at around 7% - 10% of the general population, with an increasing trend, probably associated with the increase in diseases that accompany the aging of the world population, changes in lifestyle, the increase in the incidence of diabetes mellitus, and the improvement of treatments for some diseases, such as cancer survival after chemotherapy, but with subsequent adverse effects. This means that the burden of chronic NeP is also increasing and has repercussions on economic, health and quality of life costs for the affected people. Therefore, personalized interventions are recommended with a multidisciplinary approach to the management of this disease .
The causes of NeP can be multiple. The Tax Society Pain Taxonomy (AAPT) developed, in collaboration with different public and private entities, diagnostic criteria for central NeP that are organized according to the multidimensional framework of the AAPT: central diagnostic criteria, common characteristics, medical comorbidities and common psychiatric, neurobiological, psychosocial and functional consequences and supposed neurobiological and psychosocial mechanisms, risk factors and protective factors .
But if its diagnosis is complex and its etiology and epidemiology varied, the therapeutic management is more complicated, which requires periodic updates. NeuPSIG affirms that the inadequate response to pharmacological treatments constitutes a substantial unmet need in patients with NeP and recommends for future trials the use of pain relief scales, patient and physician global impression of change, validated measures of patient quality. NeP and sleep assessment, assessment of mood, functional capacity, and quality of life .
From an occupational point of view, the medical bibliography contains specific publications on prevalent pathologies, caused or aggravated by work, with associated NeP. Among others, the carpal tunnel syndrome    and chronic cervical and lumbar pain ; The relationship of age, gender and tobacco consumption with this group of pathologies that present with chronic NeP is also relevant   . Post-traumatic pain directly affects the work environment, especially after traumatic occupational accidents and commuting or traffic accidents during work, and its management is often complex since appropriate treatment options must be considered to minimize the sequelae .
Highlight as specific NeP in the workplace that is derived from exposures to neurotoxic substances, such as acute carbon monoxide poisoning or late neurotoxicity due to toluene, where early action is essential to prevent the development of neuropathy and improve prognosis .
The scientific literature collects data that support the fact that the presence of NeP is associated with a greater burden of disease in the population, with chronicity in its evolution and that is reflected in terms of quality of life, health status, work experience and direct medical costs . Along with the personal, individual cost, the cost of NeP for society must be assessed for all aspects: direct medical costs, loss of ability to work, loss of caregivers’ ability to work and possibly increased need for institutionalization or other assistance for daily life activities. A more complete estimate of efficacy, utility and costs would facilitate future research regarding the profitability of the therapies used in the treatment of NeP .
In Spain, the experience of pain represents a substantial burden both for people and for the country’s economy. It is reflected in the questionnaires commonly used to measure the impact of pain (both SF-12 and SF-6D) , especially with regard to severe pain, but it also implies less participation in work activity and greater absenteeism and presenteeism, with substantially higher patterns of use of health resources  . The researchers affirm that this type of pain and its impact far outweighs the consequences provided by the more traditional assessments of health-related quality of life (HRQoL) deficits, in addition to being the main factor associated with increased visits medical, emergency services and in need of hospitalizations .
The basis of this protocol is to homogenize the assessment of the impact of NeP including all those factors that may condition the result. Although many studies have evaluated individual aspects, such as the profitability of the treatments, the significant heterogeneity among them prevents reaching a homogeneous synthesis of the results. The standardized methodology and the improved reports would allow more reliable comparisons between the studies . Strategies are proposed to maximize the results, employing, when possible, agents that address both pain and comorbidities in order to restore function and improve function, quality of life of the patient .
Previously proposed assessment tools, such as the pain DETECT Project, already have long-standing experience, with more than 300,000 patients assessed, providing one of the world’s largest data sets on chronic pain, and generating subgroups of patients based on their individual sensory profiles, with the idea of being able to stratify the treatment and, ultimately, to be able to reach a personalized therapy. Today, it is used for clinical and research purposes all around the world .
The protocol that we present here within the AlVaDoNe  project serves as a new tool, with a broad focus, although more specific in occupational health and that could be validated in the future.
5. Preventive Recommendations
The main preventive recommendation in relation to the protection of workers with chronic NeP is to reduce risk exposure and facilitate their social and occupational integration, through different actions:
• With correct health surveillance, care coordination in the process of diagnosis, treatment, control and monitoring by all those involved: occupational health, primary care and specialties, specifically with the pain units, hospital care and Organisms public health.
• With application, within the scope of the specific competencies of the Prevention Services, of all technical and sanitary measures aimed at reducing the risk in the work performance of the affected people to act, both in primary and secondary prevention, or limit their consequences through all available options: training and specific information for workers; adoption of organizational and preventive measures, collective and individual; health surveillance aimed at detection and protection of especially sensitive workers; and coordinated care work.
It is recommended:
1) In cases of mild pain, without significant interference in daily life and/or work, preventive surveillance actions.
2) In cases of moderate pain, which limits some activities of daily life and/or work, in addition to preventive surveillance, assess possible adaptations that minimize the risk in their usual work or job changes.
3) In cases of severe pain, which limits many activities of daily life and/or work and generates some type of dependence on the person for some of them, assess actions for processing temporary and/or permanent disability and, in any case, support the affected person with the necessary reports for its processing.
4) In cases of extreme pain, which limits the majority of activities of daily life and work, even the most basic and generates extensive dependence on the person, facilitate management towards disability and disability procedures and support the affected person with the necessary reports for its processing.
In Spain, Law 31/1995, on Occupational Risk Prevention (LPRL)  establishes the right of workers to effective protection in terms of safety and health at work. One of the instruments used by Occupational Medicine to control and monitor the working health population status and the impact of working conditions on them is Health Surveillance, through an individualized assessment of each worker with the performance of specific medical examinations based on the risks of the position (individual surveillance), and a subsequent joint analysis of all the results obtained in the company (collective surveillance).
The assessment of work aptitude is the evaluation of the psychophysical capacity of the individual to carry out their work without risk to their own health or that of others, based on the relationship between work demands and the health of the individual who is going to do it.
It is the final result of the specific evaluation of the health state as an individual health intervention within the framework of the surveillance of the worker’s health, and it is also necessary for the Occupational Physician to have a thorough knowledge of the detailed demands and requirements of the job, understanding by job the set formed by the physical place, the tools, tasks, duties and responsibilities assigned to a person in a work environment.
For the assessment from the perspective of Health Surveillance of a worker with NeP, the clinical history and physical examination are particularly relevant, since in most cases the results of the complementary tests have little correlation with the functional impairment of these patients. The clinical history should collect the severity and evolution of the symptoms and the functional repercussion they entail, analyze the response to the received treatments and their repercussion in the physical and emotional spheres. In a complementary way, the necessary laboratory or imaging examinations will be added, the most useful being electromyography.
The NeP Assessment Protocol is shown as a tool that helps the professional to assess the consequences of NeP in the patient’s daily life, socially and at work.
No patient/worker should be evaluated without having diagnostic confirmation of neuropathic pain: clinical data and, if possible, confirmation of nerve injury with electromyography.
In all cases, for a global assessment in the workplace of the patient with NeP, in addition to the clinical-therapeutic aspects, it is necessary to consider personal and work aspects, due to their interrelation with pain and the influence of pain on the quality of social and work life of the patient/worker.
 Treede, R.D., Jensen, T.S., Campbell, J.N., Cruccu, G., Dostrovsky, J.O., Griffin, J.W., et al. (2008) Neuropathic Pain: Redefinition and a Grading System for Clinical and Research Purposes. Neurology, 70, 1630-1635.
 Finnerup, N., Haroutounian, S., Kamerman, P., Baron, R., Bennett, D., Bouhassira, D., et al. (2016) Neuropathic Pain: An Updated Grading System for Research and Clinical Practice. Pain, 157, 1599-606.
 Finnerup, N.B., Attal, N., Haroutounian, S., McNicol, E., Baron, R., Dworkin, R.H., et al. (2015) Pharmacotherapy for Neuropathic Pain in Adults: A Systematic Review and Meta-Analysis. The Lancet Neurology, 14, 162-173.
 Colloca, L., Ludman, T., Bouhassira, D., Baron, R., Dickenson, A.H., Yarnitsky, D., et al. (2017) Neuropathic Pain. Nature Reviews Disease Primers, 3, Article No. 17002.
 Widerström-Noga, E., Loeser, J.D., Jensen, T.S. and Finnerup, N.B. (2017) AAPT Diagnostic Criteria for Central Neuropathic Pain. The Journal of Pain, 18, 1417-1426.
 Haanpää, M., Attal, N., Backonja, M., Baron, R., Bennett, M., Bouhassira, D., et al. (2011) NeuPSIG Guidelines on neuropathic Pain Assessment. Pain, 152, 14-27.
 Lazaro, R.P. and Eagan, T.S. (2017) Concurrent Musculoskeletal and Soft Tissue Pain in the Upper Extremity Can Affect the Treatment and Prognosis of Carpal Tunnel Syndrome: Redefining a Common Condition. Journal of Pain Research, 10, 2497-2502.
 Fan, Z.J., Harris-Adamson, C., Gerr, F., Eisen, E.A., Hegmann, K.T., Bao, S., et al. (2015) Associations between Workplace Factors and Carpal Tunnel Syndrome: A Multi-Site Cross Sectional Study. American Journal of Industrial Medicine, 58, 509-518.
 Harris-Adamson, C., Eisen, E.A., Neophytou, A., Kapellusch, J., Garg, A., Hegmann, K.T., et al. (2016) Biomechanical and Psychosocial Exposures Are Independent Risk Factors for Carpal Tunnel Syndrome: Assessment of Confounding Using Causal Diagrams. Occupational and Environmental Medicine, 73, 727-734.
 Sihawong, R., Sitthipornvorakul, E., Paksaichol, A. and Janwantanakul, P. (2016) Predictors for Chronic Neck and Low Back Pain in Office Workers: A 1-Year Prospective Cohort Study. Journal of Occupational Health, 58, 16-24.
 Marin, T.J., Van Eerd, D., Irvin, E., Couban, R., Koes, B.W., Malmivaara, A., et al. (2017) Multidisciplinary Biopsychosocial Rehabilitation for Subacute Low Back Pain. Cochrane Database of Systematic Reviews, 6, CD002193.
 Salt, E., Wright, C., Kelly, S. and Dean, A. (2011) A Systematic Literature Review on the Effectiveness of Non-Invasive Therapy for Cervicobrachial Pain. Manual Therapy, 16, 53-65.
 Kostova, V. and Koleva, M. (2001) Back Disorders (Low Back Pain, Cervicobrachial and Lumbosacral Radicular Syndromes) and Some Related Risk Factors. Journal of the Neurological Sciences, 192, 17-25.
 Hatch, M.N., Cushing, T.R., Carlson, G.D. and Chang, E.Y. (2018) Neuropathic Pain and SCI: Identification and Treatment Strategies in the 21st Century. Journal of the Neurological Sciences, 384, 75-83.
 Park, G.Y., Kwon, D.R. and Jung, W.B. (2018) Unilateral Brachial Plexus Injury Following Carbon Monoxide Intoxication: A Case Report. Medicine, 97, e11699.
 Langley, P.C., Van Litsenburg, C., Cappelleri, J.C. and Carroll, D. (2013) The Burden Associated with Neuropathic Pain in Western Europe. Journal of Medical Economics, 16, 85-95.
 Vilagut, G., Ferrer, M., Rajmil, L., Rebollo, P., Permanyer-Miralda, G., Quintana, J.M., et al. (2005) El Cuestionario de Salud SF-36 español: Una década de experiencia y nuevos desarrollos. Gaceta Sanitaria, 19, 135-150.
 Langley, P.C., Ruiz-Iban, M.A., Molina, J.T., De Andres, J. and Castellón, J.R.G.-E. (2011) The Prevalence, Correlates and Treatment of Pain in Spain. Journal of Medical Economics, 14, 367-380.
 Langley, P.C., Molina, J.T., Ferri, C.M., Hernández, C.P., Varillas, A.T. and Ruiz-Iban, M.A. (2011) The Association of Pain with Labor Force Participation, Absenteeism, and Presenteeism in Spain. Journal of Medical Economics, 14, 835-845.
 Langley, P., Hernández, C.P., Ferri, C.M., Hidalgo, D.R. and López, M.L. (2011) Pain, Health Related Quality of Life and Healthcare Resource Utilization in Spain. Journal of Medical Economics, 14, 628-638.
 Ruiz-Negrón, N., Menon, J., King, J.B., Ma, J.J. and Bellows, B.K. (2019) Cost-Effectiveness of Treatment Options for Neuropathic Pain: A Systematic Review. PharmacoEconomics, 37, 669-688.
 Freynhagen, R., Tölle, T.R., Gockel, U. and Baron, R. (2016) The painDETECT Project—Far More than a Screening Tool on Neuropathic Pain. Current Medical Research and Opinion, 32, 1033-1057.