Systematic review of the effectiveness of self-initiated interventions to decrease pain and sensory disturbances associated with peripheral neuropathy

Peripheral neuropathy (PN) is a term that is used to describe a range of neuropathic symptoms that arise from disruptions in the structure and function of peripheral sensory, motor, and autonomic neurons [1, 2]. Studies from the USA and Europe report that PN occurs in 2.4% of the general population and increases to 8% in those over 55 years of age [3]. PN occurs in a number of chronic medical conditions (e.g., diabetes) or as a result of exposure to neurotoxic drugs [4‐7]. In terms of specific medical conditions, approximately 50% of patients with human immunodeficiency virus (HIV) [8], 26% of patients with diabetes [9], and 30 to 40% of oncology patients who receive neurotoxic chemotherapy [10] report PN symptoms.

Typically, patients with PN report tingling and numbness, as well as burning or shooting pains during and following the course of the disease and treatment [7, 11‐14]. Regardless of its etiology, effective pharmacological treatments for PN are not available [15, 16]. Pain associated with PN is not effectively treated with opioid or adjuvant analgesics [11, 13, 17, 18], and some of these treatments have side effects that outweigh their potential benefits [9]. While reductions in PN-related pain were found with anti-depressants (venlafaxine [19], duloxetine [20]), results vary considerably among patients. Anti-convulsants (e.g., pregabalin, gabapentin) show similar variations in efficacy [21]. To manage the symptoms of PN, which often persist for several months to years, patients use a range of nonpharmacological treatments [22‐25]. While acupuncture [26], whole-body vibration [27], physical therapy [28], reflexology massage [29], and light therapy [30] have been evaluated as treatments for PN, responses are highly variable.

Peripheral neuropathy can be a chronic condition for many patients. While pharmacological and nonpharmacological treatments for PN have variable success [9, 31, 32], the potential benefits of self-management strategies to decrease chronic PN symptoms and improve function and quality of life are not well described [33‐40]. In particular, the potential benefits of nonpharmacological interventions that incorporate patient self-management have received limited attention. That is, self-management refers to specific, targeted, intentional actions that individuals engage in to manage the symptoms and outcomes associated with specific diseases or to prevent the reoccurrence of symptoms or functional deficits [34, 37, 40]. In the context of PN, self-management could include steps that patients take to reduce PN-related symptoms, including pain, numbness, or tingling [22‐24, 41].

The value of self-management strategies for patients with chronic conditions in general is well documented. Findings suggest that patients with chronic conditions who prioritize and engage in self-management activities that promote a sense of personal well-being and provide physical, emotional, or spiritual comfort report better quality of life and higher levels of personal adjustment to the changes generated by their illness and accompanying symptoms [36, 37, 39].

Self-management activities to relieve disease or treatment-related symptoms can be classified as either supported self-management (i.e., those that are initiated and require support and education by a clinician) or self-initiated strategies (i.e., those that patients initiate independently). Self-initiated actions are described as those that arise from an internal decision to take some form of action, usually in response to an internal stimulus [42]. Self-initiated strategies for PN symptoms include massage, heat therapy, cold therapy, magnet therapy, exercise, walking, rest, meditation, and transcutaneous electrical nerve stimulation (TENS) [22‐25]. Patients who engage in these strategies aim to reduce the severity of their symptoms (e.g., pain, numbness, tingling, allodynia) and increase overall comfort and well-being [22‐25]. Heat therapy, massage, and TENS are examples of self-initiated self-management measures that are used by patients who experience pain, including PN-related pain, because of their relatively low cost, ease of access, and perceived efficacy of such interventions [23‐25, 43‐47].

The purpose of this review is to evaluate the perceived effectiveness of self-initiated, self-management strategies in reducing PN symptoms. For the purpose of this review, a “self-initiated self-management strategy” is defined as an activity that patients can initiate independently and maintain on their own, with no required input from clinicians, to provide comfort or relief from the symptoms of PN and improve quality of life. Self-initiated strategies such as heat/cold therapy, massage, meditation, exercise, and TENS therapy are activities that people experiencing PN symptoms can attempt regardless of their financial or geographic status or access to health services. This review thus complements other reviews which have examined the efficacy of medication [9, 48, 49], and supplements and integrated therapies typically prescribed or administered by clinicians [41, 50‐52]. Other reviews have examined self-initiated strategies including exercise [53‐55] and TENS [56] on their own. As such, this review adds to existing literature by focusing on those activities which patients can self-initiate in relation to managing PN symptoms, and synthesizing findings from the various activities which are classified within this definition.

This systematic review summarizes the results of 16 quantitative studies. Methods suggested in the Joanna Briggs Institute (JBI) manual for systematic reviews directed the process of conducting and reporting this review [57, 58]. Previous research has identified a range of self-initiated self-management activities that people experiencing PN symptoms report attempting to alleviate symptoms and increase well-being [22‐25]. The search strategy for this review has been informed by that research and focuses on a more restricted range of activities that may be considered self-initiated self-management activities in that patients can initiate and maintain the activities with no required input from clinicians.

This review sought to identify the effectiveness of self-initiated self-management strategies in alleviating self-reported PN symptoms. This review suggests that a range of self-initiated strategies, including massage, hot baths, TENS therapy, exercise, and meditation, may be effective in reducing self-reported PN symptoms and may improve aspects of quality of life for those living with PN. Fourteen of the 16 studies recorded some positive effects regarding outcomes measured, including pain, quality of life, and general health [59, 61, 63‐73]. These positive findings highlight the potential benefits of these interventions for patients with PN, although the high risk of bias in nearly all studies included in this review means results should be considered with caution. Further research in this area is needed.

Notwithstanding the limitations of available research, a number of possible explanations could account for the positive findings identified in this review. For example, in the case of DPN, adoption of various behavior changes, including diet modification and exercise, can reduce the severity of diabetes itself [61, 81, 82], thereby reducing the adverse effects of this disease. Five of the studies included in this review sought to determine the efficacy of exercise in reducing the symptoms of DPN [61, 64, 66‐68], with all reporting reductions in symptom scores and improvements in quality of life score. While similarities in the expression and experience of DPN and PN of other etiologies such as CIPN or HIV-related PN have been reported, responses to different interventions may vary between the groups in accordance with the mechanism of action of those interventions [76, 77, 80].

While a direct causal relationship between the original mechanism of injury and the means to reverse this damage has been suggested only for DPN, other strategies such as heat therapy, exercise, massage, and TENS may have benefits beyond localized symptom management [45, 64]. Heat, massage, and exercise improve blood flow to affected areas, which increases tissue perfusion and oxygenation and enhances the removal of inflammatory mediators that promote cellular dysfunction [45, 61, 64]. The reduction in pain symptoms associated with TENS and exercise may be explained by decreases in pro-inflammatory cytokines and the release of endogenous opioids and serotonin [71, 83, 84]. In addition, heat therapy, massage, and TENS may reduce symptoms through stimulation of larger nerve fibers which influences pain perception [44‐46, 84].

Although 14 of the 16 studies included in this review reported positive outcomes associated with a number of self-initiated self-management strategies for PN, it is difficult to compare these results within and between interventions due to the variety of instruments used to measure PN. Within the same intervention category, there was typically some variation with respect to the etiology of PN as well as the instruments used to measure PN symptoms, pain, and quality of life. This inconsistency makes it very difficult to compare the effectiveness of any intervention even when studies evaluated interventions for PN that arose from the same etiology. Future research would benefit from consistency in the use of instruments to measure PN symptoms, pain, and quality of life.

This review highlighted other considerations when undertaking symptom management studies. For example, while not the primary focus for this review, several studies involved the use of objective outcome measures, such as nerve conduction, in addition to self-reported measures. Pre- and post-intervention changes were not observed using these objective measures, even where patients’ self-reported perception of symptoms did reflect improvements [64, 66, 67, 71]. With the exception of McCrary et al. [68], who suggested that self-reported improvements in CIPN symptom severity may be related to perceived improvements in quality of life or through adaptation to deficits over time, the studies in this review did not explore possible reasons for the differences in findings when both objective and subjective measures were used [68]. Nevertheless, these differences highlight the importance of including self-report measures in symptom management research, given the subjective and deeply personal nature of how symptoms from a range of chronic conditions are experienced [34, 85, 86]. Subjectively perceived changes in symptom experiences are worthy of investigation in their own right, as important changes in patient experiences may be overlooked if objective measures alone are used [87]. These findings provide further support for symptom management theories, such as the theory of symptom management [88], which highlight the importance of an individual’s perceptions of symptoms and the relationship between these perceptions and the use of self-management strategies.

This review identified that studies that evaluated the effectiveness of heat therapy, exercise, TENS, and mindfulness/meditation interventions to reduce the symptoms of PN, or improve quality of life for those affected, report predominantly favorable results. However, the low quality of the studies included in this review means that recommendations should be made with caution. Although a few studies identified the strategies that people with PN engage in to manage their symptoms independently [22‐25], the studies considered in this review suggest that the potential benefits from interventions such as heat therapy, meditation/mindfulness, exercise, or TENS therapy for people with PN in terms of symptom relief and improved quality of life warrant further investigation [37, 38, 89].

Clinicians have a role in encouraging patients to identify strategies to reduce PN-related symptoms and to determine the efficacy of interventions on a trial and error basis. While studies of self-initiated self-management interventions to date have not been of high quality, available findings suggest that some patients with PN symptoms report that heat therapy, exercise, mindfulness/meditation, or TENS was effective in reducing their symptoms. Just as the perception of pain and other symptoms associated with PN is experienced on a very individual basis, so is the perception of respite from symptoms. Therefore, patients may therefore benefit from experimenting with the application of these strategies [25] given that they are for the most part associated with minimal risk. Health care professionals can empower patients by directing them to resources that will allow them to make informed decisions about strategies that may work for them, while helping them to understand any risks and safety considerations required with individual strategies aimed at reducing PN symptoms [37, 90].