Case series of non-freezing cold injury: the modern clinical syndrome

Environmental factors and their impact on chronic pain development and maintenance

It is more than recognized and accepted that the environment affects the physiological responses of all living things, from bacteria to superior vertebrates, constituting an important factor in the evolution of all species. Environmental influences range from natural processes such as sunlight, seasons of the year, and rest to complex processes like stress and other mood disorders, infections, and air pollution, being all of them influenced by how each creature deals with them. In this chapter, it will be discussed how some of the environmental elements affect directly or indirectly neuropathic pain, a type of chronic pain caused by a lesion or disease of the somatosensory nervous system. For that, it was considered the edge of knowledge in translational research, thus including data from human and experimental animals as well as the applicability of such findings.

Can iloprost be used for treatment of cold weather injury at the point of wounding in a forward operating environment? A literature review

INTRODUCTION

Cold Weather Injury (CWI) represents a spectrum of pathology, the two main divisions being Freezing Cold Injury (FCI) and Non-Freezing Cold Injury (NFCI). Both are disabling conditions associated with microvascular and nerve injury often treated hours after initial insult when presenting to a healthcarestablishment. Given that iloprost is used for the treatment of FCI, could it be used in a forward operating environment to mitigate treatment delay? Is there a role for its use in the forward treatment of NFCI? This review sought to evaluate the strength of evidence for the potential use of iloprost in a forward operating environment.

METHODS

Literature searches were undertaken using the following question for both FCI and NFCI: in [patients with FCI/NFCI] does [the use of iloprost] compared to [standard care] reduce the incidence of [long-term complications]. Medline, CINAHL and EMBASE databases were searched using the above question and relevant alternative terminology. Abstracts were reviewed before full articles were requested.

RESULTS

The FCI search yielded 17 articles that were found to refer to the use of iloprost and FCI. Of the 17, one referred to pre-hospital treatment of frostbite at K2 base camp; however, this was utilising tPA. No articles referred to pre-hospital use in either FCI or NFCI.

DISCUSSION

Although evidence exists to support the use of iloprost in the treatment of FCI, its use to date has been in hospital. A common theme is delayed treatment due to the challenges of evacuating casualties from a remote location. There may be a role for iloprost in the treatment of FCI; however, further study is required to better understand the risk of its use.

Nonfreezing Cold Injury and Cold Intolerance in Paddlesport

INTRODUCTION

Nonfreezing cold injury (NFCI) occurs when tissues are subjected to prolonged cooling that causes tissue damage, but not freezing. Long-term effects include cold intolerance, with allodynia, pain, or numbness of the affected limb. Those who participate in outdoor paddlesports are at particular risk.

METHODS

This is an epidemiological study that aimed to determine the risk factors for paddlesport athletes developing NFCI and chronic cold intolerance in their hands. Secondary outcomes were to correlate cumulative cold exposure with the development of cold intolerance and to identify risk factors for developing NFCI or cold intolerance. Six hundred nine athletes responded to a survey distributed by their national governing body obtaining demographic and activity details, symptoms of NFCI, and a cold intolerance severity score (CISS).

RESULTS

Twenty-three percent reported symptoms consistent with acute NFCI. The median CISS was 31 y (interquartile range 25-43), and 15% had a pathological CISS defined as >50. Females and individuals with Raynaud's phenomenon or migraines had a significantly higher CISS (P<0.05). Regression analysis found that females, smokers, and those with Raynaud's phenomenon or a previous nerve injury had a significantly higher risk of developing pathological cold intolerance (CISS >50). There was no correlation between cumulative cold exposure and CISS.

CONCLUSIONS

A large proportion of paddlesport athletes undertaking activity in cold conditions have a pathological CISS or episodes consistent with NFCI. Cumulative cold exposure was not associated with a pathologically high CISS. The risk factors were female sex, smokers, and those suffering from either Raynaud's phenomenon or nerve injury.

Capsaicin 8% Patch Treatment in Non-Freezing Cold Injury: Evidence for Pain Relief and Nerve Regeneration

Introduction: Neuropathic pain associated with Non-freezing Cold Injury (NFCI) is a major burden to military service personnel. A key feature of NFCI is reduction of the intra-epidermal nerve fibre density in skin biopsies, in keeping with painful neuropathy. Current oral treatments are generally ineffective and have undesirable side effects. Capsaicin 8% patch (Qutenza) has been shown to be well-tolerated and effective for reducing neuropathic pain, for up to 3 months after a single 30-minute application.

Methods: In this single-centre open label study, 16 military participants with NFCI (mean duration 49 months) received 30-minute Capsaicin 8% patch treatment to the feet and distal calf. Pain symptoms were assessed using a pain diary (with the 11-point Numerical Pain Rating Scale, NPRS) and questionnaires, the investigations included skin biopsies, performed before and three months after treatment.

Results: Participants showed significant decrease in spontaneous pain (mean NPRS: −1.1, 95% CI: 0.37 to 1.90; p = 0.006), and cold-evoked pain (−1.2, 95% CI: 0.40 to 2.04; p = 0.006). The time-course of pain relief over 3 months was similar to other painful neuropathies. Patient Global Impression of Change showed improvement (p = 0.0001).

Skin punch biopsies performed 3 months after the patch application showed significant increase of nerve fibres with structural marker PGP9.5 (intra-epidermal nerve fibres [IENFs], p < 0.0001; sub-epidermal nerve fibres [SENFs]; p =< 0.0001), and of regenerating nerve fibres with their selective marker GAP43 (p = 0.0001). The increase of IENFs correlated with reduction of spontaneous (p = 0.027) and cold-evoked pain (p = 0.019).

Conclusions: Capsaicin 8% patch provides an exciting new prospect for treatment of NFCI, with regeneration and restoration of nerve fibres, for the first time, in addition to pain relief.