Progesterone - new therapy in mild carpal tunnel syndrome? Study design of a randomized clinical trial for local therapy

Local corticosteroid injection versus placebo for carpal tunnel syndrome

BACKGROUND

Carpal tunnel syndrome (CTS) is a very common clinical syndrome manifested by signs and symptoms of irritation of the median nerve at the carpal tunnel in the wrist. Direct and indirect costs of CTS are substantial, with estimated costs of two billion US dollars for CTS surgery in the USA in 1995 alone. Local corticosteroid injection has been used as a non-surgical treatment for CTS many years, but its effectiveness is still debated.

OBJECTIVES

To evaluate the benefits and harms of corticosteroids injected in or around the carpal tunnel for the treatment of carpal tunnel syndrome compared to no treatment or a placebo injection.

SEARCH METHODS

We used standard, extensive Cochrane search Methods. The searches were 7 June 2020 and 26 May 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-randomised trials of adults with CTS that included at least one comparison group of local injection of corticosteroid (LCI) into the wrist and one group that received a placebo or no treatment.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcome was 1. improvement in symptoms at up to three months of follow-up. Our secondary outcomes were 2. functional improvement, 3. improvement in symptoms at greater than three months of follow-up, 4. improvement in neurophysiological parameters, 5. improvement in imaging parameters, 6. requirement for carpal tunnel surgery, 7. improvement in quality of life and 8.

ADVERSE EVENTS

We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We included 14 trials with 994 participants/hands with CTS. Only nine studies (639 participants/hands) had useable data quantitatively and in general, these studies were at low risk of bias except for one quite high-risk study. The trials were conducted in hospital-based clinics across North America, Europe, Asia and the Middle East. All trials used participant-reported outcome measures for symptoms, function and quality of life. There is probably an improvement in symptoms measured at up to three months of follow-up favouring LCI (standardised mean difference (SMD) -0.77, 95% confidence interval (CI) -0.94 to -0.59; 8 RCTs, 579 participants; moderate-certainty evidence). Up to six months this was still evident favouring LCI (SMD -0.58, 95% CI -0.89 to -0.28; 4 RCTs, 234 participants/hands; moderate-certainty evidence). There is probably an improvement in function measured at up to three months favouring LCI (SMD -0.62, 95% CI -0.87 to -0.38; 7 RCTs, 499 participants; moderate-certainty evidence). We are uncertain if there is a difference in median nerve DML at up to three months of follow-up (mean difference (MD) -0.37 ms, 95% CI -0.75 to 0.02; 6 RCTs, 359 participants/hands; very low-certainty evidence). The requirement for surgery probably reduces slightly in the LCI group at one year (risk ratio 0.84, 95% CI 0.72 to 0.98; 1 RCT, 111 participants, moderate-certainty evidence). Quality of life, measured at up to three months of follow-up using the Short-Form 6 Dimensions questionnaire (scale from 0.29 to 1.0; higher is better) probably improved slightly in the LCI group (MD 0.07, 95% CI 0.02 to 0.12; 1 RCT, 111 participants; moderate-certainty evidence). Adverse events were uncommon (low-certainty evidence). One study reported 2/364 injections resulted in severe pain which resolved over "several weeks" and 1/364 injections caused a "sympathetic reaction" with a cool, pale hand that completely resolved in 20 minutes. One study (111 participants) reported no serious adverse events, but 65% of LCI-injected and 16% of the placebo-injected participants experienced mild-to-moderate pain lasting less than two weeks. About 9% of participants experienced localised swelling lasting less than two weeks. Four studies (229 participants) reported that they experienced no adverse events in their studies. Three studies (220 participants) did not specifically report adverse events.

AUTHORS' CONCLUSIONS

Local corticosteroid injection is effective for the treatment of mild and moderate CTS with benefits lasting up to six months and a reduced need for surgery up to 12 months. Where serious adverse events were reported, they were rare.

Progesterone: A Steroid with Wide Range of Effects in Physiology as Well as Human Medicine

Progesterone is a steroid hormone traditionally linked with female fertility and pregnancy. In current reproductive medicine, progesterone and its analogues play crucial roles. While the discovery of its effects has a long history, over recent decades, various novel actions of this interesting steroid have been documented, of which its neuro- and immunoprotective activities are the most widely discussed. Discoveries of the novel biological activities of progesterone have also driven research and development in the field of progesterone analogues used in human medicine. Progestogen treatment has traditionally and predominately been used in maintaining pregnancy, the prevention of preterm labor, various gynecological pathologies, and in lowering the negative effects of menopause. However, there are also various other medical fields where progesterone and its analogues could find application in the future. The aim of this work is to show the mechanisms of action of progesterone and its metabolites, the physiological and pharmacological actions of progesterone and its synthetic analogues in human medicine, as well as the impacts of its production and use on the environment.

Anti-allodynic and anti-inflammatory effects of 17α-hydroxyprogesterone caproate in oxaliplatin-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy is a disabling condition induced by several frequently used chemotherapeutic drugs including the front-line agent oxaliplatin (OXA). Symptoms are predominantly sensory with the development of neuropathic pain. Alternative dosing protocols and treatment discontinuation are the only available therapeutic strategies. The aim of our work was to evaluate the potential of a synthetic derivative of progesterone, 17α-hydroxyprogesterone caproate (HPGC), in the prevention and treatment of OXA-evoked painful neuropathy. We also evaluated glial activation at the dorsal root ganglia (DRG) and spinal cord levels as a possible target mechanism underlying HPGC actions. Male rats were injected with OXA and HPGC following a prophylactic (HPGCp) or therapeutic (HPGCt) scheme (starting either before or after chemotherapy). The development of hypersensitivity and allodynic pain and the expression of neuronal and glial activation markers were evaluated. When compared to control animals, those receiving OXA showed a significant decrease in paw mechanical and thermal thresholds, with the development of allodynia. Animals treated with HPGCp showed patterns of response similar to those detected in control animals, while those treated with HPGCt showed a suppression of both hypersensitivities after HPGC administration. We also observed a significant increase in the mRNA levels of activating transcription factor 3, the transcription factor (c-fos), glial fibrillary acidic protein, ionized calcium binding adaptor protein 1, interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNFα) in DRG and spinal cord of OXA-injected animals, and significantly lower levels in rats receiving OXA and HPGC. These results show that HPGC administration reduces neuronal and glial activation markers and is able to both prevent and suppress OXA-induced allodynia, suggesting a promising therapeutic strategy.

Comparative effectiveness of ultrasound and paraffin therapy in patients with carpal tunnel syndrome: a randomized trial

BACKGROUND

Conclusive evidence indicating an effective treatment for carpal tunnel syndrome (CTS), a common entrapment neuropathy, is lacking. Ultrasound therapy (US therapy) has long been used as one of the combination treatments for CTS. In addition, paraffin bath therapy has been applied widely as a physical modality in treating patients with hand conditions. The purpose of this randomized trial was to compare the efficacy of combining a wrist orthosis with either US therapy or paraffin bath therapy in treating CTS patients.

METHODS

Patients with CTS were randomized into two groups. All patients received a wrist orthosis. Twice per week, one group underwent paraffin therapy, and the other group underwent ultrasound therapy. Each patient received a questionnaire, physical examination and nerve conduction study of the upper extremities before and after treatment for eight weeks.

RESULTS

Sixty patients were recruited, and 47 completed the study. Statistical analysis revealed significant improvements in symptom severity scores in both groups. After adjusting for age, gender and baseline data, the analysis of covariance revealed a significant difference in the functional status score between two groups.

CONCLUSIONS

The combination of ultrasound therapy with a wrist orthosis may be more effective than paraffin therapy with a wrist orthosis.

TRIAL REGISTRATION

Clinicaltrial.gov: NCT02278289 Oct 28, 2014.

Revisiting the roles of progesterone and allopregnanolone in the nervous system: resurgence of the progesterone receptors

Progesterone is commonly considered as a female reproductive hormone and is well-known for its role in pregnancy. It is less well appreciated that progesterone and its metabolite allopregnanolone are also male hormones, as they are produced in both sexes by the adrenal glands. In addition, they are synthesized within the nervous system. Progesterone and allopregnanolone are associated with adaptation to stress, and increased production of progesterone within the brain may be part of the response of neural cells to injury. Progesterone receptors (PR) are widely distributed throughout the brain, but their study has been mainly limited to the hypothalamus and reproductive functions, and the extra-hypothalamic receptors have been neglected. This lack of information about brain functions of PR is unexpected, as the protective and trophic effects of progesterone are much investigated, and as the therapeutic potential of progesterone as a neuroprotective and promyelinating agent is currently being assessed in clinical trials. The little attention devoted to the brain functions of PR may relate to the widely accepted assumption that non-reproductive actions of progesterone may be mainly mediated by allopregnanolone, which does not bind to PR, but acts as a potent positive modulator of γ-aminobutyric acid type A (GABA(A) receptors. The aim of this review is to critically discuss effects of progesterone on the nervous system via PR, and of allopregnanolone via its modulation of GABA(A) receptors, with main focus on the brain.

Progesterone reduces the expression of spinal cyclooxygenase-2 and inducible nitric oxide synthase and prevents allodynia in a rat model of central neuropathic pain

BACKGROUND

Spinal cord injury (SCI) results in the development of chronic pain that is refractory to conventional treatment. Progesterone, a neuroprotective steroid, may offer a promising perspective in pain modulation after central injury. Here, we explore the impact of progesterone administration on the post-injury inflammatory cascade involving the enzymes cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) at the spinal cord level. We also analyse pain behaviours, the profile of glial cell activation, and IκB-α mRNA levels, as an index of NF-κB transactivation.

METHODS

We used biochemical, immunohistochemical and molecular techniques, as well as behavioural studies, to investigate the effects of progesterone in a well-characterized model of central neuropathic pain.

RESULTS

Injured animals receiving progesterone presented reduced mRNA levels of the proinflammatory enzymes, as well as decreased COX-2 activity and nitrite levels, as compared to vehicle-treated injured rats. Further, animals receiving the steroid exhibited lower levels of IκB-α mRNA, suggesting decreased NF-κB transactivation. Progesterone administration also attenuated the injury-induced increase in the number of glial fibrillary acidic protein and OX-42 positive cells both at early and late time points after injury, and prevented the development of mechanical and thermal allodynia. Further, when injured rats received early progesterone administration for a critical period of time after injury, they did not display allodynic behaviours even after the treatment had stopped.

CONCLUSIONS

Our results suggest that progesterone, by modulating early neuroinflammatory events triggered after SCI, may represent a useful strategy to prevent the development of central chronic pain.

Progesterone increases the release of brain-derived neurotrophic factor from glia via progesterone receptor membrane component 1 (Pgrmc1)-dependent ERK5 signaling

Progesterone (P4) is cytoprotective in various experimental models, but our understanding of the mechanisms involved is still incomplete. Our laboratory has implicated brain-derived neurotrophic factor (BDNF) signaling as an important mediator of P4's protective actions. We have shown that P4 increases the expression of BDNF, an effect mediated by the classical P4 receptor (PR), and that the protective effects of P4 were abolished using inhibitors of Trk receptor signaling. In an effort to extend our understanding of the interrelationship between P4 and BDNF signaling, we determined whether P4 influenced BDNF release and examined the role of the classical PR and a putative membrane PR, progesterone receptor membrane component-1 (Pgrmc1), as mediators of this response. Given recent data from our laboratory that supported the role of ERK5 in BDNF release, we also tested whether P4-induced BDNF release was mediated by ERK5. In this study, we found that P4 and the membrane-impermeable P4 (P4-BSA) both induced BDNF release from cultured C6 glial cells and primary astrocytes. Both these cells lack the classical nuclear/intracellular PR but express high levels of membrane-associated PR, including Pgrmc1. Using RNA interference-mediated knockdown of Pgrmc1 expression, we determined that P4-induced BDNF release was dependent on the expression of Pgrmc1, although pharmacological inhibition of the PR failed to alter the effects of P4. Furthermore, the BDNF release elicited by P4 was mediated by ERK5, and not ERK1/2. Collectively, our data describe that P4 elicits an increase in BDNF release from glia via a Pgrmc1-induced ERK5 signaling mechanism and identify Pgrmc1 as a potential therapeutic target for future hormone-based drug development for the treatment of such degenerative diseases as Alzheimer's disease as well as other diseases wherein neurotrophin dysregulation is noted.

Ectopic uterine tissue as a chronic pain generator

While chronic pain is a main symptom in endometriosis, the underlying mechanisms and effective therapy remain elusive. We developed an animal model enabling the exploration of ectopic endometrium as a source of endometriosis pain. Rats were surgically implanted with autologous uterus in the gastrocnemius muscle. Within two weeks, visual inspection revealed the presence of a reddish-brown fluid-filled cystic structure at the implant site. Histology demonstrated cystic glandular structures with stromal invasion of the muscle. Immunohistochemical studies of these lesions revealed the presence of markers for nociceptor nerve fibers and neuronal sprouting. Fourteen days after surgery rats exhibited persistent mechanical hyperalgesia at the site of the ectopic endometrial lesion. Intralesional, but not contralateral, injection of progesterone was dose-dependently antihyperalgesic. Systemic administration of leuprolide also produced antihyperalgesia. In vivo electrophysiological recordings from sensory neurons innervating the lesion revealed a significant increase in their response to sustained mechanical stimulation. These results are consistent with clinical and pathological findings observed in patients with endometriosis, compatible with the ectopic endometrium as a source of pain. This model of endometriosis allows mechanistic exploration at the lesion site facilitating our understanding of endometriosis pain.

Evidences for antinociceptive effect of 17-α-hydroxyprogesterone caproate in carpal tunnel syndrome

Growing evidence of neuroprotective and analgesic effects by progesterone (PROG) has been obtained in experimental animal models of neuropathy. In this paper, we report the results of the first experimental study to test the efficacy of PROG in a human neuropathy. The effects of a local administration of 17-alpha-hydroxyprogesterone caproate (17HPC) has been studied in patients with carpal tunnel syndrome (CTS) and compared with those of a local administration of corticosteroid (CS) in a analogous CTS group. Sixteen women affected by mild CTS were selected. Clinical, electrophysiological and ultrasonographic data of the median nerve were quantified at 0 (pre-injection), 1 and 6 months after CS or 17HPC injection. One month after injection, both 17HPC and CS groups exhibited similar reduction in pain scores, whereas only the 17HPC-treated group still manifested symptoms relief 6 months after. Only in CS-treated patients, improvement of the clinical data correlated with ultrasonographic and electrophysiological changes of the median nerve. The present study indicates that intra-carpal injection with a long-acting PROG derivative is effective for relief of symptoms in CTS. This effect is apparently mediated by a mechanism distinct from that of the CS.

Role of neuroactive steroids in the peripheral nervous system

Several reviews have so far pointed out on the relevant physiological and pharmacological role exerted by neuroactive steroids in the central nervous system. In the present review we summarize observations indicating that synthesis and metabolism of neuroactive steroids also occur in the peripheral nerves. Interestingly, peripheral nervous system is also a target of their action. Indeed, as here reported neuroactive steroids are physiological regulators of peripheral nerve functions and they may also represent interesting therapeutic tools for different types of peripheral neuropathy.

Differential cellular FGF-2 upregulation in the rat facial nucleus following axotomy, functional electrical stimulation and corticosterone: a possible therapeutic target to Bell's palsy

BACKGROUND

The etiology of Bell's palsy can vary but anterograde axonal degeneration may delay spontaneous functional recovery leading the necessity of therapeutic interventions. Corticotherapy and/or complementary rehabilitation interventions have been employed. Thus the natural history of the disease reports to a neurotrophic resistance of adult facial motoneurons leading a favorable evolution however the related molecular mechanisms that might be therapeutically addressed in the resistant cases are not known. Fibroblast growth factor-2 (FGF-2) pathway signaling is a potential candidate for therapeutic development because its role on wound repair and autocrine/paracrine trophic mechanisms in the lesioned nervous system.

METHODS

Adult rats received unilateral facial nerve crush, transection with amputation of nerve branches, or sham operation. Other group of unlesioned rats received a daily functional electrical stimulation in the levator labii superioris muscle (1 mA, 30 Hz, square wave) or systemic corticosterone (10 mgkg-1). Animals were sacrificed seven days later.

RESULTS

Crush and transection lesions promoted no changes in the number of neurons but increased the neurofilament in the neuronal neuropil of axotomized facial nuclei. Axotomy also elevated the number of GFAP astrocytes (143% after crush; 277% after transection) and nuclear FGF-2 (57% after transection) in astrocytes (confirmed by two-color immunoperoxidase) in the ipsilateral facial nucleus. Image analysis reveled that a seven days functional electrical stimulation or corticosterone led to elevations of FGF-2 in the cytoplasm of neurons and in the nucleus of reactive astrocytes, respectively, without astrocytic reaction.

CONCLUSION

FGF-2 may exert paracrine/autocrine trophic actions in the facial nucleus and may be relevant as a therapeutic target to Bell's palsy.