Discussion
This prospective randomized controlled study included 36 patients diagnosed with De Quervain tenosynovitis. Patients were evaluated with VAS and DHI at baseline then at 1 and 12 months after the end of the treatment. Hand functions seemed to be improved at the first and 12th month follow-up examinations in both groups. The 12th month follow-up VAS scores were lower in the NT group than in the control group therefore, and there was no significant difference in hand functions between the two groups in long-term follow-up. In the NT group, no patient had Finkelstein test positivity at the first month follow-up, and the positivity rate at 12 months was 16.7%.
Pain is the most common problem in accomplishing daily living activities for patients with De Quervain tenosynovitis. The primary goal of treatment of tenosynovitis is pain relief and regaining hand functions.
The effectiveness of treatment in De Quervain tenosynovitis has been previously evaluated in many studies. In a retrospective study of 222 hands, which investigated the effectiveness of corticosteroid injection, treatment success was achieved in the first 2 injections in 73% of patients in total. In 26% of patients, corticosteroid injection treatment failed or there was a need for surgery.2
In another study, Lane et al. reported 76% treatment success in a study population treated with corticosteroid injection and there was need for surgery in 4% of the patients.15 In the current study, the treatment success rate in the short and long-term follow-up after treatment was >80% in the neural therapy group.
When viewed in terms of adverse effect profile, in previous studies that have paid particular attention to the side-effects of corticosteroid injections, the authors have reported difficulty in maintaining blood glucose regulation for a few days after the injection, especially in patients with diabetes mellitus. 16
Another study investigating the effectiveness of corticosteroid injections reported adverse effects such as skin atrophy and hypopigmentation at a high rate of up to 60% even in ultrasound-guided injections. 17 Therefore, it has been emphasized that corticosteroid injection should not be considered as completely free of adverse effects. In the current study, no adverse effects were detected in any patient in the neural therapy group.
In a study in which the long-term treatment efficacy for De Quervain tenosynovitis was evaluated, 13.7% of the patients required repeated injections during the mean follow-up period of 54 months, 5.9% had a partial response, and 2% had no response. 18 In the current study, the treatment success rate in the NT group at 12 months was 83%.
Acupuncture is a rarely used treatment modality for De Quervain tenosynovitis and few studies have been conducted on this subject. In a study which evaluated the short-term effectiveness of corticosteroid injection versus acupuncture treatment, there was reported to be no superiority of one method over the other in the short term in respect of pain. 6 However, some authors have stated that acupuncture should not be recommended as a priority treatment in De Quervain tenosynovitis. 19 Comprehensive long-term results investigating the effect of acupuncture on hand functions and pain are not available.
Recent studies have shown that De Quervain tenosynovitis is not just stenosing of the tendons but also has a tissue inflammation aspect.20 Local anesthetics have anti-inflammatory effects in addition to nerve blocking and membrane stabilizer effects.21 Therefore, local injection of procaine can provide an anti-inflammatory effect and reduce edema, resulting in reduced stenosis in the fibro-osseous canal. This could explain the decrease in pain and functional improvement in the current study.
To the best of our knowledge no previous study in the literature has evaluated the
efficacy of local anesthetics in the treatment of De Quervain tenosynovitis, but another issue that should be noted is that local anesthetics have been added to the injection solution with corticosteroids in many studies, because as stated above, local anesthetics also have anti-inflammatory activity.4,6,18,22 Therefore, corticosteroids alone may not be responsible for all the pain relief and functional improvement demonstrated in these studies.
Trigger points are described as palpable and hypersensitive spots in muscles, which may lead to the referred pain. 23,24Trigger point injection contributed to the treatment in the current study to eliminate the effect caused by referred pain. Nazlıkul et al. reported that local anesthetic injection to trigger points of the piriformis muscle decreased pain and improved function in patients with low back pain. 25
In the human body, the sympathetic system has an effect on pain, by affecting tissue perfusion. Decreased perfusion causes hypertonus of the muscles and hyperalgesia. Neural therapy can regulate the autonomic nervous system and restore decreased blood flow to tissue by blocking the pathological signals of the sympathetic system.26In addition it has also been shown that the sympathetic nervous system has a pathological memory responsible for musculoskeletal pain.10,27 This pathological memory, also known as neuronal signature, is considered to start when pro-inflammatory cytokines released from sympathetic nerve endings cause nociceptive stimulation due to tissue damage. The sympathetic efferent-nociceptive afferent connection, which occurs as a short circuit over time, may result in central sensitization. If this system is activated with continuous stimulation at the spinal cord and brain level, neuroplasticity develops and pathological pain memory occurs.
This is the most important mechanism of neural therapy approaches. However, the pathophysiology of chronic pain still remains unclear. It is known that chronic nociceptive stimulation leads to overactivation of central sensory transmission and causes central sensitization. Nociceptive transmission at spinal-supraspinal levels and sympathetic activity in a wide dynamic range of neurons can be stopped by membrane stabilization that is achieved by local anesthetic injection.26,28 The pain-free condition seen in the long-term follow up of the patients who underwent neural therapy may have been caused by the effect of local anesthetics to erase the pathological memory in these sympathetic system neurons and prevent nociceptive transmission at spinal-supraspinal levels. Similarly, this mechanism seems to be effective in Finkelstein test negativity in long-term follow-up.
Stellate ganglion injection may alleviate the pain by breaking this vicious circle.29,30,31 The decrease in pain and improvement in hand function may have been achieved by these mechanisms in the NT group patients.
Procaine was used as the local anesthetic in this study. The anti-inflammatory and autonomic nervous system regulatory effect of procaine can be considered responsible for the decrease in pain and improvements in functionality. No adverse effects were seen in any patient.
There were some limitations to this study, primarily the low number of patients. Further studies with a greater number of patients will provide more valuable results. Another limitation of the current study was the non-blinded method, so it can be suggested that further studies should be performed double blinded.