Causalgia--reflex sympathetic dystrophy--sympathetically maintained pain: myth and reality

A Korean nationwide investigation of the national trend of complex regional pain syndrome vis-à-vis age-structural transformations

Background

The present study employed National Health Insurance Data to explore complex regional pain syndrome (CRPS) updated epidemiology in a Korean context.

Methods

A CRPS cohort for the period 2009-2016 was created based on Korean Standard Classification of Diseases codes alongside the national registry. The general CRPS incidence rate and the yearly incidence rate trend for every CRPS type were respectively the primary and secondary outcomes. Among the analyzed risk factors were age, sex, region, and hospital level for the yearly trend of the incidence rate for every CRPS. Statistical analysis was performed via the chi-square test and the linear and logistic linear regression tests.

Results

Over the research period, the number of registered patients was 122,210. The general CRPS incidence rate was 15.83 per 100,000, with 19.5 for type 1 and 12.1 for type 2. The condition exhibited a declining trend according to its overall occurrence, particularly in the case of type 2 (P < 0.001). On the other hand, registration was more pervasive among type 1 compared to type 2 patients (61.7% vs. 38.3%), while both types affected female individuals to a greater extent. Regarding age, individuals older than 60 years of age were associated with the highest prevalence in both types, regardless of sex (P < 0.001).

Conclusions

CRPS displayed an overall incidence of 15.83 per 100,000 in Korea and a declining trend for every age group which showed a negative association with the aging shift phenomenon.

The pain threshold of high-threshold mechanosensitive receptors subsequent to maximal eccentric exercise is a potential marker in the prediction of DOMS associated impairment

Background

Delayed-onset muscle soreness (DOMS) refers to dull pain and discomfort in people after participating in exercise, sport or recreational physical activities. The aim of this study was to detect underlying mechanical thresholds in an experimental model of DOMS.

Methods

Randomised study to detect mechanical pain thresholds in a randomised order following experimentally induced DOMS of the non-dominant arm in healthy participants. Main outcome was the detection of the pressure pain threshold (PPT), secondary thresholds included mechanical detection (MDT) and pain thresholds (MPT), pain intensity, pain perceptions and the maximum isometric voluntary force (MIVF).

Results

Twenty volunteers (9 female and 11 male, age 25.2 ± 3.2 years, weight 70.5 ± 10.8 kg, height 177.4 ± 9.4 cm) participated in the study. DOMS reduced the PPT (at baseline 5.9 ± 0.4 kg/cm²) by a maximum of 1.5 ± 1.4 kg/cm² (-24%) at 48 hours (p < 0.001). This correlated with the decrease in MIVF (r = -0.48, p = 0.033). Whereas subjective pain was an indicator of the early 48 hours, the PPT was still present after 72 hours (r = 0.48, p = 0.036). Other mechanical thresholds altered significantly due to DOMS, but did show no clinically or physiologically remarkable changes.

Conclusions

Functional impairment following DOMS seems related to the increased excitability of high-threshold mechanosensitive nociceptors. The PPT was the most valid mechanical threshold to quantify the extent of dysfunction. Thus PPT rather than pain intensity should be considered a possible marker indicating the athletes’ potential risk of injury.

A possible role of the locus coeruleus in complex regional pain syndrome

Heightened sensitivity to painful stimulation commonly spreads from the affected limb to the ipsilateral forehead in patients with complex regional pain syndrome (CRPS). In addition, acoustic startle evokes greater auditory discomfort and increases in limb pain when presented on the affected than unaffected side. In contrast, limb pain ordinarily evokes analgesia in the ipsilateral forehead of healthy participants, and acoustic startle suppresses limb pain. Together, these findings suggest that hemilateral and generalized pain control mechanisms are disrupted in CRPS, and that multisensory integrative processes are compromised. Failure to inhibit nociceptive input from the CRPS-affected limb could sensitize spinal and supraspinal neurons that receive convergent nociceptive and auditory information from hemilateral body sites. Somatosensory, auditory, and emotional inputs may then aggravate pain by feeding into this sensitized nociceptive network. In particular, a disturbance in hemilateral pain processing that involves the locus coeruleus could exacerbate the symptoms of CRPS in some patients.

Complex regional pain syndrome type I: incidence and prevalence in Olmsted county, a population-based study

The objective of this study is to undertake a population based study on the incidence, prevalence, natural history, and response to treatment of complex regional pain syndrome (CRPS). All Mayo Clinic and Olmsted Medical Group medical records with codes for reflex sympathetic dystrophy (RSD), CRPS, and compatible diagnoses in the period 1989-1999 were reviewed as part of the Rochester Epidemiology Project. We used IASP criteria for CRPS. The study population was in the Olmsted County, Minnesota (1990 population, 106,470). The main outcome measures were CRPS I incidence, prevalence, and outcome. Seventy-four cases of CRPS I were identified, resulting in an incidence rate of 5.46 per 100,000 person years at risk, and a period prevalence of 20.57 per 100,000. Female:male ratio was 4:1, with a median age of 46 years at onset. Upper limb was affected twice as commonly as lower limb. All cases reported an antecedent event and fracture was the most common trigger (46%). Excellent concordance was found between symptoms and signs and vasomotor symptoms were the most commonly present. Three phase bone scan and autonomic testing diagnosed the condition in >80% of cases. Seventy-four percent of patients underwent resolution, often spontaneously. CRPS I is of low prevalence, more commonly affects women than men, the upper more than the lower extremity, and three out of four cases undergo resolution. These results suggest that invasive treatment of CRPS may not be warranted in the majority of cases.

Usefulness of transcranial magnetic stimulation to predict the development of reflex sympathetic dystrophy poststroke: a pilot study

OBJECTIVE

To investigate the predictive value of transcranial magnetic stimulation (TMS) for the development of reflex sympathetic dystrophy (RSD) poststroke.

DESIGN

Blind clinical assessment of 2 groups of stroke patients defined on the basis of absent or preserved motor evoked potentials (MEPs) on the affected side.

SETTING

Stroke rehabilitation center.

PATIENTS

Twenty stroke patients between the ages of 41 and 85 years, undergoing rehabilitation.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

MEPs from upper limbs 30 days poststroke, Motricity Index, and scoring of RSD using the Enjalbert Scale 73 days poststroke.

RESULTS

A good correlation was found between Motricity Index and TMS results (P<.01). Average Enjalbert scores were significantly different between the 2 groups (P=.03). No significant correlation was found between Enjalbert scores and the Motricity Index.

CONCLUSIONS

Although no significant relationship was found between upper-limb motor impairment and intensity of RSD 10 weeks after stroke, the TMS responses permitted the early categorization of patients into 2 groups that developed significantly different average Enjalbert scores 1 to 2 months later when this clinical condition was fully developed.

Sympathetically maintained pain

Reflex sympathetic dystrophy (RSD) is a controversial condition, redefined in 1996 by an ad hoc International Association for the Study of Pain (IASP) task force. One of the strongest critiques against the entire concept of sympathetic-dependent pain is that patients labeled as having RSD harbor in reality a somatoform disorder. Here clinical cases are described to prove that other organic medical conditions may exist other than RSD and still present the clinical picture of pain, sensory, and vasomotor disorders and trophic changes. The analysis of each patient illustrates how the inappropriate diagnosis of RSD may lead to increased worsening of pain intensity, or delay the proper diagnosis, and consequently the appropriate treatment.

Intrathecal baclofen for the treatment of dystonia in patients with reflex sympathetic dystrophy

BACKGROUND AND METHODS

Patients with reflex sympathetic dystrophy (also known as the complex regional pain syndrome) may have dystonia, which is often unresponsive to treatment. Some forms of dystonia respond to the intrathecal administration of baclofen, a specific gamma-aminobutyric acid-receptor (type B) agonist that inhibits sensory input to the neurons of the spinal cord. We evaluated this treatment in seven women who had reflex sympathetic dystrophy with multifocal or generalized tonic dystonia. First, we performed a double-blind, randomized, controlled crossover trial of bolus intrathecal injections of 25, 50, and 75 microg of baclofen and placebo. Changes in the severity of dystonia were assessed by the woman and by an investigator after each injection. In the second phase of the study, six of the women received a subcutaneous pump for continuous intrathecal administration of baclofen and were followed for 0.5 to 3 years.

RESULTS

In six women, bolus injections of 50 and 75 microg of baclofen resulted in complete or partial resolution of focal dystonia of the hands but little improvement in dystonia of the legs. During continuous therapy, three women regained normal hand function, and two of these three women regained the ability to walk (one only indoors). In one woman who received continuous therapy, the pain and violent jerks disappeared and the dystonic posturing of the arm decreased. In two women the spasms or restlessness of the legs decreased, without any change in the dystonia.

CONCLUSIONS

In some patients, the dystonia associated with reflex sympathetic dystrophy responds markedly to intrathecal baclofen.

Complex regional pain syndrome of the lower extremity: a retrospective study of 33 patients

Even when diagnosed early and treated appropriately, patients with complex regional pain syndrome (CRPS), a condition that can lead to severe painful dysfunction of the limb, may continue to have long-term pain. A retrospective study was conducted of 33 patients with a positive history of CRPS I, CRPS II, or sympathetically maintained pain (SMP) of the lower limb who were treated in either a clinical setting or a pain management center. The average age of individuals diagnosed with CRPS was 43.5 +/- 12.6 (mean +/-SD) years with 60% being female. The most common diagnosis was CRPS I (75.8%) followed by SMP (21.2%), and finally CRPS II (3.0%). The dominant etiology was confirmed as trauma (73%), with the remaining nine cases resulting from elective foot surgery. Fractures were the most common type of injury (45%) and excision of neuroma was the most frequent elective surgical procedure (30%). Time from injury to diagnosis in patients with foot and ankle trauma was 3.9 +/- 3.0 months and from elective surgery to diagnosis was 9.1 +/- 4.0 months (t test, p < .001). Thirteen patients were contacted for long-term follow-up with an average of 3.5 years after initial diagnosis. There was no difference when the pain rating at long-term follow-up was compared to the initial rating (6.2 +/- 1.2 vs. 7.3 +/- 0.6; p = .287), and 11 continue to have more than moderate pain. Thus, many patients with CRPS who seem to be successfully treated, and are discharged from care, still have severe pain years later.

Causalgia and reflex sympathetic dystrophy: does the sympathetic nervous system contribute to the generation of pain?

The striking response of causalgia and reflex sympathetic dystrophy (RSD) to sympatholytic procedures together with signs of autonomic nervous system abnormalities suggest that the sympathetic efferent system can generate or enhance pain (sympathetically maintained pain, SMP). This concept is supported by human and animal experiments indicating that sympathetic activity and catecholamines can activate primary afferent nociceptors. Some clinical evidence, however, calls the SMP concept into question and alternative explanations have been advanced. In this review, we describe the clinical features of causalgia and RSD and the evidence for sympatholytic efficacy. The major barrier to proving the SMP concept is that all available sympatholytic procedures are problematic. We conclude that, although the weight of current evidence supports the SMP concept and its relevance to causalgia and RSD, it remains unproven by scientific criteria. More careful adherence to diagnostic criteria and well-controlled trials of sympatholysis are needed to finally settle the issue.

Painful peripheral neuropathies

This article reviews the current pathophysiology of painful peripheral neuropathies, their differential diagnosis, and management.

Correlation between autotomy-behavior and current theories of neuropathic pain

The past 10 years have brought several new experimental models with which to study chronic neuropathic pain in animals. Consequently, our knowledge about the mechanisms subserving neuropathic pain in humans has improved. However, the first animal model that was used for studying this type of chronic pain was the autotomy-model which can still be considered as a useful tool for pain studies. The present review assesses some of the similarities and differences between autotomy-model and more recent models of experimental traumatic mononeuropathy. In addition, it considers some of the similarities between the results obtained in clinical studies and in autotomy studies.

Understanding vulvodynia

Vulvodynia is a difficult management problem. In this review article, the clinical subsets of vulvodynia including recurrent vulvovaginal candidiasis, vulvar vestibulitis syndrome and dysaesthetic vulvodynia are described. Their aetiology is discussed and available therapies are presented.

Preservation of skin vasoconstrictor responses in chronic atherosclerotic peripheral vascular disease

Peripheral neuropathy is often found in ischemic limbs with nondiabetic atherosclerotic peripheral vascular disease (PVD). Sensory symptoms such as burning pain are common in severely ischemic limbs, and sympathectomy has been undertaken for ischemic rest pain. The authors assessed noninvasive quantitative skin vasomotor reflexes in toes and standard systemic cardiovascular autonomic tests in 44 PVD subjects with varying severity of limb ischemia, 30 age-matched control subjects, and nine PVD subjects associated with diabetes. Skin vasoconstrictor reflexes to inspiratory gasp, Valsalva maneuver, and postural change, and the postischemic reactive hyperemic response, were evaluated by the measurement of skin blood flow on toe pads by use of a laser Doppler flowmeter. Vasoconstrictor responses were not significantly different between PVD toes, even in severely ischemic limb, and age-matched controls. Reactive hyperemia was significantly less in PVD than in controls. Cardiovagal and systemic vasoconstrictor reflexes were also evaluated. All PVD subjects showed normal systemic cardiovascular reflexes. In contrast, these reflexes were severely impaired in diabetic PVD. The authors demonstrated that skin vasoconstrictive sympathetic reflex is preserved in chronically ischemic limbs with PVD, suggesting that sympathetic nerve fibers are relatively resistant to chronic ischemia.

Treatment of chronic regional pain syndrome using manipulation therapy and regional anesthesia

In a 4-year period, 17 consecutive patients with posttraumatic chronic regional pain syndrome were treated with a new technique, Movelat manipulation therapy. At average follow-up of 8 months, satisfactory results were achieved in 15 patients (88%), but 2 patients, 1 with digital nerve injury and 1 with ulnar nerve injury, did not respond to the therapy. Factors associated with good clinical response include chronic regional pain syndrome type I, i.e., dystrophy produced by a trauma to the hand but not involving a specific nerve injury, early-stage disease (within 3 months after trauma), and involvement of the upper limbs. Complications were rare and mild (pain over the tourniquet site in 3%, temporary dizziness in 1%). This therapy is simple and safe and recommended for early treatment of chronic regional pain syndrome.

Medical and pharmacologic management of upper extremity neuropathic pain syndromes

Written from a neurologic and therapeutically conservative perspective, this review advocates fundamentally medical and pharmacologic management of upper extremity neuropathic pain syndromes, including chronic regional pain syndromes, formerly classified reflex sympathetic dystrophy (RSD) and causalgia. Mandatory steps include, first, a prompt serious attempt to localize the nerve lesion whenever possible using complete, sophisticated neurologic examinations, then thoughtfully selected conventional neurophysiologic and radiologic tests. Strongly discouraged are promiscuous use of "RSD" to describe all neuropathic pains, and diagnostic reliance upon thermography and uncontrolled sympathetic blocks. Conservative multidisciplinary diagnostic and treatment teams should often possess a nucleus of neurologist and hand therapist, plus additional consultants including psychiatric. Every physician and therapist managing neuropathic pain must consider psychologic and wellness issues within their responsibilities. Prompt referral to an experienced surgeon is crucial for decompression or repair of relevant, significant, objectively proven (ideally neurophysiologically) nerve and root lesions. Ambiguous professional colloquialisms, "central pain" and "central sensitization," unfortunately provide value-laden pretexts for premature invasive treatments, and animate the truly dreadful concept "central RSD". Various classes of conventional oral non-narcotic adjuvant analgesics are reviewed, and the inevitability of their empiric, non-formulaic administration. No patient-specific, rationally-identifiable molecular receptor/switch can be deduced clinically or tripped mechanistically to terminate chronic pain. Two promising new non-narcotic centrally-active medications, gabapentin and tramadol, are highlighted as harbingers of future progress. The neglected subtle art of prescription writing is stressed, particularly for medication-sensitive patients. Medical cost containment should promote critical, long overdue outcomes studies comparing conservative and invasive pain treatments.

Vulvar vestibulitis syndrome: a critical review

OBJECTIVE

Vulvar vestibulitis syndrome (VVS) is thought to be the most frequent cause of dyspareunia in premenopausal women and is one of the major subtypes of vulvodynia. Vulvar vestibulitis is a chronic, persistent clinical syndrome characterized by severe pain on vestibular touch or attempted vaginal entry, exquisite tenderness to a cotton-swab palpation of the vestibular area, and physical findings confined to vestibular erythema. The purpose of this paper is to critically review the descriptive, diagnostic, etiologic, and treatment studies on VVS. Methodological problems are highlighted, and future guidelines for research are proposed.

DATA SOURCES

References were obtained from a MEDLINE search covering the period from January 1984 until June 1995. The indexing term "vulvar vestibulitis" was used, and the search was constrained to English-language articles. References from other relevant sources, such as texts and bibliographies, were also included.

STUDY SELECTION

All articles pertaining to VVS were reviewed.

DATA EXTRACTION

All data relevant to the descriptive, diagnostic, etiologic, and treatment aspects of VVS were included.

DATA SYNTHESIS

Pain symptomatology tends to be underemphasized in the current descriptive studies. The trend in etiological research is to focus on biomedical factors such as candidiasis and human papillomavirus (HPV). Only a few studies adopt a nonreductionnist approach. Surgery is the treatment option with the highest reported success rate. Medical management is underinvestigated, considering its widespread use. Pain management techniques such as biofeedback and behavior therapy show promising results.

CONCLUSIONS

A pain syndrome conceptualization is suggested as the most useful approach for solving current empirical and clinical problems.

Clinical neurophysiology laboratory tests to assess the nociceptive system in humans

This paper presents some currently available neurophysiological tools that are helpful in the clinical setting to evaluate and document neuropathic disturbances that may be associated with pain. The specific tests described in this discussion are quantitative sensory tests (QSTs), autonomic tests (ATs), microneurography (MCNG), and laser evoked potentials (LEPs). Quantitative sensory testing of the nociceptive system includes the thermal stimulation (TST) and current perception threshold (CPT) tests. The ATs applicable to some patients with pain are sudomotor and vasomotor tests. The quantitative sudomotor axon reflex test (QSART), resting sweat output (RSO), and sympathetic skin response (SSR) are the tests for sudomotor involvement. The vasomotor system is tested by measuring skin temperature (surface thermistor or thermography) at rest and, in some cases, after provocative maneuvers. In addition, MCNG (intraneural recording of single nerve fibers or fascicles of nerves) allows examiners to look directly at muscle and skin sympathetic efferent output in normal subjects without pain or with experimental pain and in patients with neuropathic pain. This technique also provides a means of studying the physiology of primary afferent fibers in persons with neurogenic pain. Recent development of LEPs that incorporate the use of painful infrared laser-induced stimuli allow selective study of the nociceptive system, both the central and peripheral portions.

Recovery of upper limb motor function in tetraplegia with stellate ganglion block treatment of reflex sympathetic dystrophy: a case report

Recovery of motor function in spinal cord injury usually does not occur beyond 2 yr from the date of injury and is rare beyond 8 yr. We present a case of a gentleman with a right C-5 motor, left T-5 motor, bilateral T-5 sensory tetraplegia, sustained after a fall in September 1985, who developed reflex sympathetic dystrophy of his right arm. This pain failed to resolve during the next 8 yr, despite conservative treatment consisting of range of motion, contrast baths, transcutaneous electrical nerve stimulation unit, and tricyclic antidepressants. Furthermore, his pain was refractory to dorsal rhizotomy in 1987. Subsequent follow-up visits documented ongoing pain and weakness of the right arm, with a stable injury pattern. Approximately 8 yr after initial injury, the patient underwent a series of eight stellate ganglion blocks, with the surprising result of improvement in Kendall graded motor function. This improvement was enough to represent a change in the motor level of spinal cord injury from C-6 to C-7, with a resultant increase in functional abilities. The improvement of motor function after stellate ganglion blocks for treatment of reflex sympathetic dystrophy is unprecedented and indicates that its aggressive treatment in patients with myelopathies may hasten motor recovery and, thus, functional gains. Physiologic explanations for this phenomenon include (1) resolution of pain inhibition, (2) improvement in disturbed microcirculation, and (3) resolution of sympathetic inhibition of mu-motor neurons via internuncial neurons.

Complex regional pain syndrome

Reflex sympathetic dystrophy is a complex progressive and potentially devastating condition generally affecting the extremities. Because clinical presentation is variable, diagnosis can be difficult. Recently, the Special interest Group of Pain and the Sympathetic Nervous System of the International Association for the Study of Pain developed a new taxonomy to help acknowledge and differentiate the features of reflex sympathetic dystrophy and causalgia. These are categorized under the heading of complex regional pain syndrome. Sympathetically maintained pain is also recognized as a separate component to this group of conditions. The authors present this new taxonomy and present cases of each condition.

Distribution of substance P in the spinal cord of patients with syringomyelia

The distribution of substance P, a putative neurotransmitter and pain-related peptide, was studied using the peroxidase-antiperoxidase immunohistochemical method in the spinal cords obtained from autopsy of 10 patients with syringo-myelia and 10 age- and sex-matched, neurologically normal individuals. Substance P immunoreactivity was present in axons and in terminal-like processes in close apposition to neurons in the first, second, and third laminae of the dorsal horn. Smaller amounts of peroxidase-positive staining were found in the fifth lamina of the dorsal horn, the intermediolateral nucleus, the intermediomedial nucleus, and the ventral horn. In nine of 10 patients with syringomyelia, there was a substantial increase in substance P immunoreactivity in the first, second, third, and fifth laminae below the level of the lesion. A marked reduction or absence of staining was present in segments of the spinal cord occupied by the syrinx. Central cavities produced bilateral abnormalities, whereas eccentric cavities produced changes that were ipsilateral to the lesion. No alterations in staining were found in the spinal cord of an asymptomatic patient with a small central syrinx. The authors conclude that syringomyelia can be associated with abnormalities in spinal cord levels of substance P, which may affect the modulation and perception of pain.

Dysesthetic pain in patients with syringomyelia

Dysesthethic pain is a common complaint of patients with syringomyelia, traumatic paraplegia, and various myelopathic conditions. Because cavitary lesions of the spinal cord can be defined with good resolution by magnetic resonance imaging, syringomyelia provides a potential model for examining anatomic correlates of central pain. In this study, a syndrome of segmental dysesthesias, characterized by burning pain, hyperesthesia, and a variable incidence of trophic changes, was described by 51 of 137 patients (37%) with syringomyelia at the time of clinical presentation. Complete magnetic resonance scans, including axial images, demonstrated extension of the syrinx into the dorsolateral quadrant of the spinal cord on the same side and at the level of pain in 43 of 51 patients (84%). Surgical treatment of syringomyelia resulted in the relief or improvement of dysesthetic pain in 22 of 37 patients (59%), but 15 patients (41%) reported no improvement or an intensification of pain despite collapse of the syrinx. Postoperative dysesthetic pain was often a disabling complaint that responded poorly to medical therapy, including analgesics, sedatives, antiepileptics, antispasmodics, and anti-inflammatory agents. In most cases, there was a gradual improvement of symptoms, although six patients continued to complain of pain 24 to 74 months postoperatively. Prompt but transient relief was achieved in two of two patients with regional sympathetic blocks, and prolonged relief was achieved in one patient by stellate ganglionectomy. We conclude that painful dysesthesias can be caused by a disturbance of pain-modulating centers in the dorsolateral quadrant of the spinal cord and have certain causalgia-like features that respond in an unpredictable way to surgical collapse of the syrinx.

Reflex sympathetic dystrophy of the lower extremity in tetraplegia: case report

Reflex sympathetic dystrophy (RSD) of the upper extremities has been reported to occur following complete and incomplete injuries of the cervical cord. Such reports describe the value of the three-phase radionuclide bone scan (TPBS) in differentiating RSD from pain of other sources. To our knowledge, RSD of the lower extremities has not been reported in a patient with tetraplegia. We report a case of lower extremity RSD in a patient with complete traumatic injury of the cervical cord. The case illustrates the use of the TPBS to differentiate RSD from heterotopic ossification (HO) in the lower extremities. THe successful use of the alpha-adrenergic blocker, phenoxybenzamine, in the treatment of RSD is described. Follow-up to 30 months has shown no evidence of recurrence, and complete resolution of the scintigraphic findings.

Capsaicin and the cause of causalgia

From self-experimentation, I propose that the pain which occurs after application of capsaicin is causalgia and that this "capsaicin causalgia" is due to actual or functional depletion of neuropeptides such as substance P. This idea could provide an objective definition of the causalgic syndromes and improve the means of diagnosis. The analogy with capsaicin causalgia could also be extended to the pain of epidermal necrolysis, solar and thermal burns, and leprosy. The concept could lead to a better treatment of these causalgic syndromes by modulation of neuropeptide concentration or responsivity, or by mitigation of the consequences of its depletion.

[The efficacy of naftidrofuryl on unexpected autonomic symptoms following carpal tunnel surgery]

Symptoms of sympathetic lability occur 30 days after carpal tunnel surgery in about 2.6% cases. A double-blind placebo controlled clinical trial of naftidrofuryl was conducted in 195 patients. It demonstrated that these symptoms occur during the two-week-period after surgery, and that some patients are particularly exposed to an unexpected course (i.e. women and more than 50 years) during the third and fourth weeks after surgery. In this study, patients treated with naftidrofuryl showed a reduction of some symptoms of sympathetic lability, and stabilisation of the unfavourable course observed in patients with placebo; this preventive efficacy of naftidrofuryl could be due to its 5-HT2 receptor blocking action, which is responsible for vasoconstriction and platelet and erythrocytes aggregation. Naftidrofuryl though improves arteriolar haemodynamics, limiting the development of pain and oedema.