Raynaud's phenomenon

Raynaud's Phenomenon: Reviewing the Pathophysiology and Management Strategies

Raynaud's phenomenon (RP) is a multifactorial vasospastic disorder characterized by a transient, recurrent, and reversible constriction of peripheral blood vessels. RP is documented to affect up to 5% of the general population, but variation in its prevalence is commonly recognized owing to many factors, including varied definitions, gender, genetics, hormones, and region. Furthermore, RP may be idiopathic or be a clinical manifestation of an underlying illness. Patients with RP classically describe a triphasic discoloration of the affected area, beginning with pallor, followed by cyanosis, and finally ending with erythema. This change in color spares the thumb and is often associated with pain. Each attack may persist from several minutes to hours. Moreover, the transient cessation of blood flow in RP is postulated to be mediated by neural and vascular mechanisms. Both structural and functional alterations observed in the blood vessels contribute to the vascular abnormalities documented in RP. However, functional impairment serves as a primary contributor to the pathophysiology of primary Raynaud's. Substances like endothelin-1, angiotensin, and angiopoietin-2 play a significant role in the vessel-mediated pathophysiology of RP. The role of nitric oxide in the development of this phenomenon is still complex. Neural abnormalities resulting in RP are recognized as either being concerned with central mechanisms or peripheral mechanisms. CNS involvement in RP may be suggested by the fact that emotional distress and low temperature serve as major triggers for an attack, but recent observations have highlighted the importance of locally produced factors in this regard as well. Impaired vasodilation, increased vasoconstriction, and several intravascular abnormalities have been documented as potential contributors to the development of this disorder. RP has also been observed to occur as a side effect of various drugs. Recent advances in understanding the mechanism of RP have yielded better pharmacological therapies. However, general lifestyle modifications along with other nonpharmacological interventions remain first-line in the management of these patients. Calcium channel blockers, alpha-1 adrenoreceptor antagonists, angiotensin-converting enzyme inhibitors, nitric oxide, prostaglandin analogs, and phosphodiesterase inhibitors are some of the common classes of drugs that have been found to be therapeutically significant in the management of RP. Additionally, anxiety management, measures to avoid colder temperatures, and smoking cessation, along with other simple modifications, have proven to be effective non-drug strategies in patients experiencing milder symptoms.

A Non-Invasive IR Sensor Technique to Differentiate Parkinson's Disease from Other Neurological Disorders Using Autonomic Dysfunction as Diagnostic Criterion

Early diagnosis of Parkinson's disease (PD) plays a critical role in effective disease management and delayed disease progression. This study reports a technique that could diagnose and differentiate PD from essential tremor (ET) in its earlier stage using a non-motor phenotype. Autonomic dysfunction, an early symptom in PD patients, is caused by α-synuclein pathogenesis in the central nervous system and can be diagnosed using skin vasomotor response to cold stimuli. In this study, the investigations were performed using data collected from 20 PD, 20 ET and 20 healthy subjects. Infrared thermography was used for the cold stress test to observe subjects' hand temperature before and after cold stimuli. The results show that the recovery rate of hand temperature was significantly different between the groups. The data obtained in the cold stress test were verified using Pearson's cross-correlation technique, which showed that few disease parameters like medication and motor rating score had an impact on the recovery rate of hand temperature in PD subjects. The characteristics of the three groups were compared and classified using the k-means clustering algorithm. The sensitivity and specificity of these techniques were analyzed using an Receiver Operating Characteristic (ROC) curve analyzer. These results show that this non-invasive technique can be used as an effective tool in the diagnosis and differentiation of PD in its early stage.

Sudden onset peripheral visual deficit secondary to retinal artery spasm in Raynaud's phenomenon

A 32-year-old doctor, who has a medical history of primary Raynaud's disease and previous scotomas, presented to eye clinic with sudden onset blurring of vision (infero-nasally) with no other associated symptoms. The patient had good visual acuity bilaterally (6/6) and no anterior chamber activity or conjunctival hyperaemia. Findings consistent with a nerve fibre layer infarct were noted in the right eye, with unremarkable examination of the left eye. Optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) images were obtained, which showed an area of capillary shut down in keeping with a nerve fibre layer lesion. Previous literature pertaining to similar symptoms is sparse with symptoms such as migraines, epilepsy and visual loss being stated. This case provides further evidence of Raynaud's associated retinal artery spasm, with complete resolution at 4 weeks. We also demonstrate the accessibility of OCT and more importantly OCTA for investigation of sudden onset visual deficit.

Scleroderma in Children and Adolescents: Localized Scleroderma and Systemic Sclerosis

Scleroderma is a rare disease that has two main forms: localized scleroderma (LS) and systemic sclerosis (SSc). Both are chronic diseases, can present in different patterns (subtypes), and are associated with extracutaneous involvement in pediatric patients. Morbidity and mortality is much worse for juvenile SSc with patients at risk for life-threatening lung, heart, and other visceral organ fibrosis and vasculopathy. Mortality is extremely rare in juvenile LS, but morbidity is common, with patients at risk for severe disfigurement and functional impairment. Scleroderma treatment is directed towards controlling inflammation and managing specific problems. Early diagnosis can greatly improve outcome.

Points to consider-Raynaud's phenomenon in systemic sclerosis

RP is an exaggerated vasospastic response to cold or emotion. Randomized, double-blind, placebo-controlled trials with either parallel group or cross-over trials should be mainly considered. Cross-over design, which is good for early phase trials of immediate or very short-term outcomes, is important in a condition as heterogeneous as RP: a wash-out period between treatment arms should always be included to minimize the possibility of a period (carry-over) effect. Duration of RP trials is usually constrained by the need to complete these over a single season, usually winter when the weather is colder. For cross-over trials, each treatment arm tends to be 4 weeks or less. Frequency and duration of attacks, and the Raynaud's Condition Score are widely used outcome measures. There is increasing interest in physiological laboratory endpoints, for example laser Doppler imaging at least for early phase trials.

From microvasculature to fibroblasts: Contribution of anti-endothelial cell antibodies in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by skin and internal organ fibrosis, caused by microvascular dysfunction. In recent years, the hypothesis that anti-endothelial cell antibodies (AECA) play a key role in microvascular damage seems to be increasingly convincing. In fact, AECA can induce antibody-dependent cellular apoptosis and stimulate the microvasculature to release pro-inflammatory and pro-fibrotic cytokines. Human-microvascular-endothelial-cells (MVECs) were stimulated with SSc sera (with and without AECA) and with sera from healthy donors. The conditioned MVEC culture media were then added to fibroblast cultures obtained from control skin (CTR), non-affected skin of SSc patients (NA), and affected skin of the same sclerodermic (SSc) patients, respectively. AECA contributed to the MVEC increased release of endothelin-1 (ET-1) in the culture medium and to MVEC apoptosis. Fibroblast (CTR, NA, and SSc) proliferation was increased after treatment with AECA-positive conditioned media, compared to AECA-negative and control conditioned media. Furthermore, both AECA-positive (in major contribution) and AECA-negative conditioned media were responsible for alpha-smooth-muscle-actin (αSMA) over-expression in all fibroblast cultures, compared to control conditioned media. Fibroblast type I collagen synthesis was upregulated by both SSc conditioned media (with and without AECA). Finally, the synthesis of fibroblast transforming-growth-factor-beta (TGF-β) was statistically higher in AECA-positive conditioned media, compared to AECA-negative and control conditioned media. These findings support the concept that AECA may mediate the crosstalk between endothelial damage and dermal-fibroblast activation in SSc.

Plexin-D1/Semaphorin 3E pathway may contribute to dysregulation of vascular tone control and defective angiogenesis in systemic sclerosis

Introduction

The vascular and nervous systems have several anatomic and molecular mechanism similarities. Emerging evidence suggests that proteins involved in transmitting axonal guidance cues, including members of class III semaphorin (Sema3) family, play a critical role in blood vessel guidance during physiological and pathological vascular development. Sema3E is a natural antiangiogenic molecule that causes filopodial retraction in endothelial cells, inhibiting cell adhesion by disrupting integrin-mediated adhesive structures. The aim of the present study was to investigate whether in systemic sclerosis (SSc) Plexin-D1/Sema3E axis could be involved in the dysregulation of vascular tone control and angiogenesis.

Methods

Sema3E levels were measured by quantitative colorimetric sandwich ELISA in serum samples from 48 SSc patients, 45 subjects with primary Raynaud's phenomenon (pRP) and 48 age-matched and sex-matched healthy controls. Immunofluorescence staining on skin sections from 14 SSc patients and 12 healthy subjects was performed to evaluate Sema3E and Plexin-D1 expression. Western blotting was used to assess Plexin-D1/Sema3E axis in human SSc and healthy dermal microvascular endothelial cells (SSc-MVECs and H-MVECs, respectively) at basal condition and after stimulation with recombinant human vascular endothelial growth factor (VEGF), SSc and healthy sera. Capillary morphogenesis on Matrigel was performed on H-MVECs treated with healthy, pRP or SSc sera in the presence of Sema3E and Plexin-D1 soluble peptides.

Results

Serum Sema3E levels were significantly higher both in pRP subjects and SSc patients than in controls. In SSc, Sema3E levels were significantly increased in patients with early nailfold videocapillaroscopy (NVC) pattern compared to active/late patterns and pRP, and in patients without digital ulcers versus those with ulcers. In SSc skin, Sema3E expression was strongly increased in the microvascular endothelium. Cultured SSc-MVECs showed higher levels of phosphorylated Plexin-D1 and Sema3E expression than H-MVECs, and stimulation with SSc sera increased phosphorylated Plexin-D1 and Sema3E in H-MVECs. The addition of Sema3E-binding Plexin-D1 soluble peptide significantly attenuated the antiangiogenic effect of SSc sera on H-MVECs.

Conclusions

Our findings suggest that Plexin-D1/Sema3E axis is triggered in SSc endothelium and may have a role in the dysregulation of angiogenesis and vascular tone control by inducing neuro-vascular mechanism alterations clinically evident in particular in the early disease phases.

Nonarteriosclerotic vascular disease

Thromboangiitis obliterans, or Buerger disease, is a chronic nonatherosclerotic endarteritis manifesting as inflammation and thrombosis of distal extremity small and medium-sized arteries resulting in relapsing episodes of distal extremity ischemia. Takayasu arteritis is a rare syndrome characterized by inflammation of the aortic arch, pulmonary, coronary, and cerebral vessels, presenting with cerebrovascular symptoms, myocardial ischemia, or upper extremity claudication in young, often female, patients. Kawasaki disease is a small- and medium-vessel acute systemic vasculitis of young children, with morbidity and mortality stemming from coronary artery aneurysms. Microscopic polyangiitis, Churg-Strauss syndrome, and Wegener granulomatosis are systemic small-vessel vasculitides, affecting arterioles, capillary beds and venules, and each presenting with variable effects on the pulmonary, renal and gastrointestinal systems.

Late appearance and exacerbation of primary Raynaud's phenomenon attacks can predict future development of connective tissue disease: a retrospective chart review of 3,035 patients

To assess the prognostic value of the age at onset of Raynaud's (RP) and of a history of exacerbation of RP attacks for the development of connective tissue disease (CTD) in patients initially found to have primary Raynaud's. 3,035 patients with primary RP (2,702 women and 333 men) were followed for an average of 4.8 years (range from 1 to 10 years). At baseline and every 6 months, they were screened for signs and symptoms of CTD. At 4.8 years of follow-up, 54.7 % patients remained as primary RP, 8.1 % had developed suspected secondary RP, and 37.2 % had developed a definite CTD. Primary RP patients had an earlier onset of RP (mean age of 32.2 years) than those with suspected (mean age 36.5 years, P = .007) or definite secondary RP associated with CTD (mean age of 39.8 years, P = .004). RP beginning before the age of forty was not significantly associated with the development of CTD. Conversely, the appearance of RP after the age of 40 was significantly associated with the development of CTD (P = .00001). Worsening of RP attacks predicted the development of CTD, especially systemic sclerosis (relative risk [RR] of 1.42), scleroderma overlap syndrome (RR of 1.18), and mixed CTD (RR of 1.18). Patients whose onset of RP occurred past 40 years of age and those with worsening RP attacks were at risk for the future development of CTD.

Evaluation of the effect of Bosentan treatment on proinflammatory cytokine serum levels in patients affected by Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized by vascular and fibrotic changes in the skin and in internal organs. Endothelin-1 (ET-1) is a peptide that has a role in promoting both vascular injury and the fibrotic process in SSc; indeed, patients with systemic sclerosis have higher levels of ET-1 compared with healthy subjects. Moreover, ET-1 enhances expression of pro-inflammatory cytokines in animal model. Bosentan is a dual endothelin receptor antagonist approved for the treatment of pulmonary arterial hypertension and digital ulcers in scleroderma patients. In animal models and in vitro models, after treatment with Bosentan, a significant reduction of cytokine (TNF α, IFN γ,IL-8, IL-4) levels was observed. The aim of the study is to verify whether Bosentan treatment in SSc patients can reduce circulating cytokines levels. We enrolled 10 patients affected by SSc with digital ulcers and/or pulmonary hypertension, treated with Bosentan 125 mg twice daily. Patients were tested for cytokines and ET-1 level before treatment and after 12 months. The cytokines tested were IL-10, IL-2, IL-4, IL-5, IL-6, IL-8, GM-CSF, IFN-γ and TNF. Levels of ET-1, IL-10, IL-4, IL-5, GM-CSF and TNFalpha did not show consistent modification during treatment with Bosentan in respect to baseline, while IL-2, IL-6, IL-8 and IFN-γ were significantly decreased. Bosentan significantly reduced IL-2, IL-6, IL-8 and IFN- γ levels in SSc patients, probably slowing progression to fibrosis and vascular damage. This is the first report showing a decrease of profibrotic and proinflammatory cytokines levels in humans during treatment with Bosentan.

Intracellular α(2C)-adrenoceptors: storage depot, stunted development or signaling domain?

G-protein coupled receptors (GPCRs) are generally considered to function as cell surface signaling structures that respond to extracellular mediators, many of which do not readily access the cell's interior. Indeed, most GPCRs are preferentially targeted to the plasma membrane. However, some receptors, including α(2C)-Adrenoceptors, challenge conventional concepts of GPCR activity by being preferentially retained and localized within intracellular organelles. This review will address the issues associated with this unusual GPCR localization and discuss whether it represents a novel sub-cellular niche for GPCR signaling, whether these receptors are being stored for rapid deployment to the cell surface, or whether they represent immature or incomplete receptor systems.

Digital ischemia in scleroderma spectrum of diseases

Systemic Sclerosis (Scleroderma, SSc) is a disease of unknown etiology characterized by widespread vasculopathy and extracellular matrix deposition leading to fibrosis and autoimmune processes. Digital ischemia (digital ulcers (DUs)) is the hallmark of SSc-related vasculopathy and is characterized by endothelial dysfunction leading to intimal proliferation and thrombosis. It happens frequently (30% of the patients each year) and it is associated with significant morbidity. This paper summarizes the current information regarding pathogenesis, definitions, management, and exploratory therapies in DUs associated with SSc.

Care of patients with scleroderma in the intensive care setting

Scleroderma or systemic sclerosis (SSc) is a connective tissue disease (CTD) associated with fibrosing and vascular complications involving multiple organs. The care of these patients in the critical care setting is frequently challenging due to multiple complications and refractory organ involvement. However, awareness of specific organ involvement associated with scleroderma can allow many complications to be anticipated and effectively treated. Cardiac involvement can lead to arrhythmias and heart failure, whereas pulmonary involvement can be associated with pulmonary arterial hypertension, fibrosis, or both. Renal vascular disease and scleroderma renal crisis (SRC), once a uniformly fatal complication, is particularly important to recognize early, as it can be treated successfully. Gastrointestinal involvement can lead to bleeding, aspiration, obstruction, and malabsorption. Severe Raynaud may lead to digital ischemia and gangrene. Therapies must target involved organ system or organ systems. Corticosteroids, a mainstay for related CTDs, do not typically provide any benefit and may cause harm. Vasodilators can effectively treat vascular complications but must target the appropriate vascular bed. Proactive utilization of proton pump inhibitors, recognition of bleeding from gastrointestinal vascular ectasia, and nutritional support can considerably ameliorate gastrointestinal morbidities. Effective treatment of fibrotic complications remains elusive and is the current frontier for scleroderma therapeutics.

Primary Raynaud phenomenon and small-fiber neuropathy: is there a connection? A pilot neurophysiologic study

The pathophysiologic factors of primary Raynaud phenomenon (RP) are unknown. Preliminary evidence from skin biopsy suggests small-fiber neuropathy (SFN) in primary RP. We aimed to quantitatively assess SFN in participants with primary RP. Consecutive patients with an a priori diagnosis of primary RP presenting to our outpatient rheumatology clinic over a 6-month period were invited to participate. Cases of secondary RP were excluded. All participants were required to have normal results on nailfold capillary microscopy. Assessment for SFN was accomplished with autonomic reflex screening, which includes quantitative sudomotor axonal reflex test (QSART), and cardiovagal and adrenergic function testing, thermoregulatory sweat test (TST), and quantitative sensory test (QST) for vibratory, cooling, and heat-pain sensory thresholds. Nine female participants with a median age of 38 years (range 21-46 years) and a median symptom duration of 9 years (range 5 months-31 years) were assessed. Three participants had abnormal results on QSART, indicating peripheral sudomotor autonomic dysfunction. Two participants had evidence of large-fiber involvement with heat-pain thresholds on QST. Heart rate and blood pressure responses to deep breathing, Valsalva maneuver, and 70° tilt were normal for all participants. Also, all participants had normal TST results. In total, three of the nine participants had evidence of SFN. The presence of SFN raises the possibility that a subset of patients with primary RP have an underlying, subclinical small-fiber dysfunction. These data open new avenues of research and therapeutics for this common condition.

Skin ulcers in systemic sclerosis: determinants of presence and predictive factors of healing

BACKGROUND

Skin ulcers are common vascular complications of systemic sclerosis (SSc).

OBJECTIVE

The aim of the study was to identify clinical, biologic, and imaging parameters that constitute risk factors for the occurrence and persistence of skin ulcers.

METHODS

One hundred thirty Italian SSc patients were examined at entry and after 20 months of follow-up.

RESULTS

The diffuse SSc phenotype with avascular areas on capillaroscopy, thrombophilia, and systemic inflammation as defined by interleukin 6 plasma levels, represented the major risk factors for ulcer development. Infection was associated with a risk of poor or no healing, and cardiopulmonary involvement was a major comorbid factor in patients with ulcers. The presence of infection and avascular areas represented the main determinants for ulcer healing.

LIMITATIONS

Our data should be confirmed with a longer follow-up period since skin ulcers represent a frequent vascular complication in scleroderma patients.

CONCLUSION

Aggressive therapies aiming at improving angiogenesis and controlling infection and the course of the disease appear to be crucial to obtain ulcer healing.

Vascular disease in scleroderma: angiogenesis and vascular repair

Vascular abnormalities are one of the primary pathologic components of scleroderma. An early vascular indicator is aberrant nail fold capillaries that appear to undergo a switch from a pro- to anti-angiogenic process. Later in the disease process, ineffective and aberrant wound healing becomes apparent with frequent and widespread fibrosis. Pulmonary hypertension, largely due to the loss of pulmonary arterial vasculature, is frequently observed in late stages of the disease. The common theme of all these processes is abnormal regeneration of the vasculature and ongoing vascular losses due to defective maintenance of the vasculature. Although most aspects of vascular injury in scleroderma are poorly understood, certain biologic themes are beginning to emerge that are important in understanding scleroderma-related vascular disease.

Current drug therapy for scleroderma and secondary Raynaud's phenomenon: evidence-based review

(1) Scleroderma and secondary Raynaud's phenomenon are frequently associated with increased morbidity for which no specific standardised treatment guidelines exist. (2) Current therapies for scleroderma target the immune system, with the goal of reducing inflammation and secondary tissue injury and fibrosis. Therapy targeting underlying vascular disease is designed to improve the symptoms of Raynaud's phenomenon and to reduce ischemic injury to involved organs. (3) Few controlled trials of therapy used for scleroderma are completed, and current treatments are largely based on organ-specific therapy and uncontrolled case series suggesting disease modification. (4) Recent randomised, controlled trials in scleroderma demonstrate promising results in the treatment of interstitial lung disease with cyclophosphamide, and vascular disease of the lungs and digits with endothelin receptor antagonists, the phosphodiesterase inhibitor sildenafil and prostacyclins, while trials with methotrexate show only modest benefit in controlling scleroderma-associated skin disease. (5) Prostacyclins are a therapeutic option in patients with secondary Raynaud's phenomenon. Modest benefits have also been shown with alpha1-antagonists and calcium channel blockers, while the effect of ACE inhibitors has been variable. Some data suggest some benefits to the use of the phosphodiesterase inhibitor sildenafil, the serotonin uptake inhibitor fluoxetine and the angiotensin receptor inhibitor losartan.

In vivo endothelial denudation disrupts smooth muscle caveolae and differentially impairs agonist-induced constriction in small arteries

Experiments were performed to determine the effects of endothelial denudation in vivo on vasoconstrictor responses of mouse tail artery segments in vitro. A sterile wire (70 microm diameter) was inserted into tail arteries of anesthetized mice to mechanically denude the endothelium, and the animals were allowed to recover for 48 hours. The function of pressurized tail artery segments was then studied in vitro. Intimal injury markedly reduced endothelium-dependent relaxation to acetylcholine. Constriction evoked by the selective alpha1-adrenoceptor (alpha1-AR) agonist, phenylephrine, was not affected by in vivo endothelial denudation, indicating that the contractile function of vascular smooth muscle cells (VSMCs) was not impaired. However, constriction to the selective alpha2-AR agonist UK14304 or to endothelin-1 was significantly inhibited. Confocal microscopy of intact tail arteries localized caveolin-1 to punctuate structures, arranged in rows on or close to the surface of VSMCs. After in vivo endothelial denudation, this pattern was disrupted and caveolin-1 was localized to intracellular sites. When VSMC caveolae were disrupted in control arteries using the cholesterol acceptor methyl-beta-cyclodextrin, there was a similar impairment in constriction to endothelin-1 or alpha2-AR stimulation, but not alpha1-AR activation. These results suggest that intimal injury to small cutaneous arteries disrupts VSMC surface caveolae and selectively impairs constriction to stimuli that are dependent on these structures for signaling.

Estrogen increases smooth muscle expression of α2C-adrenoceptors and cold-induced constriction of cutaneous arteries

Raynaud's phenomenon, which is characterized by intense cold-induced constriction of cutaneous arteries, is more common in women compared with men. Cold-induced constriction is mediated in part by enhanced activity of α2C-adrenoceptors (α2C-ARs) located on vascular smooth muscle cells (VSMs). Experiments were therefore performed to determine whether 17β-estradiol regulates α2C-AR expression and function in cutaneous VSMs. 17β-Estradiol (0.01–10 nmol/l) increased expression of the α2C-AR protein and the activity of the α2C-AR gene promoter in human cultured dermal VSMs, which was assessed following transient transfection of the cells with a promoter-reporter construct. The effect of 17β-estradiol was associated with increased accumulation of cAMP and activation of the cAMP-responsive Rap2 GTP-binding protein. Transient transfection of VSMs with a dominant-negative mutant of Rap2 inhibited the 17β-estradiol-induced activation of the α2C-AR gene promoter, whereas a constitutively active mutant of Rap2 increased α2C-AR promoter activity. The effects of 17β-estradiol were inhibited by the estrogen receptor (ER) antagonist, ICI-182780 (1 μmol/l), and were mimicked by a cell-impermeable form of the hormone (estrogen:BSA) or by the selective ER-α receptor agonist 4,4′,4‴-(4-propyl-[1H]-pyrazole-1,3,5-triyl)tris-phenol (PPT; 10 nmol/l) or the selective ER-β receptor agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN; 10 nmol/l). Therefore, 17β-estradiol increased expression of α2C-ARs by interacting with cell surface receptors to cause a cAMP/Rap2-dependent increase in α2C-AR transcription. In mouse tail arteries, 17β-estradiol (10 nmol/l) increased α2C-AR expression and selectively increased the cold-induced amplification of α2-AR constriction, which is mediated by α2C-ARs. An estrogen-dependent increase in expression of cold-sensitive α2C-ARs may contribute to the increased activity of cold-induced vasoconstriction under estrogen-replete conditions.

[Etiologic possibilities for the development of rheumatic diseases through environmental mechanisms]

Living beings and the environment that supports them have a mutual interdependence and therefore any event that occurs within an ecosystem affects all parts. The influence that the environment has on subjects that maydevelop an illness has been amply recognized. For some autoimmune diseases such as systemic lupus erythematosus (SLE), the possibility of its development under ultraviolet light and prolonged exposure to sunlight has been recognized. Microorganisms may activate other illnesses such as reactive arthritis. Substances such as alfalfa are also able to unleash disease activity. Laboratory workers who manipulate sera of patients with autoimmune rheumatic disorders develop antibodies to the sera that they are working with. It is thus that environmental sciences and focused research allow the development of a new approach to the study of possible pathogenic mechanisms in the appearance of certain rheumatic disorders. This article reviews the main existing evidence and proposes certain hypotheses derived from it.

Current concepts in normal and defective angiogenesis: implications for systemic sclerosis

Vascular abnormalities are a major component of systemic sclerosis, but little is known about the events or mechanisms that initiate vascular injury and prevent its repair. Early stages of systemic sclerosis are characterized by an exaggerated angiogenic response later replaced by defective wound healing and fibrosis. In this review, we summarize the current knowledge of the angiogenic imbalance in systemic sclerosis.

Assessment of nailfold capillaroscopy by x 30 digital epiluminescence (dermoscopy) in patients with Raynaud phenomenon

BACKGROUND

Dermoscopy is a useful tool for dermatologists to study melanocytic lesions. Its possible usefulness in the assessment of capillary nailfold morphological changes (capillaroscopy) has recently been advocated.

OBJECTIVES

To assess the practical utility of digital epiluminescence microscopy as a capillaroscopic instrument in patients with Raynaud phenomenon (RP). To compare the sensitivity and specificity rates obtained by epiluminescence microscopy with those previously reported with conventional capillaroscopic devices.

METHODS

Fifty-six consecutive patients with primary RP (PRP; n = 5) or secondary RP (SRP; n = 51) (11 men and 45 women in total) were included in the study. A control group of 10 healthy subjects was also evaluated. Twenty-six patients (46%) had systemic sclerosis (SS), 12 (21%) presystemic sclerosis (pre-SS), one (2%) dermatopolymyositis-SS, one (2%) mixed connective tissue disease, two (4%) Sjögren syndrome, two (4%) an overlap syndrome, one (2%) rheumatoid arthritis and six (11%) other connective tissue diseases. Capillary nailfold changes were studied using a nonportable digital epiluminescence device (magnification x 30). Following a systematized protocol, capillary nailfold morphology, density and distribution were evaluated. Several capillaroscopic patterns were identified (normal, sclerodermic, nonspecific, nondiagnostic) as previously defined. A possible relationship between capillary nailfold changes and the intensity of RP or the presence of associated autoimmune diseases was assessed.

RESULTS

The sclerodermic pattern showed a sensitivity of 76.9% and a specificity of 90.9% in SS. A typical capillaroscopic SS pattern was observed in 73% of cases of limited SS and in 82% of cases of diffuse SS. Patients with Sjögren syndrome and dermatopolymyositis-SS showed a nonspecific capillaroscopic pattern. All patients with PRP presented a normal capillaroscopic pattern. A normal capillaroscopic pattern was also observed in 11 of 12 patients with pre-SS. In one of two patients presenting severe sclerodactyly and in all patients showing hand oedema (three of 56), capillaroscopic changes could not be evaluated. Avascular areas correlated significantly with severe RP (P < 0.002), bone resorption (P < 0.007) and diffuse SS (P < 0.008).

CONCLUSIONS

Digital epiluminescence seems to be a useful and reliable technique in the evaluation of capillary nailfold morphological changes. This technical variation allows the identification of specific capillaroscopic patterns associated with connective tissue diseases. It also permits us to differentiate PRP from SRP. The results obtained with this technique are similar to those previously reported using standard capillaroscopy devices.

Antiangiogenic plasma activity in patients with systemic sclerosis

OBJECTIVE

Systemic sclerosis (SSc; scleroderma) is a systemic connective tissue disease with an extensive vascular component that includes aberrant microvasculature and impaired wound healing. The aim of this study was to investigate the presence of antiangiogenic factors in patients with SSc.

METHODS

Plasma samples were obtained from 30 patients with SSc and from 10 control patients without SSc. The samples were analyzed for the ability of plasma to affect endothelial cell migration and vascular structure formation and for the presence of antiangiogenic activity.

RESULTS

Exposure of normal human microvascular dermal endothelial cells to plasma from patients with SSc resulted in decreased cell migration (mean +/- SEM 52 +/- 5%) and tube formation (34 +/- 6%) compared with that in plasma from control patients (P < 0.001 for both). SSc plasma contained 2.9-fold more plasminogen kringle 1-3 fragments (angiostatin) than that in control plasma. The addition of angiostatin to control plasma resulted in inhibition of endothelial cell migration and proliferation similar to that observed in SSc plasma. In vitro studies demonstrated that granzyme B and other proteases contained in T cell granule content cleave plasminogen and plasmin into angiostatin fragments.

CONCLUSION

Plasminogen conformation in patients with SSc enables granzyme B and granule content protease to limit the proangiogenic effects of plasmin and increase the levels of antiangiogenic angiostatin. This increase in angiostatin production may account for some of the vascular defects observed in patients with SSc.

Rheumatoid arthritis in dermatology

Rheumatoid arthritis (RA) is a chronic progressive disorder characterized by symmetric inflammatory arthritis in association with systemic symptoms. Although considered a "joint disease," RA is associated with involvement in diverse organ systems, including the skin. Common manifestations include Raynaud phenomenon, rheumatoid nodules, and rheumatoid vasculitis. As with other extra-articular manifestations, dermatologic involvement tends to occur in patients with more severe RA. In addition to manifestations related to the disease, there are also sundry dermatologic reactions related to the medications used to treat RA. Understanding the etiology and therapy for cutaneous manifestations of RA will help optimize patient care.

[Raynaud's phenomenon]

Raynaud's phenomenon is characterized by repeated daily attacks of ischemia followed by reperfusion at the acrallevel. It is a frequent syndrome found in medical practice; and it can be considered as primary or secondary to other conditions, including rheumatic autoimmune diseases. Current classification had clinical and therapeutic implications. Careful clinical evaluation is the most reliable and reproducible method in the diagnosis of Raynaud's phenomenon. Several risk factors had been associated in the genesis of Raynaud's phenomenon; however, its pathogenesis remains elusive although recently, considerable progress in disease mechanism had been described. Such advances are directing new lines of therapy.

Autoimmune connective tissue disease: scleroderma

Scleroderma is an umbrella term for a spectrum of rare and complex autoimmune connective tissue diseases, the cause and pathogenesis of which is only partially defined. Scleroderma can be divided into two main subgroups--systemic and localized--but the hallmark of both is skin fibrosis. As yet no drug has been found to be effective in reversing the disease process, however early intervention has been shown to give maximum benefit. Due to the chronic nature of the condition a multidisciplinary approach is essential and the nurse's input from an early stage is vital in supporting the patient to manage both their medical treatment and their activities of daily living.

Thoracoscopic sympathectomy for Raynaud's phenomenon--a long term follow-up study

OBJECTIVES

To assess the long term results of thoracoscopic sympathectomy for Raynaud's phenomenon.

DESIGN, MATERIALS AND METHODS

A retrospective study of 34 consecutive patients who were treated for Raynaud's phenomenon by thoracoscopic sympathectomy from 1996 to 2005. Eight patients presented with ulcerations of the digits and 10 had severe ischaemia without ulcerations. The hospital records were retrieved and questionnaires were mailed to the patients for follow-up.

RESULTS

The questionnaire was answered by 91% of patients after a median follow-up time of 40 months. An immediate effect was seen in 83% of the patients but symptoms recurred in 60% during the follow-up period. Compensatory sweating occurred in 63 and 30% reported gustatory sweating. Thirteen patients (43%) regretted having the operation.

CONCLUSION

The majority of patients with Raynaud's phenomenon have an excellent immediate effect from thoracoscopic sympathectomy and one third achieve a long lasting effect. Side effects are frequent. We now only use thoracoscopic sympathectomy in severe cases of Raynaud's phenomenon.

Iloprost treatment in patients with Raynaud's phenomenon secondary to systemic sclerosis and the quality of life: a new therapeutic protocol

OBJECTIVES

To evaluate the clinical efficacy and the effects on the quality of life of iloprost, a prostacyclin analogue, used according to a new protocol in patients with Raynaud's phenomenon secondary to systemic sclerosis.

METHODS

In this randomized study, we treated 30 patients with iloprost, given by intravenous infusion, at progressively increasing doses (from 0.5 to 2 ng/kg/min) over a period of 6 h each day for 10 days in two consecutive weeks, with repeated cycles at regular intervals of 3 months for 18 months. The results were compared with those obtained in 30 other patients who received the same drug but with different dosing schemes.

RESULTS

The total average daily duration of the attacks, the average duration of a single attack and the average daily frequency of the attacks were reduced significantly in all treatment groups, but the comparison between the groups demonstrated significant differences between patients treated with the new protocol and the others at later times (12 and 18 months). The effects on the quality of life in the group treated with the new protocol, evaluated with the Short Form-36, demonstrated a marked improvement regarding both the scale relating to the physical aspect of the illness and, especially, the scale relating to the mental aspect.

CONCLUSIONS

In patients with systemic sclerosis, cyclic intravenous iloprost infusion is efficacious in the treatment of Raynaud's phenomenon. The protocol that we used, compared with others, not only has favourable clinical effects but also leads to a marked improvement in the quality of life.

Understanding, assessing and treating Raynaud's phenomenon

PURPOSE OF REVIEW

New insights in the pathophysiology and molecular mechanisms implicated in cutaneous vasomotor response to cooling are emerging from recent literature. These advances are introducing significant changes in the management of Raynaud's phenomenon. In this review, we outline how these new findings are leading to novel methods of assessment and new opportunities for specific targeted therapy.

RECENT FINDINGS

New potential targets for treatment of Raynaud's phenomenon derive from experimental observations. Increased protein tyrosine kinase activity and tyrosine phosphorylation have been described in vascular smooth muscle cells in response to cooling and are linked to excessive alpha2-adrenergic response. Activation of Rho/Rho kinase pathway is triggered by increase of reactive oxygen species and up-regulates alpha2c-adrenergic receptors on the surface of vascular smooth muscle cells, thus determining an excessive vasoconstrictive response to cooling. This observation generated pilot trials testing rho-kinase inhibitors and alpha2c-adrenergic receptors antagonists in vasospastic conditions with encouraging results. Therapies already in use for pulmonary hypertension are also showing an effect in Raynaud's phenomenon. Studies evaluating anti-endothelin-1 (bosentan), phosphodiesterases inhibitors (sildenafil), and prostanoids (given for critical digital ischemia) in the treatment of Raynaud's phenomenon all determined improvement of symptoms and/or digital ischemic lesions. Novel techniques for better visualization and quantification of cutaneous microvascular defects are under development. The hope is that these new tools will allow earlier discrimination between primary and secondary Raynaud's phenomenon as well as a better way to predict outcome and response to therapy.

SUMMARY

Remarkable progress towards a rational approach to the management and treatment of Raynaud's phenomenon is emerging.

Digital ulcers in patients with systemic sclerosis

Digital ulcers (DU), defined as necrotic lesions located at distal digits or overlying bony prominences, occur in up to 50% of patients with limited or diffuse systemic sclerosis (SSc). These lesions are extremely painful and lead to substantial functional disability. The pathogenesis of DU differs depending on their location. DU located at distal aspects of digits are thought to be related to tissue ischemia from several processes, including vasospasm secondary to Raynaud's phenomenon, intimal fibro-proliferation, and thrombosis of digital arteries. DU located over bony prominences, such as the phalangeal joints and elbows, are thought to be due to repetitive microtrauma and difficulty healing due to atrophic, avascular tissue overlying the joints. Management of DU include non-pharmacologic and pharmacologic modalities. This review summarizes the current available and investigational therapies for the treatment and prevention of DU in patients with SSc.

Reactive oxygen species from smooth muscle mitochondria initiate cold-induced constriction of cutaneous arteries

Cold constricts cutaneous blood vessels by selectively increasing the activity of smooth muscle alpha2-adrenoceptors (alpha2-ARs). In mouse tail arteries, alpha2-AR constriction is mediated by alpha2A-ARs at 37 degrees C, whereas the cold-induced augmentation in alpha2-AR activity is mediated entirely by alpha2C-ARs. Cold causes translocation of alpha2C-ARs from the trans-Golgi to the plasma membrane, mediated by cold-induced activation of RhoA and Rho kinase. The present experiments analyzed the mechanisms underlying these responses. Mouse tail arteries were studied in a pressure myograph. Cooling the arteries (28 degrees C) caused a rapid increase in reactive oxygen species (ROS) in smooth muscle cells, determined by confocal microscopy of arteries loaded with the ROS-sensitive probes, dichlorodihydrofluorescein or reduced Mitotracker Red. The inhibitor of mitochondrial complex I rotenone (10 micromol/l), the antioxidant N-acetylcysteine (NAC; 20 mmol/l), or the cell-permeable mimic of superoxide dismutase MnTMPyP (50 micromol/l) did not affect vasoconstriction to alpha2-AR stimulation (UK-14304) at 37 degrees C but dramatically inhibited the response at 28 degrees C. Indeed, these ROS inhibitors abolished the cold-induced increase in alpha2-AR constrictor activity. NAC (20 mmol/l) or MnTMPyP (50 micromol/l) also abolished the cold-induced activation of RhoA in human cultured vascular smooth muscle cells and the cold-induced mobilization of alpha2C-ARs to the cell surface in human embryonic kidney 293 cells transfected with the receptor. The combined results suggest that cold-induced constriction is mediated by redox signaling in smooth muscle cells, initiated by mitochondrial generation of ROS, which stimulate RhoA/Rho kinase signaling and the subsequent mobilization of alpha2C-ARs to the cell surface. Altered activity of ROS may contribute to cold-induced vasospasm occurring in Raynaud's phenomenon.

Estrogens and Neuropeptides in Raynaud's Phenomenon

Raynaud's phenomenon (RP) is characterized by ischemia and reperfusion of the extremities. Vasomotor instability is due to a microcirculatory disturbance that may be linked to different events involving the endothelium or peripheral nerve terminals. Endothelium and nerve endings "sense" the modifications of the microenvironment and both of them release factors that contribute to find a balance between vasolidation and vasoconstriction. Moreover, estrogens may contribute to control vascular tone regulating finger skin circulation. A loss of neuropeptides has been shown in secondary RP where supplementation with factors derived from nerve endings has been demonstrated to induce a potent vasolidation. Estrogen administration improved endothelial dysfunction in secondary RP. Neuropeptides and estrogens thus share the endothelial-dependent pathway, usually mediated by nitric oxide, in inducing vasolidation. The network directed by the endothelium is in reality controlled by a neuro-hormonal axis composed by neuropeptides and estrogens. This delicate balance keeps the vascular tone, and its dysfunction may lead to a dysregulation of vascular tone, manifest in clinics as a primary or secondary RP.

Digital ulcers in systemic sclerosis: Prevention by treatment with bosentan, an oral endothelin receptor antagonist

OBJECTIVE

Recurrent digital ulcers are a manifestation of vascular disease in patients with systemic sclerosis (SSc; scleroderma) and lead to pain, impaired function, and tissue loss. We investigated whether treatment with the endothelin receptor antagonist, bosentan, decreased the development of new digital ulcers in patients with SSc.

METHODS

This was a randomized, prospective, placebo-controlled, double-blind study of 122 patients at 17 centers in Europe and North America, evaluating the effect of treatment on prevention of digital ulcers. The primary outcome variable was the number of new digital ulcers developing during the 16-week study period. Secondary assessments included healing of existing digital ulcers and evaluation of hand function using the Scleroderma Health Assessment Questionnaire.

RESULTS

Patients receiving bosentan had a 48% reduction in the mean number of new ulcers during the treatment period (1.4 versus 2.7 new ulcers; P = 0.0083). Patients who had digital ulcers at the time of entry in the study were at higher risk for the development of new ulcers; in this subgroup the mean number of new ulcers was reduced from 3.6 to 1.8 (P = 0.0075). In patients receiving bosentan, a statistically significant improvement in hand function was observed. There was no difference between treatment groups in the healing of existing ulcers. Serum transaminase levels were elevated to >3-fold the upper limit of normal in bosentan-treated patients; this elevation is comparable with that observed in previous studies of this agent. Other side effects were similar in the 2 treatment groups.

CONCLUSION

Endothelins may play an important role in the pathogenesis of vascular disease in patients with SSc. Treatment with the endothelin receptor antagonist bosentan may be effective in preventing new digital ulcers and improving hand function in patients with SSc.

Coexistence of erythromelalgia and Raynaud's phenomenon

Erythromelalgia is characterized by spontaneous recurrent episodes of redness, heat, and pain of the extremities that can be triggered or worsened by heat. Raynaud's phenomenon occurs in response to cold exposure and presents as pallor of the fingers or toes, often followed by cyanosis and rubor. Although the 2 conditions may appear to be opposites in symptomatology and clinical presentation, there are very rare reports of their coexistence. A case of coexistent erythromelalgia and Raynaud's phenomenon is presented. The pathophysiology is reviewed to elucidate a common mechanism underlying some cases of the 2 seemingly opposite conditions. A review of the literature indicates that causative and pathophysiologic similarities between the 2 conditions may exist in some cases. Rare reports of coexistence of the 2 disease processes further strengthen such research findings.

Current research and theories on the pathogenesis of acute laminitis in the horse

A large number of studies have been undertaken in recent years aimed at furthering our understanding of the complex mechanisms underlying the common and debilitating condition of acute laminitis in the horse. Many of these studies have either reinforced or cast doubt on previously held theories on the pathogenesis of this disease, while others have suggested new mechanisms which may play a key role in its development. This review seeks to put the current hypotheses into the context of this recent body of evidence. While a unifying theory may not yet seem to be achievable, this review demonstrates that most of the current theories are not mutually exclusive. Studies utilising in vitro and in vivo models of the disease, particularly addressing the areas of inflammation, haemodynamic disturbances and enzyme activation in the hoof, as well as the preceding events occurring in the hindgut, have helped to explain many clinical observations of the disease and may possibly lead to more effective therapies and means of prevention in the future.

Regulation of alpha(2)-adrenoceptors in human vascular smooth muscle cells

This study analyzed the regulation of alpha2-adrenoceptors (alpha2-ARs) in human vascular smooth muscle cells (VSMs). Saphenous veins and dermal arterioles or VSMs cultured from them expressed high levels of alpha2-ARs (alpha2C > alpha2A, via RNase protection assay) and responded to alpha2-AR stimulation [5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK-14,304, 1 microM)] with constriction or calcium mobilization. In contrast, VSMs cultured from aorta did not express alpha2-ARs and neither cultured cells nor intact aorta responded to UK-14,304. Although alpha2-ARs (alpha2C >> alpha2A) were detected in aortas, alpha2C-ARs were localized by immunohistochemistry to VSMs of adventitial arterioles and not aortic media. In contrast with aortas, aortic arterioles constricted in response to alpha2-AR stimulation. Reporter constructs demonstrated higher activities for alpha2A- and alpha2C-AR gene promoters in arteriolar compared with aortic VSMs. In arteriolar VSMs, serum increased expression of alpha2C-AR mRNA and protein but decreased expression of alpha2A-ARs. Serum induction of alpha2C-ARs was reduced by inhibition of p38 mitogen-activated protein kinase (MAPK) with 2 microM SB-202190 or dominant-negative p38 MAPK. UK-14,304 (1 microM) caused calcium mobilization in control and serum-stimulated cells: in control VSMs, the response was inhibited by the alpha2A-AR antagonist BRL-44408 (100 nM) but not by the alpha2C-AR antagonist MK-912 (1 nM), whereas after serum stimulation, MK-912 (1 nM) but not BRL-44408 (100 nM) inhibited the response. These results demonstrate site-specific expression of alpha2-ARs in human VSMs that reflects differential activity of alpha2-AR gene promoters; namely, high expression and function in venous and arteriolar VSMs but no detectable expression or function in aortic VSMs. We found that alpha2C-ARs can be dramatically and selectively induced via a p38 MAPK-dependent pathway. Therefore, altered expression of alpha2C-ARs may contribute to pathological changes in vascular function.

The vasculopathy of Raynaud's phenomenon and scleroderma

The scleroderma (SSc) disease process involves dramatic dysfunction in acute and chronic vascular regulatory mechanisms; it presents initially with heightened vasoconstrictor or vasospastic activity and progresses to structural derangement or vasculopathy of the microcirculation. This article discusses the regulatory mechanisms that contribute to this dysfunction and the vascular changes in the context of the other aspects of the SSc disease process in a novel attempt to integrate the individual pathologies of the disease process.

Skin blood flow in adult human thermoregulation: how it works, when it does not, and why

The thermoregulatory control of human skin blood flow is vital to the maintenance of normal body temperatures during challenges to thermal homeostasis. Sympathetic neural control of skin blood flow includes the noradrenergic vasoconstrictor system and a sympathetic active vasodilator system, the latter of which is responsible for 80% to 90% of the substantial cutaneous vasodilation that occurs with whole body heat stress. With body heating, the magnitude of skin vasodilation is striking: skin blood flow can reach 6 to 8 L/min during hyperthermia. Cutaneous sympathetic vasoconstrictor and vasodilator systems also participate in baroreflex control of blood pressure; this is particularly important during heat stress, when such a large percentage of cardiac output is directed to the skin. Local thermal control of cutaneous blood vessels also contributes importantly--local warming of the skin can cause maximal vasodilation in healthy humans and includes roles for both local sensory nerves and nitric oxide. Local cooling of the skin can decrease skin blood flow to minimal levels. During menopause, changes in reproductive hormone levels substantially alter thermoregulatory control of skin blood flow. This altered control might contribute to the occurrence of hot flashes. In type 2 diabetes mellitus, the ability of skin blood vessels to dilate is impaired. This impaired vasodilation likely contributes to the increased risk of heat illness in this patient population during exposure to elevated ambient temperatures. Raynaud phenomenon and erythromelalgia represent cutaneous microvascular disorders whose pathophysiology appears to relate to disorders of local and/or reflex thermoregulatory control of the skin circulation.

Raynaud's phenomenon in children: a retrospective review of 123 patients

OBJECTIVE

To examine the clinical presentation and disease associations of Raynaud's phenomenon (RP) in children and adolescents.

METHODS

A systematic retrospective chart review was conducted of 123 cases drawn from 2 computerized databases at the Children's Hospital of Boston. Participants aged <19 years with episodic reversible color changes in the extremities were examined. Case records were analyzed for clinical presentation, disease associations, and physical examination and laboratory findings.

RESULTS

In contrast to the findings of smaller pediatric series reported to date, the large majority of our patients-approximately 70%-did not have a recognized underlying connective tissue disease. For both primary and secondary RP, approximately 80% of patients were female, and mean age of onset was similar in the 2 groups. Biphasic or triphasic color changes were less common than monophasic changes and were no more common in secondary than primary RP. Findings predictive of secondary RP were limited to the presence of antinuclear antibodies and abnormal nailfold capillaries. Antiphospholipid antibodies were found at some time in at least 21% of patients with both primary and secondary RP.

CONCLUSIONS

RP in children, as in adults, principally affects girls and is frequently free of association with connective tissue disease. Antinuclear antibody positivity and abnormal nailfold capillaries correlate with secondary disease. Antiphospholipid antibodies are surprisingly common, a new finding of uncertain implications.

Targeting mediators of vascular injury in scleroderma

Increasing evidence suggests that the vasculopathy of scleroderma is mediated by a number of soluble factors and involves a complex interaction between endothelial cells, smooth muscle cells, extracellular matrix, intravascular coagulation factors, and circulating cells. Novel therapeutic approaches beyond vasodilator therapy are being developed by recognizing important molecular pathways involved in scleroderma vascular disease. The success of this strategy is most evident in pulmonary hypertension, an often fatal complication of scleroderma. In this article, the authors explore therapies for scleroderma that target endothelial cells, smooth muscle cells, reactive oxygen species, and circulating blood cells. The authors highlight clinical trials that have investigated the role of prostacyclin (and its analogues) and bosentan in managing scleroderma-related pulmonary hypertension. Finally, the authors look at the potential role of biomarkers as surrogate indicators of active vascular disease in scleroderma.

Raynaud's phenomenon

Raynaud's phenomenon is characterised by episodic vasospasm of the fingers and toes typically precipitated by exposure to cold. Mild Raynaud's is common and is not usually a harbinger of clinically important disability; its onset, however, can be startling and uncomfortable for patients, and the well recognised association in some cases with systemic rheumatic conditions often precipitates aggressive assessments for underlying diseases. Advances in vascular physiology have shed light on the role of the endothelium as well as endothelium-independent mechanisms in the altered vasoregulation of Raynaud's. We review clinical aspects of the disorder and new insights with respect to pathophysiology, and we discuss potential new therapeutics based on the disease mechanism, such as prostacyclin analogues, serotonin antagonists, and calcitonin gene-related peptides.