Cortical reorganization during recovery from complex regional pain syndrome.

Objective: To characterize reorganization of the primary somatosensory cortex (S1) during healing process in complex regional pain syndrome (CRPS).

Background: Recently, the authors showed extensive reorganization of the S1 cortex contralateral to the CRPS affected side. Predictors for these plastic changes were CRPS pain and the extent of mechanical hyperalgesia.

Comparison of continuous wave Doppler ultrasound of the radial artery and laser Doppler flowmetry of the fingertips with sympathetic stimulation.

Laser Doppler is widely used to evaluate sympathetic vasoconstrictor function. Continuous wave (cw)-Doppler of the radial artery may be an alternative but less expensive approach to quantify sympathetically induced resistance changes in the peripheral vascular system. In order to compare the power of both methods, this study was performed with simultaneous assessment of cw Doppler and laser Doppler flowmetry in volunteers.

Catecholamine release in human skin--a microdialysis study.

Dermal microdialysis might be a promising tool to investigate properties of sympathetic neurons in the skin as investigation of peripheral noradrenergic neurons in humans usually relies on highly variable vasoconstrictor reflexes or on indirect measurements like skin temperature recordings. To evaluate this technique, 21 experiments were performed in 15 healthy subjects with four intracutaneous microdialysis fibers (diameter, 200 microm; cutoff, 5 kDa) at hands or feet. After 60 min, saline perfusion tyramine at concentrations of 0.

A polymorphic locus in the intron 16 of the human angiotensin-converting enzyme (ACE) gene is not correlated with complex regional pain syndrome I (CRPS I).

Exaggerated neurogenic inflammation has been recognized to be one reason for many CRPS symptoms. Since angiotensin-converting enzyme (ACE) is a key enzyme for the termination of neurogenic inflammation, it has been selected as a candidate gene for CRPS predisposition. A previous report of an insertion/deletion (I/D) polymorphism in intron 16 within the ACE gene implicated an increased risk to develop CRPS I associated with the D allele.

Facilitated neurogenic inflammation in unaffected limbs of patients with complex regional pain syndrome.

Pain, edema, increased skin temperature, reddening and trophic changes characterize complex regional pain syndrome (CRPS). Recently, we have been able to show facilitated neurogenic inflammation on the affected limb. In the current study unaffected limbs were examined after resolution of the CRPS symptoms to assess possible generalized changes predisposing to CRPS.

Electrically stimulated axon reflexes are diminished in diabetic small fiber neuropathies.

Axon reflex mediated flare depends on the density and the function of cutaneous C-fibers and may be impaired in diabetic neuropathy. We induced neurogenic axon reflex flare by intracutaneous electrical stimulation and analyzed size and intensity of the flare on the dorsum of the foot and ventral thigh with laser Doppler imaging (LDI). We investigated 12 diabetic subjects with small fiber neuropathies (SFNs), 5 diabetic subjects without neuropathy (NO-Ns), and 14 healthy control subjects.

Patterns of cortical reorganization in complex regional pain syndrome.

Objective: To use magnetoencephalography to assess possible cortical reorganization in the primary somatosensory cortex (S1) of patients with complex regional pain syndrome (CRPS).

Background: Patterns of pain and sensory symptoms in CRPS may indicate plastic changes of the CNS.

Methods: Magnetic source imaging was used to explore changes in the cortical representation of digits (D) 1 and 5 in relation to the lower lip on the unaffected and affected CRPS side in 12 patients.

Botulinum toxin type B blocks sudomotor function effectively: a 6 month follow up.

This study analyzes the suppression of sweat gland activity by botulinum toxin type B. We injected botulinum toxin type B (between 2 and 1000 mouse units subcutaneously) in the lateral side of both lower legs in 15 healthy volunteers. Sweat tests were carried out before botulinum toxin type B injections, and at 3 wk, 3 mo, and 6 mo.

No alpha-adrenoreceptor-induced C-fiber activation in healthy human skin.

In healthy volunteers, flare responses induced by norepinephrine (NE) iontophoresis have been observed. However, as NE iontophoresis is a combined electrical and chemical stimulus axon, reflexes cannot be directly linked to pharmocological activity of NE. Different concentrations of NE, clonidine (CL), and phenylephrine (PE) (NE: 10(-10)-10(-3) M; CL and PE: 10(-8)-10(-3) M) were applied via intradermal microdialysis fibers into the skin of healthy volunteers.

Use of gabapentin to reduce chronic neuropathic pain in Fabry disease.

The effect of the anticonvulsant gabapentin on neuropathic pain was studied in six male patients with Fabry disease, aged 15-45 years. After 4 weeks of treatment, pain, as measured using the Brief Pain Inventory, was decreased compared with baseline. Treatment was generally well tolerated.

Substance-P-induced protein extravasation is bilaterally increased in complex regional pain syndrome.

Pain, mechanical hyperalgesia, edema, increased skin temperature, and skin reddening are characteristic symptoms of acute complex regional pain syndrome (CRPS). We have recently demonstrated facilitated neurogenic inflammation on the affected limb. To further elucidate the underlying mechanisms, exogenous substance P (SP) in ascending concentrations (10(-9), 10(-8), 10(-7), 10(-6) M) was intradermally applied to the affected and the unaffected limbs, respectively, in two groups of 11 CRPS patients each using the microdialysis technique.

Tissue hypoxia in complex regional pain syndrome.

Untreated complex regional pain syndrome (CRPS) may progress from acute stages with increased hair and nail growth in the affected limb to chronic stages with atrophy of the skin, muscles and bones. The aim of this study was to investigate whether tissue hypoxia could be one mechanism responsible for this late CRPS symptoms. Nineteen patients with CRPS and two control groups (healthy control subjects, surgery patients with edema) participated in this study.

Differential effects of surgical sympathetic block on sudomotor and vasoconstrictor function.

Objective: To assess the effects of a surgical block of the sympathetic chain at the T2 level on vasoconstriction and palmar sweating in patients with palmar hyperhidrosis.

Methods: In a prospective study, sympathetic vasoconstriction was measured by laser-Doppler imaging and by computer-assisted infrared thermography (rewarming kinetics following immersion of both hands in ice water [4 degrees C, 30 seconds]) in 61 patients with hyperhidrosis preoperatively and 2 days and 3 months postoperatively. In addition, palmar sweating preoperatively and 3 months postoperatively was assessed by quantitative sudometry.

Micro-lightguide spectrophotometry as an intraoral monitoring method in free vascular soft tissue flaps.

Purpose: The aim of this prospective study was to measure the hemoglobin oxygen saturation (HbO(2)%) and relative Hb concentration of free vascular soft tissue flaps using micro-lightguide spectrophotometry. The objective was to measure the normal range and topographic differences in HbO(2)% and rel. Hb conc.

Botulinum Toxin A reduces neurogenic flare but has almost no effect on pain and hyperalgesia in human skin.

Botulinum toxin A (BoNT/A) has been used therapeutically to treat muscular hypercontractions and sudomotor hyperactivity. There is increasing evidence that BoNT/A might also have analgesic properties, in particular in headache. In the present investigation we tested the often cited hypothesis that BoNT/A-induced analgesia can be attributed to inhibition of neuropeptide release from nociceptive nerve fibers.

Mechanisms of neuropathic pain and their importance in Fabry disease.

Unlabelled: One of the most prominent features of Fabry disease is neuropathic pain. Neuropathic pain occurs after neuronal damage. In contrast to inflammatory or trauma-related pain, which normally helps to maintain or restore body functions, neuropathic pain tends to become chronic, and must therefore be considered a 'pathological' pain.

Assessment of the neurogenic flare reaction in small-fiber neuropathies.

To improve sensitivity of the analysis of axon reflex flare reaction, the authors used a laser Doppler scanner and analyzed flare intensity and size induced by histamine iontophoresis simultaneously at the foot and thigh in patients with small-fiber neuropathy (n = 10) and controls (n = 9). Flare size, but not laser Doppler flux, clearly distinguished patients from controls at both locations (p < 0.01) and may be useful for evaluation of small-fiber neuropathies.

Sudomotor testing predicts the presence of neutralizing botulinum A toxin antibodies.

The increasing number of patients being treated with botulinum toxin A complex (BoNT/A) has led to a higher incidence of neutralizing anti-BoNT/A antibodies (ABAs). Because BoNT/A is known to inhibit sweating, here we report sudometry as a possibility for predicting the presence of ABA. Sixteen patients suffering from spasmodic torticollis were selected: in 2 patients, BoNT/A treatment continued to be effective, in 9 patients, the treatment effect was impaired, and in 5 patients, secondary treatment failure developed.

Influence of vagus nerve stimulation on histamine-induced itching.

Objective: To investigate whether vagus nerve stimulation (VNS) reduces pruritus in humans.

Background: Recently, it has been shown that VNS has antinociceptive and antidepressant effects in humans.

Methods: Eleven patients were investigated before (baseline) and during chronic VNS treatment.

[Sudeck's atrophy: pathophysiology and treatment of a complex pain syndrome].

Unlabelled: Sudeck's atrophy: pathophysiology and treatment of a complex pain syndrome.

Summary: The "Morbus Sudeck" or Complex Regional Pain Syndrome (CRPS) forms a typical triad of motor, sensory and autonomic symptoms. It is clinically characterized by spontaneous pain and hyperalgesia not limited to a single nerve territory and disproportionate to the inciting event.

[Mechanism-based treatment principles of neuropathic pain].

Traditionally, neuropathic pain has been classified due to aetiology of nerve damage-traumatic, inflammatory or metabolic, for instance. Based on this classification, pain therapy often is insufficient. Recent research revealed different mechanisms, which are responsible for the generation of pain after nerve lesion.

[Vagus nerve stimulation - a new option for the treatment of chronic pain syndromes?].

Electrical stimulation of the vagal nerve (VNS) has become an established method for treating medically refractory epilepsies. From animal experiments it is well known that depending on the stimulation intensity VNS can elicit both inhibition and facilitation of nociception. Recent physiologic investigations demonstrated a similar influence of VNS on pain perception in patients treated by chronic VNS.

The important role of neuropeptides in complex regional pain syndrome.

Objective: To test the contribution of neurogenic inflammation and neuropeptide release to the pathophysiology of complex regional pain syndrome (CRPS).

Background: CRPS is characterized by edema and increased skin temperature, sympathetic dysfunction and pain, or hyperalgesia. This investigation was prompted by a recent study by the authors that suggested a facilitated neurogenic inflammation in CRPS.