Laser evoked potentials back pain

RATIONALE: Spinal cord stimulation (SCS) is an effective option for neuropathic pain treatment. New technological developments, as high-frequency (HF) and theta burst stimulation (TBS), have shown promising results, although putative mechanisms of action still remain debated. METHODS: thirty patients with lower back pain were enrolled and underwent LF, HF, and TBS. Laser evoked potentials (LEPs) were recorded by using a Nd:YAG laser. Amplitudes and latencies of the main two components (N1, N2/P2) were compared among different experimental sessions...

BACKGROUND: Repetitive painful laser stimuli lead to physiological laser-evoked potential (LEP) habituation, measurable by a decrement of the N2/P2 amplitude. The time course of LEP-habituation is reduced in the capsaicin model for peripheral and central sensitization and in patients with migraine and fibromyalgia. In the present investigation, we aimed to assess the time course of LEP-habituation in a neuropathic pain syndrome, i.e. painful radiculopathy. METHODS: At the side of radiating pain, four blocks of 25 painful laser stimuli each were applied to the ventral thigh at the L3 dermatome in 27 patients with painful radiculopathy...

BACKGROUND: Based upon studies using mechanical pin-prick, pressure, electrical or heat stimuli applied to painful and/or pain-free parts of the body, chronic low back pain (CLBP) has been shown to be associated with generalized and enhanced pain sensitivity and altered brain responses to noxious stimuli. To date, no study examined the processing of noxious laser heat pulses, which are known to selectively excite thermal nociceptors located in the superficial skin layers, in CLBP. METHODS: We studied laser heat pain thresholds (LHPTs) and nociceptive laser-evoked brain electrical potentials (LEPs) following skin stimulation of the pain-affected back and the pain-free abdomen using noxious laser heat stimulation in 16 CLBP patients and 16 age- and gender-matched healthy controls (HCs)...

We investigated the effects of total and rapid eye movement (REM) sleep deprivation on the thermal nociceptive threshold and pain perception using the objective laser-evoked potential (LEP) and the subjective visual analogue scale (VAS). Twenty-eight male adult volunteers were assigned into Control (CTRL), Total (T-SD), and REM (REM-SD) Sleep Deprivation groups. The T-SD and REM-SD volunteers were totally or selectively deprived of sleep for 2 and 4 consecutive nights, respectively. Pain parameters were measured daily during the experimental period...

Clinical studies have revealed that up to 92% of major depressed patients report pain complaints such as back or abdominal pain. Furthermore, patients suffering from depression exhibit increased superficial pain thresholds and decreased ischemic (deep) pain thresholds during experimental pain testing in comparison to healthy controls. Here, we aimed to investigate a putative role of Aδ- and C-fibre activation in altered pain perception in the disease. Laser-evoked potentials (LEPs) of 27 unmedicated depressed patients and 27 matched controls were recorded...

The radicular pain syndrome is a major problem in public health care that can lead to chronic back and leg pain in 30%. Ischalgia and back pain are the most prominent signs of dorsal root affection. Until now, no clinical or neurophysiological test procedure exists that evaluates the function of the dorsal root and predicts the prognosis of patients suffering from RPS. We have recently demonstrated that laser-evoked potentials (LEP) are able to demonstrate dorsal root damage. With this study, we investigated 54 patients with acute radicular symptoms and compared LEP parameters (side to side difference of latency and amplitude, transformed to a z-score) with their state of health after 3 months to calculate their predictive value for outcome prognosis...

Endogenous pain modulation may provide facilitation or inhibition of nociceptive input by three main mechanisms. Firstly, modification of synaptic strength in the spinal dorsal horn may increase or decrease transmission of nociceptive signals to the brain. Secondly, local dorsal horn interneurons provide both feed-forward and feed-back modulation to spinothalamic and spinobulbar projection neurons. Thirdly, descending systems originating in the brainstem exert top-down modulation of nociceptive input at the spinal level...

OBJECTIVES: Several types of lasers are available for eliciting laser evoked responses (LEPs). In order to understand advantages and drawbacks of each one, and to use it properly, it is important that the pattern of skin heating is known and duly considered. This study was aimed at assessing the skin temperature during and immediately after irradiation with pulses by Nd:YAP and CO(2) lasers. MATERIALS AND METHODS: The back of the non-dominant hand was irradiated in 8 subjects...

To investigate the pathways of noxious information in the spinal cord in humans, we recorded cortical potentials following the stimulation of A-delta fibers using a YAG laser applied to two cutaneous points on the back at the C7 and Th10 level, 4cm to the right of the vertebral spinous process. A multiple source analysis showed that four sources were activated; the primary somatosensory cortex (SI), bilateral parasylvian region (Parasylvian), and cingulate cortex. The activity of the cingulate cortex had two components (N2/P2)...

OBJECTIVE: The aim of this study was to investigate the analgesic efficacy of Neodolpasse, a fixed-dose combination of orphenadrine and diclofenac, compared with those of its single active ingredients in a human pain model. METHODS: The study was designed as a randomised, double-blind, placebo-controlled, four-period crossover study. Twenty-four healthy female and male subjects received single infusions of Neodolpasse, orphenadrine, diclofenac or saline solution over 60 minutes...

The present investigation aimed to elucidate the analgesic efficacy of 30 mg of intravenous orphenadrine citrate (CAS 4682-36-4) in a human pain model. Eighteen healthy female and male subjects were enrolled and received single infusions of 30 mg orphenadrine citrate and matching placebo in two periods which were separated by a 1 week washout period. The study was designed as a randomised, double-blind, placebo-controlled, two-period, cross-over trial. The intended neurogenic inflammation and hyperalgesia were induced by topical, occlusive application of 1% capsaicin solution (INCI: Capsicum frutescens, containing capsaicinoides from Capsicum annuum annuum, CAS 84603-55-4) for 30 min on defined skin areas of the back...

Extensive pre-clinical investigations have shown that the tricyclic compound ReN1869 ((R)-1-(3-(10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene)-1-propyl)-3-piperidine carboxylic acid, CAS 170149-99-2) is a potent H1-antagonist with pronounced antinociceptive properties. In this human phase-I trial the effect of different acute and multiple doses of ReN1869 on capsaicin induced neurogenic inflammation and hyperalgesia was investigated. Twenty-one healthy male subjects were enrolled in this randomised, double-blind, three-period, crossover trial design--consisting of acute and one week b...

Functional diagnostics of the dorsal root are especially effective via nociceptive fibers on account of less intersegmental overlap compared to large-diameter fibers of the mechanoreceptive afferents. Laser-evoked potentials (LEP) are induced by short, painful heat stimuli. The aim of this work was to describe changes of the LEP in cases of dorsal root damage. The recorded LEP changes will be discussed with regard to their prognostic value as well as pathophysiologic aspects of dorsal root damage. Dorsal root function was tested in 21 patients suffering from clinically proven radiculopathy in one of the segments L4 to S1...

We recorded electrically stimulated somatosensory evoked potentials (electric SEPs) and pain-related SEPs following CO2 laser stimulation (CO2 laser SEPs) from a 17-year-old patient affected by myotonic dystrophy whose MRI disclosed a large syrinx extending from spinal level C2 to S3. Careful clinical and electromyographic examinations revealed no motor or sensory disturbances, apart from myotonia. The only abnormality noted in median and ulnar nerve short-latency electric SEPs (recorded with a non-cephalic reference electrode) was the absence of cervical component N13, the other SEP responses (N9, N10, N11, P14, N20) being normal...