Michael Teepker

Pain sensitivity and descending inhibition of pain in Parkinson’s disease

Background: Patients suffering from Parkinson’s disease (PD) often complain about painful sensations. Recent studies detected increased subjective pain sensitivity and increased spinal nociception, which appeared to be reversible by dopaminergic treatment. Possibly, reduced descending pain inhibition contributes to this finding. Objective: Subjective pain thresholds as well as nociceptive reflex thresholds were investigated to isolate potential loci of the pathophysiological changes within the pain pathway. In addition, the diffuse noxious inhibitory control (DNIC) system as one form of descending control was assessed. Method: 15 patients with PD and 18 controls participated in the study. Electrical and heat pain thresholds as well as the nociceptive flexion reflex (NFR) thresholds were determined. Thereafter, the electrical pain thresholds were measured once during painful heat stimulation (conditioning stimulation) and twice during innocuous stimulation (control stimulation). Results: Patients with PD exhibited lower electrical and heat pain thresholds as well as lower NFR thresholds. Suppression of the electrical pain thresholds during painful heat stimulation (conditioning stimulation) compared with control stimulation did not differ significantly between the groups. No differences in the thresholds between patients with PD with and without clinical pain were seen. Conclusions: Finding the NFR threshold to be decreased in addition to the decreased electrical and heat pain thresholds indicates that the pathophysiological changes either already reside at or reach down to the spinal level. Reduced activation of the DNIC system was apparently not associated with increased pain sensitivity, suggesting that DNIC-like mechanisms do not significantly contribute to clinical pain in PD.

Serum Concentrations of s100b and NSE in Migraine

Background.— The protein s100b indicates astrocytal damage as well as dysfunction of the blood‐brain barrier (BBB), and neuron‐specific enolase (NSE) is regarded as a marker for neuronal cell loss. Recently, s100b was shown to be a potentially useful marker for migraine in children. In this study, we investigated the levels of s100b and NSE in adult migraineurs during and after migraine attacks in order to gain some more insight into migraine pathophysiology.

Diffusion tensor imaging in episodic cluster headache.

Background.— Cluster headache (CH) is a rare headache disorder with severe unilateral headache bouts and autonomic symptoms. The pathophysiology of CH is not completely understood. Using a voxel‐based morphometric paradigm or functional imaging, a key role of the hypothalamus and the pain matrix could be demonstrated during CH episodes. However, there are no diffusion tensor imaging (DTI) data investigating the white matter microstructure of the brain in patients with CH. Therefore, we used DTI to delineate microstructural changes in patients with CH in a headache‐free state.

2-OH-estradiol, an endogenous hormone with neuroprotective functions

We compared the neuroprotective effects of the catecholestrogen 2-hydroxy-estradiol (2-OH-E(2)) to the actions of 17-beta-estradiol (E(2)), since catecholestrogens have been clinically implicated in the pathophysiology of major depression and other psychiatric diseases. Using the hippocampal HT22 cell line as a well-established in vitro model system, we here show that the extent of the neuroprotective effects of 2-OH-E(2) was significantly increased compared to the physiological estrogen E(2) at equimolar concentrations after a toxic challenge with hydrogen peroxide. Statistically significant effects of neuroprotection as measured by survival of HT22 cells were detectable at concentrations of 1 and 10 microM of 2-OH-E(2) or E(2). Studies on the time-dependence of the evoked reactions showed that a pre-incubation and a post-incubation up to 30 min with a dose of 10 microM of 2-OH-E(2) resulted in a significant decrease in cell death after incubation with hydrogen peroxide if compared to E(2). Further characterization of the effects in rat brain homogenates with an assay for the induction of cellular lipid peroxidation (LPO) revealed, that 2-OH-E(2) was more effective in the reduction of LPO than E(2) in equimolar concentrations. This indicates a pharmacologically relevant effect of this hormone metabolite and a mechanism of action, which does not involve the classical estrogen receptor. In conclusion, the catecholestrogen 2-OH-E(2) induces increased neuroprotective actions in comparison to the major physiological estrogen E(2), suggesting a clinically relevant physiological function of catecholestrogens during health and disease.

The Effects of Oral Contraceptives on Detection and Pain Thresholds As Well As Headache Intensity During Menstrual Cycle in Migraine

(Headache 2011;51:92‐104)

Endogenous pain inhibition during menstrual cycle in migraine

Migraine is a common headache disorder that can vary menstrually in women and has been linked to an impairment of endogenous pain inhibitory systems. One of these endogenous pain inhibitory systems, namely conditioned pain modulation (CPM; formerly diffuse noxious inhibitory controls‐like), has been shown to be affected by the menstrual cycle. The aim of this study was to examine CPM over the menstrual cycle in migraineurs and healthy controls.

Transkranielle Magnetstimulation und Motorkortexstimulation bei neuropathischen Schmerzen

ZusammenfassungDie nichtinvasive und invasive Motorkortexstimulation können therapierefraktäre neuropathische Schmerzen verbessern. Mit der hochfrequenten repetitiven transkraniellen Magnetstimulation (rTMS) des kontralateralen Motorkortex können kurzzeitige therapeutische Effekte erzielt und der Effekt einer epiduralen Motorkortexstimulation (MCS) vorhergesagt werden. Der vorliegende Artikel fasst die aktuellen Erkenntnisse zu Anwendung, Mechanismen und Therapieeffekten der kortikalen Stimulation bei neuropathischen Schmerzen zusammen.AbstractNon-invasive and invasive cortical stimulation allows the modulation of therapy-refractory neuropathic pain. High-frequency repetitive transcranial magnetic stimulation (rTMS) of the contralateral motor cortex yields therapeutic effects at short-term and predicts the benefits of epidural motor cortex stimulation (MCS). The present article summarizes the findings on application, mechanisms and therapeutic effects of cortical stimulation in neuropathic pain.

Transcranial magnetic stimulation and motor cortex stimulation in neuropathic pain

ZusammenfassungDie nichtinvasive und invasive Motorkortexstimulation können therapierefraktäre neuropathische Schmerzen verbessern. Mit der hochfrequenten repetitiven transkraniellen Magnetstimulation (rTMS) des kontralateralen Motorkortex können kurzzeitige therapeutische Effekte erzielt und der Effekt einer epiduralen Motorkortexstimulation (MCS) vorhergesagt werden. Der vorliegende Artikel fasst die aktuellen Erkenntnisse zu Anwendung, Mechanismen und Therapieeffekten der kortikalen Stimulation bei neuropathischen Schmerzen zusammen.AbstractNon-invasive and invasive cortical stimulation allows the modulation of therapy-refractory neuropathic pain. High-frequency repetitive transcranial magnetic stimulation (rTMS) of the contralateral motor cortex yields therapeutic effects at short-term and predicts the benefits of epidural motor cortex stimulation (MCS). The present article summarizes the findings on application, mechanisms and therapeutic effects of cortical stimulation in neuropathic pain.

Pain in Parkinson's Disease: Current Concepts and a New Diagnostic Algorithm

Pain is a significant burden for patients with Parkinsons disease (PD) with a high impact on quality of life. The present article aims at summarizing epidemiological, pathophysiological, clinical, and neurophysiological data regarding pain in PD.

Effects of Paired-pulse Transcranial Magnetic Stimulation of the Motor Cortex on Perception of Experimentally Induced Pain

ObjectiveWe investigated the influence of paired-pulse transcranial magnetic stimulation (ppTMS) of the motor cortex (M1) on perception of noxious electrical stimuli. The nociceptive flexion reflex response was assessed to determine spinal effects. MethodsIn the first experiment, the effect of ppTMS of M1 on perception of noxious stimulation of the sural nerve was assessed by varying the stimulus onset asynchronies (SOAs) and the order of the stimulations (−400, −75, −25, 25, 125, 400 ms and control ppTMS, negative sign: ppTMS precedes the noxious stimulation). Effects of a preceding ppTMS on the RII and the RIII response of the nociceptive flexion reflex were investigated for SOAs of −400 and −75 ms. The effects of ppTMS of M1 and of the occipital cortex (Oz) on noxious stimulation of the radial nerve were investigated in a second experiment. Visual analogue scales were used to assess pain intensity and unpleasantness. ResultsThe results revealed increased pain unpleasantness scores for SOAs of −75, −25, 25, and 400 ms and decreased pain intensity scores for a SOA of −400 ms, when the sural nerve and M1 were stimulated. An increase of the area of the RII response was found for a SOA of −75 ms. For stimulation of the radial nerve, ppTMS of Oz but not of M1 increased the perceived pain at a SOA of 25 ms. DiscussionThe facilitatory component of ppTMS led to increased pain perception when applied during the cortical process of Aδ fiber-mediated input, whereas the subsequent inhibitory component may lead to the opposite effect on the subsequent noxious stimulation.