Matthias Karst

Repetitive Transcranial Magnetic Stimulation for the Treatment of Chronic Pain – A Pilot Study

Invasive electrical stimulation of the motor cortex has been reported to be of therapeutic value in pain control. We were interested whether noninvasive repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex might also act beneficially. Twelve patients with therapy-resistant chronic pain syndromes (mean age 51.3 ± 12.6, 6 males) were included in a pilot study. They were treated with rTMS of the corresponding motor cortex area for 20 min (20 Hz, 20 × 2 s trains, intensity 80% of motor threshold) and sham stimulation (sequence-controlled cross-over design). Some of the patients (6/6) had an analgesic effect, but for the whole group, the difference between active and sham stimulation did not reach a level of significance (active rTMS: mean VAS reduction –4.0 ± 15.6%; sham rTMS: –2.3 ± 8.8%). Further studies using different rTMS stimulation parameters (duration and frequency of rTMS) or stimulation sites (e.g. anterior cingulate gyrus) are strongly encouraged.

Auricular acupuncture for dental anxiety: a randomized controlled trial.

Auricular acupuncture can be an effective treatment for acute anxiety, but there is a lack of direct comparisons of acupuncture to proven standard drug treatments. In this study we compared the efficacy of auricular acupuncture with intranasal midazolam, placebo acupuncture, and no treatment for reducing dental anxiety. Patients having dental extractions (n = 67) were randomized to (i) auricular acupuncture, (ii) placebo acupuncture, and (iii) intranasal midazolam and compared with a no treatment group. Anxiety was assessed before the interventions, at 30 min, and after the dental extraction. Physiological variables were assessed continuously. With the no treatment group as control, the auricular acupuncture group, and the midazolam group were significantly less anxious at 30 min as compared with patients in the placebo acupuncture group (Spielberger Stait-Trait Anxiety Inventory X1, P = 0.012 and <0.001, respectively). In addition, patient compliance assessed by the dentist was significantly improved if auricular acupuncture or application of intranasal midazolam had been performed (P = 0.032 and 0.049, respectively). In conclusion, both, auricular acupuncture and intranasal midazolam were similarly effective for the treatment of dental anxiety.

Pressure pain threshold and needle acupuncture in chronic tension-type headache – a double-blind placebo-controlled study

&NA; In order to examine the role of muscular mechanisms in chronic tension‐type headache a study with needle acupuncture was performed. Needle acupuncture could be of therapeutic value because it has shown some positive effects in myofascial pain syndromes. We performed a double‐blind, placebo‐controlled study with 39 patients (mean age 49.0 years, SD=14.8) fulfilling the International Headache Society criteria for chronic tension‐type headaches. Participants were randomly assigned to verum or placebo condition. Six weeks after end of treatment no significant differences between placebo and verum could be observed with respect to visual analogue scale and frequency of headache attacks. Nevertheless, pressure pain thresholds significantly increased for the verum group. The findings of our study support the hypothesis that peripheral mechanisms – such as increased muscle tenderness – only play a minor role in the pathogenesis of chronic tension‐type headache.

Needle acupuncture in tension‐type headache: a randomized, placebo‐controlled study

A study with needle acupuncture was performed in tension-type headache employing a new placebo acupuncture method. Sixty-nine patients (mean age 48.1 years, sd = 14.1) fulfilling the International Headache Society criteria for tension-type headache were randomly assigned to verum or placebo condition. No significant differences between placebo and verum with respect to visual analogue scale and frequency of headache attacks could be observed immediately, 6 weeks and 5 months after the end of treatment. There was a significant but weak improvement in quality of life parameters (clinical global impressions, Nottingham Health Profile) after verum treatment. In decision tree analyses, the changes in clinical global impressions and headache frequency depended significantly on primary headache frequency with a limit value of 24.5 days headache per month. High values in the von Zerssen Depression Score resulted in high mean visual analogue scale values.

Mitigation of post-traumatic stress symptoms by Cannabis resin: a review of the clinical and neurobiological evidence.

It is known from clinical studies that some patients attempt to cope with the symptoms of post-traumatic stress disorder (PTSD) by using recreational drugs. This review presents a case report of a 19-year-old male patient with a spectrum of severe PTSD symptoms, such as intense flashbacks, panic attacks, and self-mutilation, who discovered that some of his major symptoms were dramatically reduced by smoking cannabis resin. The major part of this review is concerned with the clinical and preclinical neurobiological evidence in order to offer a potential explanation of these effects on symptom reduction in PTSD. This review shows that recent studies provided supporting evidence that PTSD patients may be able to cope with their symptoms by using cannabis products. Cannabis may dampen the strength or emotional impact of traumatic memories through synergistic mechanisms that might make it easier for people with PTSD to rest or sleep and to feel less anxious and less involved with flashback memories. The presence of endocannabinoid signalling systems within stress-sensitive nuclei of the hypothalamus, as well as upstream limbic structures (amygdala), point to the significance of this system for the regulation of neuroendocrine and behavioural responses to stress. Evidence is increasingly accumulating that cannabinoids might play a role in fear extinction and antidepressive effects. It is concluded that further studies are warranted in order to evaluate the therapeutic potential of cannabinoids in PTSD.

Role of Cannabinoids in the Treatment of Pain and (Painful) Spasticity

Both the discovery of the endocannabinoid system (ECS) and its role in the control of pain and habituation to stress, as well as the significant analgesic and antihyperalgesic effects in animal studies, suggest the usefulness of cannabinoids in pain conditions. However, in human experimental or clinical trials, no convincing reduction of acute pain, which may be caused by a pronociceptive, ECS-triggered mechanism on the level of the spinal cord, has been demonstrated. In contrast, in chronic pain and (painful) spasticity, an increasing number of randomized, double-blind, placebo-controlled studies have shown the efficacy of cannabinoids, which is combined with a narrow therapeutic index. Patients with unsatisfactory response to other methods of pain therapy and who were characterized by failed stress adaptation particularly benefited from treatment with cannabinoids. None of the attempts to overcome the disadvantage of the narrow therapeutic index, either by changing the route of application or by formulating balanced cannabinoid preparations, have resulted in a major breakthrough. Therefore, different methods of administration and other types of cannabinoids, such as endocannabinoid modulators, should be tested in future trials.

In vivo myograph measurement of muscle contraction at optimal length

BackgroundCurrent devices for measuring muscle contraction in vivo have limited accuracy in establishing and re-establishing the optimum muscle length. They are variable in the reproducibility to determine the muscle contraction at this length, and often do not maintain precise conditions during the examination. Consequently, for clinical testing only semi-quantitative methods have been used.MethodsWe present a newly developed myograph, an accurate measuring device for muscle contraction, consisting of three elements. Firstly, an element for adjusting the axle of the device and the physiological axis of muscle contraction; secondly, an element to accurately position and reposition the extremity of the muscle; and thirdly, an element for the progressive pre-stretching and isometric locking of the target muscle.Thus it is possible to examine individual in vivo muscles in every pre-stretched, specified position, to maintain constant muscle-length conditions, and to accurately re-establish the conditions of the measurement process at later sessions.ResultsIn a sequence of experiments the force of contraction of the muscle at differing stretching lengths were recorded and the forces determined. The optimum muscle length for maximal force of contraction was established. In a following sequence of experiments with smaller graduations around this optimal stretching length an increasingly accurate optimum muscle length for maximal force of contraction was determined. This optimum length was also accurately re-established at later sessions.ConclusionWe have introduced a new technical solution for valid, reproducible in vivo force measurements on every possible point of the stretching curve. Thus it should be possible to study the muscle contraction in vivo to the same level of accuracy as is achieved in tests with in vitro organ preparations.

The Nonpsychotropic Cannabinoid Cannabidiol Modulates and Directly Activates Alpha-1 and Alpha-1-Beta Glycine Receptor Function

Loss of inhibitory synaptic transmission within the dorsal horn of the spinal cord plays a key role in the development of chronic pain following inflammation or nerve injury. Inhibitory postsynaptic transmission in the adult spinal cord involves mainly glycine. Cannabidiol is a nonpsychotropic plant constituent of Cannabis sativa. As we hypothesized that non-CB receptor mechanisms of cannabidiol might contribute to its anti-inflammatory and neuroprotective effects, we investigated the interaction of cannabidiol with strychnine-sensitive α1 and α1β glycine receptors by using the whole-cell patch clamp technique. Cannabidiol showed a positive allosteric modulating effect in a low micromolar concentration range (EC50 values: α1 = 12.3 ± 3.8 μmol/l and α1β = 18.1 ± 6.2 μmol/l). Direct activation of glycine receptors was observed at higher concentrations above 100 μmol/l (EC50 values: α1 = 132.4 ± 12.3 μmol/l and α1β = 144.3 ± 22.7 μmol/l). These in vitro results suggest that strychnine-sensitive glycine receptors may be a target for cannabidiol mediating some of its anti-inflammatory and neuroprotective properties.

Pain measurements and side effect profile of the novel cannabinoid ajulemic acid

Preclinical findings on ajulemic acid (AJA) showed analgesic and anti-allodynic effects without psychoactive properties making it an appealing substance for the treatment of pain. A recently published randomized double-blind crossover clinical trial described the pain-reducing effects and side effect profile of AJA on 21 patients with chronic neuropathic pain. In this report from this same sample the effects of AJA on the mechanical hypersensitivity, on pain, and on psychological and physical performance were further characterized. During a 5-week study period, patients were divided into two 7-day treatment groups receiving either AJA or placebo capsules first, respectively. All patients received 40 and 80 mg of AJA or placebo daily in each treatment period. Pain measurements included the determination of mechanical hypersensitivity using the von Frey hair method as well as the visual analog scale (VAS), for which the number needed to treat (NNT) was calculated. The side effect profile of the compound was evaluated using psychotropic and physical measurements as well as obtaining reports on possible subjective side effects. The results showed no significant reduction in mechanical hypersensitivity (p=0.052), although a tendency towards pain reduction could be seen. The VAS score showed significant pain reduction (p=0.021) and NNT values for 30% pain relief were 2.14 for the first treatment group and 5.29 for the second treatment group. No significant findings were observed regarding psychotropic or physical measurements. Reported subjective side effects were mainly dry mouth, tiredness and dizziness and did not increase with dose elevation. Overall, these study findings indicate that AJA shows pain-reducing effects on patients with chronic neuropathic pain without clinically relevant psychotropic or physical side effects.

Credibility of a Newly Designed Placebo Needle for Clinical Trials in Acupuncture Research

Objective: To test the credibility of a newly designed placebo needle for acupuncture research. Design : Analysis of data on credibility of true and placebo interventions of a randomised, placebo-controlled, patient- and evaluator-blind clinical trial. Patients and Setting: The study was carried out at a university department for physical medicine and rehabilitation. 68 patients (age 48.1 ± 14.1 years, mean ± SD) fulfilling the criteria of the International Headache Society for tension-type headache were enrolled into the study. Interventions: Group 1 (treatment) was assigned to traditional needle placement and manipulation, whereas in group 2 (control) a new placebo device was used. Outcome Parameters: After the first treatment with real or placebo acupuncture, patients were asked to fill in a questionnaire on credibility. In addition, after 3 or 4 treatments, patients were asked for the feeling of needle insertion and deqi. Results: No difference between real and placebo acupuncture was detected with respect to the credibility of the treatment (p > 0.05). Needle insertion was recognised in all patients in the real acupuncture group and in all but 4 patients of the placebo group (p < 0.05). deqi was reported by 84% of patients in the real acupuncture group and by 34% of patients in the placebo group (p < 0.001). Conclusion: Acupuncture with the placebo needle device described here is of high credibility, and does not differ from that of real acupuncture treatment. However, to achieve comparable prick sensations in both treatment conditions, careful training with the placebo needle is needed. Furthermore, from these results arise new questions with respect to the placebo response of placebo needles. Further investigations are warranted to test if placebo needles are active controls.