Resting-state fMRI study of acute migraine treatment with kinetic oscillation stimulation in nasal cavity.

Kinetic oscillatory stimulation (KOS) in the nasal cavity is a non-invasive cranial nerve stimulation method with promising efficacy for acute migraine and other inflammatory disorders. For a better understanding of the underlying neurophysiological mechanisms of KOS treatment, we conducted a resting-state functional magnetic resonance imaging (fMRI) study of 10 acute migraine patients and 10 normal control subjects during KOS treatment in a 3 T clinical MRI scanner. The fMRI data were first processed using a group independent component analysis (ICA) method and then further analyzed with a voxel-wise 3-way ANOVA modeling and region of interest (ROI) of functional connectivity metrics. All migraine participants were relieved from their acute migraine symptoms after 10-20 min KOS treatment and remained migraine free for 3-6 months. The resting-state fMRI result indicates that migraine patients have altered intrinsic functional activity in the anterior cingulate, inferior frontal gyrus and middle/superior temporal gyrus. KOS treatment gave rise to up-regulated intrinsic functional activity for migraine patients in a number of brain regions involving the limbic and primary sensory systems, while down regulating temporally the activity for normal controls in a few brain areas, such as the right dorsal posterior insula and inferior frontal gyrus. The result of this study confirms the efficacy of KOS treatment for relieving acute migraine symptoms and reducing attack frequency. Resting-state fMRI measurements demonstrate that migraine is associated with aberrant intrinsic functional activity in the limbic and primary sensory systems. KOS in the nasal cavity gives rise to the adjustment of the intrinsic functional activity in the limbic and primary sensory networks and restores the physiological homeostasis in the autonomic nervous system.

Kinetic oscillation stimulation as treatment of acute migraine: a randomized, controlled pilot study.

OBJECTIVE: To assess the relief of migraine pain, especially in the acute phase, by comparing active treatment, ie, kinetic oscillation stimulation (KOS) in the nasal cavity, with placebo. BACKGROUND: Exploratory trials testing the efficacy of KOS on migraine patients indicated that this treatment could be a fast-acting remedy for acute migraine pain. METHOD: Thirty-six patients were randomized 1:1 using a placebo module to active or placebo treatment in this double-blinded parallel design study. Treatment was administered with a minimally invasive inflatable tip oscillating catheter. Symptom scores (0-10 visual analog scale) were obtained before treatment, every 5 minutes during treatment, at 15 minutes, 2, and 24 hours post-treatment, as well as daily (0-3 migraine pain scale) from 30 days pretreatment until Day 60 post. Thirty-five patients were evaluated (active n=18, placebo n=17). The primary end-point was the change in average pain score from before treatment to 15 minutes after treatment. RESULTS: Patients who received active treatment reported reduced pain, eg, average visual analog scale pain scores fell from 5.5 before treatment to 1.2 15 minutes after, while the corresponding scores for recipients of placebo fell from 4.9 to 3.9. The changes in pain scores differed between the 2 treatments by 3.3 points (95% confidence interval: 2.3, 4.4), P<.001. Already 5 minutes into the treatment, the difference (1.9 points) was significant (P=.007). The difference was likewise significant at 2 hours post-treatment (3.7 points, P<.001). One patient experienced an adverse event (a vasovagal reaction with full spontaneous recovery) during placebo treatment. CONCLUSION: KOS is an effective and safe treatment for acute migraine pain.

[Pain more painful in women. Gender perspective neglected in research on the biological mechanisms of pain]. / Smärta mer smärtsam hos kvinnor. Genusperspektiv eftersatt i forskning om smärtans biologiska mekanismer.

There are some sex differences in the perception of defined noxious stimuli, with females being more sensitive than males in both rodents and humans. Using imaging techniques gender differences of the brain were recently demonstrated in neurophysiological response and pain perception to heating of the skin. Many chronic pain states are more common and/or aggressive in women than in men, i.e. migraine, pain in rheumatic disease and some cardiac pains. There are also sex differences in the pain relieving effects of certain drugs, i.e. opioids and NSAID:s. Since the details of the mechanisms which govern the biological differences between the sexes in health and disease are largely unknown there is scope for additional studies. It is anticipated that such research will reveal new important gender related data which will elucidate the background to a number of ailments and contribute to the development of better and/or quite new treatments of different patients, e.g. patients with chronic pain syndromes.

Noradrenaline-evoked pain in neuralgia.

We have tested the effects of cutaneous application of noradrenaline in 35 patients presenting with neuropathic pain. Depending on the outcome of sympatholytic interventions the patients were considered to have sympathetically maintained pain (SMP; n = 25) or sympathetically independent pain (SIP; n = 10). Iontophoretic application or cutaneous injection of noradrenaline into symptomatic skin aggravated pain and mechanical or thermal hyperalgesia in 7/25 SMP patients. Results from differential nerve blocks suggested that noradrenaline-induced ongoing pain and heat hyperalgesia were signalled by unmyelinated afferents, while touch-evoked pain and cold hyperalgesia were signalled by myelinated afferents. In none of the remaining 18/25 SMP patients, 10 SIP patients or 18 normal subjects did application of noradrenaline result in any appreciable increase of pain. A follow-up of 12 patients (initially 9 SMP, 3 SIP) after 12-16 years showed that one individual (previously SMP) was healthy, while 3 patients still suffered from SMP and 8 from SIP. Of the 5 SMP patients who had noradrenaline-induced pain at the initial examination, only 1 SMP patient still responded to noradrenaline with pain and hyperalgesia. Three other patients had changed to SIP and 1 individual was healthy. None of these 4 and none of the 7 initially noradrenaline-unresponsive patients experienced pain to the noradrenaline challenge at follow-up. Thus, cutaneous noradrenaline application can aggravate the pain in some, but not all SMP patients. THe abnormal noradrenaline reaction can change over time as can the pain relieving effects of sympatholytic therapy.

Beneficial effects of ketamine in a chronic pain state with allodynia, possibly due to central sensitization.

Allodynia is a well-known component of neuropathic pain resulting from injury to the nervous system. Clinical pain states with allodynia in connection with longstanding superficial wounds have, however, not been reported in the literature. In this case a chronic pain state developed in a previously healthy 17-year-old girl in and around a persistently suppurating appendectomy wound. There was no spontaneous pain but pronounced allodynia in the wound and in the surrounding skin. Quantitative thermal tests showed abnormal thresholds for several sensory modalities confirming abnormal processing of sensory input from the involved area. The pattern of sensory abnormalities evaluated with thermal testing changed transiently and the allodynia diminished during a phentolamine block. Since the pain responded poorly to opioids and ketamine has been reported to reduce allodynia, it was administered in a sub-dissociative bolus dose during wound dressing. The wound was essentially unchanged after treatment for 3 months but the allodynia and sensory aberrations had decreased significantly. We interpret these results as a de-sensitizing effect in the long term of repeated NMDA-receptor blockade by ketamine in a chronic pain state, with indications of central sensitization, partially maintained by sympathetic activity.

Continuous naloxone administration via osmotic minipump decreases autotomy but has no effect on nociceptive threshold in the rat.

Rats with unilaterally sectioned sciatic nerves were continuously administered naloxone HCl (80 or 800 micrograms/h) or equivalent volumes of saline (1 or 10 microliters/h) subcutaneously via osmotic minipumps over a 2 or 5 week period. Rats receiving 80 micrograms/h naloxone for 5 weeks exhibited significantly less self-mutilation (autotomy) of the denervated foot than saline controls or rats receiving 80 micrograms/h naloxone for 2 weeks. The nociceptive threshold of intact rats infused with the same dose of naloxone was tested on a hot plate. In these animals there was no influence on the nociceptive threshold during naloxone administration for 1 week. Autotomy was also reduced in rats infused with 800 micrograms/h naloxone. The nociceptive threshold of intact rats infused with this dose of naloxone or an equivalent volume of saline (10 microliters/h) was increased, suggesting that the presence of the larger osmotic pump caused analgesia.

Stress-related pain behavior in rats with peripheral nerve injuries.

The effects of cold stress were studied on rats with unilaterally sectioned sciatic nerves. Behaviors suggestive of pain occurred in a number of these animals. These behaviors vanished when removing the rats from the stressful environment. Some severely painful syndromes in man might in part be due to mechanisms similar to those underlying the described behaviors in rats.