Biomedical subjects

Thorsten Bartsch

Publications and source records attributed to Thorsten Bartsch.

6 recordsLinked to original sources

PubMed2006

Medication overuse headache.

Medication overuse headache (MOH) has developed into the third most common type of headache after tension-type headache and migraine. The prevalence of MOH is approximately 1% of the world's population and it shows an increasing trend as recent studies reveal a common involvement throughout the ages, even starting in childhood. All antiheadache drugs, such as triptans, analgesics, ergots and opioids, along with the common combination substances currently on the pharmacological market are capable of inducing MOH. New data on specific clinical features and mean critical monthly dosages and mean critical monthly intake frequencies are now available. The only effective treatment concept is consequent withdrawal therapy. Data of prospective studies on relapse rates and predictors of relapse after successful withdrawal therapy are presented.

Analgesics↗

PubMed2005

Migraine and the neck: new insights from basic data.

The clinical presentation of pain in patients with migraine showing spread and referral of pain throughout the trigeminal and cervical innervation territories accompanied by hyperalgesia and allodynia indicates a dynamic trigemino-cervical interaction. The physiologic mechanisms may be convergence of trigemino-cervical afferents and central sensitization of trigemino-cervical neurons leading to dynamic neuroplastic changes during migraine. This review highlights the clinical phenotype and mechanisms of how nociceptive input from neck structures of the upper cervical spine are integrated into the trigemino-cervical system. The nociceptive input into the spinal cord also is subject to a modulation by segmental mechanisms in the spinal cord and by inhibitory projections from brain stem structures such as the periaqueductal gray. The functional relevance of these basic mechanisms is discussed with reference to recent studies using neurostimulation of afferent nerves aiming at pain modulation in patients with migraine.

Electric Stimulation Therapy↗

PubMed2003

Central neuromodulation in chronic migraine patients with suboccipital stimulators: a PET study.

Electrical stimulation of primary sensory afferents is known to have an antinociceptive effect. Animal and functional imaging studies suggest a role for supraspinal structures in this response. Eight patients with chronic migraine (> or =15 days per month of attacks of migraine without aura), who had shown a marked beneficial response to implanted bilateral suboccipital stimulators, were studied. Stimulation evoked local paraesthesia, the presence of which was a criterion of pain relief. On stimulation, the headache began to improve instantaneously and was completely suppressed within 30 min. On switching off the stimulation, the headache recurred instantly and peaked within 20 min. PET scans were performed using regional cerebral blood flow (rCBF) as a marker of neuronal activity. Each patient was scanned in the following three states: (1) stimulator at optimum settings: patient pain-free but with paraesthesia; (2) stimulator off: patient in pain and no paraesthesia; (3) stimulator partially activated: patient with intermediate levels of pain and paraesthesia. All scans were processed and analysed using Statistical Parametric Mapping (SPM) 99. There were significant changes in rCBF in the dorsal rostral pons, anterior cingulate cortex (ACC) and cuneus, correlated to pain scores, and in the ACC and left pulvinar, correlated to stimulation-induced paraesthesia scores. The activation pattern in the dorsal rostral pons is highly suggestive of a role for this structure in the pathophysiology of chronic migraine. The localization and persistence of activity during stimulation is exactly consistent with a region activated in episodic migraine, and with the persistence of activation of that area after successful treatment. The dorsal rostral pons may be a locus of neuromodulation by suboccipital stimulation. In addition, suboccipital stimulation modulated activity in the left pulvinar.

Adult↗

PubMed2003

Trigeminal antinociception induced by bicuculline in the periaqueductal gray (PAG) is not affected by PAG P/Q-type calcium channel blockade in rat.

We have recently shown that injection of the P/Q-type (Ca(v)2.1/alpha(1A)) calcium channel blocker, omega-agatoxin IVA, into the periaqueductal gray (PAG) facilitates meningeal dural stimulation-evoked trigeminal nociceptive processing. We injected the GABA(A) antagonist bicuculline into the PAG in addition to the agatoxin and observed bicuculline's effect on neurons responding to dural stimulation recorded in the trigeminal nucleus caudalis of rats in order to determine if P/Q channel-mediated changes acted through GABAergic mechanisms. The inhibition of trigeminal nociceptive neurons characteristic of bicuculline administered into the PAG was maintained in the presence of blocked PAG P/Q-type calcium channels. This suggests the PAG descending pain modulatory pathway is not affected by P/Q-type calcium channel blockade at the postsynaptic GABAergic inhibitory interneuron and the facilitation produced by agatoxin is mediated by another mechanism. These findings have implications for disorders involving the PAG or P/Q-type channels, such as migraine, in particular for the development of preventative treatments, suggesting GABAergic and voltage-gated calcium channels could be separately modulated.

Animals↗

PubMed2002

P/Q-type calcium-channel blockade in the periaqueductal gray facilitates trigeminal nociception: a functional genetic link for migraine?

The discovery of mis-sense mutations in the alpha1A subunit of the P/Q-type calcium channel in patients with familial hemiplegic migraine indicates the potential involvement of dysfunctional ion channels in migraine. The periaqueductal gray (PAG) region of the brainstem modulates craniovascular nociception and, through its role in the descending pain modulation system, may contribute to migraine pathophysiology. In this study we sought to investigate the possible link between the genetic mutations found in migraineurs and the PAG as a modulator of craniovascular nociception. We microinjected the P/Q-type calcium-channel blocker omega-agatoxin IVA into the rat ventrolateral PAG (vlPAG). We examined its effect on the nociceptive transmission of second-order neurons recorded in the trigeminal nucleus caudalis and activated by stimulation of the parietal dura mater. After injection of agatoxin into the vlPAG (n = 20) responses to dural stimulation were facilitated by 143% (p < 0.0001) for Adelta-fiber activity and 180% for C-fiber activity (p < 0.05). Similarly, spontaneous background activity increased by 163% (p < 0.0001). These results demonstrate that P/Q-type calcium channels in the PAG play a role in modulating trigeminal nociception and suggest a role for dysfunctional P/Q-type calcium channels in migraine pathophysiology.

Animals↗

PubMed2002

Stimulation of the greater occipital nerve induces increased central excitability of dural afferent input.

Patients with primary headaches often report pain that involves not only the front of the head, innervated by the first (ophthalmic) division of the trigeminal nerve, but also the back of the head, innervated by the greater occipital nerve (GON) that is a branch of the C(2) spinal root. The aim of this work was to study the physiology of trigeminocervical input in a model of cranial nociception by describing a population of nociceptive neurones that receive convergent input from the supratentorial dura and the GON. Rats were anaesthetized with pentobarbital, paralysed and ventilated. The parietal dura above the middle meningeal artery was stimulated through a closed cranial window. The GON was exposed in the neck and stimulated. Recordings were made from 67 neurones (52 wide dynamic range neurones/15 nociceptive-specific-neurones) in the C(2) spinal dorsal horn, which responded to stimulation of the dura and the GON. Most neurones showed receptive fields corresponding to the first trigeminal division as well as input from C(2) skin and muscle. Neurones were recorded in superficial and deep layers of the dorsal horn. All neurones tested received input from the ipsilateral and contralateral GON (n = 5). The responses to dural stimulation were analysed before and after stimulation of the GON. Supramaximal electrical stimulation of the GON (20 s to 5 min) enhanced afferent dural input in 8/20 neurones. Application of the C-fibre activator mustard oil (MO) to the cutaneous receptive field or suboccipital muscles innervated by the GON induced an increased excitability of dural responses in 8/12 and 9/10 neurones, respectively. Stimulation of muscle afferents had a significant longer facilitatory effect than cutaneous stimulation (P < 0.05). These results show that a considerable population of neurones show convergent input from both dura as well as cervical cutaneous and muscle territories, which supports the view of a functional continuum between the caudal trigeminal nucleus and upper cervical segments involved in cranial nociception. The facilitatory effect of GON stimulation on dural stimulation suggests a central mechanism at the second order neurone level. This mechanism may be important in pain referral from cervical structures to the head and therefore have implications for most forms of primary headache.

Afferent Pathways↗