Neuromodulatory approaches to the treatment of trigeminal autonomic cephalalgias

The posterior hypothalamus exerts opposing effects on nociception via the A7 catecholamine cell group in rats

Stimulation of the posterior hypothalamic area (PH) produces antinociception in rats and humans, but the precise mechanisms are unknown. The PH forms anatomical connections with the parabrachial area, which contains the pontine A7 catecholamine cell group, a group of spinally projecting noradrenergic neurons known to produce antinociception in the dorsal horn. The aim of the present study was to determine whether PH-induced antinociception is mediated in part through connections with the A7 cell group in female Sprague-Dawley rats, as measured by the tail flick and foot withdrawal latency. Stimulation of the PH with the cholinergic agonist carbachol (125 nmol) produced antinociception that was blocked by pretreatment with atropine sulfate. Intrathecal injection of the α(2)-adrenoceptor antagonist yohimbine reversed PH-induced antinociception, but the α(1)-adrenoceptor antagonist WB4101 facilitated antinociception. Intrathecal injection of normal saline had no effect. In a separate experiment, cobalt chloride, which reversibly arrests synaptic activity, was microinjected into the A7 cell group and blocked PH-induced antinociception. These findings provide evidence that the PH modulates nociception in part through connections with the A7 catecholamine cell group through opposing effects. Antinociception occurs from actions at α(2)-adrenoceptors in the dorsal horn, while concurrent hyperalgesia occurs from actions of norepinephrine at α(1)-adrenoceptors. This hyperalgesic response likely attenuates antinociception from PH stimulation.

Occipital Nerve Stimulation for Refractory Headache in the Chiari Malformation Population

BACKGROUND:

Chronic occipital and suboccipital headache is a common symptom in patients with Chiari I malformation. These headaches may persist despite appropriate surgical treatment of the underlying pathology via suboccipital decompression, duraplasty, and cerebrospinal fluid diversion. Occipital nerve stimulation has been shown to be effective in the treatment of a variety of occipital headache/pain syndromes.

OBJECTIVE:

To review retrospectively our experience with occipital nerve stimulation in patients with a primary diagnosis of Chiari malformation and a history of chronic occipital pain intractable to medical and surgical therapies.

METHODS:

We present a retrospective analysis of our series of 22 patients with Chiari malformation and persistent occipital headaches who underwent occipital neurostimulator trials and, after successful trials, permanent stimulator placement. A trial was considered successful with > 50% pain relief as assessed with a standard Visual Analog Scale score. Patients with a successful trial underwent permanent placement approximately 1 to 2 weeks later. Patients were assessed postoperatively for pain relief via the Visual Analog Scale.

RESULTS:

Sixty-eight percent of patients (15 of 22) had a successful stimulator trial and proceeded to permanent implantation. Of those implanted, 87% (13 of 15) reported continued pain relief at a mean follow-up of 18.9 months (range, 6–51 months). Device-related complications requiring additional surgeries occurred in 40% of patients.

CONCLUSION:

Occipital stimulation may provide significant long-term pain relief in selected Chiari I malformation patients with persistent occipital pain. Larger and longer-term studies are needed to further define appropriate patient selection criteria and to refine the surgical technique to minimize device-related complications.

Cluster headache: clinical features and therapeutic options

BACKGROUND

Cluster headache is the most common type of trigemino-autonomic headache, affecting ca. 120 000 persons in Germany alone. The attacks of pain are in the periorbital area on one side, last 90 minutes on average, and are accompanied by trigemino-autonomic manifestations and restlessness. Most patients have episodic cluster headache; about 15% have chronic cluster headache, with greater impairment of their quality of life. The attacks often possess a circadian and seasonal rhythm.

METHOD

Selective literature review

RESULTS

Oxygen inhalation and triptans are effective acute treatment for cluster attacks. First-line drugs for attack prophylaxis include verapamil and cortisone; alternatively, lithium and topiramate can be given. Short-term relief can be obtained by the subcutaneous infiltration of local anesthetics and steroids along the course of the greater occipital nerve, although most of the evidence in favor of this is not derived from randomized clinical trials. Patients whose pain is inadequately relieved by drug treatment can be offered newer, invasive treatments, such as deep brain stimulation in the hypothalamus (DBS) and bilateral occipital nerve stimulation (ONS).

CONCLUSION

Pharmacotherapy for the treatment of acute attacks and for attack prophylaxis is effective in most patients. For the minority who do not gain adequate relief, newer invasive techniques are available in some referral centers. Definitive conclusions as to their value cannot yet be drawn from the available data.

Paroxysmal Hemicrania in Children—Symptoms, Diagnostic Criteria, Therapy and Outcome

Whereas paroxysmal hemicrania (PH) is studied extensively in adults, even case reports of PH in children are rare. We present the first prospective follow-up study on PH in children. Our aim was to investigate whether differences exist between paediatric and adult patients. We assessed all children with chronic headache who were referred to our paediatric out-patient pain clinic within 3 years based on interviews and validated questionnaires. Among 628 patients we found five children with PH (0.8%) and three with probable PH (0.5%), in total 1.3%. Pain characteristics, autonomic symptoms and treatment response to indomethacin were similar to adult PH patients. Our results demonstrate that the International Headache Society classification of PH is also applicable to children. We suspect that PH has been underdiagnosed in children and therefore suboptimally treated thus far.

Deep brain stimulation for medically intractable cluster headache

Cluster headache is the most severe primary headache disorder known. Ten to 20% of cases are medically intractable. DBS of the posterior hypothalamic area has shown effectiveness for alleviation of cluster headache in many but not all of the 46 reported cases from European centers and the eight cases studied at the University of California, San Francisco. This surgical strategy was based on the finding of increased blood flow in the posterior hypothalamic area on H(2)(15)O PET scanning during spontaneous and nitroglycerin-induced cluster headache attacks. The target point used, 4-5 mm posterior to the mamillothalamic tract, is in the border zone between posterior hypothalamus, anterior periventricular gray matter, and inferior thalamus. Recently, occipital nerve stimulation has shown efficacy, calling in question the use of DBS as a first line surgical therapy. In this report, we review the indications, techniques, and outcomes of DBS for cluster headache.

Paroxysmal otalgia due to compression of the intermediate nerve: a distinct syndrome of neurovascular conflict confirmed by neuroimaging

✓The authors present the case of a 52-year-old female patient with a 6-year history of intractable paroxysmal otalgia. Preoperative magnetic resonance (MR) angiography demonstrated an anterior inferior cerebellar artery loop compressing the intermediate nerve in the seventh/eighth cranial nerve complex inside the internal auditory canal. The pain resolved completely after a microvascular decompression via a retromastoid craniotomy. To the best of the authors' knowledge, the combined neuroimaging and intraoperative findings of this case provide a unique demonstration that vascular compression of the intermediate nerve can be the exclusive cause of paroxysmal otalgia. Magnetic resonance imaging and MR angiography can establish the causative mechanism and distinguish this otalgia due to vascular compression of the intermediate nerve from other pain syndromes that are designated as geniculate neuralgia (GN). The present case indicates that intermediate nerve neuralgia is a distinct syndrome of neurovascular conflict and a variant of GN. The causative classification of GN should be reexamined with the use of advanced MR imaging.