Chronic stimulation of the posterior hypothalamic region for cluster headache: technique and 1-year results in four patients

[Hypothalamic deep brain stimulation for treatment of cluster headache]

Extremely severe, unilateral, recurrent facial pain and headache, accompanied by autonomic symptoms and signs, can be identified as cluster headache attacks (CH). Despite optimal pharmacological treatment, 20% of patients will not achieve satisfactory improvement. The severity of pain is so extreme that CH has been a cause of multiple suicidal attempts among patients ineffectively treated because of CH. Hypermetabolism of ipsilateral posterior hypothalamus observed in PET studies led to multiple attempts of deep brain stimulation (DBS) utilization in CH treatment. The authors present current opinions about DBS treatment in CH. A socioeconomic analysis of neuromodulatory treatment of CH is presented.

Deep brain stimulation in the treatment of depression

OBJECTIVE

To present the technique of deep brain stimulation (DBS) and to evaluate the studies conducted on DBS in the treatment of therapy-refractory major depressive disorder (MDD).

METHOD

A review of the literature on DBS in the treatment of MDD was conducted.

RESULTS

The results of DBS in MDD have been presented in 2 case reports and 3 studies of 47 patients operated upon in 5 different target areas. Positive effects have been presented in all studies and side effects have been minor. DBS in the nucleus accumbens resulted in a mean reduction of Hamilton depression rating scale (HDRS) of 36% after 1 year and 30% of the 10 patients achieved remission. DBS in the internal capsule/ventral striatum resulted in a reduction of 44% after 1 year, and at the last evaluation after in mean 2 years, 40% of the 15 patients were in remission. The 20 patients with subcallosal cingulated gyrus DBS had a reduction of HDRS of 52% after 1 year, and 35% were within 1 point from remission or in remission.

CONCLUSION

DBS is a promising treatment for therapy-refractory MDD. The published experience is, however, limited, and the method is at present an experimental therapy.

Deep brain stimulation in trigeminal autonomic cephalalgias

Cluster headache (CH), paroxysmal hemicrania (PH), and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT syndrome) are primary headaches grouped together as trigeminal autonomic cephalalgias (TACs). All are characterized by short-lived unilateral head pain attacks associated with oculofacial autonomic phenomena. Neuroimaging studies have demonstrated that the posterior hypothalamus is activated during attacks, implicating hypothalamic hyperactivity in TAC pathophysiology and suggesting stimulation of the ipsilateral posterior hypothalamus as a means of preventing intractable CH. After almost 10 years of experience, hypothalamic stimulation has proved successful in preventing pain attacks in approximately 60% of the 58 documented chronic drug-resistant CH patients implanted at various centers. Positive results have also been reported in drug-resistant SUNCT and PH. Microrecording studies on hypothalamic neurons are increasingly being performed and promise to make it possible to more precisely identify the target site. The implantation procedure has generally proved safe, although it carries a small risk of brain hemorrhage. Long-term stimulation is proving to be safe: studies on patients under continuous hypothalamic stimulation have identified nonsymptomatic impairment of orthostatic adaptation as the only noteworthy change. Studies on pain threshold in chronically stimulated patients show increased threshold for cold pain in the distribution of the first trigeminal branch ipsilateral to stimulation. When the stimulator is switched off, changes in sensory and pain thresholds do not occur immediately, indicating that long-term hypothalamic stimulation is necessary to produce sensory and nociceptive changes, as also indicated by clinical experience that CH attacks are brought under control only after weeks of stimulation. Infection, transient loss of consciousness, and micturition syncope have been reported, but treatment interruption usually is not required.

Deep brain stimulation for psychiatric disorders

BACKGROUND

Deep brain stimulation (DBS), an established treatment for some movement disorders, is now being used experimentally to treat psychiatric disorders as well. In a number of recently published case series, DBS yielded an impressive therapeutic benefit in patients with medically intractable psychiatric diseases.

METHODS

This review of the use of DBS to treat psychiatric disorders is based on literature retrieved from a selective Pubmed search for relevant keywords, reference works on the topic, and the authors' own research.

RESULTS

Studies have been performed on the use of DBS to treat medically intractable obsessive-compulsive disorder, depressive disorders, and Tourette syndrome. The case numbers in the cited publications were small, yet at least some of them involved a methodologically sound investigation. Thus, in some studies, the strength of the effect was controlled with a double-blinded interval in which the stimulation was turned off. In general, the primary symptoms were found to improve markedly, by 35% to 70%, although not all patients responded to the treatment. Adverse effects of DBS were very rare in most studies and could usually be reversed by changing the stimulation parameters.

CONCLUSIONS

The results of DBS for psychiatric disorders that have been published to date are encouraging. They open up a new perspective in the treatment of otherwise intractable disorders. Nonetheless, the efficacy, mechanism of action, and adverse effects of DBS for this indication still need to be further studied in methodologically adequate trials that meet the highest ethical standard.

Safety and efficacy of deep brain stimulation in refractory cluster headache: a randomized placebo-controlled double-blind trial followed by a 1-year open extension

Chronic cluster headache (CCH) is a disabling primary headache, considering the severity and frequency of pain attacks. Deep brain stimulation (DBS) has been used to treat severe refractory CCH, but assessment of its efficacy has been limited to open studies. We performed a prospective crossover, double-blind, multicenter study assessing the efficacy and safety of unilateral hypothalamic DBS in 11 patients with severe refractory CCH. The randomized phase compared active and sham stimulation during 1-month periods, and was followed by a 1-year open phase. The severity of CCH was assessed by the weekly attacks frequency (primary outcome), pain intensity,sumatriptan injections, emotional impact (HAD) and quality of life (SF12). Tolerance was assessed by active surveillance of behavior, homeostatic and hormonal functions.During the randomized phase, no significant change in primary and secondary outcome measures was observed between active and sham stimulation. At the end of the open phase, 6/11 responded to the chronic stimulation(weekly frequency of attacks decrease [50%), including three pain-free patients. There were three serious adverse events, including subcutaneous infection, transient loss of consciousness and micturition syncopes. No significant change in hormonal functions or electrolytic balance was observed. Randomized phase findings of this study did not support the efficacy of DBS in refractory CCH, but open phase findings suggested long-term efficacy in more than 50% patients, confirming previous data, without high morbidity. Discrepancy between these findings justifies additional controlled studies (clinicaltrials.gov number NCT00662935).

Neurostimulation therapy in intractable headaches

A proportion of chronic headache patients become refractory to medical treatment and severely disabled. In such patients various neurostimulation methods have been proposed, ranging from invasive procedures such as deep-brain stimulation to minimally invasive ones like occipital nerve stimulation. They have been applied in single cases or small series of patients affected with varying headache disorders: cervicogenic headache, hemicrania continua, posttraumatic headache, chronic migraine, and cluster headache. Although favorable results were reported overall, it is premature to consider neurostimulation as a treatment with established utility in refractory headaches. At present, the most detailed clinical studies have been performed in intractable chronic cluster headache (iCCH) patients, who represent about 1% of all chronic cluster headache (CCH) patients. Various lesional interventions have been attempted in these patients, none with lasting benefits. In recent years, non-destructive neurostimulation methods have raised new hope. Hypothalamic deep-brain stimulation (hDBS) acts rapidly and has lasting efficacy, but is not without risk. Occipital nerve stimulation (ONS) was studied in two trials on a total of 17 iCCH patients. Clinical efficacy was found to be very satisfactory by most patients and by the investigators. Although slightly less efficacious than hDBS, ONS has the advantage of being rather harmless and reversible. At this stage, it should be preferred as first-line invasive therapy for iCCH. Recent case reports mention the efficacy of supraorbital (SNS) and vagal (VNS) nerve stimulation. Whether these neurostimulation methods have a place in the management of iCCH patients remains to be determined.

SUCCESSFUL TREATMENT OF CHRONIC PAROXYSMAL HEMICRANIA WITH POSTERIOR HYPOTHALAMIC STIMULATION

OBJECTIVE

Chronic paroxysmal hemicrania (CPH) is a rare, unilateral primary headache syndrome. Recent studies suggest hypothalamic dysfunction as the likely cause of CPH. Therapeutic response to deep brain stimulation of the hypothalamus has been observed in the treatment of related trigeminal autonomic cephalgias. We explored the therapeutic effectiveness of posterior hypothalamic stimulation for the treatment of CPH in a patient intolerant of medical management.

CLINICAL PRESENTATION

A 43-year-old woman with CPH reported acute onset of lancinating, unilateral headache pain focused about the right orbit. These debilitating headaches were accompanied by ipsilateral nasal congestion, conjunctival injection, tearing, and ptosis lasting minutes before resolving spontaneously. The patient exhausted attempts at medical management.

TECHNIQUE

A deep brain stimulator microelectrode was placed under stereotactic guidance. The posterior hypothalamic target was 3 mm posterior, 5 mm inferior, and 2 mm ipsilateral to the midcommissural point. The electrode was connected to a standard pulse generator and set to final amplitude of 1.5 V, a pulse width of 60 microseconds, and a frequency of 185 Hz.

CONCLUSION

The patient's headache symptoms were durably alleviated with intraoperative activation. No complications were observed. This preliminary success suggests a role for posterior hypothalamic stimulation as a safe and effective treatment in patients with medically refractory CPH. As a therapeutic incremental innovation, this off-label use of technology for symptomatic therapy contributes to results of studies that support a central pathophysiological role for hypothalamic dysfunction in headaches classified among the trigeminal autonomic cephalgias.

Hypothalamic stimulation for trigeminal neuralgia in multiple sclerosis patients: efficacy on the paroxysmal ophthalmic pain

Trigeminal neuralgia is a disorder characterized by paroxysmal pain arising in one or more trigeminal branches; it is commonly reported in multiple sclerosis. In multiple sclerosis patients the ophthalmic branch may be frequently involved and the risks carried by neurosurgical ablative procedures are higher including major adverse effects such as corneal reflex impairment and keratitis. The objective of this works is to assess the role of posterior hypothalamus neuromodulation in the treatment of trigeminal neuralgia in multiple sclerosis patients. Five multiple sclerosis patients suffering from refractory recurrent trigeminal neuralgia involving all three trigeminal branches underwent deep brain stimulation of the posterior hypothalamus. The rationale of this intervention emerges from our earlier success in treating pain patients suffering from trigeminal autonomic cephalalgias. After follow-up periods that ranged from 1 to 4 years after treatment, the paroxysmal pain arising from the first trigeminal branch was controlled, whereas the recurrence of pain in the second and third trigeminal branches necessitated repeated thermorhizotomies to control in pain in two patients after 2 years of follow-up. In conclusion, deep brain stimulation may be considered as an adjunctive procedure for treating refractory paroxysmal pain within the first trigeminal division so as to avoid the complication of corneal reflex impairment that is known to follow ablative procedures.

Pathophysiology of trigeminal autonomic cephalalgias

Cluster headache, paroxysmal hemicrania, and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) are primary headaches recently classified together as trigeminal autonomic cephalalgias (TACs). The causes of these headaches have long been debated, with "peripheral" hypotheses in opposition to "central" hypotheses. The available information indicates that the pain originates from within the brain in cluster headache. The hypothalamic activation observed during TAC attacks by use of functional neuroimaging, and the success of hypothalamic stimulation as a treatment, confirm that the posterior hypothalamus is crucial in the pathophysiology of these headaches. The posterior hypothalamus is now known to modulate craniofacial pain, and hypothalamic activation occurs in other pain disorders, suggesting that this brain area is likely to have a more complex role in the pathophysiology of TACs than that of a mere trigger. Hypothalamic activation might play a part in terminating rather than triggering attacks, and might also give rise to a central permissive state, allowing attacks to take place.

Deep brain stimulation: current and future perspectives

Deep brain stimulation (DBS) has been used to treat various neurological and psychiatric disorders. Over the years, the most suitable surgical candidates and targets for some of these conditions have been characterized and the benefits of DBS well demonstrated in double-blinded randomized trials. This review will discuss some of the areas of current investigation and potential new applications of DBS.

Neurostimulation approaches to primary headache disorders

PURPOSE OF REVIEW

Conventional management options in medically intractable chronic-headache syndromes, such as chronic migraine, chronic cluster headache and hemicrania continua, are often limited. This review summarizes the current concepts, approaches and outcome data of invasive device-based neurostimulation approaches using occipital-nerve stimulation and deep-brain stimulation.

RECENT FINDINGS

Recently, there has been considerable progress in neurostimulation approaches to medically intractable chronic-headache syndromes. Previous studies have analysed the safety and efficacy of suboccipital neurostimulation in drug-resistant chronic-headache syndromes such as in chronic migraine, chronic cluster headache and hemicrania continua. The studies suggest suboccipital neurostimulation can have an effect even decades after onset of headaches, thus representing a possible therapeutic option inpatients that do not respond to any medication. Similarly, to date over 50 patients with cluster headaches underwent hypothalamic deep-brain stimulation. From these, an average of 50-70% did show a significant positive response.

SUMMARY

These findings will help to further elucidate the clinical potential of neurostimulation in chronic headache.

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.

Cluster headache: pharmacological treatment and neurostimulation

Cluster headache is a primary headache syndrome that is characterized by excruciatingly severe, strictly unilateral attacks of orbital, supraorbital or temporal pain, which last 15-180 min and are accompanied by ipsilateral autonomic manifestations (e.g. lacrimation and rhinorrhea). The attacks typically occur with circadian rhythmicity, being experienced at fixed hours of the day or night. In episodic cluster headache, attacks usually occur daily in 6-12-week bouts (cluster periods) followed by remission periods. In chronic cluster headache there is no notable remission. Cluster headache attacks reach full intensity very quickly and abortive agents need to be administered without delay. The pathophysiology of cluster headache is imperfectly understood and treatment has so far been mainly empirical. However, neuroimaging studies have prompted the successful use of hypothalamic stimulation to treat the condition. More recently, the less invasive technique of occipital nerve stimulation has shown promise in drug-refractory chronic cluster headache. This Review discusses both acute and preventive treatments for cluster headache and includes suggestions of how to use the available medications. The rationale, study results and selection criteria for neurostimulation procedures are also summarized, as are the disadvantages of these procedures.

Neurostimulation for primary headache disorders

Neurostimulation has emerged as a potential treatment option for patients with chronic, disabling, intractable primary headache disorders. Although safety and efficacy data are limited in quantity, there is accumulating experience with the use of peripheral nerve stimulation for the treatment of intractable occipital neuralgia, cluster headache, migraine, and less common headache disorders. Deep brain stimulation has been used to treat intractable chronic cluster headache and short-lasting unilateral neuralgiform headache with conjunctival injection and tearing. This article discusses the theorized mechanisms of action of these novel treatment modalities and summarizes current knowledge regarding safety and efficacy of neurostimulation for the treatment of headache.

Microelectrode recording in the posterior hypothalamic region in humans

INTRODUCTION

Deep brain stimulation of the posterior hypothalamic region (PHR) is an emerging technique for the treatment of medically intractable cluster headache. Few reports have analyzed single unit neuronal recordings in the human PHR. We report properties of spontaneous neuronal discharge in PHR for 6 patients who underwent DBS for cluster headaches.

METHODS

Initial target coordinates, determined by magnetic resonance imaging stereotactic localization, were 2 mm lateral, 3 mm posterior, and 5 mm inferior to the midpoint of the anterior commissure-posterior commissure plane. A single microelectrode penetration was performed beginning 10 mm above the anatomic target, without systemic sedation. Single units were discriminated off-line by cluster cutting in principal components space. Discharge rates, interspike intervals, and oscillatory activity were analyzed and compared between ventromedial thalamic and hypothalamic units.

RESULTS

Six patients and 24 units were evaluated. Units in the PHR had a slow, regular spontaneous discharge with wide, low-amplitude action potentials. The mean discharge rate of hypothalamic neurons was significantly lower (mean +/- standard deviation, 13.2 +/- 12.2) than that of medial thalamic units (28.0 +/- 8.2). Oscillatory activity was not detected. Microelectrode recording in this region caused no morbidity.

CONCLUSION

The single-unit discharge rate of neurons in the PHR of awake humans was 13.2 Hz and was significantly lower than medial thalamic neurons recorded dorsal to the target. The findings will be of use for microelectrode localization of the cluster headache target and for comparison with animal studies.

Trigeminal autonomic cephalalgias: a review and implications for dentistry

BACKGROUND

The authors review the epidemiology, clinical features, pathophysiology, diagnosis, treatment, orofacial presentations and dental implications of trigeminal autonomic cephalalgias (TACs): cluster headache (CH), paroxysmal hemicrania (PH) and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT).

TYPES OF STUDIES REVIEWED

The authors conducted PUBMED searches for the period from 1968 through 2007 using the terms "trigeminal autonomic cephalalgias," "cluster headache," "paroxysmal hemicrania," "short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing," "epidemiology," "pathophysiology," "treatment," "oral," "facial" and "dentistry." They gave preference to articles reporting randomized, controlled trials and those published in English-language peer-reviewed journals.

RESULTS

TACs refers to a group of headaches characterized by unilateral head pain, facial pain or both with accompanying autonomic features. Although their pathophysiologies are unclear, CH, PH and SUNCT may be differentiated according to their clinical characteristics. Current treatments for each of the TACs are useful in alleviating the pain, with few refractory cases requiring surgical intervention. Patients with TACs often visit dental offices seeking relief for their pain.

CLINICAL IMPLICATIONS

Although the prevalence of TACs is small, it is important for dentists to recognize the disorder and refer patients to a neurologist. This will avoid the pitfall of administering unnecessary and inappropriate traditional dental treatments in an attempt to alleviate the neurovascular pain.

Treatment of cluster headache in pregnancy and lactation

Cluster headache is a rare disorder in women, but has a serious impact on the affected woman's life, especially on family planning. Women with cluster headache who are pregnant need special support, including the expertise of an experienced headache centre, an experienced gynaecologist and possibly a teratology information centre. The patient should be seen through all stages of the pregnancy. A detailed briefing about the risks and safety of various treatment options is mandatory. In general, both the number of medications and the dosage should be kept as low as possible. Preferred treatments include oxygen, subcutaneous or intranasal sumatriptan for acute pain and verapamil and prednisone/prednisolone as preventatives. If there is a compelling reason to treat the patient with another preventative, gabapentin is the drug of choice. While breastfeeding, oxygen, sumatriptan and lidocaine for acute pain and prednisone/prednisolone, verapamil, and lithium as preventatives are the drugs of choice. As the individual pharmacokinetics differ substantially, adverse drug effects should be considered if unexplained symptoms occur in the newborn.

Pain and psycho-affective disorders

The subject of human pain can be subdivided into two broad categories: physical pain and psychological pain. Since the dawn of human consciousness, each of these two forms of pain-one clearly physical, the other having more to deal with the mind-have played a central role in human existence. Psychological pain and suffering add dimensions that go far beyond the boundaries of its physical counterpart. In the past 50 years, one of the more remarkable accomplishments of medical science has been to increasingly enable the clinician to impact, as never before, each of these critical realms of human existence. Our intention is, therefore, to initially describe a few of the many exciting neuroscientific and neurosurgical advances that have been made in the treatment of various types of pain and to speculate on some of the emergent questions that we believe need to be addressed. After this is accomplished, we will then use this information as a kind of two-pronged philosophical entrance into questions of the mind, brain, and soul that we feel are necessary to bring back into the sphere of the modern physician's practice. The goal of this article is two-fold: 1) to share some of our exciting research and 2) to renew the interest in timeless questions, such as that of the mind-brain and the brain-mind, in the conversation of the modern neurosurgeon. The International Association for the Study of Pain divides pain into two broad functions and anatomical categories. In this framework, "nociceptive" pain is defined as the kind of physical pain that results when the tissue is damaged. Given this perspective, such pain is usually considered a consequence of one's defense against one's environment. The other pain is the "neuropathic" one resulting from a lesion or a dysfunction of the human nervous system. As such, we will take the risk of crossing beyond the boundaries of neurosurgery and venture into boundaries that, at another time, might seem more natural to the discipline of psychiatry for two reasons. The first is that psychiatry seems to be so focused on the brain-its biochemistry and pharmacology--that questions of mind and soul have become rare and almost negligible. The second is to follow the course of the results of our own clinical investigations that have taken us into that very human world where questions of physical pain, psychological pain, and the experience of suffering abound. Today, however, the strategy of neuromodulation offers the advantage of being precisely tailored in neuroanatomical terms and, even more importantly, of being altogether reversible. At both our own Istituto Neurologico C. Besta and many other neurosurgical centers worldwide, many procedures have been reported in which implant neuromodulation devices successfully treat pain. For example, long-term stimulation of the spinal cord has been fairly effective in the treatment of neuropathic pain, multiple sclerosis, and various other forms of pain. Good results have been obtained in treating peripheral vascular diseases and sympathetic reflex dystrophy syndrome. Good results have also been achieved in trigeminal nerve stimulation and peripheral nerve stimulation. In the case of thalamic stimulation, there has also been an improvement of symptoms, but a long-term degree of tolerance was noticed. Hypothalamic stimulation has also been seen to be effective in controlling trigeminal autonomic cephalalgic pain, as well as the facial pain that is known to occur in multiple sclerosis. Motor cortex stimulation was found to occasionally have good results in treating neuropathic pain, whereas occipital nerve stimulation was found to achieve good results in controlling chronic cluster headache and other chronic headaches, although with only short-term follow-up so far. Recent reports of functional magnetic resonance imaging have prompted us to propose exciting new neurosurgical targets that may be effective in treating psychoaffective disorders. Our results appear to be more than promising so far. It appears that neuropathic pain and psychoaffective disorders seem to be sharing an anatomophysiological common background at the Brodmann Area 25 of the anterior cingulated gyrus. On the basis of these exciting findings, we believe that it is reasonable to suggest that neuropathic pain and psychoaffective disorders may ultimately be managed with complementary or, at least, similar, therapeutic strategies, each of which lie within the domain of the neurosurgeon.

Sphenopalatine ganglion radiofrequency ablation for the management of chronic cluster headache

OBJECTIVES

Chronic cluster headache patients are often resistant to pharmacological management. Percutaneous radiofrequency ablation (RFA) of the sphenopalatine ganglion (SPG) was shown before to improve episodic cluster headache but not chronic cluster headache. We were interested to examine the effect of such intervention in patients with intractable chronic cluster headache who failed pharmacological management.

METHODS

Fifteen patients with chronic cluster headache, who experienced temporary pain relief following SPG block, underwent percutaneous RFA via the infrazygomatic approach under fluoroscopic guidance. Collected data include demographic variables, onset and duration of the headache, mean attack intensity (MAI), mean attack frequency (MAF), and pain disability index (PDI) before and up to 18 months after procedure.

RESULTS

At 1-, 3-, 6-, 12-, 18-month follow-up, the MAI was 2.6, 3.2, 3.2, 3.4, 4.2, respectively (P < .0001, P < .0001, P < .0001, P < .0005, P < .003, respectively). The PDI improved from 55 (baseline) to 17.2 and 25.6 at 6 and 12 months respectively (P < .001). The MAF improved from 17 attacks/week to 5.4, 6.4, 7.8, 8.6, 8.3 at 1-, 3-, 6-, 12-, 18-month follow-up visits (P < .0001, P < .0001, P < .0001, P < .002, P < .004, respectively).

CONCLUSION

Our data showed that percutaneous RFA of the SPG is an effective modality of treatment for patients with intractable chronic cluster headaches. Precise needle placement with the use of real-time fluoroscopy and electrical stimulation prior to attempting radiofrequency lesioning may reduce the incidence of adverse events.

Lessons from 8 years' experience of hypothalamic stimulation in cluster headache

Neuroimaging studies in cluster headache (CH) patients have increased understanding of attack-associated events and provided clues to the pathophysiology of the condition. They have also suggested stimulation of the ipsilateral posterior inferior hypothalamus as a treatment for chronic intractable CH. After 8 years of experience, stimulation has proved successful in controlling the pain attacks in almost 60% of chronic CH patients implanted at various centres. Although hypothalamic implant is not without risks, it has generally been performed safely. Implantation affords an opportunity to perform microrecordings of individual posterior hypothalamic neurons. These studies are at an early stage, but suggest the possibility of identifying precisely the target site by its electrophysiological characteristics. Autonomic studies of patients undergoing posterior hypothalamic stimulation provide further evidence that long-term stimulation is safe, revealing that it can cause altered modulation of the mechanisms of orthostatic adaptation without affecting the baroreflex, cardiorespiratory interactions or efferent sympathetic and vagal functions. Chronically stimulated patients have an increased threshold for cold pain at the site of the first trigeminal branch ipsilateral to the stimulated side; when the stimulator is switched off, changes in sensory and pain thresholds do not occur immediately, suggesting that long-term stimulation is required to induce sensory and nociceptive changes. Posterior inferior hypothalamic stimulation is now established as a treatment for many chronic CH patients. The technique is shedding further light on the pathophysiology of the disease, and is also providing clues to functioning of the hypothalamus itself.

Hypothalamic deep brain stimulation for cluster headache: experience from a new multicase series

Deep brain stimulation (DBS) of the posterior hypothalamus was found to be effective in the treatment of drug-resistant chronic cluster headache. We report the results of a multicentre case series of six patients with chronic cluster headache in whom a DBS in the posterior hypothalamus was performed. Electrodes were implanted stereotactically in the ipsilateral posterior hypothalamus according to published coordinates 2 mm lateral, 3 mm posterior and 5 mm inferior referenced to the mid-AC-PC line. Microelectrode recordings at the target revealed single unit activity with a mean discharge rate of 17 Hz (range 13-35 Hz, n = 4). Out of six patients, four showed a profound decrease of their attack frequency and pain intensity on the visual analogue scale during the first 6 months. Of these, one patient was attack free for 6 months under neurostimulation before returning to the baseline which led to abortion of the DBS. Two patients had experienced only a marginal, non-significant decrease within the first weeks under neurostimulation before returning to their former attack frequency. After a mean follow-up of 17 months, three patients are almost completely attack free, whereas three patients can be considered as treatment failures. The stimulation was well tolerated and stimulation-related side-effects were not observed on long term. DBS of the posterior inferior hypothalamus is an effective therapeutic option in a subset of patients. Future controlled multicentre trials will need to confirm this open-label experience and should help to better define predictive factors for non-responders.