Occipital nerve block prior to occipital nerve stimulation for refractory chronic migraine and chronic cluster headache: myth or prediction?

BACKGROUND: Occipital nerve stimulation (ONS) results in beneficial outcomes, with marked pain relief, in otherwise intractable chronic migraine (CM) and chronic cluster headache (CCH). Some studies have reported that a positive response to occipital nerve block (ONB) administered prior to ONS predicts a positive response to ONS. However, other studies concerned with proper patient selection claimed no predictive value for ONB. The aim of this study was to re-evaluate the usefulness and predictive value of ONB prior to ONS. METHODS: Literature searches on the predictive value of ONB were performed in MEDLINE and PubMed. Patient data were extracted and a pooled analysis was performed. RESULTS: The literature review revealed 133 patients with CM and seven patients with CCH who received preoperative ONB. To date, a randomized controlled study examining the relationship between ONB and ONS has not been conducted in patients with CM. CONCLUSIONS: Current literature suggests that ONB does not sufficiently predict ONS responsiveness in patients with refractory CM and CCH; this important issue requires further investigation.

Safety and efficacy of peripheral nerve stimulation of the occipital nerves for the management of chronic migraine: long-term results from a randomized, multicenter, double-blinded, controlled study.

BACKGROUND: Recent studies evaluated short-term efficacy and safety of peripheral nerve stimulation (PNS) of the occipital nerves for managing chronic migraine. We present 52-week safety and efficacy results from an open-label extension of a randomized, sham-controlled trial. METHODS: In this institutional review board-approved, randomized, multicenter, double-blinded study, patients were implanted with a neurostimulation system, randomized to an active or control group for 12 weeks, and received open-label treatment for an additional 40 weeks. Outcomes collected included number of headache days, pain intensity, migraine disability assessment (MIDAS), Zung Pain and Distress (PAD), direct patient reports of headache pain relief, quality of life, satisfaction and adverse events. Statistical tests assessed change from baseline to 52 weeks using paired t-tests. Intent-to-treat (ITT) analyses of all patients (N = 157) and analyses of only patients who met criteria for intractable chronic migraine (ICM; N = 125) were performed. RESULTS: Headache days were significantly reduced by 6.7 (±8.4) days in the ITT population (p < 0.001) and by 7.7 (±8.7) days in the ICM population (p < 0.001). The percentages of patients who achieved a 30% and 50% reduction in headache days and/or pain intensity were 59.5% and 47.8%, respectively. MIDAS and Zung PAD scores were significantly reduced for both populations. Excellent or good headache relief was reported by 65.4% of the ITT population and 67.9% of the ICM population. More than half the patients in both cohorts were satisfied with the headache relief provided by the device. A total of 183 device/procedure-related adverse events occurred during the study, of which 18 (8.6%) required hospitalization and 85 (40.7%) required surgical intervention; 70% of patients experienced an adverse event. CONCLUSION: Our results support the 12-month efficacy of PNS of the occipital nerves for headache pain and disability associated with chronic migraine. More emphasis on adverse event mitigation is needed in future research. TRIAL REGISTRATION: Clinical trials.gov (NCT00615342).

Occipital nerve stimulation in medically intractable, chronic cluster headache. The ICON study: rationale and protocol of a randomised trial.

BACKGROUND: About 10% of cluster headache patients have the chronic form. At least 10% of this chronic group is intractable to or cannot tolerate medical treatment. Open pilot studies suggest that occipital nerve stimulation (ONS) might offer effective prevention in these patients. Controlled neuromodulation studies in treatments inducing paraesthesias have a general problem in blinding. We have introduced a new design in pain neuromodulation by which we think we can overcome this problem. METHODS/DESIGN: We propose a prospective, randomised, double-blind, parallel-group international clinical study in medically intractable, chronic cluster headache patients of high- versus low-amplitude ONS. Primary outcome measure is the mean number of attacks over the last four weeks. After a study period of six months there is an open extension phase of six months. Alongside the randomised trial an economic evaluation study is performed. DISCUSSION: The ICON study will show if ONS is an effective preventive therapy for patients suffering medically intractable chronic cluster headache and if there is a difference between high- and low-amplitude stimulation. The innovative design of the study will, for the first time, assess efficacy of ONS in a blinded way.

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.

Effectiveness of osteopathy in the cranial field and myofascial release versus acupuncture as complementary treatment for children with spastic cerebral palsy: a pilot study.

CONTEXT: Case reports and clinical trials have indicated that osteopathic manipulative treatment (OMT) may improve motor function and quality of life for children with cerebral palsy. OBJECTIVE: To assess the effectiveness of osteopathy in the cranial field, myofascial release, or both versus acupuncture in children with moderate to severe spastic cerebral palsy, as measured by several outcomes instruments in a randomized controlled trial. METHODS: Children between the ages of 20 months and 12 years with moderate to severe spastic cerebral palsy were enrolled in a single-blind, randomized wait-list control pilot study. There were three arms in the study: OMT (ie, osteopathy in the cranial field, myofascial release, or both, using direct or indirect methods), acupuncture, and control (ie, nontherapeutic attention). Children who were initially randomly assigned to the control arm were subsequently randomly reassigned to the intervention arms, increasing the sample size. Outcome measures included standard instruments used in the evaluation of children with cerebral palsy. Less traditional measures were also used, including serial evaluations by an independent blind osteopathic physician and visual analog scale assessments by an independent osteopathic physician and the parents or guardians. A total of 11 outcome variables were analyzed. RESULTS: Fifty-five patients were included in the study. Individual analyses of the 11 outcome variables revealed statistically significant improvement in two mobility measures for patients who received OMT--the total score of Gross Motor Function Measurement and the mobility domain of Functional Independence Measure for Children (P<.05). No statistically significant improvements were seen among patients in the acupuncture treatment arm. CONCLUSIONS: A series of treatments using osteopathy in the cranial field, myofascial release, or both improved motor function in children with moderate to severe spastic cerebral palsy. These results can be used to guide future research into the effectiveness of OMT or acupuncture in treating children with spastic cerebral palsy.

Involvement of trigeminal subnucleus caudalis (medullary dorsal horn) in craniofacial nociceptive reflex activity.

We have previously shown that an increase in electromyographic (EMG) activity of digastric (DIG) and masseter (MASS) muscles can be reflexly evoked by injection into the rat's temporomandibular joint (TMJ) region of the small-fibre excitant and inflammatory irritant mustard oil (MO). Since the trigeminal (V) subnucleus caudalis (Vc, i.e. medullary dorsal horn) has traditionally been viewed as an essential brainstem relay site of nociceptive information from craniofacial tissues, an EMG study was carried out in 45 anaesthetized rats to determine if Vc is involved in the MO-evoked increases in jaw muscle EMG activity. The effects of histologically confirmed surgical or chemical lesions of Vc on this evoked EMG activity were tested in different groups of rats. MO injection into the left TMJ region of intact rats evoked bilateral increases in EMG activity of DIG and MASS which could be significantly reduced by surgical transection of the left caudal brainstem at the obex level; MO injection into the right TMJ region in these same rats still readily evoked increases in EMG activity. A sagittal section medial to Vc or transection at the level of the second cervical spinal segment did not produce any significant reduction in the reflexly evoked EMG activity. Neurones in Vc, as opposed to fibres of passage, appear to be important for the MO-evoked EMG activity, since injection into Vc of the neurotoxic chemical ibotenic acid significantly reduced the mustard oil-evoked EMG activity. The Vc also appears to play a role in the activation of contralateral V motoneurons, as evidenced by the activation of the contralateral DIG and MASS muscles by the injection of MO into the left TMJ region of intact rats and by the reduction of this evoked EMG activity in the contralateral DIG and MASS of rats with a surgical transection or ibotenic acid lesion of the left Vc. These findings suggest that Vc may be a critical element in the neural pathways underlying the reflex responses evoked bilaterally in DIG and MASS muscles by noxious stimulation of the TMJ region.

Which structures are sensitive to painful transcranial electric stimulation?

Electric transcranial stimulation (TCS) is useful for clinical studies. It is, however, painful and not generally used for awake subjects. By means of topical anaesthesia and nerve blockades we wanted to find out which structures of the scalp and cranium are sensitive to electric TCS. Altogether 21 subjects participated in the present study. Our data show that pain experienced by the subjects during electric TCS is brought about by activation of the pain receptors in the scalp under the stimulating electrodes. Topical anaesthetic cream is incapable of attenuating this pain. The periosteum does not seem to be much more sensitive electric stimulation than rest of the scalp. Furthermore, contractions of facial and neck muscles do not seem to have a significant role in pain generation in electric TCS. Pain can be prevented if sufficiently large areas of the scalp are properly anaesthetized before stimulation by e.g. blockade of the major nerves responsible for the sensation of the stimulus area.