Commentary on Fontaine et al.: "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"

Deep brain stimulation for chronic refractory cluster headache: A case series about long-term outcomes and connectivity analysis

OBJECTIVE

The aim of this study was to provide long-term clinical results-including "sweet spot" identification and connectomic imaging analysis-in a series of patients treated with deep brain stimulation for refractory chronic cluster headache.

BACKGROUND

Deep brain stimulation is a relatively recent indication for the treatment of refractory chronic cluster headache. This indication has generated substantial debate in recent years due to uncertainty surrounding the mechanism of action and the lack of long-term efficacy data.

METHODS

Case retrospective series of adult patients diagnosed with refractory chronic cluster headache and treated with deep brain stimulation. Demographic and clinical data were registered preoperatively and at 3, 6, 12, and 24 months. The primary endpoint was reduction in headache load, a composite score of frequency, severity, and duration of each attack. Imaging analyses (sweet spot and connectomic analyses) were performed to identify the brain regions most closely correlated with the reduction in headache load and to identify the structural networks involved. Treatment response was categorized according to the reduction in headache load, as follows: poor (<30% reduction), partial (30-50%), or high (>50%).

RESULTS

A total of 14 patients were included, with a mean (standard deviation [SD]) age of 42.4 (10.7) years and mean (SD) headache duration of 8.0 (5.8) years. Headache load scores decreased significantly from baseline to Month 24: mean (SD) 424.2 (325.9) versus 135.9 (155.7) (p = 0.001). In most patients (eight patients [58.0%]), headache load scores decreased by 50% after treatment. The other six patients showed either a partial (three [21.0%]) or poor (three [21.0%]) response. The optimized sweet spot was the lateral ventral tegmental area ((Montreal Neurological Institute) MNI coordinates of the center of mass: x = ± 9.0 mm, y = -10.6 mm, z = -3.5 mm). The connectomic analysis pointed to the probable implication of corticorubral tracts.

CONCLUSION

These findings suggest that a substantial proportion of patients with refractory chronic cluster headache obtain significant long-term clinical benefits from deep brain stimulation. Good responders were characterized by a robust improvement in headache load within 3-6 months after surgery. The lateral ventral tegmental area was identified as the best target for this indication, with the likely participation of corticorubral tracts.

Clomiphene treatment may be effective in refractory episodic and chronic cluster headache

OBJECTIVE

To describe the evolution of 15 patients who were treated for difficult-to-control episodic and chronic cluster headaches with clomiphene.

METHODS

Clomiphene treatment was used for seven chronic and eight episodic cluster headache patients. The chronic patients were refractory to the medication being used, and the episodic patients, in addition to being resistant to conventional medication, had longer cluster headache periods, exceeding the average time of previous cluster cycles. Our main analysis was of the time to pain-free, complete remission, and the length of pain-free time and complete remission.

RESULTS

Clomiphene was used for 45-180 days. The average time to being pain-free was 15 days and cluster remission was up to 60 days. The average time between being pain-free until cluster remission was 26 days.

CONCLUSIONS

Clomiphene treatment was significantly efficient. It interrupted chronicity in all patients, suggesting the capability of changing the pattern of attacks. It proved to be safe and well tolerated.

[Therapeutic neuromodulation in primary headaches]

Neuromodulatory techniques have developed rapidly in the therapeutic management of refractory headaches. Invasive procedures comprise peripheral nerve stimulation (particularly occipital nerve stimulation), vagus nerve stimulation, cervical spinal cord stimulation and hypothalamic deep brain stimulation. Transcutaneous electrical nerve stimulation, repetitive transcranial magnetic stimulation and transcranial direct current stimulation are noninvasive variants. Based on current neuroimaging, neurophysiological and clinical studies occipital nerve stimulation and hypothalamic deep brain stimulation are recommended for patients with chronic cluster headache. Less convincing evidence can be found for their use in other refractory headaches such as chronic migraine. No clear recommendation can be given for the other neuromodulatory techniques. The emerging concept of intermittent stimulation of the sphenopalatine ganglion is nonetheless promising. Robust randomized and sham-controlled multicenter studies are needed before these therapeutic approaches are widely implemented. Due to the experimental nature all patients should be treated in clinical studies. It is essential to confirm the correct headache diagnosis and the refractory nature before an invasive approach is considered. Patients should generally be referred to specialized interdisciplinary outpatient departments which closely collaborate with neurosurgeons who are experienced in the implantation of neuromodulatory devices. It is crucial to ensure a competent postoperative follow-up with optimization of stimulation parameters and adjustment of medication.