Detection of Local Field Potentials in the Ventral Tegmental Area of the Midbrain in Chronic Cluster Headache Patients Treated by Deep Brain Stimulation : a Feasibility Study

The physiopathology of trigeminal-autonomic cephalalgia, and more particularly of cluster headache (CH) is still partially unknown. Three main structures are involved: the trigeminovascular system, the cephalic afferents of the autonomic nervous system, and centrally the hypothalamus. There are many clinical arguments in favor of the involvement of the hypothalamus in CH. In addition, several radiological studies have confirmed the involvement of the posterior hypothalamic region in cluster attacks. Thus, a positron emission tomography study showed hyperactivity of the posteroinferior nucleus of the ipsilateral hypothalamus. Voxel based MRI studies have shown a bilateral increase in the volume of the inferoposterior part of the homolateral hypothalamus. The involvement of the posterior hypothalamic region or more precisely the ventral tegmental area of the midbrain therefore seems acquired, although its real role as a generator or modulator of pain remains to be precised.

Deep brain stimulation (dBS) is used in the management of chronic drug-resistant CH with an overall efficacy in 2/3 of patients. Nevertheless, its mechanism of action remains poorly understood, thus limiting the selection of patients and the optimization of care. The lack of clear neurophysiological criteria to identify the neuronal population to be targeted is a major source of uncertainty in the positioning of dBS electrodes and parameters adjustment. In order to improve the understanding and at the same time the results of this technique, obtaining in vivo electrophysiological data seems mandatory. Local fields potentials (LFP) have been recordered by in vivo by dBS in other diseases (Parkinson's disease, tremor...) and their analysis has brought new insigights in the characterization and understanding of these pathology. New generations of neurostimulator (Percept Medtronic) enables continuous recording of LFP in implanted patients. The goal of our study is the recording of LFP at the time of CH attacks via the BrainSenseTM system. This system included in the stimulator allows in vivo collection of LFP in the absence and presence of stimulation. The pathophysiological data recordered will then be correlated with the clinical benefit of the dBS ( nulber of attacks, duration, pain intensity...). As it is a feasibility study, only 5 patients will be included.