Hypothalamic activation discriminates painful and non-painful initiation of the trigeminal autonomic reflex - an fMRI study.

BACKGROUND: The role of the trigeminal autonomic reflex in headache syndromes, such as cluster headache, is undisputed but sparsely investigated. The aim of the present study was therefore, to identify neural correlates that play a role in the initiation of the trigeminal autonomic reflex. We further aimed to discriminate between components of the reflex that are involved in nociceptive compared to non-nociceptive processing. METHODS: Kinetic Oscillation Stimulation (KOS) in the left nostril was applied in order to provoke autonomic symptoms (e.g. lacrimation) via the trigeminal autonomic reflex in 26 healthy participants using functional magnetic resonance imaging. Unpleasantness and painfulness were assessed on a visual analog scale (VAS), in order to assess the quality of the stimulus (e.g. pain or no pain). RESULTS: During non-painful activation, specific regions involved in the trigeminal autonomic reflex became activated, including several brainstem nuclei but also cerebellar and bilateral insular regions. However, when the input leading to activation of the trigeminal autonomic reflex was perceived as painful, activation of the anterior hypothalamus, the locus coeruleus (LC), the ventral posteriomedial nucleus of the thalamus (VPM), as well as an activation of ipsilateral insular regions, was observed. CONCLUSION: Our results suggest the anterior hypothalamus, besides the thalamus and specific brain stem regions, play a significant role in networks that mediate autonomic output (e.g. lacrimation) following trigeminal input, but only if the trigeminal system is activated by a stimulus comprising a painful component.

Placement and Anchoring of Trigeminal Neurostimulation Electrodes: Technical Report.

BACKGROUND: Peripheral neurostimulation (PNS) for medically refractory trigeminal and craniofacial pain is an emerging alternative to traditional surgical approaches. Technical problems with craniofacial PNS have included electrode migration and erosion, limiting the utility and cost-effectiveness of this procedure. OBJECTIVE: To review our institutional surgical technique for trigeminal PNS implantation, focusing on a novel technique for electrode anchoring. METHODS: Consecutive cases of permanent craniofacial PNS placement by a single surgeon over 36 months were reviewed for surgical technique and technical outcomes. Electrodes were placed percutaneously with open anchoring to the pericranium at a separate parietal incision. RESULTS: Sixteen systems (53 electrodes) were implanted in 14 patients. Median follow-up was 13 months (range, 5-29 months). Electrode placement was successful in all cases with no intraoperative complications. There was 1 lead migration (6.3% per patient; 1.8% per lead) and no cases of erosion. Two patients (14.3%) required explant for infection, 1 of whom was successfully reimplanted. Three patients (21.4%) underwent surgical revision other than for infection. CONCLUSIONS: We present an improved method for craniofacial PNS surgery which introduces a separate incision for electrode anchoring at the parietal boss. This technique simplifies the procedure and greatly reduces rates of erosion and migration, improving patient comfort and satisfaction.

Microvascular decompression or neuromodulation in patients with SUNCT and trigeminal neurovascular conflict?

Objectives To assess the effectiveness of neuromodulation and trigeminal microvascular decompression (MVD) in patients with medically-intractable short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT). Methods Two patients with medically refractory SUNCT underwent MVD following beneficial but incomplete response to neuromodulation (occipital nerve stimulation and deep brain stimulation). MRI confirmed neurovascular conflict with the ipsilateral trigeminal nerve in both patients. Results Although neuromodulation provided significant benefit, it did not deliver complete relief from pain and management required numerous postoperative visits with adjustment of medication and stimulation parameters. Conversely, MVD was successful in eliminating symptoms of SUNCT in both patients with no need for further medical treatment or neuromodulation. Conclusion Neuromodulation requires expensive hardware and lifelong follow-up and maintenance. These case reports highlight that microvascular decompression may be preferable to neuromodulation in the subset of SUNCT patients with ipsilateral neurovascular conflict.

Technical considerations for facilitation of selective percutaneous radiofrequency neurolysis of the trigeminal nerve.

Fine points of the technique of selective percutaneous radiofrequency trigeminal neurolysis relative to patient preparation accurate and rapid foramen ovale puncture, electrode positioning, and neurolytic lesions are discussed. These measures. which have evolved from our experience in treating trigeminal neuralgia by this method over the last 4 years, have made the procedure safer and less painful but also significantly more expedient.