Multimodal acoustic-electric trigeminal nerve stimulation modulates conscious perception.

Multimodal stimulation can reverse pathological neural activity and improve symptoms in neuropsychiatric diseases. Recent research shows that multimodal acoustic-electric trigeminal-nerve stimulation (TNS) (i.e., musical stimulation synchronized to electrical stimulation of the trigeminal nerve) can improve consciousness in patients with disorders of consciousness. However, the reliability and mechanism of this novel approach remain largely unknown. We explored the effects of multimodal acoustic-electric TNS in healthy human participants by assessing conscious perception before and after stimulation using behavioral and neural measures in tactile and auditory target-detection tasks. To explore the mechanisms underlying the putative effects of acoustic-electric stimulation, we fitted a biologically plausible neural network model to the neural data using dynamic causal modeling. We observed that (1) acoustic-electric stimulation improves conscious tactile perception without a concomitant change in auditory perception, (2) this improvement is caused by the interplay of the acoustic and electric stimulation rather than any of the unimodal stimulation alone, and (3) the effect of acoustic-electric stimulation on conscious perception correlates with inter-regional connection changes in a recurrent neural processing model. These results provide evidence that acoustic-electric TNS can promote conscious perception. Alterations in inter-regional cortical connections might be the mechanism by which acoustic-electric TNS achieves its consciousness benefits.

The efficacy of real versus sham external Trigeminal Nerve Stimulation (eTNS) in youth with Attention-Deficit/Hyperactivity Disorder (ADHD) over 4 weeks: a protocol for a multi-centre, double-blind, randomized, parallel-group, phase IIb study (ATTENS).

BACKGROUND: Attention Deficit/Hyperactivity Disorder (ADHD), if severe, is usually treated with stimulant or non-stimulant medication. However, users prefer non-drug treatments due to side effects. Alternative non-medication treatments have so far only shown modest effects. External trigeminal nerve stimulation (eTNS) is a minimal risk, non-invasive neuromodulation device, targeting the trigeminal system. It was approved for ADHD in 2019 by the USA Food and Drug administration (FDA) based on a small proof of concept randomised controlled trial (RCT) in 62 children with ADHD showing improvement of ADHD symptoms after 4 weeks of nightly real versus sham eTNS with minimal side effects. We present here the protocol of a larger confirmatory phase IIb study testing efficacy, longer-term persistency of effects and underlying mechanisms of action. METHODS: A confirmatory, sham-controlled, double-blind, parallel-arm, multi-centre phase IIb RCT of 4 weeks of eTNS in 150 youth with ADHD, recruited in London, Portsmouth, and Southampton, UK. Youth with ADHD will be randomized to either real or sham eTNS, applied nightly for 4 weeks. Primary outcome is the change in the investigator-administered parent rated ADHD rating scale. Secondary outcomes are other clinical and cognitive measures, objective hyperactivity and pupillometry measures, side effects, and maintenance of effects over 6 months. The mechanisms of action will be tested in a subgroup of 56 participants using magnetic resonance imaging (MRI) before and after the 4-week treatment. DISCUSSION: This multi-centre phase IIb RCT will confirm whether eTNS is effective in a larger age range of children and adolescents with ADHD, whether it improves cognition and other clinical measures, whether efficacy persists at 6 months and it will test underlying brain mechanisms. The results will establish whether eTNS is effective and safe as a novel non-pharmacological treatment for ADHD. TRIAL REGISTRATION: ISRCTN82129325 on 02/08/2021, https://doi.org/10.1186/ISRCTN82129325 .

Short-term transcutaneous trigeminal nerve stimulation does not affect visual oddball task and paired-click paradigm ERP responses in healthy volunteers.

Recent research suggests that transcutaneous trigeminal nerve stimulation (TNS) may positively affect cognitive function. However, no clear-cut evidence is available yet, since the majority of it derives from clinical studies, and the few data on healthy subjects show inconsistent results. In this study, we report the effects of short-term TNS on event-related potentials (ERP) recorded during the administration of a simple visual oddball task and a paired-click paradigm, both considered useful for studying brain information processing functions. Thirty-two healthy subjects underwent EEG recording before and after 20 min of sham- or real-TNS, delivered bilaterally to the infraorbital nerve. The amplitude and latency of P200 and P300 waves in the simple visual oddball task and P50, N100 and P200 waves in the paired-click paradigm were measured before and after treatment. Our results show that short-term TNS did not alter any of the ERP parameters measured, suggesting that in healthy subjects, short-term TNS may not affect brain processes involved in cognitive functions such as pre-attentional processes, early allocation of attention and immediate memory. The perspective of having an effective, non-pharmacological, non-invasive, and safe treatment option for cognitive decline is particularly appealing; therefore, more research on the positive effects on cognition of TNS is definitely needed.

Non-invasive neuromodulation in the acute treatment of migraine: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: A systematic review and meta-analysis was performed to determine the efficacy of non-invasive neuromodulation modalities for the treatment of acute migraine. BACKGROUND: Although pharmacological treatments are the gold standard for the management of acute migraine, some patients may require non-pharmacological treatment options. Non-invasive neuromodulation may provide an alternative, and techniques include transcranial magnetic stimulation (TMS), non-invasive vagal nerve stimulation (nVNS), non-painful remote electrical stimulation (NRES), and external trigeminal nerve stimulation (e-TNS). METHODS: This systematic review and meta-analysis was performed following PRISMA guidelines. We searched PUBMED, EMBASE, ClinicalTrials.gov, Cochrane Center Register of Controlled Trials, and LILACS databases. We included randomized controlled clinical trials studying patients with migraine treated with any form of non-invasive neuromodulation. Primary outcome was pain freedom within 2 h post-treatment. Secondary outcomes were pain relief within 2-h post-treatment and sustained pain freedom and sustained pain relief 48 h post-treatment. RESULTS: Pooled analysis demonstrated a significant effect of non-invasive neuromodulation on pain-free rates within 2 h (RR, 1.66; 95% CI, 1.35 to 2.05; P < 0.00001) and pain relief rates within 2 h (RR, 1.52; 95% CI, 1.13 to 2.05; P = 0.005) post-treatment. Non-invasive neuromodulation had no significant effect on sustained pain freedom at 48 h (RR, 1.56; 95% CI, 0.68 to 3.59; P = 0.29) or sustained pain relief at 48 h (RR, 1.47; 95% CI, 0.57 to 3.77; P = 0.43) after administration. CONCLUSION: Neuromodulation has demonstrated some efficacy in acute migraine management and may be considered in the treatment paradigm of acute migraine in patients with contraindications to pharmacological therapies.

The Effectiveness of Trigeminal Nerve Stimulation on Traumatic Brain Injury.

OBJECTIVES: Trigeminal nerve stimulation (TNS) is a promising strategy in treating diseases of the nervous system. In this study, the effects of TNS on traumatic brain injury (TBI) were investigated in a mouse model. MATERIALS AND METHODS: TBI was induced using a weight-drop device, and TNS treatment was delivered in the first hour after the TBI. Twenty-four hours later, the mice's behavior, brain edema, and expression of inflammatory factors were tested. Functional magnetic resonance imaging also was used to explore the possible effects of TNS on brain activity. RESULTS: TNS alleviates TBI-induced neurological dysfunction in animal behavior tests, besides protecting the blood-brain barrier and reducing the level of brain edema. TNS also effectively reduces the level of tumor necrosis factor-α and interleukin 6 and downregulates the cleaved caspase-3 signaling pathway. A series of brain areas was found to be possibly regulated by TNS, thus affecting the neural functions of animals. CONCLUSION: This study elucidates the role of TNS as an effective treatment for TBI by inhibiting the occurrence of a secondary brain injury.

Programming Parameters and Techniques in Trigeminal Ganglion Stimulation for Intractable Facial Pain.

OBJECTIVES: Atypical facial pain syndromes are challenging disorders to manage and often incur limited benefit with surgery for classical trigeminal neuralgia presentations, such as microvascular decompression or ablative procedures. Neurostimulation of the trigeminal ganglion and peripheral nerves can be effective at treating atypical presentations of trigeminal facial pain affecting the V1-3 dermatomes, and the surgical techniques are well described. The stimulation parameters, however, have thus far received limited description; we therefore sought to describe programming strategies. MATERIALS AND METHODS: We performed a retrospective chart review, examining patients that underwent trigeminal ganglion stimulation (TGS) and nerve branch stimulation for atypical facial pain and trigeminal neuropathic pain, and describe the programming strategies in detail. RESULTS: We describe the use of high-frequency stimulation (1000 Hz), with alteration in pulse width (60-220 msec) and amplitude (0.5-3 V) to achieve effective treatment of refractory trigeminal facial pain. These parameters differ from existing published parameters for trigeminal nerve branch stimulation. We also describe the programming of specific contacts on each lead to target specific aspects of the individual patients' facial pain. CONCLUSIONS: The use of effective programming strategies is critical to the success of neurostimulation surgical treatments; however, the critical details in programming strategies typically receive limited description. We report on the use of several successful programming strategies for TGS, to assist pain providers in successfully applying these surgical techniques in these difficult to manage atypical facial pain syndromes.

Electroacupuncture trigeminal nerve stimulation plus body acupuncture for chemotherapy-induced cognitive impairment in breast cancer patients: An assessor-participant blinded, randomized controlled trial.

Chemotherapy causes various side effects, including cognitive impairment, known as 'chemobrain'. In this study, we determined whether a novel acupuncture mode called electroacupuncture trigeminal nerve stimulation plus body acupuncture (EA/TNS + BA) could produce better outcomes than minimum acupuncture stimulation (MAS) as controls in treating chemobrain and other symptoms in breast cancer patients. In this assessor- and participant-blinded, randomized controlled trial, 93 breast cancer patients under or post chemotherapy were randomly assigned to EA/TNS + BA (n = 46) and MAS (n = 47) for 2 sessions per week over 8 weeks. The Montreal Cognitive Assessment (MoCA) served as the primary outcome. Digit span test was the secondary outcomes for attentional function and working memory. The quality of life and multiple functional assessments were also evaluated. EA/TNS + BA treated group had much better performance than MAS-treated group on reverse digit span test at Week 2 and Week 8, with medium effect sizes of 0.53 and 0.48, respectively, although no significant differences were observed in MoCA score and prevalence of chemobrain between the two groups. EA/TNS + BA also markedly reduced incidences of diarrhoea, poor appetite, headache, anxiety, and irritation, and improved social/family and emotional wellbeing compared to MAS. These results suggest that EA/TNS + BA may have particular benefits in reducing chemotherapy-induced working memory impairment and the incidence of certain digestive, neurological, and distress-related symptoms. It could serve as an effective intervention for breast cancer patients under and post chemotherapy (trial registration: https://www.clinicaltrials.gov: NCT02457039).

Acute migraine therapy with external trigeminal neurostimulation (ACME): A randomized controlled trial.

OBJECTIVE: To assess the safety and efficacy of external trigeminal nerve stimulation for acute pain relief during migraine attacks with or without aura via a sham-controlled trial. METHODS: This was a double-blind, randomized, sham-controlled study conducted across three headache centers in the United States. Adult patients who were experiencing an acute migraine attack with or without aura were recruited on site and randomly assigned 1:1 to receive either verum or sham external trigeminal nerve stimulation treatment (CEFALY Technology) for 1 hour. Pain intensity was scored using a visual analogue scale (0 = no pain to 10 = maximum pain). The primary outcome measure was the mean change in pain intensity at 1 hour compared to baseline. RESULTS: A total of 109 participants were screened between February 1, 2016 and March 31, 2017. Of these, 106 patients were randomized and included in the intention-to-treat analysis (verum: n = 52; sham: n = 54). The primary outcome measure was significantly more reduced in the verum group than in the sham group: -3.46 ± 2.32 versus -1.78 ± 1.89 ( p < 0.0001), or -59% versus -30% ( p < 0.0001). With regards to migraine subgroups, there was a significant difference in pain reduction between verum and sham for 'migraine without aura' attacks: mean visual analogue scale reduction at 1 hour was -3.3 ± 2.4 for the verum group versus -1.7 ± 1.9 for the sham group ( p = 0.0006). For 'migraine with aura' attacks, pain reduction was numerically greater for verum versus sham, but did not reach significance: mean visual analogue scale reduction at 1 hour was -4.3 ± 1.8 for the verum group versus -2.6 ± 1.9 for the sham group ( p = 0.060). No serious adverse events were reported and five minor adverse events occurred in the verum group. CONCLUSION: One-hour treatment with external trigeminal nerve stimulation resulted in significant headache pain relief compared to sham stimulation and was well tolerated, suggesting it may be a safe and effective acute treatment for migraine attacks. STUDY PROTOCOL: ClinicalTrials.gov Identifier: NCT02590939.

Effect of a 10-day transcutaneous trigeminal nerve stimulation (TNS) protocol for depression amelioration: A randomized, double blind, and sham-controlled phase II clinical trial.

BACKGROUND: Major depressive disorder (MDD) is one of the leading causes of disability in the world. However, treatment options are still limited, and marked by high refractoriness rates, new approaches are needed to optimize clinical improvement. Trigeminal nerve stimulation (TNS) is an innovative neuromodulation strategy consisting on the application of an electric current over the trigeminal nerve that propagates stimuli towards brain areas involved in mood control. OBJECTIVE: We examined the effects of TNS in MDD after a 10-day experimental protocol. METHODS: This was a randomized, double blind, and sham-controlled phase II study with 24 patients with severe MDD. Patients underwent a 10-day intervention protocol and were assessed with the 17-item Hamilton Depression Rating Scale (HDRS-17) at following three observation points: baseline (T1), after 10 days (T2), and after one month of the last stimulation session (T3). Main clinical outcome analysis of variance (ANOVA) was performed. RESULTS: Patients in the active group presented a mean reduction of 36.15% in depressive symptoms after the stimulation protocol. There was a significant interaction between group and time regarding HDRS-17 scores (F = 3.18; df = 2; p = 0.0456). Post hoc analyses exhibited a statistically significant difference between active and sham group symptoms at T2 (p = 0.040) and T3 (p = 0.026), which highlights the sustained amelioration of depressive symptoms. CONCLUSION: The present study found amelioration of depressive symptoms for patients undergoing a 10-day stimulation protocol of TNS, and this was sustained after one month of follow-up.

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.

Effects of acute trigeminal nerve stimulation on rest EEG activity in healthy adults.

Trigeminal nerve stimulation (TNS) is a non-invasive neuromodulation method which is increasingly used for its beneficial effects on symptoms of several neuropsychiatric disorders such as drug-resistant epilepsy. Sites and mechanisms of its action are still unknown. The present study was aimed at investigating the physiological effects of acute TNS on rest electroencephalographic (EEG) activity. EEG was recorded with a 19-channel EEG system from 18 healthy adults who underwent 20 min of sham- and real-TNS (cycles of 30 s ON and 30 s OFF) in two separate sessions. EEG was continuously acquired in the 10-min preceding TNS, during TNS in the "OFF" period and throughout 10 min after TNS. Mean frequency, total power over the 0.5-48 Hz frequency range and absolute power for delta, theta, alpha, beta and gamma bands were analyzed by a discrete Fast Fourier Transform algorithm. Interhemispheric and intrahemispheric coherences were also analyzed for each band at different time points. Intra- and interhemispheric coherences were significantly reduced for the beta frequencies only during real-TNS (p = 0.002 and p = 0.006, respectively). No TNS effect on the power spectra of any band was detected. A trend of increase in the mean EEG frequency total power during real-TNS (p = 0.03) and of decrease in interhemispheric gamma coherence after real-TNS (p = 0.01) was observed. Acute TNS may induce a spatially diffuse desynchronization of fast EEG rhythms in healthy adults, this desynchronization may underpin the antiepileptic effect of TNS described by clinical studies.

Short-term trigeminal neuromodulation does not alter sleep latency in healthy subjects: a pilot study.

It has been reported that during and/or after acute trigeminal nerve stimulation (TNS) a state of sedation, decreased attention and vigilance, with a tendency to fall asleep, occurs. Whether these effects are due to a hypnotic action of TNS is yet to be demonstrated. This pilot study investigates whether acute TNS affects the latency of sleep using the Multiple Sleep Latency Test (MSLT) in healthy subjects. MSLT was performed in 14 healthy subjects after 20 min of real- and a sham-TNS, delivered in two different sessions. Mean latency of sleep across the five naps accorded and the latency of sleep for each nap was determined. All subjects reported a state of relaxation or drowsiness after the real-TNS session. Repeated-measures ANOVA showed no significant differences in sleep latency between the real and sham conditions. The sedative effects of acute TNS do not seem associated to a hypnotic effect.

Cerebral metabolism before and after external trigeminal nerve stimulation in episodic migraine.

Background and aim A recent sham-controlled trial showed that external trigeminal nerve stimulation (eTNS) is effective in episodic migraine (MO) prevention. However, its mechanism of action remains unknown. We performed 18-fluorodeoxyglucose positron emission tomography (FDG-PET) to evaluate brain metabolic changes before and after eTNS in episodic migraineurs. Methods Twenty-eight individuals were recruited: 14 with MO and 20 healthy volunteers (HVs). HVs underwent a single FDG-PET, whereas patients were scanned at baseline, directly after a first prolonged session of eTNS (Cefaly®) and after three months of treatment (uncontrolled study). Results The frequency of migraine attacks significantly decreased in compliant patients ( N = 10). Baseline FDG-PET revealed a significant hypometabolism in fronto-temporal areas, especially in the orbitofrontal (OFC) and rostral anterior cingulate cortices (rACC) in MO patients. This hypometabolism was reduced after three months of eTNS treatment. Conclusion Our study shows that metabolic activity of OFC and rACC, which are pivotal areas in central pain and behaviour control, is decreased in migraine. This hypometabolism is reduced after three months of eTNS. eTNS might thus exert its beneficial effects via slow neuromodulation of central pain-controlling areas, a mechanism also previously reported in chronic migraine and cluster headache after percutaneous occipital nerve stimulation. However, this finding needs to be confirmed by further studies using a sham condition.

Transcutaneous trigeminal nerve stimulation induces a long-term depression-like plasticity of the human blink reflex.

The beneficial effects of trigeminal nerve stimulation (TNS) on several neurological disorders are increasingly acknowledged. Hypothesized mechanisms include the modulation of excitability in networks involved by the disease, and its main site of action has been recently reported at brain stem level. Aim of this work was to test whether acute TNS modulates brain stem plasticity using the blink reflex (BR) as a model. The BR was recorded from 20 healthy volunteers before and after 20 min of cyclic transcutaneous TNS delivered bilaterally to the infraorbital nerve. Eleven subjects underwent sham-TNS administration and were compared to the real-TNS group. In 12 subjects, effects of unilateral TNS were tested. The areas of the R1 and R2 components of the BR were recorded before and after 0 (T0), 15 (T15), 30 (T30), and 45 (T45) min from TNS. In three subjects, T60 and T90 time points were also evaluated. Ipsi- and contralateral R2 areas were significantly suppressed after bilateral real-TNS at T15 (p = 0.013), T30 (p = 0.002), and T45 (p = 0.001), while R1 response appeared unaffected. The TNS-induced inhibitory effect on R2 responses lasted up to 60 min. Real- and sham-TNS protocols produced significantly different effects (p = 0.005), with sham-TNS being ineffective at any time point tested. Bilateral TNS was more effective (p = 0.009) than unilateral TNS. Acute TNS induced a bilateral long-lasting inhibition of the R2 component of the BR, which resembles a long-term depression-like effect, providing evidence of brain stem plasticity produced by transcutaneous TNS. These findings add new insight into mechanisms of TNS neuromodulation and into physiopathology of those neurological disorders where clinical benefits of TNS are recognized.

Optimizing Stimulation in a Case of Facial Pain Through "Cross-Talk" of Peripheral and Central Leads: A Case Report.

OBJECTIVES: To describe inter-lead (cross-talk) stimulation between a trigeminal nerve lead and a cervical epidural lead for the treatment of facial pain in a 69-year-old patient with empty nose syndrome. MATERIALS AND METHODS: A trial implant was performed with a peripheral V2 trigeminal lead and a C1-C2 lead in cross-talk configuration. During permanent implant, the V2 lead was placed uneventfully while the central lead could only be advanced to C3-C4. RESULTS: During the trial, pain decreased by 70%. One month after permanent implant, the patient still experienced a 60-70% reduction in pain levels and a decrease from ten to two weekly pain episodes. Nine months post implant, the patient reported complete pain relief (0/10 on a numeric rating scale ranging from 0 to 10) and medications were discontinued. Infrequent exacerbations (3/10) were controlled by increasing stimulation. Three years post implant, the patient continued to have no baseline pain and could easily control exacerbations. CONCLUSION: Cross-talk configuration between a peripheral and a central lead created a more efficient stimulation technique. The resulting paresthesia was superior to that obtained from either lead alone and exceeded the paresthesia obtained from the combination of the two leads when used simultaneously, without an inter-lead configuration.

Trigeminal Nerve Stimulation for Comorbid Posttraumatic Stress Disorder and Major Depressive Disorder.

OBJECTIVES: External stimulation of the trigeminal nerve (eTNS) is an emerging neuromodulation therapy for epilepsy and depression. Preliminary studies suggest it has an excellent safety profile and is associated with significant improvements in seizures and mood. Neuroanatomical projections of the trigeminal system suggest eTNS may alter activity in structures regulating mood, anxiety, and sleep. In this proof-of-concept trial, the effects of eTNS were evaluated in adults with posttraumatic stress disorder (PTSD) and comorbid unipolar major depressive disorder (MDD) as an adjunct to pharmacotherapy for these commonly co-occurring conditions. MATERIALS AND METHODS: Twelve adults with PTSD and MDD were studied in an eight-week open outpatient trial (age 52.8 [13.7 sd], 8F:4M). Stimulation was applied to the supraorbital and supratrochlear nerves for eight hours each night as an adjunct to pharmacotherapy. Changes in symptoms were monitored using the PTSD Patient Checklist (PCL), Hamilton Depression Rating Scale (HDRS-17), Quick Inventory of Depressive Symptomatology (QIDS-C), and the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q). RESULTS: Over the eight weeks, eTNS treatment was associated with significant decreases in PCL (p = 0.003; median decrease of 15 points; effect size d 1.5), HDRS-17 (p < 0.001; 42% response rate, 25% remission; d 2.1), and QIDS-C scores (p < 0.001; d 1.8), as well as an improvement in quality of life (Q-LES-Q, p < 0.01). eTNS was well tolerated with few treatment emergent adverse events. CONCLUSIONS: Significant improvements in PTSD and depression severity were achieved in the eight weeks of acute eTNS treatment. This novel approach to wearable brain stimulation may have use as an adjunct to pharmacotherapy in these disorders if efficacy and tolerability are confirmed with additional studies.

Trigeminal nerve stimulation modulates brainstem more than cortical excitability in healthy humans.

Multiple sites in the central nervous system (CNS) have been hypothesized to explain the beneficial effects of transcutaneous trigeminal nerve stimulation (TNS) on several disorders. This work investigated the acute effects of TNS on the excitability of brainstem and intracortical circuits, as well as on sensorimotor integration processes at cortical level in physiological conditions. Brainstem excitability was evaluated in seventeen healthy subjects measuring the R1 and R2 areas of the blink reflex (BR) and its recovery cycle, with cortical excitability and sensorimotor integration assessed by probing short-interval (SICI) and long-interval (LICI) intracortical inhibition, with short-interval (SICF), intracortical facilitation (ICF), short-latency (SAI) and long-latency (LAI) inhibition measuring motor potentials evoked in the first dorsal interosseous muscle by TMS of the contralateral motor cortex. Neurophysiological parameters were assessed, in seventeen healthy subjects, before and after cyclic 20-min TNS delivered bilaterally to the infraorbital nerve. After TNS, the area of the R2 was significantly reduced (p = 0.018). By contrast, R1 area and R2 recovery cycle were unaffected. Similarly, SICI, ICF, LICI, SICF, SAI and LAI appeared unaltered after TNS. These data suggest that, in normal subjects, TNS mainly acts on brainstem polysynaptic circuits mediating the R2 component of the BR and plays a minor role in modifying the activity of higher-level structures involved in the R2 recovery cycle and in modulation of cortical excitability. A further investigation of a chronic TNS-induced effect may disclose a higher potential for TNS in producing measurable after effects on its CNS targets.

Effect of a 10-day trigeminal nerve stimulation (TNS) protocol for treating major depressive disorder: a phase II, sham-controlled, randomized clinical trial.

BACKGROUND: Considering both the burden determined by major depressive disorder (MDD) itself and the high refractoriness and recurrence index, alternative strategies, such as trigeminal nerve stimulation (TNS), are the cutting edge instruments to optimize clinical response and to avoid treatment discontinuation and relapse of symptoms. Trigeminal nerve stimulation is an incipient simple, low-cost interventional strategy based on the application of an electric current over a branch of the trigeminal nerve with further propagation of the stimuli towards brain areas related to mood symptoms. METHOD: The study was a phase II, randomized, sham-controlled trial with 40 patients with MDD. Patients with moderate or severe depressive symptoms as assessed by adequate clinical scales underwent a 10-day intervention protocol. Regarding main clinical outcome, analysis of variance (ANOVA) was performed to evaluate mean change scores in depressive symptoms as assessed by the HDRS-17 between baseline (t1), after intervention protocol (t2), and during one-month follow-up (t3). RESULTS: There was a significant interaction between the mean percentage changes in depressive symptoms according to the HDRS in the two groups across the three assessments (F=6.38, df=2, p=0.0033). Post hoc analyses (Bonferroni method) demonstrated a statistically significant difference between depressive symptoms at baseline and t1 (p=0.01) and between depressive symptoms at baseline and t2 (p=0.009). No severe adverse effects were reported. DISCUSSION: Our results in the present controlled trial highlight the possibility of more practical treatment protocols for clinical research, which are similar to those for different neuromodulation strategies such as transcranial direct current stimulation (tDCS). The in-office administration of TNS in our protocol is similar to the schedule for repetitive transcranial magnetic stimulation (rTMS), though over fewer treatment sessions. CONCLUSION: Further controlled studies will contribute to the establishment of the clinical relevance of this new treatment strategy for MDD.

A prospective long-term study of external trigeminal nerve stimulation for drug-resistant epilepsy.

BACKGROUND: External trigeminal nerve stimulation (eTNS) is an emerging noninvasive therapy for drug-resistant epilepsy (DRE). We report the long-term safety and efficacy of eTNS after completion of a phase II randomized controlled clinical trial for drug-resistant epilepsy. METHODS: This was a prospective open-label long-term study. Subjects who completed the phase II randomized controlled trial of eTNS for DRE were offered long-term follow-up for 1year. Subjects who were originally randomized to control settings were crossed over to effective device parameters (30s on, 30s off, pulse duration of 250s, frequency of 120Hz). Efficacy was assessed using last observation carried forward or parametric imputation methods for missing data points. Outcomes included change in median seizure frequency, RRATIO, and 50% responder rate. RESULTS: Thirty-five of 50 subjects from the acute double-blind randomized controlled study continued in the long-term study. External trigeminal nerve stimulation was well tolerated. No serious device-related adverse events occurred through 12months of long-term treatment. At six and twelve months, the median seizure frequency for the original treatment group decreased by -2.39 seizures per month at 6 months (-27.4%) and -3.03 seizures per month at 12 months (-34.8%), respectively, from the initial baseline (p<0.05, signed-rank test). The 50% responder rates at three, six, and twelve months were 36.8% for the treatment group and 30.6% for all subjects. CONCLUSION: The results provide long-term evidence that external trigeminal nerve stimulation is a safe and promising long-term treatment for drug-resistant epilepsy.

Trigeminal nerve stimulation (TNS) protocol for treating major depression: an open-label proof-of-concept trial.

BACKGROUND: Major depressive disorder (MDD) is an incapacitating mental disorder associated with significant personal, social, and economic impairment. Patients with MDD present lower quality of life and higher prevalence of medical conditions, including epilepsy. Noninvasive brain stimulation (NIBS) is a technique that might aid in overcoming some of the current challenges related to pharmacotherapy. Trigeminal nerve stimulation is an incipient, simple, low-cost interventional strategy based on the application of an electric current over a branch of the trigeminal nerve with further propagation of the stimuli toward brain areas related to mood symptoms. METHODS: We performed an open-label proof-of-concept trial using TNS for MDD. To the best of our knowledge, we present a TNS interventional protocol that has not been evaluated for MDD hitherto. RESULTS: A total of 11 patients were studied, with a mean age of 50.36 years (sd: 11.8 from 30 to 60). Only one patient was male. Regarding the main outcome, there was a reduction of depressive symptoms with a mean score of 5.72 (sd: 2.24) (p<0.001) on the HDRS-17. Considering a categorical analysis, all patients presented clinical response defined as a reduction of scores of at least 50%. Only one patient did not reach a remission score (defined as an HDRS score lower than 8). DISCUSSION: In the current neuromodulation scenario, clinical results have been working as truly hypothesis-driven forces, i.e., empirical observation and data analysis from different studies have been highlighting possible mechanisms related to the neurobiological functioning of neuromodulation strategies. The present results, however significant, need to be taken as hypothesis-driven given the study design. Data generalization is jeopardized due to the present study lacking a control group. Our results, therefore, may be overestimated due to intrinsic characteristics such as the placebo effect and Hawthorne effect. CONCLUSION: We present a proof-of-concept trial evaluating a new TNS protocol for depression. Data analysis underscores a significant participation of TNS in ameliorating depressive symptoms of patients with moderate or severe depressive episode. Further controlled studies will contribute to establish the clinical relevance of this new strategy for MDD.