Masseter Inhibitory Reflex Research Articles

A Prediction Rule for the Dystonic Spread of Blepharospasm: A 4-Year Prospective Cohort Study.

Blepharospasm (BSP), focal dystonia with the highest risk of spread, lacks clear understanding of early spreading risk factors and objective prognostic indicators. We aimed to identify these risk factors through clinical and electrophysiological assessments, and to establish a predictive model for dystonic spread in BSP. We prospectively followed BSP patients for 4 years, collecting data on dystonic spread, and conducting electrophysiological evaluations. The blink reflex, masseter inhibitory reflex, and trigeminal somatosensory evoked potential were assessed. Univariable and multivariable Cox proportional hazard regression models were used to assess clinical characteristics associated with BSP dystonic spread. A predictive model was constructed using a nomogram, and performance of the model was evaluated using the area under the receiver operating characteristic curve. A total of 136 enrolled participants (mean age 56.34 years) completed a 4-year follow-up. Among them, 62 patients (45.6%) showed spread to other body regions. Multivariable Cox regression analysis showed that a high Hamilton Anxiety Scale score (hazard ratio 1.19, 95% confidence interval 1.13-1.25, p < 0.001), prolonged trigeminal somatosensory evoked potential mandibular branch P1-N2 peak interval (hazard ratio 1.11, 95% confidence interval 1.02-1.21, p = 0.017), and elevated trigeminal somatosensory evoked potential mandibular branch P1-N2 peak amplitude (hazard ratio 1.26, 95% confidence interval 1.12-1.41, p < 0.001) were independent risk factors for BSP dystonic spread within 4 years. Combining these factors, the predictive models demonstrated excellent discriminative ability, with the receiver operating characteristic curve score being 0.797, 0.790, 0.847, and 0.820 at 1, 2, 3 and 4 years after enrollment, respectively. We established a predictive model with significant value for anticipating dystonic spread in BSP, offering crucial evidence. These findings contribute essential insights into the early clinical identification of the development and evolution of BSP diseases. ANN NEUROL 2024.

Effect of Different Treatment Modalities on Masseter Inhibitory Reflex in Patients with Sleep Bruxism: A Case-Control Study

Background: Sleep bruxism (SB) is a parafunctional oral habit that is frequently related to sleep arousals. The masseter inhibitory reflex (MIR) causes reflex inhibition of voluntary contractions of the elevator muscles induced by intense peri- or intraoral mechanical or electrical stimulations. This study aimed to investigate the changes in MIR of patients with SB, and the effect of different treatment modalities on MIR. Methods: In this case-control study, 100 individuals were randomly assigned to four groups (n=25) of conservative treatment (G1), occlusal splint treatment (G2), low-level laser therapy (LLLT) treatment (G3); and control (G4). The MIR was tested in all participants before and one month after treatment. Results: All MIR components of the patients had longer right and left SP1 and right and left SP2 latencies (P=0.017, P=0.043, P&lt;0.001, and P=0.04, respectively), and shorter right and left SP1 and right and left SP2 durations (P=0.021, P=0.021, P&lt;0.001, and P&lt;0.001, respectively) as compared to the control group. The right SP1 and SP2 latencies were prolonged in G3 versus G1 and G2 (P=0.026 and P&lt;0.001, respectively); whereas, the left SP2 latency was prolonged in G2 compared with G1. The right and left SP2 duration was not significantly different among the three treated groups. The left SP1 duration was not significantly different among the three treated groups. Gender had no effect on MIR parameters. Conclusion: SB patients had an abnormal MIR response. LLLT was the most effective compared to other treatment modalities.

Monopolar tDCS might affect brainstem reflexes: A computational and neurophysiological study

ObjectiveTo assess whether monopolar multi-electrode transcranial direct current stimulation (tDCS) montages might selectively affect deep brain structures through computational predictions and neurophysiological assessment. MethodsElectric field distribution in deep brain structures (i.e., thalamus and midbrain) were estimated through computational models simulating tDCS with two monopolar and two monopolar multi-electrode montages. Monopolar multi-electrode tDCS was then applied to healthy subject, and effects on pontine and medullary circuitries was evaluated studying changes in blink reflex (BR) and masseter inhibitory reflex (MIR). ResultsComputational results suggest that tDCS with monopolar multi-electrode montages might induce electric field intensities in deep brain structure comparable to those in grey matter, while neurophysiological results disclosed that BR and MIR were selectively modulated by tDCS only when cathode was placed over the right deltoid. ConclusionsMulti-electrode tDCS (anodes over motor cortices, cathode over right deltoid) could induce significant electric fields in the thalamus and midbrain, and selectively affect brainstem neural circuits. SignificanceMulti-electrode tDCS (anodes over motor cortices, cathode over right deltoid) might be further explored to affect brainstem activity, also in the context of non-invasive deep brain stimulation.

Electrophysiological evidence of subclinical trigeminal dysfunction in patients with COVID-19 and smell impairment: A pilot study.

BackgroundSmell and taste disturbances are among the most frequent neurological symptoms in patients with COVID-19. A concomitant impairment of the trigeminal nerve has been suggested in subjects with olfactory dysfunction, although it has not been confirmed with objective measurement techniques. In this study, we explored the trigeminal function and its correlations with clinical features in COVID-19 patients with impaired smell perception using electrophysiological testing.MethodsWe enrolled 16 consecutive patients with mild COVID-19 and smell impairment and 14 healthy controls (HCs). Olfactory and gustatory symptoms were assessed with self-reported questionnaires. Electrophysiological evaluation of the masseter inhibitory reflex (MIR) and blink reflex (BR) was carried out to test the trigeminal function and its connections within the brainstem.ResultsMasseter inhibitory reflex (MIR) analysis revealed higher latency of ipsilateral and contralateral early silent period in patients when compared with HCs. No significant differences between groups were detected as regards the duration of the early and late silent period. However, several patients showed a prolonged duration of the early silent period. BR evaluation disclosed only an increased amplitude of early components in patients.ConclusionsPatients with COVID-19 and smell impairment show a subclinical trigeminal nerve impairment. Trigeminal alterations mainly involve the oligosynaptic pathway, as a result of either direct viral damage or secondary neuroinflammation of the peripheral trigeminal fibers, whereas the polysynaptic ponto-medullary circuits seem to be spared. The prolonged duration of the early silent period and the increased amplitude of early BR response might reflect a compensatory upregulation of the trigeminal function as a consequence of the olfactory dysfunction.

Effects of sagittal split osteotomy on brainstem reflexes.

This prospective study was designed to assess whether patients with skeletal deformities show characteristic masseter inhibitory reflex (MIR) and blink reflex (BR) patterns. A secondary aim was to investigate whether these reflexes change following bilateral sagittal split osteotomy (BSSO). Fourteen consecutive patients who underwent single-jaw BSSO and 14classI subjects who constituted the control group were enrolled into the study. MIR and BR, obtained by the stimulation of supraorbital (SBR) and mental nerves (MBR), were electrophysiologically recorded. Sensory impairment in the mental nerve distribution was clinically tested. Three evaluation periods were specified as immediately before (T0), 1month (T1) and 6months (T2) after surgery. MIR early silent period duration was significantly shorter in the patients at T0 (p < 0.001). Sensory deficits developed on 23sides after BSSO, of which, 17recovered after 6months. At T1, MBR was inelicitable bilaterally in 3patients and unilaterally in 2patients. These responses were still unrecordable bilaterally in 1patient, and unilaterally in 4patients at T2. MIR were unrecordable on 18sides at T1 and recovered on 11sides at T2. There were no parallels between the clinical sensory deficits and the abnormal results of the reflexes. Shorter MIR in patients with dentofacial abnormalities may be areflection of an adapted trigeminal reflex mechanism. Although MBR and MIR abnormalities do not develop parallel to the clinical sensory deficits, their course might provide insights into the disturbed trigeminal reflex pathways.

The Effect of Cold on the Trigeminal Reflexes

Objective: Effects of muscle cooling on the spinal stretch and monosynaptic reflexes have been studied to describe the properties of Group I and II afferents of muscle spindles. Masseter muscle differs from extremity muscles in structural and numerical features of the muscle spindles. The aim of this study was to examine the muscle spindle afferent features of masseter muscle by applying cold to understand the role of Group I and II afferents in reflexes of masseter. Patients and Methods: We included 12 healthy subjects (7 females and 5 males) in the study. Masseter inhibitory reflex (MIR), jaw tendon reflex (JTR), trigeminal motor evoked potential (MEP), and trigeminal somatosensory evoked potential (SEP) were studied before and after cold application. Left masseter muscle was cooled down to 18°C. We compared the data obtained before and after cold application. Results: After cold application, the mean total duration of MIR was shortened and it was absent in four subjects. The mean amplitude of JTR was higher after cold application (P = 0.018) without any significant change in latency. The mean latency of MEP was delayed without any change in amplitude (P = 0.003). There was no significant difference in SEPs. Conclusions: Changes observed in MIR, JTR, and MEP could not be ascribed to any specific type of muscle spindle afferents. Delayed mean reflex latencies were attributed to the effect of cold on nerve conduction. Summation of peripheral cold and pain receptor features, spindle afferents, and cortical mechanisms might have caused cold-associated changes.

Brainstem reflexes in neuro-Behçet disease

We hypothesized that brainstem responses may allow detection of functional brainstem changes in patients with neuro-Behçet Disease (NBD). Thus, we recorded electrically-induced blink reflex (eBR), auditory blink reflex (aBR) and electrically-induced masseter inhibitory reflex (eMIR) in 16patients with NBD. However, these neurophysiological tests proved to have a poor overall sensitivity compared to neuroimaging for the diagnosis of brainstem lesions. They also showed low sensitivity for the differential diagnosis of focal pontine lesion versus diffuse brainstem disease in NBD.

Objective Assessment of Lingual Nerve Microsurgical Reconstruction.

Lingual nerve (LN) injury is one of the most serious consequences of oral surgery. Prompt microsurgical reconstruction of the nerve can alleviate most of those symptoms leading to satisfactory functional recovery.Thirty-five patients with partial to complete LN injury underwent surgery in the period between January 2006 and May 2015. All patients underwent a preoperative clinical and neurological evaluation with the assessment of lingual tactile and pain sensory thresholds and masseteric inhibitory reflex.All patients underwent explorative surgery and direct microneurorrhaphy of distal and proximal stumps in case of complete lesion, while the removal of traumatic neuroma and the following microneurorrhaphy of distal and proximal stumps of the injured nerve was performed in case of incomplete lesion. Nerve grafting has always been avoided because of distal stump mobilization obtained by severing the submandibular branch of the LN.All patients but 1 exhibited good recovery of tongue sensation, never complete, both clinically and electrophysiologically: recovery of the excitability of masseteric inhibitory reflex suppression components SP1 and SP2 was observed, often with increased latencies but consistent with a functional recovery.All patients feeling pain preoperatively experienced complete relief of algic symptoms.The early microsurgical approach is the most suitable choice for the treatment of LN injuries.

74. Brainstem excitability in Hemifacial Spasm and Post-Facial Palsy Synkinesias and effects of botulinum toxin

Hemifacial Spasm (HFS) and Post-Facial Palsy Syndrome (PFPS) are characterised by synkinesias which electrophysiological hallmark is the lateral spread of the blink reflex, but functional and anatomical evidence of this phenomenon is lacking. To evaluate brainstem excitability in the facial and trigeminal pathways of the affected and unaffected side in HFS and PFPS and modifications induced by botulinum toxin treatment (BoNT-A). The Blink Reflex (BR), BR Recovery Cycle (BRRC) and Masseter Inhibitory Reflex (MIR) were assessed in HFS (n = 10) and PFPS (n = 7), before and after BoNT-A. Facial palsy (FP; n = 4), used as lesional model, and healthy controls (n = 8), were also assessed. BR and MIR were normal in all groups. In all patients BRRC analysis revealed a central hyperexcitability pattern following direct and indirect stimulation on both affected (p = 0.000007) and unaffected (p = 0.00007) sides, with highest effect at 500 ms interstimulus interval. BoNT-A injection did not affect this pattern in all patient groups. These preliminary results may indicate a brainstem compensatory attempt in response to a facial damage which is severe and temporary in PFPS and subtler but persistent in HFS. Central effects of BoNT-A should be searched at a higher level than the brainstem.

P.2.h.012 - Mediterranean diet and mood

We aimed to investigate the influence of high frequency repetitive transcranial magnetic stimulation (rTMS) of the motor cortex on excitability of the masseter inhibitory reflex (MIR) in healthy subjects. Our goal in conducting this study was to obtain a better understanding of the subcortical and cortical networks related to the excitability of the central masticatory pathway.Twenty healthy volunteers participated in this study. MIRs were evaluated both before and after high frequency rTMS to elicit motor evoked potentials (MEPs) using single- and double-shock techniques over the motor cortex. During measurements, the latency and duration of silent periods (SPs) with single magnetic stimulation, and the recovery of SP2 with the double-shock technique, were recorded in basal conditions and immediately after high frequency rTMS. The “real” rTMS condition consisted of 20 stimulus trains delivered at 10 Hz with a 5-s stimulation duration and an intensity of 70% of the active motor threshold (AMT) over the right optimal motor spot for the masseter muscle.were also compared to those obtained after “sham” rTMS 1 week laterUsing the double-shock technique, SP2 recovery time was significantly shorter after high frequency rTMS compared to the basal condition (from 100 to 400 ms; p < 0.001), while at ISIs of 500 and 600 ms, no significant effect was observed (p = 0.084, p = 0.948). There was also no significant change in the SP latency or duration between groups (p > 0.05).High frequency, sub-threshold rTMS of the motor cortex had a facilitative after-effect on the excitability of the MIR. This effect was likely mediated through increased cortical drive to brainstem reflex pathways, which would ultimately accelerate MIR recovery.

Nociceptive masseter inhibitory reflex in patients with myofascial tempromandibular disorders and healthy controls

Nociceptive masseter inhibitory reflex in patients with myofascial tempromandibular disorders and healthy controls

P267 Swallowing and brainstem reflexes before and after mandibular sagittal split osteotomy

Objectives To study the electrophysiological parameters of swallowing and related brainstem reflexes before and after bilateral mandibular sagittal split osteotomy in patients with mandibular dentoskeletal deformities. Methods The patients were divided into 3 groups based on the occlusion pattern, Group I (Angle Class III malocclusion, 7 patients), Group II (Angle Class II malocclusion, 4 patients) and Controls (Class I occlusion, 12 healthy subjects). Swallowing reflex with 3–20 ml water bolus, blink reflexes (BR) with supraorbital and mental nerve stimulation, and masseter inhibitory reflex (MIR) during maximal intercuspidation were studied. Electrophysiological tests were repeated postoperatively in 2nd and 7th months. Results Oral preparation and triggering the pharyngeal phase of swallowing was shorter in Group II (especially with 15–20 ml water) and longer in Group I, as compared to the controls. Oral period shortened after surgery in Group I. In Group II, 2 patients had piecemeal deglutition during swallowing of 10–20 ml water, and one of them became normal after surgery. At the postoperative 2nd month examination, BR with mental nerve stimulation was suppressed bilaterally (with a unilaterally absent MIR) in one patient in Group I and unilaterally in one patient in Group II, with subsequent recovery. Discussion and conclusion Oral phase of swallowing is shorter in Group II, possibly due to the low volume capacity of the oral cavity. BR and MIR abnormalities substantiates the reversible inferior alveolar nerve damage. Significance This study combines the electrophysiological swallowing tests and brainstem reflexes in patients with mandibular malocclusion both before and after surgery.

Excitability of the masseter inhibitory reflex after high frequency rTMS over the motor cortex: A study in healthy humans

ObjectiveWe aimed to investigate the influence of high frequency repetitive transcranial magnetic stimulation (rTMS) of the motor cortex on excitability of the masseter inhibitory reflex (MIR) in healthy subjects. Our goal in conducting this study was to obtain a better understanding of the subcortical and cortical networks related to the excitability of the central masticatory pathway. MethodsTwenty healthy volunteers participated in this study. MIRs were evaluated both before and after high frequency rTMS to elicit motor evoked potentials (MEPs) using single- and double-shock techniques over the motor cortex. During measurements, the latency and duration of silent periods (SPs) with single magnetic stimulation, and the recovery of SP2 with the double-shock technique, were recorded in basal conditions and immediately after high frequency rTMS. The “real” rTMS condition consisted of 20 stimulus trains delivered at 10Hz with a 5-s stimulation duration and an intensity of 70% of the active motor threshold (AMT) over the right optimal motor spot for the masseter muscle. Resultswere also compared to those obtained after “sham” rTMS 1 week later ResultsUsing the double-shock technique, SP2 recovery time was significantly shorter after high frequency rTMS compared to the basal condition (from 100 to 400ms; p<0.001), while at ISIs of 500 and 600ms, no significant effect was observed (p=0.084, p=0.948). There was also no significant change in the SP latency or duration between groups (p>0.05). ConclusionsHigh frequency, sub-threshold rTMS of the motor cortex had a facilitative after-effect on the excitability of the MIR. This effect was likely mediated through increased cortical drive to brainstem reflex pathways, which would ultimately accelerate MIR recovery.

Brainstem Reflexes in Systemic Lupus Erythematosus Patients Without Clinical Neurological Manifestations.

We aimed to assess central and peripheral nervous system involvement in systemic lupus erythematosus (SLE) patients without any neurological signs and symptoms by performing electrophysiological investigations. Thirty-eight SLE patients and 35 healthy volunteers participated in this study. Peripheral nerve conduction and brainstem reflexes were evaluated by performing nerve conduction studies (NCSs) and blink reflex (BR) and masseter inhibitory reflex (MIR) recordings. Eleven patients (29%) had an abnormality in at least 1 NCS parameter, and 1 (2.6%) patient was diagnosed with polyneuropathy. The number of patients with abnormal BR and MIR was 23 (60.5%) and 14 (37%), respectively. The contralateral R2 latency of BR and the silent period 1 (SP1) latency of MIR were significantly prolonged in the patients compared with the controls (p=0.015 and p<0.001, respectively). This study showed that irrespective of peripheral nervous system involvement, brainstem reflexes could be affected in SLE patients even without clinical neurological findings. Brainstem reflex abnormalities suggested that the functional integrity of the inhibitory or excitatory interneurons in the lateral caudal pons and lateral medulla is disturbed in SLE patients.

Brainstem reflex excitability changes in patients with amyotrophic lateral sclerosis.

In this study we explored brainstem reflex excitability changes, blink reflex recovery cycles (BRRCs), and masseter inhibitory reflexes (MIRs) in patients with amyotrophic lateral sclerosis (ALS). Fourteen ALS patients and 14 healthy control subjects were recruited. The BRRC was examined at interstimulus intervals (ISIs) of 100, 200, 300, 400, 500, and 600 ms. The latencies and durations of silent period 1 (SP1) and silent period 2 (SP2) of the MIR were measured. Decreased R2 area suppression was prominent in the ALS group at ISIs of 200, 300, and 400 ms (P < 0.02), whereas no significant differences between groups at 100, 500, and 600 ms ISIs (P > 0.05) were observed. SP2 duration was significantly prolonged in the ALS group compared with controls (P = 0.01). Brainstem inhibitory and excitatory interneuronal activity is altered in ALS, possibly brought about by physiological and morphological changes at the cortical or bulbar levels. Muscle Nerve 56: 925-929, 2017.

How Sleep Bruxism and Tension Headaches Affect the Masseter Inhibitory Reflex

Sleep bruxism (SB) is classified as a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. In recent years, the inhibition of the masseter inhibitory reflex (MIR) has been shown to result in increased bite force during sleep bruxism events. Tension type headaches (TTH) are a hallmark symptom reported by sleep bruxism patients and affect the MIR very similarly to SB.

Sleep bruxism is related to decreased inhibitory control of trigeminal motoneurons, but not with reticulobulbar system.

Sleep bruxism (SB) is a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep. We aimed to understand the abnormal networks related to the excitability of masticatory pathways in patients with SB. Eleven patients with SB and age- and gender-matched 20 healthy subjects were prospectively enrolled in our study. The masseter inhibitory reflex (MIR) after electrical stimulation and auditory startle reaction (ASR) were examined. For MIR responses, durations of early and late silent period (SP) were shorter and the degree of suppression of SPs was significantly lower in SB group in comparison to those obtained in healthy subjects. The ASR responses even of the masseter muscle, however, were similar between patients with SB and healthy individuals. Abnormal MIR provides support for the decreased inhibitory control of the central masticatory circuits in SB whereas normal ASR suggests the integrity and normal functioning of brainstem pathways mediating startle reaction. Although the sample size is small, our results are in line with previous findings and suggest an abnormally decreased inhibition in trigeminal motoneurons to masseter muscle rather than reticulobulbar pathways in patients with SB.

Comparison of brainstem reflex abnormalities in patients with multiple sclerosis, Behçet and stroke and its topodiagnostic value

Background Our current understanding of brainstem reflex physiology comes chiefly from the classic anatomical–functional correlation studies that traced the central circuits underlying brainstem reflexes and establishing reflex abnormalities as markers for specific areas of lesion. Our aim is to investigate the correlation between the brainstem reflex abnormalities and lesion localization in three different diseases with brainstem lesions. Methods Masseter inhibitory and blink reflexes were studied in 21 multiple sclerosis, 15 stroke and 17 Behcet’s disease patients with brainstem lesions on brain magnetic resonance imagings. The reflex responses were compared with those of 20 healthy subjects of comparable age. SPSS for Windows 11.5 package was employed for statistical processing. Results Latency abnormalities of the blink and the masseter inhibitory reflexes were the most prominent in MS group. No significant differences were found in duration and degree of suppression among the groups in MIR responses. The highest abnormality percentages in MS group were in R1component of blink reflex (% 71, 4) and S2 component of masseter inhibitory reflex (% 90, 5). And also R1 of BR and S2 of MRI were the most abnormal responses in the all groups compared to other parameters. Conclusions Distinct reflex abnormalities indicate lesions at specific sites. A number of lesions suspected on clinical data may be confirmed by reflex findings only and not by imaging studies. Reflex testing can be utilized to demonstrate multiple lesions and evaluate dissemination of central nervous involvement in patients with brainstem lesions. Increased abnormality percentage in MS group may be explained by the fact that supratentoriel lesions affect brainstem reflex responses. Since lesions in Behcet’s disease are localised in mesencephalon commonly, superior to MIR and BR circuits, the abnormality in this group is much less relatively.

Brainstem reflexes in patients with sleep bruxism: Masseter inhibitory reflex responses and auditory startle reaction

Background Sleep bruxism (SB) is a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep. Neurophysiologic methods offer approaches to study the excitability in SB by recording the motor potentials evoked by masseter muscles and masseter inhibitory reflex (MIR). Auditory startle reaction (ASR) has been found to be increased in restless leg syndrome but it has not been studied in SB. We aimed to show the hyperexcitability in the central jaw motor pathways in patients with SB by studying MIR and ASR responses. Methods 10 patients (mean age 48,4 ± 10,2 years; 8 male and 2 female) and 20 healthy subjects (mean age 34,4 ± 11,2 years; 6 male and 14 female) were enrolled in the study. The EMG activity was recorded from two masseter muscles by surface electrodes. The duration and latency of early and late silent periods and suppression ratios obtained from patient and control groups were compared. ASR was recorded from o. oculi, masseter, sternocleidomastoid, biceps brachii and tibialis anterior muscles and probability and latencies were evaluated. SPSS for Windows 11.5 package was employed. Results The differences in silent period onset latencies between patients and normal subjects were not significant but durations of early and late silent periods were shorter in SB group. Conclusions These results may indicate a reduced capacity for inhibition by the circuits responsible for the late period in SB and this increased excitability in central motor pathways could derive from an impaired modulation of subcortical structures especially brainstem inhibitory circuits and not from altered cortical mechanisms. Since ASR did not differ between the control and patient groups, it can be possible to say that there’s no abnormality in brainstem and reticulospinal circuits in SB patients.

Trigeminal somatosensory evoked potentials in assessment of craniofacial pain: Preliminary results

Background Craniofacial pain syndromes include various kinds of primary and secondary headaches, most of which are related to trigeminal system such as trigeminal neuralgia, trigeminal neuropathy, cluster headache or other trigeminal autonomic cephalalgia. Blink reflex, masseter inhibitory reflex, jaw jerk and trigeminal laser-evoked potentials are known to be more reliable in neurophysiological testing of trigeminal system and electrophysiologic testing of trigeminal reflexes accurately distinguishes symptomatic and classic trigeminal neuropathy. Here, we aimed to evaluate the reliability and stability of trigeminal nerve somatosensory evoked potentials (TSEP) in less frequently encountered craniofacial pain syndromes. Patients and method TSEP and blink reflex (BR) were recorded in 10 patients with craniofacial pain during the active disease period and in 25 healthy individuals. The latencies of N2, P2 and N3 waves as well as amplitudes of N2/P1 and N2/P2 were measured. Results We could not obtain TSEP in three patients (30%) whereas it was elicited in all healthy subjects ( p = 0.01). All of the patients without TSEP response had idiopathic etiology and only one of them also lacked BR responses. Latencies appeared to be longer in patients with craniofacial pain compared to healthy subjects. However, BR responses were symmetrical and within normal ranges. Conclusion Keeping in mind the low number of participants included, we think that TSEP is able to be obtained in a stable manner in healthy subjects and it may be more capable to reflect changes in pain conditions compared to BR.