Trigeminal Function Research Articles

Computational fluid dynamic analysis of aggressive turbinate reductions: is it a culprit of empty nose syndrome?

Empty nose syndrome (ENS) remains highly controversial, with aggressive inferior turbinate reduction (ITR) or mucociliary dysfunction frequently implicated. However, the appropriate degree of ITR is highly debatable. We applied individual computed tomography (CT)-based computational fluid dynamics (CFD) to 5 patients receiving relatively aggressive ITR but with no ENS symptoms, and compared them to 27 symptomatic ENS patients who all had histories of aggressive ITRs, and 42 healthy controls. Patients' surgical outcomes were confirmed with 22-item Sino-Nasal Outcome Test (SNOT-22) (ITR: 6.40 ± 4.56; ENS: 58.2 ± 15.9; healthy: 13.2 ± 14.9), Nasal Obstruction Symptom Evaluation (NOSE) scores (ITR: 4.00 ± 2.24; ENS: 69.4 ± 17.1; healthy: 11.9 ± 12.9), and Empty Nose Syndrome 6-Item Questionnaire (ENS6Q) (≥11 for ENS). Both aggressive ITR without ENS symptoms and symptomatic ENS patients had significantly lower nasal resistance (ITR: 0.059 ± 0.020 Pa·s/mL; ENS: 0.052 ± 0.015 Pa·s/mL; healthy: 0.070 ± 0.021 Pa·s/mL) and higher cross-sectional areas surrounding the inferior turbinate (ITR: 0.94 ± 0.21 cm2 ; ENS: 1.19 ± 1.05 cm2 ; healthy: 0.42 ± 0.22 cm2 ) than healthy controls. The lack of significant differences among patient groups indicated similar degrees of surgeries between ITR with and without ENS symptom cohorts. However, symptomatic ENS patients have paradoxical significantly less airflow in the inferior meatus (ITR: 47.7% ± 23.6%; ENS: 25.8% ± 17.6%; healthy: 36.5 ± 15.9%; both p < 0.01), but higher airflow around the middle meatus (ITR: 49.7% ± 22.6%; ENS: 66.5% ± 18.3%; healthy: 49.9% ± 15.1%, p < 0.0001) than aggressive ITR without symptoms and controls. Aggressive ITR patients have increased inferior meatus airflow as expected (p < 0.05). This imbalanced airflow produced less inferior wall-shear-stress distribution among symptomatic ENS patients only (ITR: 42.45% ± 11.4%; ENS: 32.2% ± 12.6%; healthy: 49.7% ± 9.9%). ENS patients (n = 12) also had impaired nasal trigeminal function, as measured by menthol lateralization detection thresholds (ITR: 15.2 ± 1.2; ENS: 10.3 ± 3.9; healthy: 13.8 ± 3.09, both p < 0.0001). Surprisingly, aggressive ITR patients without ENS symptoms have better menthol lateralization detection thresholds (LDTs) than healthy controls. Although turbinate tissue loss is linked with ENS, the degree of ITR that might distinguish postoperative patient satisfaction in their nasal breathing vs development of ENS symptoms is unclear. Our results suggest that a combination of distorted nasal aerodynamics and loss of mucosal sensory function may potentially lead to ENS symptomology.

Correlation of tissue eosinophil count and chemosensory functions in patients with chronic rhinosinusitis with nasal polyps after endoscopic sinus surgery.

To investigate the correlation of tissue eosinophil count and chemosensory functions in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) after endoscopic sinus surgery (ESS). This was a cross-sectional study including 40 patients with a history of ESS for CRSwNP recruited consecutively. Visual analog scale score and the Lund-Kennedy endoscopic score were recorded. Biopsies of the ethmoidal sinus mucosal were performed and evaluated. Chemosensory functions were measured by Sniffin' Sticks and chemosensory event-related potentials (CSERP). The associations between chemosensory functions and tissue eosinophil count were analyzed using Spearman correlation and partial correlation after adjusting the confounding factors. Kendall's tau-b correlation was performed between sneezing score and CSERP with ethyl alcohol (EAL) stimulation. Olfactory and trigeminal nerve function was successfully evaluated using CSERP. Postoperative tissue eosinophil count was correlated with threshold (T) score (partial correlation coefficient r = - 0.460, p = 0.012) and CSERP peak latency for olfactory (N1: partial r = 0.471, p = 0.010; P2: partial r = 0.487, p = 0.007) and mixed olfactory-trigeminal (N1: partial r = - 0.516, p = 0.008; P2: partial r = - 0.590, p = 0.002). There were also correlations between T score and N1 latency with phenyl ethyl alcohol (PEA) (partial r = - 0.560, p < 0.001), between sneezing score and N1 latency with EAL (Kendall's tau-b = - 0.40, p = 0.005). Postoperative tissue eosinophilia is significantly associated with postoperative olfactory disorders as assessed by Sniffin' Sticks and CSERP peak latency. Furthermore, olfaction as measured by T score correlates with olfactory ERP latency in inflammation-associated olfactory dysfunction. Trigeminal sensitivity also appears to relate to tissue eosinophilia, indicating mucosal inflammation can affect both sensory systems in the nose.

IoCT-guided percutaneous radiofrequency ablation for trigeminal neuralgia: how I do it.

Percutaneous trigeminal nerve rhizotomy is usually performed by free-handed puncture of the foramen ovale under radiographic control with the patient kept semiconscious. The procedure has thus been reported to be highly uncomfortable for both the patient and surgeon. To our knowledge, this is the first description of a technique that includes precise navigated, CT-guided puncture of the foramen with the patient in general anesthesia and confirmation of needle placement by intraoperative CT. Radiofrequency ablation of the trigeminal nerve was guided by intraoperative CT navigation with neuromonitoring of trigeminal nerve function. The patient was kept under general anesthesia during the procedure. CT-guided percutaneous trigeminal nerve rhizotomy is a safe and efficient treatment strategy for the management of trigeminal neuralgia without the need of the patient being in a semiconscious state.

Non-invasive vagus nerve stimulation: effects on trigeminal laser evoked potentials

A portable transcutaneous non-invasive device that stimulates the cervical portion of the vagus nerve has been developed (GammaCore®) for the treatment of migraine. Cervical nVNS was shown to rapidly inhibit cortical spreading depression in rodents, providing important insights into the mode of action of nVNS. We aimed to test the effects of cervical nVNS on cortical responses and Gamma Band Oscillations (GBO) induced by painful laser stimuli delivered to the right and left forehead and hands in a cohort of twenty-eight migraine patients. Patients were selected and randomly assigned to active or sham nVNS stimulation on the neck bilaterally with GammaCore®. We recorded Laser evoked responses (LEPs) by stimulating bilaterally the hand and the forehead, in basal condition, during nVNS and sham stimulation and two minutes after stimulation. We observed a significant reduction of amplitude of the P2 wave from the forehead during active nVNS, as compared to basal and sham stimulation. However LEPs amplitude immediately recovered after stimulation session. The sham device induced an evident reduction of LEP amplitude, though not significant in respect to active device. Active nVNS seems to have a transitory effect on the transmission of trigeminal pain, which can contribute to induce changes of trigeminal function improving migraine.

Local experience with radiosurgery for vestibular schwannomas and recommendations for management.

There are many treatment options for vestibular schwannomas (VSs), including radiosurgery. Previous studies have shown good outcomes for smaller tumours. We report the results of a seven-year cohort of patients with VS who were treated at our centre using a linear accelerator-based stereotactic radiosurgery system. We retrospectively reviewed the case notes and magnetic resonance (MR) images of patients with VS treated with radiosurgery. Treatment was administered as either a single 13 Gy session or 25 Gy in five sessions. At our centre, only larger or higher Koos grade VSs, were routinely treated with hypofractionated radiosurgery. Tumour response and hearing were assessed using RECIST criteria and Gardner-Robertson scale, respectively. Other toxicities were assessed using physical examination and history-taking. Freedom from radiological progression was estimated with the Kaplan-Meier method. 46 patients received single-fraction radiosurgery and 31 received hypofractionated radiosurgery. Median follow-up duration was 40.6 months. 29 patients had prior surgery to remove the tumour (median size 1.68 cm3). One patient who had symptomatic increase in tumour size (> 20% in largest diameter) was treated conservatively and subsequently showed stable disease on MR imaging. Progression-free survival was 98.7%. Another patient had symptomatic oedema requiring ventriculoperitoneal shunt insertion. 11 patients had serviceable hearing before radiotherapy and 72.7% of them retained useful hearing (20.1 dB mean decline in pure tone average). Facial and trigeminal nerve functions and sense of equilibrium were preserved in > 90% of patients. Radiosurgery is effective and safe for small VSs or as an adjunct therapy after microsurgery.

Decreased electrogustometric taste sensitivity in patients with acquired olfactory dysfunction.

Cross-modal chemosensory dysfunction between olfaction and gustation is not well known. 180 participants were classified into three groups (60 with olfactory dysfunction, 60 with gustatory dysfunction and 60 healthy controls without chemosensory dysfunction). Olfactory functions were obtained with Sniffin Sticks; gustatory function was measured by suprathreshold gustatory stimuli (taste sprays) and a quasi-threshold measure of taste function (taste strips) for five taste qualities (sweet, salty, sour, bitter and umami). Electric taste threshold was measured using electrogustometry (EGM). In addition, group differences in dietary behaviors were investigated with a specifically designed questionnaire. Patients with olfactory dysfunction had increased electric taste thresholds and decreased scores for the umami taste strip test as compared to healthy controls. Overall there was no major difference between patients with chemosensory dysfunction and healthy controls regarding dietary behaviors, although some patients certainly exhibited dietary problems. Importantly, patients with taste loss, but not patients with smell loss, exhibited a higher degree of depression than controls. Patients with olfactory dysfunction showed decreased taste sensitivity which suggested an interaction between the chemical senses taste, trigeminal function, and olfaction. This provides the basis for including both smell and taste psychophysical assessment in clinical practices. In addition, patients with taste loss appeared to suffer most from chemosensory dysfunction.

Radiotherapy in patients with vestibular schwannoma and neurofibromatosis type 2: clinical results and review of the literature.

To evaluate the long-term outcome of patients with vestibular schwannoma (VS) and neurofibromatosis type 2 (NF2) treated with fractionated stereotactic radiotherapy (FSRT) or stereotactic radiosurgery (SRS). Sixteen VS in 14 patients with NF2 were treated with FSRT (n = 14) and SRS (n = 2). Patients with tumor progression and/or progression of clinical symptoms were selected for treatment. For patients treated with FSRT a median total dose of 57.6 Gy was prescribed with a median fractionation of 5 × 1.8 Gy per week. For patients who underwent SRS a median single dose of 17 Gy was prescribed to the 80% isodose. FSRT and SRS were well tolerated. Local control rate was 94% for a median follow-up time of 131 months; 2- and 5-year progression-free survival were 100%. The probability of maintaining the pretreatment hearing level was 44%. Useful hearing preservation was 33%. Cranial nerve toxicity was moderate. Trigeminal nerve function worsened in 2 patients (12%) and facial nerve function in 3 patients (19%). One patient developed a new tinnitus. FSRT and SRS are both safe and effective noninvasive and minimally invasive treatment options for patients with VS in the setting of NF2. The long-term local control rates are excellent. Functional hearing preservation is worse in patients with VS and NF2 than in patients with sporadic VS.

Investigation of the abnormal nasal aerodynamics and trigeminal functions among empty nose syndrome patients.

Abnormal nasal aerodynamics or trigeminal functions have been frequently implicated in the symptomology of empty nose syndrome (ENS), yet with limited evidence. Individual computed tomography (CT)-based computational fluid dynamics (CFD) was applied to 27 ENS patients to simulate their nasal aerodynamics and compared with 42 healthy controls. Patients' symptoms were confirmed with Empty Nose Syndrome 6-item Questionnaire (ENS6Q), 22-item Sino-Nasal Outcome Test (SNOT-22), and Nasal Obstruction Symptom Evaluation (NOSE) scores. Nasal trigeminal sensitivity was measured with menthol lateralization detection thresholds (LDTs). ENS patients had significantly lower (∼25.7%) nasal resistance and higher (∼2.8 times) cross-sectional areas compared to healthy controls (both p < 0.001). Despite inferior turbinate reductions, CFD analysis demonstrated that ENS patients had increased airflow concentrated in the middle meatus region (66.5% ± 18.3%) compared to healthy controls (49.9% ± 15.1%, p < 0.0001). Significantly less airflow (25.8% ± 17.6%) and lower peak wall shear stress (WSS) (0.58 ± 0.24 Pa) were found in the inferior meatus (vs healthy: 36.5% ± 15.9%; 1.18 ± 0.81 Pa, both p < 0.05), with the latter significantly correlated with the symptom scores of ENS6Q (r = -0.398, p = 0.003). Item-wise, complaints of "suffocation" and "nose feels too open" were also found to be significantly correlated with peak WSS around the inferior turbinate (r = -0.295, p = 0.031; and r = -0.388, p = 0.004, respectively). These correlations were all negative, indicating that less air-mucosal stimulations resulted in worse symptom scores. ENS patients (n = 12) also had impaired menthol LDT when compared to healthy controls (p < 0.0001). This is the first CFD examination of nasal aerodynamics in a large cohort of ENS patients. The results indicated that a combination of loss of neural sensitivity and poorer inferior air-mucosal stimulation may potentially lead to ENS symptomology.

71. Intraoperative blink reflex monitoring during microvascular decompression for trigeminal neuralgia

Microvascular decompression surgery (MVD) is an established technique for refractory trigeminal neuralgia. In order to reduce the risk of 5°, 7° and 8° cranial nerve lesions, intraoperative monitoring is recommended. To evaluate intraoperative BR modification during MVD surgery. Considering the reflex arc, BR could be useful to monitor sensory part of trigeminal nerve, facial nerve and brainstem function during MVD. We evaluated BR intraoperative modifications in all patients who underwent MVD surgery for trigeminal neuralgia from 2013 to 2016. All the patients underwent surgery with monitoring of BAEPs, EMG free run, BR and direct nerves stimulation. BR was recorded in 14/18 patients. In 12/14 R1 amplitude was stable; these patients didn’t report postoperative facial or trigeminal nerve lesions. In 2/14 we observed intraoperative decrease of R1 amplitude. In one patient, we recorded B and C train at EMG free run; after the operation, he experienced a transient facial palsy. In the other patient, we didn’t record spontaneous pathological EMG activity in facial muscles and we recorded stable amplitude responses after direct nerves stimulation. After the operation, he reported hemifacial hypoesthesia. BR can be an integrative monitoring technique during MVD surgery.

The Disputed Discovery of Facial and Trigeminal Nerve Function: Revisiting the Contributions of Herbert Mayo and Charles Bell.

The first description of the voluntary motor function of the facial nerve and separate sensory-motor contributions of the trigeminal nerve is most commonly attributed to Charles Bell. However, a review of the original scientific accounts and subsequent historical publications question the validity of this credit. The objective of the present historical analysis is to clarify the contributions of Herbert Mayo toward discovering the functions of the fifth and seventh cranial nerves and to raise awareness of this historical controversy within the medical literature. Review of Charles Bell's and Herbert Mayo's original dissertations published between 1821 and 1823, and subsequent reports relevant to these primary works. Bell's submissions to the Royal Society of London in 1821 and 1822 describe the seventh nerve as the "respiratory nerve of the face" responsible for involuntary coordination of facial movement with the organs of respiration. Separately, Bell states that the fifth nerve is responsible for sensibility and voluntary movement of the facial muscles. In these accounts, Bell only peripherally alludes to the motor function of the seventh nerve and often comments inaccurately on fifth and seventh cranial nerve innervation. In contrast, in 1822 and 1823, Herbert Mayo first accurately and unequivocally defined the voluntary motor function of the facial nerve and sensory-motor function of the trigeminal nerve on the basis of his detailed experiments. The ultimate transfer of acknowledgment to Bell was rooted in surreptitious reworking of Bell's original dissertations and personal attacks against Mayo rather than arguments of scientific merit. Several notable clinicians and anatomists have contributed to our current understanding of the anatomy and physiology of the facial and trigeminal nerves, including Charles Bell; however, Herbert Mayo should be remembered for first providing a more accurate and clear description of their separate functions.

Trigeminal system in Parkinson's disease: A potential avenue to detect Parkinson-specific olfactory dysfunction

BackgroundOlfactory dysfunction (OD) is very frequent in Parkinson's disease (PD) and observed years before diagnosis. The trigeminal system, a chemosensory system allowing for the perception of spiciness, freshness, etc., is intimately connected to the olfactory system and although usually reduced in OD the trigeminal system is not well characterized in PD. We hypothesize that measuring trigeminal sensitivity potentially allows to discriminate between OD due to PD and OD due to other causes to potentially help the development of an early diagnostic tool. ObjectiveTo evaluate olfactory and trigeminal sensitivity and perception in PD patients and compare them to participants with non-parkinsonian OD (NPOD) and to healthy controls. MethodsWe assessed olfactory function using “Sniffin’ Sticks test” and trigeminal function with the localization task in 28 PD patients, 27 healthy controls and 21 patients with OD unrelated to PD. ResultsPD patients exhibited significantly higher trigeminal sensitivity than NPOD patients (p = 0.002) and performed similar to healthy controls. In contrast, PD and NPOD patients had both similar olfactory scores, significantly below healthy controls. ConclusionThe trigeminal system seems not to be impaired in PD patients even in the presence of OD. Measuring trigeminal sensitivity may therefore allow to differentiate PD-related OD from other forms of OD.

Surgical treatment of rare metastatic tumor in Meckel’s Cave: a case report

Abstract Objectives: Metastases in Meckel’s cave are a rare tumor entity, but they should be considered in patients with a known primary malignancy and who complain of trigeminal neuralgia. Methods: The case of a patient with a left trigeminal neuralgia caused by a metastatic tumor involving the Meckel’s cave and Gasserian ganglion is reported. Preoperative symptoms included headache, trigeminal hyperesthesia and facial pain. Results: The patient underwent microsurgical resection of the tumor, obtaining a histological diagnosis and a resolution of the pain. Trigeminal motor function was preserved. Conclusion: The best treatment for tumors of Meckel’s cave, including metastases, is complete microsurgical removal. Although good results have been reported with radiosurgery, this treatment should be reserved only for nonresectable and residual tumors.

Determinants and Evaluation of Nasal Airflow Perception.

AbstractThe sensation of nasal airflow, or nasal airway patency, is an important consideration in the treatment outcome of nasal airway obstruction. Clinicians striving to optimize the nasal passageway have relied on techniques aimed at decreasing peak airway resistance across nasal valves. Nonetheless, the evaluation of the nasal airway is multifaceted, and the objective determinants of subjective nasal patency remain incompletely elucidated. While rhinomanometry, peak nasal inspiratory airflow, and acoustic rhinometry have traditionally been used in research to focus on resistance as a measure of patency, an emerging body of evidence suggests that subjective nasal patency is more significantly correlated to the dynamic change of nasal mucosal temperature. The objective of this review is to provide the technical background on nasal airflow perception and intranasal trigeminal function as crucial to those performing functional and aesthetic rhinosurgery.

Intranasal trigeminal function in patients with empty nose syndrome.

Trigeminal nerve mediates the perception of nasal airflow. This study examines whether impaired intranasal trigeminal function is a part of the paradoxical nasal obstruction sensation in patients with empty nose syndrome (ENS). Prospective case-control study in a tertiary hospital. Three groups were examined: 1) ENS patients with previous bilateral near total inferior turbinectomy, 2) patients who underwent near total inferior turbinate removal (ITR) without ENS symptoms, and 3) control participants. All participants examined with active anterior rhinomanometry, olfactory testing (extended Sniffin' Sticks test), and trigeminal testing (lateralization task using menthol and odorless solvent). Seventy-one participants were included (21 ENS patients, 18 ITR patients, and 31 controls). Analyses revealed that ENS patients had significantly lower scores on trigeminal lateralization testing than the ITR group and controls. The ENS group had also significantly lower scores in olfactory testing than controls. No statistical differences were found in rhinomanometry between groups. The gender factor was not associated with the chemosensory testing; however, this was not the case with the age factor, as trigeminal test results were negatively correlated. This study demonstrates significantly impaired intranasal trigeminal function in ENS patients when compared with ITR patients and controls. Further prospective studies are needed to clarify the role of preoperative trigeminal function of these patients and the contribution of surgery to this impairment. 3b. Laryngoscope, 127:1263-1267, 2017.

Gamma Knife radiosurgery for treatment of growing vestibular schwannomas in patients with neurofibromatosis Type 2: a matched cohort study with sporadic vestibular schwannomas.

OBJECTIVE Neurofibromatosis Type 2 (NF2) is a tumor syndrome characterized by an autosomal dominant pattern of inheritance. The hallmark of NF2 is the development of bilateral vestibular schwannomas (VSs), generally by 30 years of age. One of the first-line treatment options for small to medium-large VSs is radiosurgery. Although radiosurgery shows excellent results in sporadic VS, its use in NF2-related VS is still a topic of dispute. The aim of this study was to evaluate long-term tumor control, hearing preservation rates, and factors influencing outcome of optimally dosed, contemporary Gamma Knife radiosurgery (GKRS) for growing VSs in patients with NF2 and compare the findings to data obtained in patients with sporadic VS also treated by means of GKRS. METHODS The authors performed a retrospective analysis of 47 growing VSs in 34 NF2 patients who underwent GKRS treatment performed with either the Model C or Perfexion Leksell Gamma Knife, with a median margin dose of 11 Gy. Actuarial tumor control rates were estimated using the Kaplan-Meier method. For patient- and treatment-related factors, a Cox proportional hazards model was used to identify predictors of outcome. Trigeminal, facial, and vestibulocochlear nerve function were assessed before and after treatment. NF2-related VS patients were matched 1:1 with sporadic VS patients who were treated in the same institute, and the same indications for treatment, definitions, and dosimetry were used in order to compare outcomes. RESULTS Actuarial tumor control rates in NF2 patients after 1, 3, 5, and 8 years were 98%, 89%, 87%, and 87%, respectively. Phenotype and tumor volume had significant hazard rates of 0.086 and 22.99, respectively, showing that Feiling-Gardner phenotype and a tumor volume not exceeding 6 cm3 both were associated with significantly better outcome. Actuarial rates of serviceable hearing preservation after 1, 3, 5, and 7 years were 95%, 82%, 59%, and 33%, respectively. None of the patients experienced worsening of trigeminal nerve function. Facial nerve function worsened in 1 patient (2.5%). No significant differences in tumor control, hearing preservation, or complications were found in comparing the results of GKRS for NF2-related VS versus GKRS for sporadic VS. CONCLUSIONS With modern GKRS, the use of low margin doses for treating growing VSs in patients with NF2 demonstrates good long-term tumor control rates. Feiling-Gardner phenotype and tumor volume smaller than 6 cm3 seem to be independently associated with prolonged progression-free survival, highlighting the clinical importance of phenotype assessment before GKRS treatment. In addition, no significant differences in tumor control rates or complications were found in the matched-control cohort analysis comparing GKRS for VS in patients with NF2 and GKRS for sporadic VS. These results show that GKRS is a valid treatment option for NF2-related VS, in addition to being a good option for sporadic VS, particularly in patients with the Feiling-Gardner phenotype and/or tumors that are small to medium in size. Larger tumors in patients with the Wishart phenotype appear to respond poorly to radiosurgery, and other treatment modalities should therefore be considered in such cases.

Reliability of the nociceptive blink reflex evoked by electrical stimulation of the trigeminal nerve in humans.

The nociceptive blink reflex (nBR) can be useful to investigate trigeminal nociceptive function. The aim of this study was to estimate the reliability of the nBR evoked by electrical stimulation of the three branches of the trigeminal nerve under the following conditions: over time (test-retest and intrarater reliability) and by two examiners (interrater reliability). Twenty-one healthy participants were evaluated in two sessions (24h apart). The nBR was elicited by a so-called "nociceptive-specific" electrode placed over the entry zone of the right supraorbital (V1R), infraorbital (V2R), mental (V3R), and left infraorbital (V2L) nerve. The outcomes were individual electrical sensory (I 0) and pain thresholds (I P); root mean square (RMS), area-under-the-curve (AUC), and onset latencies of R2 responses (determined twice after a recalibration session); and stimulus-evoked pain on a 0-10 numerical rating scale. Intraclass correlation coefficients (ICCs) and Kappa statistics were computed (α=5%). ICCs were fair to excellent in 82% of the psychophysical measures (fair 21%, good 31%, excellent 30%) and in 86% of V1R, V2R, and V2L nBR parameters, whereas 52% of V3R showed poor reliability. ICCs for intrarater reliability were fair to good in 70% of measurements (fair 20%, good 50%) and in 75% of interrater measurements after the recalibration (fair 55%, good 20%). All kappa values showed at least fair agreement and the majority of the nBR measures (93%) presented moderate to excellent reliability. The nBR and its associated psychophysical measures can be considered a sufficiently reliable test. The nBR can be recommended as an electrophysiological technique to assess trigeminal nociceptive function.

Clinical features, microsurgical treatment, and outcome of vestibular schwannoma with brainstem compression

Background:Presenting symptoms, treatment considerations, and outcome are strongly related to the extension of vestibular schwannomas (VS). The aim of the current retrospective study was to analyze the clinical features, microsurgical treatment, and outcome of VS with brainstem compression.Methods:Forty-nine patients presented with VS (Hannover grading scale T4a or T4b) in our department. A subgroup analysis was performed among patients without (T4a) and with (T4b) compression and dislocation of the fourth ventricle.Results:Patients with type T4b VS presented significantly more often with long tract signs/ataxia (P < 0.05), tonsillar herniation (P < 0.001), and preoperative hydrocephalus (P < 0.01). No significant difference was found between the groups regarding hearing loss and facial nerve, trigeminal nerve, and lower cranial nerve function. Gross total resection was achieved in 83% of the cases, near total resection was achieved in 15% of the cases, and subtotal resection was performed in 2% of the cases. One patient died after massive postoperative bleeding caused by a coagulopathy. At last follow-up, 69% of the patients had excellent facial nerve function (Grade I–II) and the remaining 31% a fair outcome. Six patients (12%) required permanent ventriculoperitoneal shunting. Hearing was preserved in two patients. Forty-six patients (94%) were independent without occasional assistance (Karnofsky scale 70–100%).Conclusions:VS with brainstem compression is frequently associated with hydrocephalus, ataxia, long tract signs, multiple cranial nerve disorders, and occasionally, signs of intracranial hypertension. Primary microsurgical resection is an appropriate management option for large VS.

Investigation of chemosensitivity during and after an acute cold.

Viral rhinitis (the "common" cold) is a frequent worldwide disease. Olfactory dysfunction is one complication that arises during infection, which in most cases heals up spontaneously upon recovery, whereas in some cases it may persist as a partial or total loss of olfaction. The aim of this prospective study was to investigate the change of other chemosensory systems during a cold. Fifty-eight patients (age 18 to 69 years) with an acute cold were compared to a healthy control group (n = 59; age 19 to 63 years). All patients were examined on 2 occasions separated by approximately 4 weeks. Orthonasal, retronasal, gustatory, and trigeminal nasal function were investigated. Furthermore, ratings of real foods, in terms of intensity and pleasantness, were obtained. Compared to the control group, patients showed a decreased orthonasal (threshold and discrimination) and retronasal function. Furthermore, patients exhibited a decreased sensitivity to salt and a reduced ability to localize menthol, indicating a decreased taste and trigeminal function, respectively. Upon recovery from the infection, orthonasal olfactory and trigeminal sensitivity increased, whereas retronasal sensitivity showed no improvement and salt sensitivity decreased. This comprehensive study provides empirical evidence that chemosensory impairment is prevalent during a cold, and additionally shows for the first time that chemosensory features associated with food consumption persist postinfection.

Diabetes mellitus influences the expression of NPY and VEGF in neurons of rat trigeminal ganglion

BackgroundDiabetes mellitus (DM) influences the trigeminal nerve function by changing the pain response and transduction of the orofacial sensory pathways. It affects the inflammatory response via neuropeptide Y (NPY) and vascular endothelial growth factor (VEGF), which could potentially have a relevant role in the pathophysiology of diabetic neuropathy. The aim was to investigate expression of VEGF and NPY in subpopulations of trigeminal ganglion (TG) neurons in rat models of early DM1 and DM2. MethodsDM1 model was induced by an intraperitoneal (i.p.) injection of streptozotocin (STZ) (55mg/kg). DM2 rats were fed with a high fat diet (HFD) for two weeks and then received 35mg/kg of STZ i.p. Two weeks and 2months after the STZ-diabetes induction, rats were sacrificed and TG was immunohistochemically analyzed for detection of VEGF and NPY expression, and also double immunofluorescence labeling with isolectin (IB4) was completed. ResultsAn increased percentage of NPY+ neurons was observed 2weeks after DM1 and 2months post DM2 induction. NPY immunoreactivity was restricted to IB4-negative small-diameter and IB4+ neurons. Two weeks post induction, DM1 rats showed an increased percentage of VEGF/IB4− large neurons and DM2 rats showed an increased percentage of VEGF/IB4+ neurons. Two months after DM induction, the DM1 group showed a reduced percentage of VEGF/IB4− small neurons. ConclusionThe observed changes may play a critical role in the modulation of nociceptor activity and plasticity of primary sensory trigeminal neurons. The results contribute to the understanding of the basic pathophysiology of trigeminal diabetic neuropathy.

Effects of analgesics on olfactory function and the perception of intranasal trigeminal stimuli.

There is some evidence suggesting that analgesics have an impact on human chemosensory function, especially opioids and cannabinoids are known to interfere with olfactory function. However, largely unknown is the effect of a long-term use of analgesics on the intranasal trigeminal system so far. Here, we investigated olfactory function and the perception of intranasal trigeminal stimuli in pain patients with long-term use of analgesics compared to age-matched healthy controls. For this purpose, a psychophysical approach was chosen to measure these sensory functions in 100 chronic pain patients and 95 controls. Olfactory testing was performed using the 'Sniffin' Sticks' test kit, which involves tests for odour threshold, odour discrimination and odour identification. Further, participants were asked to rate the intensity of trigeminal stimuli by using a visual analogue scale. We observed that the chronic use of pain medication was associated with significantly reduced perception of intranasal trigeminal stimuli and olfactory function compared to age-matched controls without intake of analgesics. Results indicate that non-opioid and opioid drugs, or a combination of both did not differ in their effects on chemosensory function. Further, after eliminating the effect of a co-existing depression and the use of co-analgesics, the negative influence of analgesics on olfactory function and trigeminal perception was still evident. The observed effect might be mediated due to interaction with opioid receptors in trigeminal ganglia and nuclei or due to trigeminal/olfactory interaction. As a practical consequence, patients should be made aware of a possible impairment of their olfactory and trigeminal function under long-term analgesic treatment. WHAT DOES THIS STUDY ADD?: We observed that the chronic use of pain medication was associated with significantly reduced olfactory function and perception of intranasal trigeminal stimuli compared to age-matched controls without intake of analgesics. Non-opioid and opioid drugs did not differ in their effects on chemosensory function.