Occurrence Of Trigeminocardiac Reflex Research Articles

Prophylactic Intra-Arterial Injection of Lidocaine Prevents Trigeminocardiac Reflex During Endovascular Embolization for Dural Arteriovenous Fistula: A Report of 2 Cases

Case seriesPatients: Male, 56-year-old • Male, 57-year-oldFinal Diagnosis: Trigeminocardiac reflexSymptoms: Bradycardia • severe hemodynamic fluctuationMedication: —Clinical Procedure: —Specialty: Anesthesiology • NeurosurgeryObjective:Unusual clinical courseBackground:Trigeminocardiac reflex (TCR) is a unique brain stem reflex that manifests as the sudden onset of hemodynamic perturbation in heart rate and blood pressure as a result of stimulation of any branches of the trigeminal nerve. Onyx™ embolization in cerebrovascular interventional surgery can trigger TCR, leading to severe hemo-dynamic fluctuations and even cardiac arrest. Appropriate prophylactic approaches to prevent Onyx™ embolization-induced TCR are still lacking.Case Reports:We report the cases of 2 patients with recurrent and profound bradycardia due to TCR during endovascular Onyx™ embolization for a dural arteriovenous fistula. Prophylactic intra-arterial injection of lidocaine (10–20 mg) effectively and safely blocked the recurrence and potential occurrence of TCR. These 2 patients had reduced heart rate with either hypotension or hypertension during their TCR episodes, suggesting that stimulating a distinct cerebral artery (occipital artery versus vertebral artery branch) can initiate TCR by provoking the vagus nerve via the common neuronal pathway while simultaneously inhibiting or exciting the sympathetic pathway.Conclusions:Intra-arterial injection of lidocaine during endovascular procedures can be recommended as an effective prophylactic approach for use in the treatment of the cerebrovascular disorder where there is high risk of embolization-induced TCR.

Outcome of Internal Neurolysis for Trigeminal Neuralgia without Neurovascular Compression and Its Relationship with Intraoperative Trigeminocardiac Reflex

Background: Internal neurolysis (IN) is an effective surgical treatment for trigeminal neuralgia (TN) without neurovascular compression (NVC) or postoperative recurrence. However, the trigeminal nerve is directly manipulated during the procedure, and there is a high incidence of trigeminocardiac reflex (TCR). The aim of this study was to retrospectively analyze the outcome of IN and to explore its relationship with the occurrence of intraoperative TCR. Methods: Surgical and anesthesia records of 27 TN patients who underwent surgical treatment with IN at our department between March 2010 and September 2016 were retrospectively analyzed. Patients were divided into 2 groups on the basis of the occurrence of TCR during surgery, and clinical characteristics were compared. Pain intensity was assessed by the Barrow Neurological Institute (BNI) pain intensity score and BNI facial numbness score. Results: TCR was observed in 23 of 27 patients (85.2%); it manifested as obvious changes in mean arterial pressure and heart rate by at least 20% of the baseline values. Trigeminal nerve atrophy was found in 9 patients (33.3%). The immediate pain-free rate was 96.3%, and the “excellent” rate was 72.1% for follow-up, with a rate of numbness or hypesthesia of 97.1%. These outcomes were retrospectively compared between the TCR and non-TCR groups, and there was a nonsignificantly higher “excellent” rate in the TCR group than in the non-TCR group. Conclusions: This study demonstrated that IN is an effective treatment for TN without NVC and has a close relationship with intraoperative TCR. To our knowledge, this is the first research describing TCR during IN.

The Trigeminocardiac Reflex during the Anterior Transpetrosal Approach

Objective The anterior transpetrosal approach (ATPA), during which the trigeminal nerve (TN) is manipulated, has a risk of eliciting the trigeminocardiac reflex (TCR). The aim of this study was to assess the risk of TCR during ATPA. Methods Surgical records of 92 patients who had surgical treatment via ATPA at the Keio University Hospital between December 2005 and June 2015 were retrospectively analyzed. Patients were divided into 2 groups on the basis of the occurrence of TCR during surgery, and clinical and tumor characteristics were compared. Tumor characteristics were evaluated based on preoperative images and intraoperative findings and included the side of the lesion, size of the lesion, tumor size in Meckel cave, pathology of the disease, cavernous sinus invasion, extension into Meckel cave, and adhesion of lesion to TN. Results TCR was observed in 14 of 92 patients (15.2%). TCR occurrence was significantly related to Meckel cave tumor size (P = 0.0264) and adhesion of the lesion to TN (P = 0.0002). Conclusions This study suggests that TCR is related to Meckel cave tumor size and tumor adhesion to TN in ATPA. To our knowledge, this is the first report describing TCR during ATPA.

The Trigeminocardiac Reflex During the Anterior Transpetrosal Approach.

The anterior transpetrosal approach (ATPA), during which the trigeminal nerve (TN) is manipulated, has a risk of eliciting the trigeminocardiac reflex (TCR). The aim of this study was to assess the risk of TCR during ATPA. Surgical records of 92 patients who had surgical treatment via ATPA at the Keio University Hospital between December 2005 and June 2015 were retrospectively analyzed. Patients were divided into 2 groups on the basis of the occurrence of TCR during surgery, and clinical and tumor characteristics were compared. Tumor characteristics were evaluated based on preoperative images and intraoperative findings and included the side of the lesion, size of the lesion, tumor size in Meckel cave, pathology of the disease, cavernous sinus invasion, extension into Meckel cave, and adhesion of lesion to TN. TCR was observed in 14 of 92 patients (15.2%). TCR occurrence was significantly related to Meckel cave tumor size (P= 0.0264) and adhesion of the lesion to TN (P= 0.0002). This study suggests that TCR is related to Meckel cave tumor size and tumor adhesion to TN in ATPA. To our knowledge, this is the first report describing TCR during ATPA.

Occurrence of trigeminocardiac reflex during dental implant surgery: An observational prospective study.

Trigeminocardiac reflex (TCR) is a clinical phenomenon that manifests as s sudden onset of hemodynamic perturbations. TCR has been reported in cranio-maxillofacial surgery resulting in severe medical risks. Monitoring the hemodynamic changes during cranio-maxillofacial surgery can provide important information to ensure the continuous evaluation of patient's physical conditions. This prospective observational study was conducted to determine the hemodynamic alterations related to the possibly of occurrence of TCR in patients during dental implant surgery. One hundred and thirty-five patients (69 males and 66 females) received dental implant placement were enrolled in this study. The hemodynamic changes were evaluated by monitoring heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse oximetry (SpO2). The above data were collected before, during, and after dental implant surgery. The data demonstrated that the minimal values of HR, SBP, and DBP as well as MABP decreased significantly during operation comparing with the corresponding values before operation (p<0.0001). In addition, HR and SBP decreased significantly in post-operation stage comparing with the corresponding values in pre-operation stage (p<0.0001). Comparing to dental implant placement in the mandible, patients received dental implant placement in the maxilla had more risks to confront with MABP reduction (OR=3.98; 95% confidence interval: 1.12-13.2). A significant HR and BP reduction possibly due to TCR can occur during dental implant surgery. Therefore, the dentists should monitor the hemodynamic changes during dental implant surgery to prevent the possible occurrence of medical risks related to TCR.

Rhinitis and sleep disorders: The trigeminocardiac reflex link?

Rhinitis, allergic or non-allergic, is an inflammatory condition of the nose. It is associated with a wide range of sleep disorders that are generally attributed to nasal congestion and presence of inflammatory mediators like cytokines and interleukins. However, the pathophysiological mechanisms behind these sleep disorders remain unclear. On the other hand, the trigeminocardiac reflex (TCR) has recently been linked to various sleep disorders like obstructive sleep apnea, sleep bruxism and rapid eye movement (REM) sleep apnea. TCR can be incited by stimulation of the trigeminal nerve or the area innervated by its branches including the nasal mucosa. Trigeminal nasal afferents can be activated on exposure to noxious stimuli (mechanical or chemical) like ammonia vapors, carbon-dioxide, nicotine, hypertonic saline, air-puffs and smoke. In rhinitis, there is associated neuronal hyper-responsiveness of sensory nasal afferents due to inflammation (which can be suppressed by steroids). This may further lead to increased occurrence of TCR in rhinitis. Moreover, there is involvement of autonomic nervous system both in rhinitis and TCR. In TCR, parasympathetic over activity and sympathetic inhibition leads to sudden onset bradycardia, hypotension, apnea and gastric motility. Also, the autonomic imbalance reportedly plays a significant role in the pathophysiology of rhinitis. Thus, considering these facts we hypothesize that the TCR could be the link between rhinitis and sleep disorders and we believe that further research in this direction may yield significant development in our understanding of sleep disorders in rhinitis.

Trigeminocardiac reflex during endoscopic juvenile nasopharyngeal angiofibroma surgery: an appraisal.

Juvenile nasopharyngeal angiofibroma is a locally aggressive benign tumour which has propensity to erode the skull base. The tumour spreads along the pathways of least resistance and is in close proximity to the extracranial part of trigeminal nerve. Advancements in expanded approaches for endoscopic excision of tumours in infratemporal fossa and pterygopalatine fossa increase the vulnerability for the trigeminocardiac reflex. The manipulation of nerve and its branches during tumour dissection can lead to sensory stimulation and thus inciting the reflex. The aim of our study is to report the occurrence of trigeminocardiac reflex in endoscopic excision of juvenile nasopharyngeal angiofibroma. To describe the occurence of trigeminocardiac reflex during endoscopic endonasal excision of juvenile nasopharyngeal angiofibroma. We studied the occurrence of TCR in 15 patients (out of 242 primary cases and 52 revision cases) operated for endoscopic endonasal excision of JNA. The drop in mean arterial blood pressure and heart rate were observed and measured. To the best of our knowledge of English literature, this is the first case series reporting TCR as complication in endoscopic excision of JNA. occurence of this reflex has been mentioned in various occular, maxillofacial surgeries but its occurence during endoscopic excision of JNA has never been reported before. Manifestation of trigeminocardiac reflex during surgery can alter the course of the surgery and is a potential threat to life. It is essential for the anesthetist and surgeons to be familiar with the presentations, preventive measures and management protocols.

Incidence of trigeminocardiac reflex in maxillofacial surgery: A retrospective study

Introduction: The trigeminocardiac reflex (TCR) is a brainstem reflex that has attracted the attention of many clinical researchers, including neurosurgeons, anaesthetists, ophthalmologists, and general, plastic, and craniomaxillofacial surgeons. However, more maxillofacial surgery studies related to TCR need to be conducted in order to better understand this phenomenon. Aim: The aim of this study was to evaluate the occurrence of TCR during maxillofacial procedures performed between 2008 and 2012 including trauma, orthognathic, and reconstructive surgeries. Additionally, with a literature review provide information regarding its incidence, predisposing factors and management. Subjects and Methods: A five-year retrospective study was conducted to evaluate the charts of 56 healthy patients (classified as American Society of Anaesthesiologists class I) admitted in the Department of Oral and Maxillofacial Surgery from 2008 through 2012 at King Abdulaziz Medical City (formerly known as King Khalid National Guard Hospital), Jeddah. Information regarding the different types of procedures and occurrence of TCR in each case was collected. SPSS (V 11.5) was used to analyse the data collected. Results: The overall incidence of TCR was 20% of all the cases, with the highest percentage occurring during mid face trauma repair followed by upper face reconstructive surgeries. Conclusions: TCR can be fatal and must be taken in consideration. All craniomaxillofacial surgeons are advised to follow guidelines for the management of TCR illustrated by Arasho et al . in 2009.

Functional Outcome Changes in Surgery for Pituitary Adenomas After Intraoperative Occurrence of the Trigeminocardiac Reflex: First Description in a Retrospective Observational Study.

Trigeminocardiac reflex (TCR) represents now a nearly ubiquitary phenomenon in skull base surgery. Functional relevance of the intrainterventional TCR occurrence is hitherto only proven for vestibular schwannoma.In a retrospective observational study, 19 out of 338 (8%) enrolled adult patients demonstrated a TCR during transsphenoidal/transcranial surgery for pituitary adenomas. The 2 subgroups (TCR vs non-TCR) had similar patient's characteristics, risk factors, and histology. Preoperatively, there was a similar distribution of normal pituitary function in the TCR and non-TCR subgroups. In this TCR subgroup, there was a significant decrease of that normal pituitary function after operation (37%) compared to the non-TCR group (60%) (P < 0.03). The TCR subgroup therefore demonstrated a 3.15 times (95%CI 1.15–8.68) higher risk for non-normalizing of postoperative pituitary function compared with the non-TCR subgroup (P < 0.03).It is presented, for the first time, an impact of TCR on the functional hormonal outcome after pituitary surgery and strongly underline again the importance of the TCR in clinical daily practice. As a consequence, TCR should be considered as a negative prognostic factor of hormonal normalization after surgery for pituitary adenomas that should be included into routine practice.

Anesthetic influence on occurrence and treatment of the trigemino-cardiac reflex: a systematic literature review.

Trigeminocardiac reflex (TCR) is defined as sudden onset of parasympathetic dysrhythmia including hypotension, apnea, and gastric hypermotility during stimulation of any branches of the trigeminal nerve. Previous publications imply a relation between TCR and depth of anesthesia. To gain more detailed insights into this hypothesis, we performed a systematic literature review.Literature about occurrence of TCR was systematically identified through searching in Cochrane Central Register of Controlled Trials (CENTRAL), PubMed (MEDLINE), EMBASE (Ovid SP), and the Institute for Scientific Information (ISI Web of Sciences) databases until June 2013, as well as reference lists of articles for risk calculation. In this study, TCR was defined as drop in mean arterial blood pressure and heart rate, both >20% to baseline. We calculated intraoperative cerebral state index (CSI) of each TCR-case using a newly developed method. These data were further divided into 3 subgroups: CSI <40 (deep anesthesia), CSI 40–60 (regular anesthesia), and CSI >60 (slight anesthesia).Including 45 studies with 910 patients, 140 (15%) presented with TCR, and 770 (85%) without TCR during operation. TCR occurrence showed a 1.2-fold higher pooled risk slighter anesthesia (CSI <40: 13%, at CSI 40–60: 21%, and at CSI >60: 27%) compared with deeper anesthesia. In addition, we could discover a 1.3-fold higher pooled risk of higher MABP drop with a strong negative correlation (r = −0.935; r2 = 0.89) and a 4.5-fold higher pooled risk of asystole during TCR under slight anesthesia compared with deeper anesthesia.Our work is the first systematic review about TCR and demonstrates clear evidence for TCR occurrence and a more severe course of the TCR in slight anesthesia underlying the importance of skills in anesthesia management during skull base surgery. Furthermore, we have introduced a new standard method to calculate the depth of anesthesia.

Trigeminocardiac reflex: Some thought to the definition.

Dear Editor, We read with great interest one of the rare prospective studies related to the Trigeminocardiac Reflex (TCR) by Etezadi et al. in the September issue of the Surgical Neurology International.[6] Given the fact that most TCR evidence is based upon case reports and case series,[9] the importance of such studies become more evident. The TCR has long suffered from a lack of proper evidence for a couple of reasons: First, the nomenclature has been partly misleading, as trigeminal stimulation has been only linked to cardiac and cardiovascular changes,[10,13,14] as these are most evident during operation. It should be noted that TCR is originally coined to describe concrete autonomic changes upon stimulation of the trigeminal nerve. These changes include “sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve”.[13] None of the clinical assessments of TCR, to the best of our knowledge, have hitherto concerned the big picture.[3] Second, the reflex is elicited by the maneuvers around any of the branches of cranial nerve V or allegedly upon stimulation of Gasserian ganglion or trigeminal brainstem centers.[11,13] A direct cause and effect assessment of the trigger point of the reflex, however, is ethically not possible in humans unless in proper animal models,[9] but a generally accepted and clinically driven model, which is properly and sufficiently studied, is lacking.[1] Third, the original definition of the reflex did only describe the central part of the reflex[14] and not triggering of the reflex during stimulation of peripheral part, Gasserian ganglion or brainstem trigeminal centers and nuclei,[4,10] a fact that was only discovered recently. Proper definition of the reflex is currently an ongoing debate driven by the continuous new knowledge on this reflex.[4] Fourth, the 20% cut-off of the TCR[14] seems to decrese the true incidence of the reflex,[4] but is the best instrument to exclude common cardiovascular disturbances that are seen during operations and are not related to the reflex. According to Bohluli et al., who for the first time, systematically studied the occurrence of TCR in maxillofacial procedures through clinical trials, a mean decrease of 6.5% and 9.7% compared with baseline was recorded for Le-Fort I osteotomy, respectively, in pulse rate and mean arterial blood pressure.[2] Also in bilateral sagittal split ramus osteotomy, the locally blocked side was associated with mean decreases of 4.6% and 6.8% during splitting and manipulation, respectively, compared with baseline while these values were 17.6% and 21.5% in the control ramus.[3] It seemed that the 20% cut-off is only resulting in the exclusion of the actual cases of occurrence of TCR. Since the magnitude of the reflex seemed to be a factor of aggression of the surgical maneuver – needs verification – the reflex could always be expected and its rate is much higher that what is described throughout the literature. Fifth, not every bradycardia is TCR:[12,14] Besides the strict definition, there is a need of a clear “cause-/effect-relationship. If such clear definitions are used in every case, comparisons of the works related to TCR would be possible and consecutively systematic reviews would be help to create new knowledge.[9] Last, it is thought that the reflex involves coactivation of the sympathetic and parasympathetic reflex.[8] This belief stems mainly in oculocardiac reflex (OCR), which is part of the peripheral TCR,[10] research that has been far more extensive compared to TCR. The incidence of OCR during eye surgery is reportedly significant especially during strabismus surgery.[5] In patients with suppressed vagal tone, ventricular ectopic beats can occur along with reduced bradycardia, which could lead to an increasedrisk of arrhythmias.[7] Based on these findings and observations, the definition of TCR is an ongoing work that is substantially influenced by the continuous and increasingly new knowledge on this reflex.[4] With these new suggestions, as published recently,[4] another interesting approach to study the occurrence of TCR will be to record the mean arterial blood pressure and pulse rate drop compared with the baseline, which is immediately before the stimulation and to report the relative magnitude of the reflex for each procedure. Needless to say, the 20% decrease will still be helpful to report the “more clinically concerning” event of the reflex.

Trigeminocardiac reflex in neurosurgical practice: An observational prospective study

Background:Considering wide variations regarding the incidence of trigeminocardiac reflex (TCR) during cranial neurosurgical procedures, and paucity of reliable data, we intended to design a prospective study to determine the incidence of TCR in patients undergoing standard general anesthesia for surgery of supra/infra-tentorial cranial and skull base lesions.Methods:A total of 190 consecutive patients candidate for elective surgery of supra-tentorial, infra-tentorial, and skull base lesions were enrolled. All the patients were operated in the neurosurgical operating room of a university-affiliated teaching hospital. All surgeries were performed using sufficient depth of anesthesia achieved by titration of propofol–alfentanil mixture, adjusted according to target Cerebral State Index (CSI) values (40-60). All episodes of bradycardia and hypotension indicating the occurrence of TCR during the surgery (sudden decrease of more than 20% from the previous level) were recorded.Results:Four patients, two female and two male, developed episodes of TCR during surgery (4/190; 2.1%). Three patients showed one episode of TCR just at the end of operation when the skin sutures were applied while CSI values were 70-77 and in the last case, when small tumor samples were taken from just beneath the lateral wall of the cavernous sinus TCR episode was seen while the CSI value was 51.Conclusion:TCR is a rare phenomenon during brain surgeries when patient is anesthetized using standard techniques. Keeping the adequate depth of anesthesia using CSI monitoring method may be an advisable strategy during whole period of a neurosurgical procedure.

Determination of trigeminocardiac reflex during rhinoplasty

In most rhinoplasty procedures, osteotomies are usually required. The osteotomy areas are innervated by sensory branches of the trigeminal nerve. The trigeminocardiac reflex (TCR) is clinically defined as the sudden onset of parasympathetic activity during stimulation of the trigeminal nerve. When an osteotomy is performed or external pressure is applied over the nasal bone, the infraorbital nerve may send signals via this nerve. The aim of this prospective study is to determine the blood pressure changes and occurrence of TCR during rhinoplasty. one hundred and eight patients were enrolled into the study. Lidocaine and adrenaline combination (LAC) was injected only into the left lateral osteotomy sites. All patients underwent median, right-side, then left-side lateral osteotomies and nasal pyramid infracture. The haemodynamic changes were recorded. A 10% or more decrease in the heart rate from baseline was considered a TCR. TCR was detected in nine patients following lateral osteotomies and nasal pyramid infracture procedures (8.3%). The authors determined that LAC injection prior to osteotomy did not prevent TCR. Manipulation at or near the infraorbital nerve during rhinoplasty may cause TCR, even if local anaesthetic infiltration is used.

Trigeminocardiac Reflex, Bilateral Sagittal Split Ramus Osteotomy, Gow-Gates Block: A Randomized Controlled Clinical Trial

The behavior of trigeminocardiac reflex (TCR) during maxillofacial surgeries has not yet been sufficiently studied and knowledge of its behavior is limited to some case reports. The present study aimed to assess the occurrence of TCR in bilateral sagittal split ramus osteotomy and to determine the possible effect of Gow-Gates block on its incidence. Twenty candidates for bilateral sagittal split ramus osteotomy (included were American Society of Anesthesiologists I Class III patients with a prognathism of 3 to 5 mm) were given routine general anesthesia after at least 12 hours of fasting. All patients received Gow-Gates mandibular nerve block on 1 random side (case ramus; the other side was used as the control) after induction of general anesthesia before surgery. Pulse rate was recorded at baseline, soft tissue cutting, bone cutting, sagittal splitting, setback manipulation, and recovery. Mean pulse rate values were compared statistically using t test for the 2 sides in patients. No statistically significant differences were found between the blocked and control sides except during ramus sagittal splitting and setback manipulation (P < .0001), when a significantly decreased pulse rate was recorded for the control ramus compared with the blocked ramus. The present study provides further evidence for the complex neurophysiologic mechanism and probable prevention of peripheral TCR. The results of the present study should be further validated through future studies but already provide strong evidence that peripheral and central TCR may act differently based on slightly different pathways.

The role of the trigeminocardiac reflex in postoperative hearing function in non-vestibular schwannoma cerebellopontine angle tumors

The trigeminocardiac reflex (TCR) is a common event during skull base surgery that can lead to intraoperative arterial hypotension and bradycardia. Arterial hypotension associated with TCR can be a negative prognostic factor for postoperative auditory function and ipsilateral tinnitus in patients undergoing surgery for vestibular schwannoma (VS). In this study, the contribution of TCR to postoperative auditory function in non-VS cerebellopontine angle (CPA) tumor surgery was investigated. From a consecutive series of 102 patients with CPA tumors, we studied the occurrence of TCR and its influence on postoperative auditory function in patients with non-VS tumors. Pre- and postoperative auditory function, pre- and intraoperative mean arterial blood pressure, as well as preoperative medication, tumor size, and occurrence of TCR were evaluated. Of the 35 patients evaluated, four developed intraoperative TCR, of whom one was preoperatively deaf. Preoperative functional hearing was detected in 30/35 patients (85.7%): preoperative deafness was documented in one patient in the TCR group and in four patients in the non-TCR group. Of the 30 patients with preoperative functional hearing, 1/3 (33.3%) patients in the TCR group and 23/27 (85.2%) patients in the non-TCR group had functional hearing postoperatively. When patients with large tumors and functional, hearing were considered, only 33.3% of patients in the TCR group and 77.8% of patients in the non-TCR group remained within the same hearing classes following surgical treatment ( p = 0.1573). TCR may be a negative prognostic factor for postoperative auditory function in patients with large, non-VS CPA tumors.

Intraoperative Brainstem Auditory Evoked Potential Observations After Trigeminocardiac Reflex During Cerebellopontine Angle Surgery

The occurrence of trigeminocardiac reflex (TCR) is known to be a negative prognostic factor for hearing preservation in cerebellopontine angle tumor surgery. Our study was conducted to investigate brainstem auditory evoked potential (BAEP) changes after this reflex in cerebellopontine angle tumor surgery and to evaluate their impact on postoperative hearing function. Five of 102 consecutive patients had an intraoperative TCR (4.9%) and were retrospectively evaluated for the intraoperative BAEP changes after TCR and postoperative auditory function (7 to 10 d after surgery). One of the 5 patients was preoperatively deaf and therefore excluded from this analysis. Four patients with preoperative functional hearing developed one or more episodes of TCR. Intraoperative BAEP was maintained in 1 patient, whereas in 3 cases an acute intraoperative BAEP deterioration occurred within 2:04 to 3:27 minutes (mean 2:44 min) after TCR with increased wave latency, decreased wave amplitude, and even wave loss. Two patients had deteriorated BAEP waves until the surgical completion and were postoperatively deaf. Although no direct cause-effect relationship has yet been shown, we suggest TCR as an additional event that may cause BAEP changes. The observed BAEP alterations occurred minutes rather than seconds after the TCR incident leading to both temporary and permanent wave deterioration. This association of BAEP deterioration and TCR occurrence, however, remains yet to be proven justifying further study in the field.

Trigemino-cardiac reflex and antecedent transient ischemic attacks

Objectives: The trigemino-cardiac reflex (TCR) is a brainstem reflex that has gained enormous interest in recent years and was initially described by Schaller and coworkers as a centrally inducible reflex during skull-base surgery. In the meantime, parts of its functional consequences have been described. Here, we present a study that gives special reference to preventive factors of the TCR and investigates the hypothesis linking preceding transient ischemic attacks (TIAs) to the occurrence of TCR. Methods: We retrospectively reviewed 338 consecutive patients with the histological diagnosis of a pituitary adenoma, who were operated on from 2000 to 2006 in the Neurosurgery department of the University of Gottingen in Germany. Depending on the occurrence of intraoperative TCR, patients were divided into TCR and non-TCR groups. In 19 of these patients (6%), we found the intraoperative occurrence of the TCR. The patient characteristics between the two subgroups were comparable. Results: There was a statistically significant difference between the subgroups of precedent TIA (TCR: 11% vs non-TCR: 4%) versus nonprecedent TIA (TCR: 89% vs non-TCR: 96%) regarding the intraoperative occurrence of the TCR (χ2: p < 0.01). Conclusion: A precedent TIA less than 6 weeks before operation represents a significant risk factor for subsequent intraoperative occurrence of the TCR. Our data may indicate, for the first time, the existence of an oxygen-conserving reflex not only in animals but also in humans. Its neuroprotective effect in the context of the TCR is discussed.

Expert opinionThe trigemino-cardiac reflex: a view to the future

Expert opinionThe trigemino-cardiac reflex: a view to the future

Trigemino-cardiac reflex may be refractory to conventional management in adults

Dear Sir, We have read with great interest the recent article of Prabhakar et al. [2] that points out some important aspects about how to prevent the trigeminocardiac reflex (TCR), which we have also pinpointed in our recent articles [5, 7, 9]. But the case report of Prabhakar et al. [2] is of great importance because it demonstrates clearly that application of intravenous anticholinergics to block the muscarinic receptors of the heart—either prophylactically or after the elicit of the reflex—cannot be alone a sufficient strategy to prevent further episodes of TCR [3, 4, 8] as it prevent the occurrence of bradycardia; this recommendation is especially and additionally based on (patho)physiological knowledge [3, 4]. One has therefore to assume that the (potential) adverse effects of epinephrine in combination with pretreatment by calcium-channel blockers eliminated by atropine in Prabhakar et al. case report [2] are evoked by a reflex response through the efferent vagus nerve. From our recent investigations, it seems that insufficient microsurgical technique with coagulation may be one of the principal risk factors of subsequent intraoperative occurrence of TCR. It seems that heat—for example by the use of bipolar coagulation—may impose a big risk for the trigger of the TCR [10]. However, it is interesting that Prabhakar et al [2] found that calcium-channel blocker could have been responsible for the occurrence of the TCR in their patient, an observation that we have made also in our initial report [8]. In this context, an interesting case series of Fujita et al. [1] demonstrates that topical anesthesia with lidocaine on the exposed trigeminal nerve may prevent circulatory turbulence based on a sodium channel blockade during skull base surgery, thus, avoiding an excessive increase of general anesthesia. We are far away to understand the TCR [6], but in the last months we have step by step gain further insights in this interesting and important phenomenon of skull base surgery [5]; not at least by the work of Prabhakar et al [2]. These findings may be in line with the suggestion that the TCR is a physiological, but not a pathophysiological entity [3]. Prevention will only be possible, if we better understand the physiology of this reflex.

Trigeminocardiac reflex during surgery in the cerebellopontine angle

In different experimental studies authors have analyzed the autonomic responses elicited by the electrical, mechanical, or chemical stimulation of the trigeminal nerve system. The trigeminocardiac reflex (TCR) is a well-recognized phenomenon that consists of bradycardia, arterial hypotension, apnea, and gastric hypermotility. It occurs during ocular surgery and during other manipulations in and around the orbit. Thus far, it has not been shown that central stimulation of the trigeminal nerve can also cause this reflex. The TCR was defined as clinical hypotension with a drop in mean arterial blood pressure (MABP) of more than 20% and bradycardia lower than 60 beats/minute. Pre-, intra-, and postoperative heart rate (HR) and blood pressure were reviewed retrospectively in 125 patients who underwent surgery for tumors of the cerebellopontine angle (CPA), and they were divided into a TCR group and a non-TCR group. Of the 125 patients, 14 (11%) showed evidence of TCR during dissection of the tumor near the trigeminal nerve at the brainstem. Their HR fell 38% and their MABP fell 48% during operative procedures as compared with preoperative levels. After cessation of manipulation, the HR and the MABP returned to preoperative levels. Risk factors for the occurrence of TCR were compared with results from the literature. The authors' results show the possibility of occurrence of a TCR during manipulation of the central part of the trigeminal nerve when performing surgery in the CPA.