Bradycardia and the trigeminal nerve

Trigeminocardiac Reflex: A Review and Key Implications to Dermatologic Surgery

BACKGROUND

The trigeminocardiac reflex is a common but underreported occurrence that can vary from benign to life threatening. This reflex can be elicited by placing direct pressure on the globe of the eye or from traction of the extraocular muscles, stimulating the trigeminal nerve.

OBJECTIVE

To provide a review of potential stimuli for the trigeminocardiac reflex within dermatologic surgery and to discuss management options for the treatment of the trigeminocardiac reflex.

METHODS

PubMed and Cochrane were used to identify articles and case reports that established scenarios in which the trigeminocardiac reflex was provoked and subsequently how the reflex was managed.

RESULTS

Within the field of dermatologic surgery, the trigeminocardiac reflex can be stimulated during biopsies, cryoablations, injections, laser treatments, Mohs micrographic surgery, and oculoplastic interventions, most often occurring in an office setting. The most common presentations include significant bradycardia, hypotension, gastric hypermobility, and lightheadedness. The most definitive treatment is cessation of the inciting stimulus, monitoring, and symptomatic management. Glycopyrrolate and atropine are common treatments for severe, intractable cases of the trigeminocardiac reflex.

CONCLUSION

The trigeminocardiac reflex, while underreported and underrepresented in dermatologic literature and dermatologic surgery settings, should be considered in the setting of bradycardia and hypotension during dermatologic procedures.

Perioperative trigeminocardiac reflex in patients undergoing surgical treatment of temporomandibular joint ankylosis: A study

Purpose

The behavior of trigeminocardiac reflex (TCR) is limited to few case reports only in maxillofacial surgery, especially for temporomandibular joint (TMJ) ankylosis cases. The present study aims to find out the incidence of bradycardia due to TCR during intraoperative forceful mouth opening in TMJ ankylosis patients.

Materials and Methods

A prospective, unicentric observational study was conducted selecting those patients who were planned for osteoarthrectomy with interpositional gap arthroplasty under general anesthesia. Sixty cases of TMJ ankylosis were randomly selected from December 2018 to-03-2020. Predictor variables were patient age, gender, and type of ankylosis, and outcome variables were pulse rate, mean arterial blood pressure (MABP), and oxygen saturation level (SPO₂). Data were recorded at baseline and during intraoperative mouth opening via heister jaw stretcher. A Chi-square test was used for testing the association between variables. P values were considered statistically significant at <0.05.

Results

The sample size of 60 subjects has been divided into two age groups (10-19) years and (20-40) years. The mean standard deviation age of the patients was 18.32 ± 6.81 years. About 63.3% were male. Out of 60 cases, 14 patients developed bradycardia. The frequency of bradycardia was found 23.3%. According to logistic regression analysis, age and type of ankylosis were the significant predictors of bradycardia.

Conclusion

We conclude that bradycardia due to TCR in TMJ ankylosis patients is not an uncommon entity. Incidences are more prevalent in the age group of 10-19 years and type IV bony ankylosis. Male had a high incidence of bradycardia though P value was nonsignificant.

The Oculocardiac Reflex: A Review

BACKGROUND

A typical oculocardiac reflex (OCR) is a moderate trigemino-vagal bradycardia elicited by tension on an extraocular muscle (EOM) during strabismus surgery; however, many other orbital stimuli can elicit cardiac slowing including retinopathy of prematurity examination.

METHODS

World literature related to trigeminovagal and oculocardiac reflex covering over 15,000 patients including 51 randomized clinical trials and case reports are analyzed and reviewed. Under an ongoing observational trial in Alaska, anesthetic, patient and surgical influences on routine strabismus surgery using prospective, uniform EOM tension are compared seeking sufficient sample size to characterize this individually widely variable cardiac response.

RESULTS

With adequate sample size, and emphasizing clinical studies controlling type of EOM, muscle tension amount and duration, anticholinergic and opioid medications, the following augment OCR; rapid-acting opioids and dexmedetomidine while OCR is reduced in older patients, the right eye, less EOM tension, deeper inhaled agents, hypocarbia, anticholinergic medications and orbital block. In re-operations, the former are relatively poor predictors of subsequent OCR.

CONCLUSION

Profound bradycardia can occur in almost 10% of strabismus surgery cases without anticholinergic preventive measures, but reliable prediction of OCR remains elusive. With foreknowledge and careful anesthetic monitoring of the patient before EOM manipulation, residual adverse sequelae from OCR are fortunately very rare. Despite well over a century of experience, the teleology for this occasionally dramatic cardiac response to eye surgery is still not known.

Autonomic reflex effect of the inferior turbinate outfracture or bipolar cauterization inferior turbinate reduction surgery

PURPOSE

To compare the autonomic reflexes caused by inferior turbinate outfracture or bipolar cauterization for inferior turbinate reduction surgery.

METHODS

The investigators designed and implemented a prospective study composed of 80 patients who underwent a septoplasty with inferior turbinate reduction. The predictor variable was the type of bilateral reduction operation and included inferior turbinate outfracture with a freer elevator and 20 watts bipolar cauterization for 15 s per side after septoplasty. The primary outcome variable was the intraoperative changes of the heart rate monitored preoperatively and 20 s, 1 min, and 4 min after the turbinate reduction procedure. Other variables were systolic and diastolic blood pressure alterations after the inferior turbinate outfracture or bipolar cauterization procedure. Descriptive and bivariate statistics were computed and the P-value was set at .05.

RESULTS

The sample was composed of 160 procedures in 80 patients grouped as follows: Outfracture (n = 100) and Cauterization (n = 60). There were no significant differences between the ages; grades of the turbinate hypertrophy; preoperative heart rates; and intraoperative 4th-minute heart rates, systolic and diastolic blood pressures. However, baseline systolic (p < 0.001) and diastolic (p < 0.001) blood pressures of the bipolar cauterization group were higher than outfracture group. Bipolar cauterization did not cause any significant changes in the heart rate, systolic and diastolic blood pressures. Inferior turbinate outfracture procedure caused a significant increase in heart rate (65.4 ± 9.82, p < 0.001), systolic (103 ± 8.62, p < 0.001) and diastolic (63.5 ± 7.37, p < 0.001) blood pressures.

CONCLUSION

The results of this study suggest that during the inferior turbinate outfracture procedure, it is important to closely monitor sympathetic and parasympathetic reflexes. The surgeon, and anesthesiologist, must be aware of the early stages of the autonomic reflexes during turbinate reduction.

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.

Prenatal nicotine exposure enhances the trigeminocardiac reflex via serotonin receptor facilitation in brainstem pathways

In this study we used a rat model for prenatal nicotine exposure to test whether clinically relevant concentrations of brain nicotine and cotinine are passed from dams exposed to nicotine to her pups, whether this changes the trigeminocardiac reflex (TCR), and whether serotonergic function in the TCR brainstem circuitry is altered. Pregnant Sprague-Dawley dams were exposed to 6 mg·kg(-1)·day(-1) of nicotine via osmotic minipumps for the duration of pregnancy. Following birth dams and pups were killed, blood was collected, and brain nicotine and cotinine levels were measured. A separate group of prenatal nicotine-exposed pups was used for electrophysiological recordings. A horizontal brainstem slice was obtained by carefully preserving the trigeminal nerve with fluorescent identification of cardiac vagal neurons (CVNs) in the nucleus ambiguus. Stimulation of the trigeminal nerve evoked excitatory postsynaptic current in CVNs. Our data demonstrate that prenatal nicotine exposure significantly exaggerates both the TCR-evoked changes in heart rate in conscious unrestrained pups, and the excitatory neurotransmission to CVNs upon trigeminal afferent nerve stimulation within this brainstem reflex circuit. Application of the 5-HT1A receptor antagonist WAY 100635 (100 μM) and 5-HT2A/C receptor antagonist ketanserin (10 μM)significantly decreased neurotransmission, indicating an increased facilitation of 5-HT function in prenatal nicotine-exposed animals. Prenatal nicotine exposure enhances activation of 5-HT receptors and exaggerates the trigeminocardiac reflex.

Sudden asystole due to trigeminocardiac reflex during transsphenoidal surgery for pituitary tumor

BACKGROUND

A sudden attack of an asystolic phenomenon is an extremely rare event during transsphenoidal surgery (TSS). It may be caused by an extreme type of trigeminocardiac reflex (TCR) during the manipulation of the trigeminal nerve or its innervated structures.

CASE DESCRIPTION

We report two cases of sudden asystole and a case of severe bradycardia due to TCR during TSS. All patients were managed successfully by cessation of the surgical manipulation or with the injection of an anticholinergic agent.

CONCLUSIONS

Although TCR occurs rarely and usually is self-limiting, surgeons should be cautious of its occurrence, especially when manipulating the cavernous sinus during TSS. This allows the early detection and appropriate treatment of this manifestation. Stopping the surgical procedure as soon as TCR occurs is likely to normalize the vital parameters. In addition, if further manipulations are inevitable, the administration of anticholinergic medication should be considered cautiously to improve surgical outcomes.

Anaesthetics differentially modulate the trigeminocardiac reflex excitatory synaptic pathway in the brainstem

The trigeminocardiac reflex (TCR) occurs upon excitation of the trigeminal nerve with a resulting bradycardia and hypotension. While several anaesthetics and analgesics have been reported to alter the incidence and strength of the TCR the mechanisms for this modulation are unclear. This study examines the mechanisms of action of ketamine, isoflurane and fentanyl on the synaptic TCR responses in both neurones in the spinal trigeminal interpolaris (Sp5I) nucleus and cardiac vagal neurones (CVNs) in the Nucleus Ambiguus (NA). Stimulation of trigeminal afferent fibres evoked an excitatory postsynaptic current (EPSC) in trigeminal neurones with a latency of 1.8 ± 0.1 ms, jitter of 625 μs, and peak amplitude of 239 ± 45 pA. Synaptic responses further downstream in the reflex pathway in the CVNs occurred with a latency of 12.1 ± 1.1 ms, jitter of 0.8-2 ms and amplitude of 57.8 ± 7.5 pA. The average conduction velocity to the Sp5I neurones was 0.94 ± 0.18 mm ms(-1) indicating a mixture of A-δ and C fibres. Stimulation-evoked EPSCs in both Sp5I and CVNs were completely blocked by AMPA/kainate and NMDA glutamatergic receptor antagonists. Ketamine (10 μm) inhibited the peak amplitude and duration in Sp5I as well as more distal synapses in the CVNs. Isoflurane (300 μm) significantly inhibited, while fentanyl (1 μm) significantly enhanced, EPSC amplitude and area in CVNs but had no effect on the responses in Sp5l neurones. These findings indicate glutamatergic excitatory synaptic pathways are critical in the TCR, and ketamine, isoflurane and fentanyl differentially alter the synaptic pathways via modulation of both AMPA/kainate and NMDA receptors at different synapses in the TCR.

Trigeminocardiac reflex, bilateral sagittal split ramus osteotomy, Gow-Gates block: a randomized controlled clinical trial

PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Representation of somatosensory inputs within the cortical autonomic network

Regions of the cortical autonomic network (CAN) are activated during muscle contraction. However, it is not known to what extent CAN activation patterns reflect muscle sensory inputs, top-down signals from the motor cortex, and/or motor drive to cardiovascular structures. The present study explored the functional representation of somatosensory afferent input within the CAN with an a priori interest in the insula and ventral medial prefrontal cortex (vMPFC) (n=12). Heart rate (HR) and functional MRI data were acquired during 1) 30s periods of electrical stimulation of the wrist flexors at sub-motor (SUB; Type I,II afferents) and 2) motor thresholds (MOT; Type I,II,III afferents), 3) volitional wrist flexion at 5% maximal voluntary contraction (MVC) to match the MOT tension (VOL5%), and 4) volitional handgrip at 35% MVC to elicit tachycardia (VOL35%). Compared with rest, HR did not change during SUB, MOT, or VOL5% but increased during VOL35% (p<0.001). High frequency HR variability was 29.42±18.87 ms(2) (mean±S.D.) at rest and 39.85±27.60 ms(2) during SUB (p=0.06). High frequency HR variability was decreased during VOL35% compared to rest (p≤0.005). SUB increased activity in the bilateral posterior insula, vMPFC, subgenual anterior cingulate cortex (ACC), mid-cingulate cortex (MCC), and posterior cingulate cortex. MOT increased activity in the left posterior insula and MCC. During VOL5%, activity increased in the right anterior-mid insula. VOL35% was associated with activity in the bilateral insula as well as vMPFC and subgenual ACC deactivation. These data suggest that the left posterior insula processes sensory input from muscle during passive conditions and specifically that Type I and/or II muscle afferent stimulation during SUB impacts the vMPFC and/or subgenual ACC, regions believed to be involved in brain default mode and parasympathetic activity.

Endogenous inhibition of the trigeminally evoked neurotransmission to cardiac vagal neurons by muscarinic acetylcholine receptors

Stimulation of the nasal mucosa by airborne irritants or water evokes a pronounced bradycardia accompanied by peripheral vasoconstriction and apnea. The dive response, which includes the trigeminocardiac reflex, is among the most powerful autonomic responses. These responses slow the heart rate and reduce myocardial oxygen consumption. Although normally cardioprotective, exaggeration of this reflex can be detrimental and has been implicated in cardiorespiratory diseases, including sudden infant death syndrome (SIDS). An essential component of the diving response and trigeminocardiac reflex is activation of the parasympathetic cardiac vagal neurons (CVNs) in the nucleus ambiguus that control heart rate. This study examined the involvement of cholinergic receptors in trigeminally evoked excitatory postsynaptic currents in CVNs in an in vitro preparation from rats. CVNs were identified using a retrograde tracer injected into the fat pads at the base of the heart. Application of the acetylcholinesterase inhibitor neostigmine significantly decreased the amplitude of glutamatergic neurotransmission to CVNs on stimulation of trigeminal fibers. Whereas nicotine did not have any effect on the glutamatergic responses, the muscarinic acetylcholine receptor (mAChR) agonist bethanechol significantly decreased the excitatory neurotransmission. Atropine, an mAChR antagonist, facilitated these responses indicating this trigeminally evoked brain stem pathway in vitro is endogenously inhibited by mAChRs. Tropicamide, an m4 mAChR antagonist, prevented the inhibitory action of the muscarinic agonist bethanechol. These results indicate that the glutamatergic synaptic neurotransmission in the trigeminally evoked pathway to CVNs is endogenously inhibited in vitro by m4 mAChRs.

Trigeminocardiac reflex during Le Fort I osteotomy: a case-crossover study

OBJECTIVE

The present study aimed to assess the occurrence of trigeminocardiac reflex (TCR) during Le Fort I osteotomies.

STUDY DESIGN

This case-crossover study included 25 Le Fort I osteotomy candidates without systemically compromising conditions. Mean arterial blood pressure and pulse rate values were recorded before downfracture (DF) (MABP1, PR1), during DF (MABP2, PR2), and after DF (MABP3, PR3). The data were analyzed using repeated measure ANOVA tests (alpha = 0.05).

RESULTS

PR1 and PR3 were significantly higher than PR2 (P < .001). MABP2 value was significantly lower compared with MABP1 and MABP3 values (P < .001). PR2 and MABP2 showed a mean decrease of 6.5% and 9.7% compared with PR1 and MABP1, respectively.

CONCLUSION

Different values have been suggested for TCR. Considering the limitations, the present study may suggest a revision of the values or descriptions for TCR, at least in maxillofacial Le Fort I osteotomy.

Serotonergic modulation of the trigeminocardiac reflex neurotransmission to cardiac vagal neurons in the nucleus ambiguus

Stimulation of the trigeminal nerve evokes a dramatic decrease in heart rate and blood pressure, and this reflex has generally been termed the trigeminocardiac reflex. A subset of the trigeminocardiac reflex is the diving reflex in which the nasal mucosa is stimulated with water or air-borne chemical irritants. Activation of the diving reflex evokes a pronounced bradycardia, mediated by increased parasympathetic cardiac activity, and is the most powerful autonomic reflex. However, exaggeration of this protective response could be detrimental and has been implicated in Sudden Infant Death Syndrome (SIDS). Despite the importance and strength of the trigeminocardiac reflex, there is little information about the cellular mechanisms and brain stem pathways that constitute this reflex. To address these issues, stimulation of trigeminal afferent fibers and the evoked excitatory postsynaptic currents were recorded in cardiac vagal neurons (CVNs) in an in vitro brain stem slice preparation. This synaptic pathway is robust and activation of the trigeminal pathway often evoked action potentials in CVNs. Application of the serotonin (5-HT) reuptake inhibitor citalopram significantly enhanced these responses. Consistent with the hypothesis this pathway is endogenously modulated by 5-HT receptors the 5-HT1A receptor antagonist, WAY 100635 inhibited, whereas the 5-HT2A/C receptor antagonist, ketanserin facilitated the excitatory neurotransmission to CVNs. The 5-HT1A receptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide increased, whereas the 5-HT2 receptor agonist, alpha-methylserotonin maleate salt inhibited this reflex pathway. These results indicate stimulation of trigeminal fibers evokes a powerful excitatory and polysynaptic pathway to CVNs, and this pathway is endogenously modulated and differentially enhanced and depressed, by 5-HT1A and 5-HT2 receptors, respectively.

Trigemino-cardiac reflex during transsphenoidal surgery for pituitary adenomas: Methodological description of a prospective skull base study protocol

A systematic clinical neuroscience protocol is described for the use to examine the trigemino-cardiac reflex (TCR) response in humans. Target neurosurgical conditions are operations that require manipulations around the peripheral and central part of the trigeminal nerve and its branches, e.g. the cerebellopontine angle or the sellar region. To assess the hemodynamic and cardiac responses of patients after TCR initiation, anesthetic monitoring has been applied. The TCR is defined as a drop of more than 20% of the heart rate and the mean arterial blood pressure compared with the baseline values before the stimulus and coinciding with the surgical manipulation at or around any branches of the trigeminal nerve. By help of illustrative cases, we present for the first time preliminary results regarding the differentiation of the TCR in a central and a peripheral induction during transsphenoidal surgery of pituitary adenomas. Based on these results, we can conclude that we have developed a battery of preoperative examination procedures based on event-related diagnostics that was useful to differentiate different subgroups of TCR during transsphenoidal surgery. The presented protocol can be performed directly pre-, intra- and postoperatively and applied for assessment of TCR even in patients with known risk factors.

The impact of hypotension due to the trigeminocardiac reflex on auditory function in vestibular schwannoma surgery

Object

Surgical manipulation of the fifth cranial nerve during its intra- or extracranial course may lead to bradycardia or even asystole as well as arterial hypotension, a phenomenon described as the trigeminocardiac reflex (TCR). The authors studied the impact of this reflex on postoperative auditory function in patients undergoing vestibular schwannoma (VS) surgery.

Methods

One hundred patients scheduled for VS surgery were studied prospectively for parameters influencing the postoperative auditory function. The evaluation included sex, age, pre- and postoperative auditory function, preoperative mean arterial blood pressure, preoperative medical diseases or medication (for example, antiarrhythmia drugs), tumor size and localization, and the intraoperative occurrence of the TCR.

The TCR, which occurred in 11% of the patients, influenced the postoperative hearing function in the patients with Hannover Class T3 and T4 VSs.

With an overall hearing preservation of 47%, 11.1% of the patients in the TCR group and 51.4% of those in the non-TCR group experienced preserved hearing function postoperatively. In cases involving larger tumors (Hannover Class T3 and T4), an intraoperative TCR was associated with a significantly worse postoperative hearing function during VS surgery (p = 0.005).

Conclusions

The hypotension following TCR is a negative prognostic factor for hearing preservation in patients undergoing VS surgery. Patients’ knowledge of this can be increased pre- and postoperatively. Further study of this phenomenon will advance the understanding of the underlying mechanisms and may help to improve hearing preservation by controlling the occurrence of the TCR.

Trigemino-cardiac reflex during transsphenoidal surgery for pituitary adenomas

BACKGROUND

The trigemino-cardiac reflex (TCR) is a well-recognized phenomenon consisting of bradycardia, arterial hypotension, apnea, and gastric hypermotility. It occurs during ocular surgery or other manipulations around the orbit and can also be elicited by stimulation of the central part of the trigeminal nerve during surgery for processes of the cerebellopontine angle. The present retrospective study was conducted to determine if TCR occurs during transsphenoidal surgery in the same way.

METHODS

TCR was defined as a drop in mean arterial blood pressure (MABP) and the heart rate (HR) of more than 20% to the baseline values before the stimulus and coinciding with manipulation of the trigeminal nerve. Pre-, intra-, and postoperative HR and MABP were retrospectively reviewed in 117 patients who underwent resection of pituitary adenomas near the trigeminal nerve at the cavernous sinus in the supine position. Tumor invasiveness was classified according to the modified Hardy criteria.

RESULTS

Of the 117 patients with immunohistochemically and/or electromicroscopically proven pituitary adenoma, 12 (10%) patients demonstrated intraoperative evidence of TCR according to the strict inclusion criteria. In these 12 patients, the HR and MABP decreased by a mean of 43 and 54%, respectively, from the preoperative mean levels during microsurgical manipulation near the cavernous sinus and returned to physiological levels within 10 min after cessation of this surgical maneuver. The percentage of invasive adenomas (grade III-IV) was significantly higher in the TCR subgroup than in the non-TCR subgroup (83% versus 22%).

CONCLUSION

The present results give evidence for the first time that TCR may occur during transsphenoidal surgery in the supine position for resection of pituitary adenomas near the cavernous sinus, leading to a significant decrease in HR and MABP under a standardized anesthetic protocol.

Trigeminocardiac reflex: a unique case of recurrent asystole during bilateral trigeminal sensory root rhizotomy

BACKGROUND

The trigeminocardiac reflex is the sudden-onset of dysrhythmia and hypotension during manipulation of any of the branches of the trigeminal nerve. The trigeminal nerve and cardioinhibitory vagus nerve constitute the afferent and efferent pathways in the reflex arc. The trigeminocardiac reflex has been reported to occur during craniofacial surgery, balloon-compression rhizolysis of the trigeminal ganglion, and tumour resection in the cerebellopontine angle.

PATIENT & METHOD

A 2-year-old male patient with haemangioma near the sella turcica underwent rhizotomies of both sides of the dorsal sensory roots, of the trigeminal nerves for palliation of intractable trigeminal pain.

RESULTS

In this report, we experienced two unexpected episodes of asystole after transection of the sensory roots of the trigeminal nerves.

CONCLUSION

Sectioning of the intracranial dorsal sensory root of the trigeminal nerve provides clear evidence of the central role of the trigeminal nerve as the afferent pathway of the trigeminocardiac reflex arc.

Trigeminocardiac reflex during surgery in the cerebellopontine angle

OBJECT

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.

METHODS

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 MABP were reviewed retrospectively in 125 patients who underwent surgery for tumors of the cerebellopontine angle (CPA), and they were divided into two groups on the basis of the occurrence of the TCR during surgery. Of the 125 patients, 14 (11%) showed evidence of the TCR during dissection of the tumor near the trigeminal nerve at the brainstem. Their HRs fell 38% and their MABPs fell 48% during operative procedures as compared with preoperative levels. After cessation of manipulation, the HRs and the MABPs returned to preoperative levels. Risk factors for the occurrence of the TCR were compared with results from the literature.

CONCLUSIONS

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.

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.

Perioperative morbidity in maxillofacial orthopaedic surgery: a retrospective study

The data of 2049 patients, who underwent maxillofacial orthopaedic surgery, were retrospectively analysed for major intra- and immediate postoperative complications. Immediate life-threatening complications were very rare. They can in most cases be avoided by good anaesthetic and surgical techniques and adequate postoperative care. The most frequently encountered problem in maxillary surgery is excessive blood loss, whilst a compromised airway due to swelling is the most frequent complication in mandibular surgery. Good co-operation between anaesthetist and surgeon is essential to prevent major intraoperative and immediate postoperative problems.

Bradycardia after orbital injury. Case report

A case of severe bradycardia following orbital trauma is described. This complication caused by the oculocardiac reflex deserves attention when patients are referred for orbital trauma.