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Trigeminocardiac Reflex: A Predictable Event with Unpredictable Aspects
Perspectives Commentary on: Sudden Asystole due to Trigeminocardiac Reflex During Transsphenoidal Surgery for Pituitary Tumor by Cho et al. pp. 477.E11-477.E15.
Luigi M. Cavallo, M.D., Ph.D. Department of Neurological Sciences Division of Neurosurgery Università degli Studi di Napoli Federico II
Trigeminocardiac Reflex: A Predictable Event with Unpredictable Aspects Luigi M. Cavallo, Domenico Solari, Felice Esposito
T
he trigeminocardiac reflex (TCR) is a well-defined phenomenon consisting of the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve (7). Clinically, the TCR has been reported to occur during craniofacial and ophthalmologic surgery for many years; in neurosurgery, it was first described in 1999 during surgical treatment of a cerebellopontine angle tumor (6). The TCR has been reported in several other procedures owing to the long course of the trigeminal nerve at the skull base, such as microvascular decompression, transsphenoidal operations, and surgery for tumors around the falx. The experience of Cho et al. further enlarges the series of reports that disclose the TCR as a possible event during transsphenoidal surgery in the wall of the cavernous sinus. In our opinion, every surgeon performing skull base surgery, in particular, pituitary surgery, should be aware of the occurrence of the TCR during a surgical procedure. In these terms, the authors’ contribution is praiseworthy. The authors also show that the postoperative course is usually favorable and uneventful if the TCR is recognized early and managed adequately. Nevertheless, the TCR and its complications cannot be considered a rare event. The rate reported in the authors’ series could have been affected by the lack of a proper awareness; as they pointed out, not every variation in heart rate or blood pressure was detected. In addition, no statistical analysis could be performed because the effective number of adenomas that required manipulation of the cavernous sinus was lacking. The incidence of the TCR during transsphenoidal surgery has ranged from 7.5%–18% in major series, with at least 20% of patients reporting a decrease in heart rate and blood pressure (5,7). This value perhaps could be underestimated owing to
Key words 䡲 Asystole 䡲 Transsphenoidal pituitary surgery 䡲 Trigeminocardiac reflex
Abbreviations and Acronyms TCR: Trigeminocardiac reflex
inappropriate anesthesiology protocol or misinterpretation of presenting signs. It is clear that sudden asystole is not seen in every surgical case in which the TCR occurs. A cardiac or cardiorespiratory arrest could happen similarly, even when minimal alterations or stimulations along neuronal pathways of the reflex arches interfere with the triggering or the reflex response or both. In these cases, a (para)physiologic, predictable reaction turns into a lethal event. In a more recent series, a 1.6% incidence (8 of 502 cases) of asystole or bradycardia was reported in patients undergoing maxillofacial, orthognathic, or temporomandibular surgery (4). Nonetheless, in contrast to other microsurgical procedures, the amount of trigeminal nerve traction or compression during transsphenoidal surgery cannot be established, especially during the treatment of lesions that invade the cavernous sinus (6). It seems that any clinical presenting sign related to the TCR should have been expected in the present series. Nevertheless, before diagnosing such a pathologic entity, it is mandatory to exclude every possible cause of arterial hypotension and changes of arterial rhythm other than the TCR; above all, a cause-effect association has to be defined by examining the effectiveness of the preventive response (1). In this regard, the authors did not report any preoperative dedicated evaluation or any prevention mechanism, and the authors did not address this topic. Little data exists about prophylaxis of the TCR. There is some agreement concerning the fact that light anesthesia, hypoxia, hypercapnia, and acidosis should be corrected, all of which augment the TCR. In addition, it has been identified more recently that potent narcotics and calcium channel blockers may produce “facilitation” for this reflex, increasing the vagal tone via their inhibitory action on the sympathetic nervous system (5, 7).
Department of Neurological Sciences, Division of Neurosurgery, Università degli Studi di Napoli Federico II, Naples, Italy To whom correspondence should be addressed: Luigi Maria Cavallo, M.D., Ph.D. [E-mail: [email protected]]. Citation: World Neurosurg. (2011) 76, 5:407-408. DOI: 10.1016/j.wneu.2011.03.005
WORLD NEUROSURGERY 76 [5]: 407-408, NOVEMBER 2011
www.WORLDNEUROSURGERY.org
407
PERSPECTIVES
The TCR can be prevented either by interfering with stimulation of the afferent pathway or by blocking the efferent impulses. In the case of transsphenoidal surgeries, aside from the avoidance of predisposing factors, prophylactic treatments include cessation, or modulation, of the surgical stimulus, intravenous anticholinergic medication (nonselective muscarinic cholinergic blocker), or local anesthetic block of the afferent nerves. Anticholinergic therapy reduces but does not totally prevent either bradycardia or hypotension, and its use is associated with a wide spectrum of side effects, mostly related to activation of vagal cardioinhibitory fibers and inhibition of adrenergic vasoconstriction. In addition, atropine may cause serious cardiac arrhythmias, especially when halothane is the primary anesthetic (2, 7). The TCR should be interpreted as the expression of a central neurogenic reflex usually leading to rapid cerebrovascular vasodilation as a consequence of excitation of oxygen-sensitive neurons. By this physiologic response, the adjustments of the systemic and cerebral circulations are initiated, diverting blood to the brain or increasing its blood flow, or both; on cessation of the stimulus, the systemic and cerebrovascular adjustments return to normal suggesting that the TCR does not result in a direct effect of hypoxia on cerebral blood vessels, while regulating cerebral blood flow to most vascular beds. The parasympathetic effect of the TCR has to be intended as the side effect of a protective mechanism (2, 7).
REFERENCES 1. Blanc VF: Trigeminocardiac reflexes. Can Anesthiol 38:696-699, 1991. 2. Kumada M, Dampney RA, Reis DJ: The trigeminal depressor response: a novel vasodepressor response originating from the trigeminal system. Brain Res 119:305-326, 1977. 3. McCulloch PF, Paterson IA, West NH: An intact glutamatergic trigeminal pathway is essential for the
408
www.SCIENCEDIRECT.com
Animal studies confirmed that a similar response consisting of a redistribution of blood flow was found to occur in the so-called diving reflex (3, 5). When performing a transsphenoidal approach for the treatment of an invasive pituitary adenoma into the cavernous sinus, the occurrence of any of the aspects of the TCR could be easily anticipated. A correct understanding of the predisposing factors and clinically related symptoms is required to manage the predictable effects of such an event. In patients known to be more prone to this phenomenon, all the rescue maneuvers ranging from intravenous use of anticholinergics to the placement of a temporary pacemaker should be employed to contain the abrupt changes in heart rate. The entire surgical procedure has to be to carefully performed under constant, active monitoring of all hemodynamic parameters in strict cooperation with the anesthesiologists. In recent decades, skull base surgery has increased tremendously; new routes and strategies have been developed, and continuous improvements in terms of outcomes and the reduction of morbidity and mortality rates have been reported. In this specialty, there is an extreme need for keeping the pace; the surgeon has to look beyond, to foresee the special needs of the surgery he or she is attempting; as nature has often disclosed, some of those needs exceed the anatomic knowledge or hand skillfulness of the surgeon.
cardiac response to simulated diving. Am J Physiol 269:R669-R677, 1995. 4. Moonie GT, Ress EL, Elton D: The oculocardiac reflex during strabismus surgery. Can Anaesth Soc J 11:621, 1964. 5. Schaller B: Trigemino-cardiac reflex during transsphenoidal surgery for pituitary adenomas. Clin Neurol Neurosurg 107:468-474, 2005.
7. Schaller BJ, Buchfelder M: Trigemino-cardiac reflex in skull base surgery: from a better understanding to a better outcome? Acta Neurochir (Wien) 148:10291031, 2006. Citation: World Neurosurg. (2011) 76, 5:407-408. DOI: 10.1016/j.wneu.2011.03.005 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com
6. Schaller B, Probst R, Strebel S, Gratzl O: Trigeminocardiac reflex during surgery in the cerebellopontine angle. J Neurosurg 90:215-220, 1999.
1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2011.03.005
Luigi M. Cavallo, M.D., Ph.D. Department of Neurological Sciences Division of Neurosurgery Università degli Studi di Napoli Federico II
Trigeminocardiac Reflex: A Predictable Event with Unpredictable Aspects Luigi M. Cavallo, Domenico Solari, Felice Esposito
T
he trigeminocardiac reflex (TCR) is a well-defined phenomenon consisting of the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve (7). Clinically, the TCR has been reported to occur during craniofacial and ophthalmologic surgery for many years; in neurosurgery, it was first described in 1999 during surgical treatment of a cerebellopontine angle tumor (6). The TCR has been reported in several other procedures owing to the long course of the trigeminal nerve at the skull base, such as microvascular decompression, transsphenoidal operations, and surgery for tumors around the falx. The experience of Cho et al. further enlarges the series of reports that disclose the TCR as a possible event during transsphenoidal surgery in the wall of the cavernous sinus. In our opinion, every surgeon performing skull base surgery, in particular, pituitary surgery, should be aware of the occurrence of the TCR during a surgical procedure. In these terms, the authors’ contribution is praiseworthy. The authors also show that the postoperative course is usually favorable and uneventful if the TCR is recognized early and managed adequately. Nevertheless, the TCR and its complications cannot be considered a rare event. The rate reported in the authors’ series could have been affected by the lack of a proper awareness; as they pointed out, not every variation in heart rate or blood pressure was detected. In addition, no statistical analysis could be performed because the effective number of adenomas that required manipulation of the cavernous sinus was lacking. The incidence of the TCR during transsphenoidal surgery has ranged from 7.5%–18% in major series, with at least 20% of patients reporting a decrease in heart rate and blood pressure (5,7). This value perhaps could be underestimated owing to
Key words 䡲 Asystole 䡲 Transsphenoidal pituitary surgery 䡲 Trigeminocardiac reflex
Abbreviations and Acronyms TCR: Trigeminocardiac reflex
inappropriate anesthesiology protocol or misinterpretation of presenting signs. It is clear that sudden asystole is not seen in every surgical case in which the TCR occurs. A cardiac or cardiorespiratory arrest could happen similarly, even when minimal alterations or stimulations along neuronal pathways of the reflex arches interfere with the triggering or the reflex response or both. In these cases, a (para)physiologic, predictable reaction turns into a lethal event. In a more recent series, a 1.6% incidence (8 of 502 cases) of asystole or bradycardia was reported in patients undergoing maxillofacial, orthognathic, or temporomandibular surgery (4). Nonetheless, in contrast to other microsurgical procedures, the amount of trigeminal nerve traction or compression during transsphenoidal surgery cannot be established, especially during the treatment of lesions that invade the cavernous sinus (6). It seems that any clinical presenting sign related to the TCR should have been expected in the present series. Nevertheless, before diagnosing such a pathologic entity, it is mandatory to exclude every possible cause of arterial hypotension and changes of arterial rhythm other than the TCR; above all, a cause-effect association has to be defined by examining the effectiveness of the preventive response (1). In this regard, the authors did not report any preoperative dedicated evaluation or any prevention mechanism, and the authors did not address this topic. Little data exists about prophylaxis of the TCR. There is some agreement concerning the fact that light anesthesia, hypoxia, hypercapnia, and acidosis should be corrected, all of which augment the TCR. In addition, it has been identified more recently that potent narcotics and calcium channel blockers may produce “facilitation” for this reflex, increasing the vagal tone via their inhibitory action on the sympathetic nervous system (5, 7).
Department of Neurological Sciences, Division of Neurosurgery, Università degli Studi di Napoli Federico II, Naples, Italy To whom correspondence should be addressed: Luigi Maria Cavallo, M.D., Ph.D. [E-mail: [email protected]]. Citation: World Neurosurg. (2011) 76, 5:407-408. DOI: 10.1016/j.wneu.2011.03.005
WORLD NEUROSURGERY 76 [5]: 407-408, NOVEMBER 2011
www.WORLDNEUROSURGERY.org
407
PERSPECTIVES
The TCR can be prevented either by interfering with stimulation of the afferent pathway or by blocking the efferent impulses. In the case of transsphenoidal surgeries, aside from the avoidance of predisposing factors, prophylactic treatments include cessation, or modulation, of the surgical stimulus, intravenous anticholinergic medication (nonselective muscarinic cholinergic blocker), or local anesthetic block of the afferent nerves. Anticholinergic therapy reduces but does not totally prevent either bradycardia or hypotension, and its use is associated with a wide spectrum of side effects, mostly related to activation of vagal cardioinhibitory fibers and inhibition of adrenergic vasoconstriction. In addition, atropine may cause serious cardiac arrhythmias, especially when halothane is the primary anesthetic (2, 7). The TCR should be interpreted as the expression of a central neurogenic reflex usually leading to rapid cerebrovascular vasodilation as a consequence of excitation of oxygen-sensitive neurons. By this physiologic response, the adjustments of the systemic and cerebral circulations are initiated, diverting blood to the brain or increasing its blood flow, or both; on cessation of the stimulus, the systemic and cerebrovascular adjustments return to normal suggesting that the TCR does not result in a direct effect of hypoxia on cerebral blood vessels, while regulating cerebral blood flow to most vascular beds. The parasympathetic effect of the TCR has to be intended as the side effect of a protective mechanism (2, 7).
REFERENCES 1. Blanc VF: Trigeminocardiac reflexes. Can Anesthiol 38:696-699, 1991. 2. Kumada M, Dampney RA, Reis DJ: The trigeminal depressor response: a novel vasodepressor response originating from the trigeminal system. Brain Res 119:305-326, 1977. 3. McCulloch PF, Paterson IA, West NH: An intact glutamatergic trigeminal pathway is essential for the
408
www.SCIENCEDIRECT.com
Animal studies confirmed that a similar response consisting of a redistribution of blood flow was found to occur in the so-called diving reflex (3, 5). When performing a transsphenoidal approach for the treatment of an invasive pituitary adenoma into the cavernous sinus, the occurrence of any of the aspects of the TCR could be easily anticipated. A correct understanding of the predisposing factors and clinically related symptoms is required to manage the predictable effects of such an event. In patients known to be more prone to this phenomenon, all the rescue maneuvers ranging from intravenous use of anticholinergics to the placement of a temporary pacemaker should be employed to contain the abrupt changes in heart rate. The entire surgical procedure has to be to carefully performed under constant, active monitoring of all hemodynamic parameters in strict cooperation with the anesthesiologists. In recent decades, skull base surgery has increased tremendously; new routes and strategies have been developed, and continuous improvements in terms of outcomes and the reduction of morbidity and mortality rates have been reported. In this specialty, there is an extreme need for keeping the pace; the surgeon has to look beyond, to foresee the special needs of the surgery he or she is attempting; as nature has often disclosed, some of those needs exceed the anatomic knowledge or hand skillfulness of the surgeon.
cardiac response to simulated diving. Am J Physiol 269:R669-R677, 1995. 4. Moonie GT, Ress EL, Elton D: The oculocardiac reflex during strabismus surgery. Can Anaesth Soc J 11:621, 1964. 5. Schaller B: Trigemino-cardiac reflex during transsphenoidal surgery for pituitary adenomas. Clin Neurol Neurosurg 107:468-474, 2005.
7. Schaller BJ, Buchfelder M: Trigemino-cardiac reflex in skull base surgery: from a better understanding to a better outcome? Acta Neurochir (Wien) 148:10291031, 2006. Citation: World Neurosurg. (2011) 76, 5:407-408. DOI: 10.1016/j.wneu.2011.03.005 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com
6. Schaller B, Probst R, Strebel S, Gratzl O: Trigeminocardiac reflex during surgery in the cerebellopontine angle. J Neurosurg 90:215-220, 1999.
1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2011.03.005