|Year : 2013 | Volume
| Issue : 2 | Page : 108-110
Transient asystole after mandibular nerve block
Sujoy Banik, Arvind Chaturvedi, Ashish Bindra, Renu Bala
Department of Neuroanesthesiology, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||4-Oct-2013|
Department of Neuroanaesthesiology, Jai Prakash Narain Apex Trauma Centre, All India Institute of Medical Sciences, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
Blockade of the trigeminal nerve and its branches at various locations is a well-established procedure to treat intractable pain syndromes in the distribution of the nerve. Mandibular nerve block is a commonly performed procedure by anesthesiologists, pain physicians, as well as dental practitioners. As it is considered to be a safe procedure, it is usually performed in an outpatient setting with or without monitoring. The complications associated with mandibular nerve block include intravascular injection, hypoesthesia, dysesthesia, sensory loss in mandibular nerve distribution, facial swelling, weakness of the masseter muscle, and injury to the auditory tube leading to severe vertigo. Here, we present an uncommon complication during mandibular nerve block with lignocaine in a patient of trigeminal neuralgia who suffered transient asystole during the procedure. The case highlights the importance of monitoring and emphasizes the need for additional precautions to be taken during pain procedures particularly in high-risk populations such as geriatric patients.
Asystole, complications, chronic pain, mandibular nerve block
|How to cite this article:|
Banik S, Chaturvedi A, Bindra A, Bala R. Transient asystole after mandibular nerve block. Indian J Pain 2013;27:108-10
| Introduction|| |
Blockade of the trigeminal nerve and its branches at various locations is a well-established procedure to treat pain syndromes in the distribution of the nerve. Mandibular nerve block is a commonly performed procedure usually in an outpatient setting with or without monitoring. Used equally by anesthesiologists, pain physicians, as well as dental practitioners, it is generally considered a safe procedure resulting in desired pain control; however, rarely, serious complications are reported with it.  Here, we present a case of an elderly patient with trigeminal neuralgia who suffered transient asystole during diagnostic mandibular nerve block with lignocaine. The case highlights the importance of monitoring and emphasizes the need for additional precautions to be taken during pain procedures, especially in the geriatric population.
| Case Report|| |
An 85-year-old male patient presented at the pain clinic in our institution with complaints of sharp, lancinating pain in the left jaw and face, corresponding to the distribution of the mandibular division of the trigeminal nerve since five years. Despite regular medical therapy with carbamazepine 200 mg thrice a day and tablet gabapentin 300 mg twice a day, there was little pain relief. Hence, he was planned for mandibular nerve block. He had no comorbidities. Preprocedure vitals were stable. After ensuring nil-by-mouth (nil per os, NPO) status which was quite long (14 hours), written informed consent was obtained. The patient was taken up in the procedure room, monitors were attached [noninvasive blood pressure (NIBP), saturation of peripheral oxygen (SpO 2 )] and intravenous access was secured. After preparing the left side of the face with povidone iodine and ethyl alcohol, sterile drapes were placed. Coronoid approach for mandibular nerve block was used. The patient was placed in a supine position with head tilted to the left side. After aseptic preparation and draping of the part, the skin and subcutaneous tissue were infiltrated with 3 mL of 2% lignocaine. A 9.0 cm 22 gauge (G) needle was introduced perpendicularly in the middle of the coronal process at midpoint of the inferior border of the right zygomatic arch. The needle was advanced to hit the lateral pterygoid plate. The needle was withdrawn slightly and directed posteriorly toward the ear so that it passed the posterior border of the pterygoid plate. The needle was then carefully advanced 0.5 cm each time till the patient reported paresthesia over the mandibular region. The mandibular nerve was stimulated and the desired paresthesia and lower jaw contraction were obtained with the help of a nerve stimulator, following which 2 mL of 2 % lidocaine was injected after ensuring negative aspiration. Within a few seconds, the patient stopped breathing, became unresponsive to commands, peripheral pulses were not palpable, and asystole was noted. Immediate bag-mask ventilation with 100% oxygen and cardiac massage were initiated, following which the heart rate and blood pressure returned to normal within 20 seconds and the patient was awake and responding to commands. Intravenous fluid (500 mL dextrose normal saline) was started for adequate hydration. The procedure was abandoned, and the patient was observed for two hours during which a twelve-lead electrocardiogram (ECG) was done and consultation with a neurologist was sought. During this period, the patient had no other complaints and reported to have anesthesia and complete pain relief in the distribution of the mandibular nerve, suggesting the correct site of local anesthetic administration. He was discharged thereafter with stable vitals and neurologic function. On examination at a follow-up after a week, the patient had no deficit.
| Discussion|| |
The reported complications of mandibular nerve block are less than 1% and those described in the literature are intravascular injection, hypoesthesia, dysesthesia, sensory loss in the mandibular nerve distribution, facial swelling, weakness of the masseter muscle, and injury to the auditory tube leading to severe vertigo. ,, But we have not seen similar episodes of unresponsiveness after mandibular nerve block in the literature in the best of our searches. Development of sudden asystole is a rare but devastating complication of any interventional pain procedure. The intravascular injection of local anesthetic can affect the central nervous system or cardiovascular system leading to similar episodes of unresponsiveness and asystole. Its possibility was ruled out because of negative aspiration at the time of injection and the presence of the desired effect of the block. If the drug injected is less, excitation symptoms of the central nervous system (CNS) like seizures are seen and depression symptoms of the CNS like coma are seen with high doses. We did not encounter seizures and the patient regained consciousness within a few seconds. Another cause which we suspected was subarachnoid spread of local anesthetic leading to brain stem anesthesia. It has been reported earlier too. Its chances also were minimal as careful aspiration was done prior to injecting the drug.
The most probable etiology is either vasovagal syncope or trigeminocardiac reflex (TCR). Vasovagal syncope is mostly associated with a sudden change in posture, fear, pain, and so on. The contribution of fear and pain especially in geriatric patients is quite prominent. However, the prodromal features like lightheadedness, sweating, and vertigo were absent in our patient. TCR is manifested by the sudden development of bradycardia or asystole with hypotension on stimulation of the trigeminal nerve which sets off a reflex arc inducing a cardiac depressor response via vagal stimulation. The exact mechanism of TCR has not been completely elucidated. Current theories as to the mechanism of TCR propose that the sensory nerve endings of the trigeminal nerve send neuronal signals via the Gasserian ganglion More Details to the sensory nucleus of the trigeminal nerve, forming the afferent pathway of the reflex arc. The afferent pathway continues along the short internuncial fibers in the reticular formation to connect with the efferent pathway in the motor nucleus of the vagus nerve.  Cardioinhibitory efferent fibers rising from the motor nucleus of the vagus nerve terminate on the myocardium. These vagal stimuli provoke negative chronotropic and inotropic responses. Consequently, the clinical features of TCR range from sudden onset of sinus bradycardia to bradycardia-terminating asystole, asystole with no preceding bradycardia, arterial hypotension, apnea, and gastric hypermotility.  Percutaneous microcompression of the trigeminal ganglion for trigeminal neuralgia has been shown to induce the cardiovascular depressor response, as also during balloon inflation and posterior fossa surgery.  However, occurrence of TCR is not reported following stimulation of peripheral branches of the mandibular nerve.
We feel that the long hours of fasting together with the age of the elderly patient might have added to the burden of negative chronotropy of either vasovagal syncope or TCR. Adequate pain relief on subsequent follow-up also suggests that the mandibular nerve was stimulated. This is the first case report of the development of asystole during peripheral trigeminal nerve block procedure (mandibular nerve block), with the most probable etiology being trigeminocardiac reflex.
| Conclusion|| |
The purpose of reporting this case is to raise the awareness of possible serious complications even during peripheral nerve blocks which are usually considered as minor outpatient procedures. Proper hydration and anxiolysis should be considered especially in the elderly before carrying out even minor procedures. It is prudent to monitor the vital parameters closely; quick availability of ventilation equipment and resuscitation drugs can also prevent potential catastrophes.
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