Tonic clonic convulsions induced by low dose intrathecal bupivacaine and intraurethral lidocaine gel

Majid Akrami1, Hamed Akhavizadegan2, Farhad Afsari3
1Assistant Professor, Department of Aesthesiology

2Assistant Professor, Department of Urology

3Assistant Professor, Department of Neurology

Tehran University of Medical Sciences, Tehran (Iran)

Correspondence: Majid Akrami, Baharloo Hospital, Rahahan Sq, Behdari St, Tehran 1339973111, (Iran); E-mail: majakrami@sina.tums.ac.ir; FAX: +982155648189

ABSTRACT
Local anesthetics are commonly used as analgesic and anesthetics. The systemic toxicity of local anesthetics involves CNS and cardiovascular system. Grand mal seizure, as a critical event may occur during toxicity due to high doses, rapid entry of local anesthetic into the systemic circulation and erroneous injection of local anesthetics through the intravenous route. We would like to present a case that experienced tonic clonic convulsion in spite of administration of low dose intrathecal bupivacaine and intraurethral lidocaine gel.

Key words: Local anesthetic; Tonic clonic seizure; Bupivacaine; Lidocaine

Citation: Akrami M, Akhavizadegan H, Afsari F. Tonic clonic convulsions induced by low dose intrathecal bupivacaine and intraurethral lidocaine gel. Anaesth Pain & Intensive Care 2016;20(3):358-360

Received: 18 June 2016; Reviewed: 5 August 2016; Accepted: 20 August 2016

INTRODUCTION
Local anesthetics may result in systemic toxicity that involves central nervous or cardiovascular system. The causes of toxicity are multifactorial. There are some recognized risks including drug doses, patient factors, choice of anesthetic technique and pharmacokinetics.1 Local anesthetic systemic toxicity generally begins with central nervous system excitation followed by inhibition.  At the same time, it causes dysrhythmias and reduced systemic vascular resistance.1 Grand mal seizure can be triggered by drugs used in spinal or epidural anesthesia or marked overdose injection due to inadvertent intravascular absorption.2 There is no report of tonic clonic seizure following intrathecal administration of low dose of bupivacaine. We present a patient who developed a generalized tonic clonic seizure after intrathecal administration of low dose of bupivacaine and intraurethral usage of lidocaine2% gel simultaneously.

CASE REPORT
A 41-year old male (75 kg, 172 cm, ASA class 1) was scheduled to undergo a planned transurethral ureterolithotripsy (TUL) for treatment of urolithiasis. He had no medical problems except a history of asthma. The preoperative hemogram and biochemistry data were within normal limits. Since our routine protocol for TUL surgery involves spinal anesthesia using low dose of bupivacaine 0.5%, this protocol was performed under standard monitoring. Intrathecal bupivacaine 0.5% (10 mg Hyperbaric Marcaine™) without any adjuvant was administered in space L4-L5 via quincke type spinal needle 27G. A Cathejell with lidocaine 2% (each contains 200 mg lidocaine) was applied through urethra for easy insertion of endourethral devices. Sufficient sensory block was achieved. The urologic procedure was completed uneventfully. The patient was hemodynamically stable throughout the surgery. Approximately 40 min after administration of intrathecal bupivacaine and lidocaine gel, suddenly the patient began to experience tonic clonic seizure. There were no initial symptoms and signs like dizziness, visual or auditory disturbances, tinnitus, disorientation.3  The heart rate dropped from 89 to 45 bpm rapidly. There was no significant alteration in blood pressure or SpO2. Prolonged PR interval was detected on the electrocardiogram (ECG) without any changes in QRS or ST intervals. The patient was controlled by administration of diazepam 10 mg and midazolam 5 mg. Oxygen was delivered via mask and atropine 1 mg administered IV. The patient was not intubated because he was not full stomach, the seizure not repeated again and there was no respiratory arrest. Blood sample was immediately sent for calcium and blood glucose.  He was prescribed a loading dose of phenytoin in operating room. The patient was admitted in ICU and maintenance dose of phenytoin started. The neurologic consultation, electroencephalography (EEG) and brain computed tomography (CT) were obtained. Serum calcium, glucose, brain CT and follow up EEGs were normal. He was re-examined next day and no abnormal neurologic findings were seen. The patient was discharged and followed up for two months. There was no seizure during this period. Meanwhile, our patient signed the consent form relating to this publication.

DISCUSSION
The frequency of severe neurological complications using spinal local anesthetics has been found to be approximately 0.4/10000 by Moen et al.2 The causes of the neurologic complications induced by local anesthetics are high doses administration, diffusion of the drug towards the cephalic region and rapid absorption into the blood circulation.
  1. F. Rousseau found that plasma lidocaine concentration after the instillation of lidocaine gel 220 mg into the uterine cavity for uterine balloon thermal ablation was 272 ng / ml at 15 min after insertion, that was well below the level to cause local anesthetic toxicity.4
Based on Brosh-Nissimov study,  toxic levels of lidocaine were seen in patients following administration of lidocaine gel or topical lidocaine for painful oral lesions or bronchoscopy respectively.3 Literature documents that administration of lidocaine and bupivacaine simultaneously in rats results in systemic toxicity additively.5 Probably this was the cause of convulsions in our patient. In our case, a low dose of intrathecal bupivacaine (10 mg) and intraurethral lidocaine gel (200 mg) were used simultaneously. Considering the time of convulsion, no pervious history of seizure, normal lab data and normal EEG, we concluded that systemic toxicity of local anesthetics was responsible for this tonic clonic convulsion as two different local anesthetics had additive or synergistic effects for reducing convulsive threshold.

Drawing blood sample to measure plasma concentration of local anesthetics was not considered since low doses of local anesthetics were administered. There is one study that has reported a case of normal arterial plasma concentration of ropivacaine causing grand mal seizure after epidural injection.6
In conclusion, regarding additive and synergistic effects of drugs, the use of several types of local anesthetics simultaneously should not be assumed completely harmless. Clinicians should consider the diagnosis of CNS toxicity when dizziness, mental obtundation, acute onset of confusion and seizures occur following administration of any different kinds of local anesthetics. It must also be kept in mind that usage of low dose of intrathecal bupivacaine with other types of local anesthetics administered peripherally may result in tonic clonic seizure. This case serves as a reminder of a possible systemic toxicity of local anesthetics used in urological surgery

Conflict of interest: The authors have no proprietary or commercial interest in any materials discussed in this case report. We did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Authors’ contribution: All author managed the case and took part in the preparation of the manuscript

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