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Massachusetts General Hospital Pain Center, Department of Anesthesia and Critical Care, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
Address correspondence and reprint requests to Shihab U. Ahmed, MD, Massachusetts General Hospital Pain Center, WACC-324, Massachusetts General Hospital, 15 Parkman St., Boston, MA 02114. Address e-mail to sahmed{at}partners.org
| Abstract |
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IMPLICATIONS: Clonidine is being used increasingly as an adjuvant medication for neuropathic pain and to improve the duration of regional anesthesia. Four cases of seizures associated with the use of clonidine have been reported. We present a case of seizure after a Bier block with lidocaine and clonidine in a patient with complex regional pain syndrome type I.
| Introduction |
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2-receptor agonist, reduces hyperalgesia when injected subcutaneously. The local anesthetic lidocaine is often administered IV for various neuropathic pain conditions. Early, inadvertent, release of the tourniquet during Bier block with lidocaine can cause systemic toxicity, including seizures, from transiently high plasma levels. In this report, we present a case in which we performed a Bier block with a mixture of lidocaine and clonidine for complex regional pain syndrome type 1. Sixty minutes after injection of the medications, the tourniquet was released, 10 min after which the patient developed seizures.
| Case Report |
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Approximately 10 min after the deflation of the tourniquet, the patient complained of "not feeling well" and had rhythmic clonic movements of the upper and lower extremities for approximately 30 s, accompanied by altered consciousness and vocal automatism. He was given propofol 30 mg IV. He was breathing spontaneously but appeared to be postictal and confused, so he was given supplemental oxygen via face mask. His vital signs remained stable. During the next 2 h, he had 5 similar episodes without fully regaining clear sensorium (orientation to place and person) between episodes. The episodes were interpreted as complex partial seizures; the patient experienced aura, automatism, rhythmic jerking of the extremities, and tonic deviation of the eyes associated with impairment of consciousness without complete loss of consciousness. He was given propofol 30 mg IV for each episode. He also received 5 mg of diazepam after the first episode and another 5 mg after the fourth episode of seizure. He was escorted to the emergency room and had a head computed tomography scan, which was negative. The blood chemistry (2.5 h after tourniquet release) showed lidocaine (0.62 µg/mL) and benzodiazepine, without any illicit drugs. He was admitted for overnight observation. Four hours after the first seizure, he became fully alert and oriented but was unable to recall events after the IV infusions were started. He had an uneventful night and was discharged home on his second hospital day without recurrence of seizures.
| Discussion |
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Clonidine has many clinical uses, including treatment of hypertension, evaluation of growth hormone reserve, and differentiation of Parkinsons disease from multiple system atrophy. It is also used as an adjuvant in combination with opioids and local anesthetics for regional anesthesia and is prescribed in oral and transdermal formulations for neuropathic pain. Research suggests that clonidine suppresses central noradrenergic activity (8) by inhibiting the excitatory amino acid pathway (9) or by depleting norepinephrine (10). The interaction between norepinephrine and seizure susceptibility is not completely understood. It has been suggested that norepinephrine acts as an anticonvulsant, possibly via augmentation of inhibitory
-aminobutyric acid effects (11). By reducing the norepinephrine available in central structures, mainly the locus caeruleus, clonidine might decrease the seizure threshold.
Four cases of seizure after clonidine administration have been reported: 1) accidental clonidine ingestion in a young child, followed by complex partial seizures (12); 2) oral clonidine administration to a hypoglycemic patient (13); 3) oral clonidine test for evaluation of growth hormone reserve in a preadolescent, followed by a generalized tonic-clonic seizure (14); and 4) oral clonidine given as premedication before methohexital spike provocation for video electroencephalograph monitoring in a patient with a history of complex partial seizures (15). In the last case, the maximum spike frequency with mirror focus was found in the 10-minute recordings before the application of methohexital and 90 minutes after the ingestion of clonidine. This patient also had two complex partial seizures before being given methohexital.
In cats, pretreatment with 5-hydroxytryptophan increases susceptibility to lidocaine-induced seizures (16). Therefore, medication that increases central nervous system (CNS) levels of serotonin has the potential to decrease the seizure threshold. Notably, our patient was taking nortriptyline.
This is the first case of seizure after Bier block with clonidine and lidocaine. Both lidocaine and clonidine have potential epileptogenic effects, as described above, and the two might be synergistic in decreasing the seizure threshold in the amygdala and limbic system. By increasing the CNS serotonin level, the tricyclic antidepressant nortriptyline may have contributed to the reduction in seizure threshold.
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This article has been cited by other articles:
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S. U. Ahmed, R. Vallejo, and E. D. Hord Seizures After a Bier Block with Clonidine and Lidocaine: Is Clonidine Really the Culprit? Anesth. Analg., September 1, 2005; 101(3): 924 - 924. [Full Text] [PDF] |
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S. Datta, U. Pai, P. O. Bridenbaugh, and A. Walia Seizures After a Bier Block with Clonidine and Lidocaine: Is Clonidine Really the Culprit? Anesth. Analg., September 1, 2005; 101(3): 923 - 924. [Full Text] [PDF] |
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