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Status epilepticus (SE) refers to a life threatening condition in which the brain is in a state of persistent seizure. Definitions vary, but traditionally it is defined as one continuous seizure or recurrent seizures without regaining consciousness between seizures for greater than 30 minutes. Many doctors, however, believe that 5 minutes is sufficient to damage neurons and that seizures are unlikely to self-terminate by that time.
In known epileptics, this condition is associated with poor compliance (adherence to medication regimen), alcohol withdrawal, and metabolic disturbances. As a primary presentation it normally indicates a tumour or abscess.
Status epilepticus can be divided into two categories—convulsive and nonconvulsive, the latter of which is underdiagnosed.
Complex Partial Status Epilepticus, or CPSE, is a rare form of the condition which is marked by localized nonconvulsive seizures. This results in episodes characterized by a long-lasting stupor, staring and unresponsiveness.
Shortly after it was introduced in 1963, diazepam became the first choice for SE. Even though other benzodiazepines such as clonazepam were useful, diazepam was relied upon almost exclusively. This began to change in 1975 with a preliminary study conducted by Waltregny and Dargent, who found that its pharmacological effects were longer lasting than those of an equal dose of diazepam. This meant it did not have to be repeatedly injected like diazepam, the effects of which would wear off 5-15 minutes later in spite of its 30-hour half-life (due to extensive redistribution of diazepam outside the vascular compartment as diazepam is highly lipid soluble). It has also been found that patients who were first tried on diazepam were much more likely to require endotracheal tubing than patients who were first tried on phenobarbital, phenytoin, or lorazepam.
Today, the benzodiazepine of choice is lorazepam for initial treatment due to its long (2-8 hour) duration of action and rapid onset of action, thought to be due to its high affinity for GABA receptors and to its low lipid solubility which causes it to remain in the vascular compartment. If lorazepam is not available, then diazepam should be given. Sometimes, the failure of lorazepam alone is considered to be enough to classify a case of SE as refractory.
Phenytoin and fosphenytoin
Phenytoin was once another first-line therapy, although the prodrug fosphenytoin can be administered three times as fast and with far fewer injection site reactions. If these or any other hydantoin derivatives are used, then cardiac monitoring is a must if they are administered intravenously. Because the hydantoins take 15-30 minutes to work, a benzodiazepine or barbiturate is often co-administered. Because of diazepam's short duration of action, they were often administered together anyway.
Before the benzodiazepines were invented, there were the barbiturates, which are still used today if benzodiazepines or the hydantoins are not an option. These are used to induce a barbituric coma. The barbiturate most commonly used for this is phenobarbital. Thiopental or pentobarbital may also be used for that purpose if the seizures have to be stopped immediately or if the patient has already been compromised by the underlying illness or toxic/metabolic-induced seizures; however, in those situations, thiopental is the agent of choice.
The failure of phenobarbital therapy does not preclude the success of a lengthy comatose state induced by a stronger barbiturate such as secobarbital. Such was the case for Ohori, Fujioka, and Ohta ca. 1998, when they induced a 10-month long coma (or "anesthesia" as they called it) in a 26-year-old woman suffering from refractory status epilepticus secondary to viral encephalitis and then tapered her off the secobarbital very slowly while using zonisamide at the same time.
If this proves ineffective or if barbiturates cannot be used for some reason, then a general anesthetic such as propofol is tried; sometimes it is used second after the failure of lorazepam. This also means putting the patient on artificial respiration. Propofol has been shown to be effective in suppressing the jerks seen in myoclonus status epilepticus, but as of 2002, there have been no cases of anyone going into myoclonus status epilepticus, undergoing propofol treatment, and then not dying anyway.
The use of lidocaine in status epilepticus was first reported in 1955 by Bernhard, Boem and Hojeberg. Since then, it has been used in cases refractory to phenobarbital, diazepam, and phenytoin, and has been studied as an alternative to barbiturates and general anesthetics. Lidocaine is a sodium channel blocker and has been used where sodium channel dysfunction was suspected. However, in some studies, it was either ineffective or even harmful for most patients. The last is not so surprising in light of the fact that lidocaine has been known to cause seizures in humans and laboratory animals at doses greater than 15 µg/mL or 2-3 mg/kg.
References and end notes
- ^ Wijdicks, Eelco F. M., Parisi JE, Sharbrough FW (February 1994). Prognostic value of myoclonus status in comatose survivors of cardiac arrest. Annals of Neurology 35 (2): 239-43. PMID 8109907.
- ^ McDonough, John H., A. Benjamin, Joseph D. McMonagle, Thomas Rowland, Shih Tsung-Ming (February 2004). Effects of fosphenytoin on nerve agent-induced status epilepticus. Drug and Chemical Toxicology 27 (1): 27-39. PMID 15038246.
- ^ Waltregny, Alain, Jérôme Dargent (September/October 1975). Preliminary study of parenteral lorazepam in status epilepticus. Acta Neurologica Belgica 75 (5): 219-29. PMID 3939.
- ^ Walker, JE, RW Homan, MR Vasko, IL Crawford, RD Bell, WG Tasker (September 1979). Lorazepam in status epilepticus. Annals of Neurology 6 (3): 207-13. PMID 43112.
- ^ Orr, Richard A., Robert J. Dimand, Shekhar T. Venkataraman, Valerie A. Karr, Kathleen J. Kennedy (September 1991). Diazepam and intubation in emergency treatment of seizures in children. Annals of Emergency Medicine 20 (9): 1009-13. PMID 1877765.
- ^ Appleton, Richard, A. Sweeney, Imti Choonara, Joan Robson, Elizabeth Molyneux. (August 1995). Lorazepam versus diazepam in the acute treatment of epileptic seizures and status epilepticus. Developmental Medicine and Child Neurology 37 (8): 682-8. PMID 7672465.
- ^ Pang, Trudy, Lawrence J. Hirsch (July 2005). Treatment of Convulsive and Nonconvulsive Status Epilepticus. Current Treatment Options in Neurology 7 (4): 247-259. PMID 15967088.
- ^ Ohori, Nobuhira, Fujioka Y, Ohta M. (May 1998). [Experience in managing refractory status epilepticus caused by viral encephalitis under long-term anesthesia with barbiturate: a case report]. Rinsho Shinkeigaku 38 (5): 474-7. PMID 9806000. (Japanese)
- ^ Pourrat, X, JM Serekian, D Antier, J. Grassin (June 9, 2001). [Generalized tonic-clonic status epilepticus: therapeutic strategy]. Presse Médicale 30: 1031-6. PMID 11433696. (French).
- ^ Marik, Paul E., Joseph Varon (2004). The management of status epilepticus. Chest 126 (2): 582-91. PMID 15302747.
- ^ Wijdicks, Eelco F.M. (July 2002). Propofol in myoclonus status epilepticus in comatose patients following cardiac resuscitation. Journal of Neurology Neurosurgery and Psychiatry 73 (1): 94-5. PMID 12082068.
- ^ Bernhard, CG, Bohm E, Hojeberg S (August 1955). A new treatment of status epilepticus; intravenous injections of a local anesthetic (lidocaine). AMA Archives of Neurology and Psychiatry 74 (2). PMID 14397899.
- ^ Aggarwal, Praveen, Jyoti Prakash Wali (May 1993). Lidocaine in refractory status epilepticus: a forgotten drug in the emergency department. American Journal of Emergency Medicine 11 (3): 243-4. PMID 93257009.
- ^ Sugiyama, N, Hamano S, Mochizuki M, Tanaka M, Eto Y (November 2004). [Efficacy of lidocaine on seizures by intravenous and intravenous-drip infusion]. No To Hattatsu 36 (6): 451-4. PMID 15560386. (Japanese)
- ^ Sawaishi Yukio, Yano Tamami, Enoki Masamichi, and Takada Goro (February 2002). Lidocaine-dependent early infantile status epilepticus with highly suppressed EEG. Epilepsia 43 (2): 201-4. PMID 11903470.
- ^ Tanabe Takuya, Suzuki Shuuhei, Shimakawa Shuichi, Yamashiro Kuniteru, Tamai Hiroshi (January 1999). Problems of intravenous lidocaine treatment in status epilepticus or clustering seizures in childhood. No To Hattatsu 31 (1): 14-20. PMID 10025129. (Japanese)
- ^ DeToledo, John C. (June 2000). Lidocaine and Seizures. Therapeutic Drug Monitoring 22 (3): 320-322. PMID 10850400.
- ^ Steven C. Schachter. Lidocaine. epilepsy.com/professionals. Adapted from: Najjar S, Devinsky O, Rosenberg AD, et al (2002). "Procedures in epilepsy patients" ed. Ettinger AB and Devinsky O Managing epilepsy and co-existing disorders, 499–513, Boston: Butterworth-Heinemann.
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