Correspondence
Epilepsy
N Engl J Med 2001; 345:467-469August 9, 2001
- Article
To the Editor:
In their review article on epilepsy, Browne and Holmes (April 12 issue)1 state that electroencephalographic studies should be performed 48 hours or more after a suspected seizure. We disagree. Studies of chronic partial epilepsy show that interictal epileptiform activity is more frequent after seizures (postictal activation).2 Sundaram et al.3 reported an increased probability of finding interictal discharges (up to 77 percent) when patients were studied within two days after a seizure. In a recent study of 300 consecutive patients with a first unexplained seizure in whom electroencephalography was performed within 24 hours after the seizure, epileptiform abnormalities were identified in 39 percent of adults and 59 percent of children, whereas in studies of patients in whom electroencephalography was performed 48 hours or more after the seizure, epileptiform abnormalities were identified in 10 to 27 percent of adults and 32 to 43 percent of children.4
Electroencephalographic studies should also not be delayed in patients with a prolonged confusional state or agitation after a seizure, since it is important to distinguish between postictal encephalopathy and generalized nonconvulsive status epilepticus in order to treat the latter condition promptly.5 In our opinion, performing electroencephalography within 24 hours after a suspected seizure is a valuable approach to increase diagnostic sensitivity.
5 ReferencesAlberto Primavera, M.D.
Luca Roccatagliata, M.D.
Università di Genova, 16132 Genoa, Italy
neurolab@cisi.unige. it 1
Browne TR ,Holmes GL . Epilepsy. N Engl J Med 2001;344:1145-1151
Full Text | Web of Science | Medline2
Gotman J ,Marciani MG . Electroencephalographic spiking activity, drug levels, and seizure occurrence in epileptic patients. Ann Neurol 1985;17:597-603
CrossRef | Web of Science | Medline3
Sundaram M ,Hogan T ,Hiscock M ,Pillay N . Factors affecting interictal spike discharges in adults with epilepsy. Electroencephalogr Clin Neurophysiol 1990;75:358-360
CrossRef | Medline4
King MA ,Newton MR ,Jackson GD , et al. Epileptology of the first-seizure presentation: a clinical, electroencephalographic, and magnetic resonance imaging study of 300 consecutive patients. Lancet 1998;352:1007-1011
CrossRef | Web of Science | Medline5
Fagan KJ ,Lee SI . Prolonged confusion following convulsions due to generalized nonconvulsive status epilepticus. Neurology 1990;40:1689-1694
Web of Science | Medline
To the Editor:
Drs. Browne and Holmes recommend that patients who are free of seizures be prohibited from driving for at least four months after discontinuing antiepileptic medication. The reference they cite to support this approach is an American Academy of Neurology practice parameter on discontinuing antiepileptic medication, which does not mention driving.1 My colleagues and I individualize instructions about driving. Most patients consider relinquishing driving too steep a price to pay for stopping medication. When driving is essential and the risk of a recurrent seizure is not all that low, it may make more sense to continue antiepileptic medication for some years.
The authors state that “the usual first-line drugs for primarily generalized tonic–clonic seizures are divalproex sodium and phenytoin.” Both of the articles cited in support of this statement, however, describe divalproex sodium as the drug of choice for primarily generalized epilepsy.2,3 In patients with juvenile myoclonic epilepsy, phenytoin (and carbamazepine) may aggravate myoclonic seizures.4 When possible, tonic–clonic seizures should be considered part of either a primarily generalized or a partial (localization-related) epilepsy, as they are in the International League against Epilepsy classification of seizures. There is confusion among primary care physicians about the term “generalized seizures.” At our seizure clinic, primary care trainees learn about primarily generalized epilepsy and its response to broad-spectrum agents such as divalproex sodium.
4 ReferencesFrederick Langendorf, M.D.
Hennepin County Medical Center, Minneapolis, MN 55415
lange002@tc.umn. edu 1
Practice parameter: a guideline for discontinuing antiepileptic drugs in seizure-free patients -- summary statement: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 1996;47:600-602
Web of Science | Medline2
Mattson RH . Medical management of epilepsy in adults. Neurology 1998;51:Suppl 4:S15-S20
Web of Science | Medline3
Pellock JM . Treatment of seizures and epilepsy in children and adolescents. Neurology 1998;51:Suppl 4:S8-S14
Web of Science | Medline4
Genton P ,Gelisse P ,Thomas P ,Dravet C . Do carbamazepine and phenytoin aggravate juvenile myoclonic epilepsy? Neurology 2000;55:1106-1109
Web of Science | Medline
Author/Editor Response
The authors reply:
To the Editor: The basis for our statement that electroencephalographic studies should be performed 48 hours or more after a suspected seizure is a practice parameter put forward by the American Academy of Neurology, the Child Neurology Society, and the American Epilepsy Society.1 This practice parameter states: “It is not clear what the optimal timing should be for obtaining an [electroencephalogram]. Although an [electroencephalogram] done within 24 hours of a seizure is most likely to show abnormalities, physicians should be aware that some abnormalities such as postictal slowing that can be seen on [electroencephalography] done within 24 to 48 hours of a seizure may be transient and must be interpreted with caution.” In this review for primary care physicians we selected the least complex option for the timing of electroencephalography. When an expert is available to evaluate the importance of electroencephalographic abnormalities in the postictal period, there are advantages to performing electroencephalography soon after a seizure.
We stated explicitly that the decision to discontinue antiepileptic drugs should be individualized on the basis of several considerations, including the importance of driving to the patient. If antiepileptic drugs are to be discontinued, the patient should stop driving for a period that reflects the risk of a recurrent seizure. Many seizures recur during the period of withdrawal of antiepileptic drugs, and 75 to 80 percent of recurrences occur during the first year after withdrawal.2-4 The four-month figure is the minimal amount of time that driving should be prohibited after the discontinuation of antiepileptic drugs, and a case can be made for making one year the minimum.
Phenytoin and valproic acid have both been used successfully for decades to treat primarily generalized tonic–clonic seizures. There are no studies comparing phenytoin and valproic acid in the management of primarily generalized tonic–clonic seizures. The choice depends primarily on the side effects. Primarily generalized tonic–clonic seizures often begin in the teens. The weight gain induced by valproic acid and the drug's reproductive and teratogenic side effects may not make it an ideal drug for young women.
The juvenile myoclonic epilepsy syndrome is associated with tonic–clonic and other types of seizures. Space did not permit a discussion of all the syndromes that may include tonic–clonic seizures. The differences between primarily generalized and secondarily generalized tonic–clonic seizures are enumerated in Table 1 of our article.
4 ReferencesThomas R. Browne, M.D.
Gregory L. Holmes, M.D.
Boston University School of Medicine, Boston, MA 02118
tbrowne@bu.edu 1
Hirtz D ,Ashwal S ,Berg A , et al. Practice parameter: evaluating a first nonfebrile seizure in children: report of the Quality Standards Subcommittee of the American Academy of Neurology, The Child Neurology Society, and The American Epilepsy Society. Neurology 2000;55:616-623
Web of Science | Medline2
Buna DK . Antiepileptic drug withdrawal -- a good idea? Pharmacotherapy 1998;18:235-241
Web of Science | Medline3
Medical Research Council Antiepileptic Drug Withdrawal Study Group
Web of Science | Medline4
Shinnar S ,Berg AT ,Moche SL , et al. Discontinuing antiepileptic drugs in children with epilepsy: a prospective study. Ann Neurol 1994;3:534-545
CrossRef | Web of Science
