Learning from Mistakes in the Diagnosis and Treatment of Epilepsyby Jennifer Gibson, PharmD | October 26, 2008
The adage of those who do not learn from history are destined to repeat it rings as true in medicine as in any other field. Learning from previous patients and past experiences — even mistakes — is the best learning tool in medicine. The treatment and diagnosis of epilepsy is no different, and a new review article published in the quarterly journal Seminars in Neurology evaluates frequent mistakes made in the diagnosis, evaluation, and treatment of epilepsy and provides practical solutions to optimize patient care.
The failure of the health care provider to obtain a detailed and correct personal and family history is the most frequent cause of misdiagnosis in any medical field. In patients with epilepsy, an accurate history leads to a correct diagnosis in up to 90% of cases. It is also important to establish if a presumed epileptic episode is, in fact, the first seizure the patient experienced, and determine the exact type of seizure. A generalized tonic-clonic seizure is often assumed to be the first epileptic seizure, but many types of seizures go unrecognized and unreported by patients and family members. These include partial seizures presenting as epigastric discomfort, sensations of déjà vu or jamais vu, feelings of derealization, episodes of vertigo, or visual hallucinations. An erroneous classification of the type and onset of epileptic seizures may lead to an incorrect antiepileptic drug (AED) selection. Incorrect treatment may worsen seizures, or at least prevent patients from becoming seizure-free. Each epileptic syndrome responds differently to each AED, but with the correct diagnosis and AED selection, more than 50% of patients have a high probability of achieving seizure freedom.
Misdiagnosis of epilepsy can also be caused by the incorrect use or interpretation of auxiliary tests. The electroencephalogram (EEG) is used to detect abnormalities in the electrical activity of the brain. Errors related to the EEG, including failure to obtain sleep recordings, failure to use specific electrodes during an EEG, and failure to recognize that the absence of epileptiform activity does not rule out epilepsy, are common. Magnetic resonance imaging (MRI) studies are also misused in the diagnosis of epilepsy. Practitioners must ensure that the correct protocol is followed for each MRI, based on the type of epilepsy suspected. The timely and precise diagnosis of epilepsy requires much attention to detail related to auxiliary medical tests.
Many options exist for the pharmacologic treatment of epilepsy, but this leads to many errors in the selection and use of AEDs. A common error is seen in patients presenting to the emergency deparment (ED) after experiencing an unprovoked, isolated seizure. Most ED protocols involve an automatic intravenous administration of high-dose phenytoin in these patients. This use is of phenytoin is often unnecessary in patients who do not pose a risk for additional seizures, but does leave a patient at risk for side effects related to phenytoin, including rash and fatigue. Many new studies report that even patients presenting to the ED with new-onset epilepsy respond well to low starting doses of AEDs, followed by a slow titration of the dose to achieve the desired effect. Few patients actually require the high loading doses of phenytoin that are used and early pharmacologic intervention does not affect a patient’s long-term prognosis.
Additionally, the incorrect monitoring of AEDs leads to errors in epilepsy treatment. Many AEDs are monitored by serum blood concentrations, rather than therapeutic effect. Therapeutic ranges are based on statistics, and may not accurately recognize a patient’s tolerance for and response to the AED. Many AEDs are discontinued when the blood level reaches a certain level, whether or not the patient is responding well to the drug or is experiencing any negative side effects. Likewise, some AEDs are bound to albumin in the blood, so serum concentrations may be artificially elevated, based on the patient’s albumin level. In these cases, the patient’s entire clinical picture should be evaluated, and decisions about treatment should not be based solely on reported laboratory values.
Other common mistakes in the pharmacologic treatment of epilepsy include not accounting for comorbid conditions or drug interactions. Patients with epilepsy may have underlying medical, neurologic, and psychiatric disorders for which they are taking medications. The most common comorbid conditions include psychiatric disorders such as mood disorders, anxiety, depression, attention deficit disorder, and psychotic disorders. Many AEDs can induce or inhibit metabolic enzymes and alter the concentrations of therapeutic drugs for other conditions. Failure to accurately recognize and treat comorbid conditions in the presence of epilepsy has a negative impact on the quality of life of patients. Many drugs can be taken safely together with AEDs, as long as the pharmacokinetic and pharmacodynamic properties are assessed accurately.
The last class of errors reported in Seminars in Neurology is the delay in surgical treatment of epilepsy. The average time from diagnosis to surgical referral is 15 to 20 years for patients with epilepsy. The review illustrates that most clinicians should be able to recognize epilepsy that is resistant to drug treatment, and therefore a potential candidate for surgical intervention, in as little as 12 to 18 months. Up to 80% of patients can achieve seizure freedom with surgery, and delays in treatment hinder improvement of quality of life, as well as increase morbidity and mortality associated with inappropriate AED treatment and inadequate epilepsy treatment.
Medicine is often more art than science, and its providers are appropriately said to be “practicing.” Every field of medicine learns from its past mistakes and achievements, and the current review demonstrates that epilepsy is no different.
Andres M. Kanner (2007). To Treat or Not to Treat…Is It Still the Question? Epilepsy Currents, 7 (6), 154-156 DOI: 10.1111/j.1535-7511.2007.00210.x
Andres Kanner (2008). Common Errors Made in the Diagnosis and Treatment of Epilepsy Seminars in Neurology, 28 (03), 364-378 DOI: 10.1055/s-2008-1079341
Andres Kanner (2008). The Use of Psychotropic Drugs in Epilepsy: What Every Neurologist Should Know Seminars in Neurology, 28 (03), 379-388 DOI: 10.1055/s-2008-1079342
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