The First Unprovoked Seizure: Evaluation and Management
by Kayla Kremer, RN, MSN, CPNP
Ms. Kremer is a Pediatric Nurse Practitioner who helped establish the New Onset Seizure Clinic at the Pediatric Epilepsy Center of St. Louis Children’s Hospital and is now in private practice.
Approximately 10% of the population will have at least one seizure at some point in their lives. Half of these will occur during childhood and adolescence, with the highest risk before age 1 year. Some people with a first seizure will eventually go on to have additional seizures and be diagnosed with epilepsy. Thus, the occurrence of a single seizure in childhood deserves careful consideration.
First of all, a distinction should be made between provoked and unprovoked seizures, since this has implications for treatment and prognosis, such as the risk of developing epilepsy. Provoked seizures are those events that result from some immediately recognizable stimulus or cause. Examples of such causes include hypoglycemia from excessive insulin in diabetic patients or fever in patients with febrile seizures. Provoked seizures may recur whenever the precipitating situation is present, but do not happen at other times in absence of the stimulus and thus do not constitute epilepsy. In contrast, unprovoked seizures do not require an immediate precipitating event. The occurrence of an unprovoked seizure suggests the possibility of an underlying neurological disorder that may predispose a child to recurrent seizures.
The evaluation of the first unprovoked seizure (FUS) must address several questions: Is this a seizure or some other paroxysmal event? Is this the first seizure? What are the characteristics of the seizure and does it represent a sign of a known syndrome or disease? How extensive should the evaluation be? Does the child need treatment with antiepileptic drugs (AEDs)? What is the risk of recurrence and long-term prognosis? This article is intended to overview the current approach to the evaluation and management of a first unprovoked seizure.
Is it the first unprovoked seizure?
It is first essential to determine whether the child had a seizure or some other paroxysmal event. There are many “spells” that can be mistaken for seizures that do not require the evaluation or treatment decisions involved in managing a first unprovoked seizure. Breathholding spells, syncope with clonic jerks, benign sleep myoclonus, shuddering attacks, tics, excessive startle responses, hyperventilation, migraine, and parasomnias are a few of the paroxysmal events occurring in childhood that are not epilegtogenic in origin. Although advanced laboratory and diagnostic testing is sometimes helpful, a thorough history and physical examination are the most important tools for determining the nature of a given “spell”.
Children who present for evaluation of single seizure are often found on detailed questioning to have a history of previous unrecognized seizures. A child with two or more unprovoked seizures has epilepsy, which is associated with a different prognosis and treatment plan than a child with FUS. Careful questioning regarding previous episodes of staring during which the child is truly unresponsive (as opposed to daydreaming) or sudden muscle jerks is important and might reveal that this is not the first event, since absence seizures and myoclonic seizures are often subtle and frequently overlooked by parents.
Clinical evaluation of a FUS by history and physical exam
The importance of an accurate and detailed history and physical exam in evaluating and characterizing a FUS cannot be overemphasized, even in this age of advanced technology. A good historical description of the seizure is critical for assessing the possible causes and prognosis of a FUS and deciding on further diagnostic evaluation and treatment. However, the process of obtaining this history can be fraught with frustration, as descriptions of the event are often sketchy or incomplete and can change with subsequent interviews. Even with a reliable witness, the suddenness of the attack and frightening appearance of the child often makes an accurate history difficult to obtain.
There are a number of characteristics of the FUS that should be explored by the history. Often the most important question is how the seizure started. Ask what was the first thing that the patient or witness observed to be abnormal, as this may help determine where in the brain the seizure started. Focal signs that indicate a partial seizure can have a variety of manifestations, including involuntary shaking or stiffening of a limited part of the body, deviation of the head or eyes to one side, subtle stereotypical movements of the hands or face (automatisms), tingling or numbness of a localized body part, or even an unusual smell, visual hallucination, or ill-defined feeling. Was the patient aware and responsive during the seizure or did they appear to be staring or unconscious? Generalized convulsive seizures involve violent rhythmic movements of the entire body, but can often start with more focal signs. The distinction between a partial and primary generalized first seizure has implications for possible etiologies and risk of recurrence and will affect the extent of the diagnostic workup.
Past medical history, growth and developmental history, family history, and other historical data may also provide relevant information that helps determine the nature and cause of the seizure and estimate prognosis and need for treatment. Patients with known neurological problems, such as a history of severe head injury, cerebral palsy or mental retardation, are at much higher risk for seizure recurrence following a FUS. A detailed family history may reveal certain familial syndromes or diseases with a specific prognosis and treatment. Social history may also give information relevant to the cause of the FUS, such as exposure to lead or drugs of abuse, as well to the practical impact of a FUS, such as the effect on employment and lifestyle. A thorough review of systems may find other non-neurological signs or risk factors associated with seizures.
The physical examination should include both a thorough general exam and a detailed age-appropriate neurological exam. The general (non-neurological) exam should focus on identifying systemic signs or risk factors that may be associated with seizures or other neurological problems, such as the dysmorphic facial features of a chromosomal disorder or the skin lesions of tuberous sclerosis. The neurological exam should obviously look for any abnormalities that would help identify an underlying neurological disease. For young or uncooperative children, simply observing the child as he moves around the room can provide an informal, but very informative, neurological assessment. Obtaining a sample of the child’s handwriting or drawing is often included in this evaluation.
The type and extent of testing to be performed after a FUS is the subject of much discussion and controversy. The basic laboratory tests to be considered in the evaluation of the initial seizure include blood studies, EEG and brain imaging. The age of the child at occurrence of the first seizure and risk factors identified in the history or on examination help determine what testing is required. Initial blood studies often include a complete blood count, electrolytes, calcium, magnesium, glucose, blood urea nitrogen, creatinine, liver enzymes, and drug screen. However, in the absence of another reason to suspect an abnormality in these blood tests, the yield of finding an abnormality after a FUS is very low. Under certain circumstances (fever, irritability, leukocytosis, or meningeal signs), a lumbar puncture may be performed.
The EEG is often the mainstay of the workup of a FUS, although it is not without problems. The diagnosis of seizure is essentially a clinical one based on the history, with the EEG adding supportive information. A single or even multiple routine EEGs often do not show epileptiform abnormalities, even in children with known epilepsy. Furthermore, normal children without a seizure disorder may incidentally have epileptiform activity on EEG. The quality of the test is dependent on the skill and pediatric experience of the technician, and the interpretation can be difficult for those unfamiliar with pediatric EEG idiosyncrasies. On the other hand, when used appropriately, an EEG can be very helpful in evaluating a FUS. In unclear clinical situations, the EEG may distinguish between partial seizures and primary generalized seizures. The presence of certain EEG abnormalities helps determine the risk of seizure recurrence. EEG may also help diagnose a specific syndrome, giving more detailed information that will affect management and prognosis.
The two most widely used imaging techniques utilized in the initial evaluation of seizures are computerized tomography (CT) and magnetic resonance imaging (MRI). These may be used to rule out hemorrhage, abscess, tumor, developmental malformations of the brain, and other structural abnormalities. The CT can be done relatively quickly, less expensively and without sedation, but involves exposure to x-ray. The MRI yields a more detailed image of structural abnormalities without this exposure, but depending on the child’s age, might require sedation and is not always available in all institutions. In institutions where both CT and MRI are available, the CT is generally used to rule out emergent processes if necessary, such as intracranial hemorrhage, requiring immediate medical intervention. The MRI is preferred for the non-emergent evaluation of the seizure patient. Imaging studies may not be needed in children who present with other paroxysmal episodes such as simple febrile seizures, breathholding spell or simple syncope, and children with obvious genetic (idiopathic) seizures such as benign Rolandic epilepsy and childhood absence seizures.
In order to devise an optimal management plan for children with FUS, an individualized assessment should be made about the relative risk of additional seizures versus the disadvantages of treatment, usually consisting of an antiepileptic drug (AED). A primary consideration is the likelihood that this episode represents an isolated event, or a harbinger of future seizures, and therefore epilepsy. If it is determined that the FUS represents the beginning of a known syndrome, such as childhood absence epilepsy, benign Rolandic epilepsy, or juvenile myoclonic epilepsy, or is due to a known neurological disorder, such as tuberous sclerosis, hypoxic-ischemic encephalopathy, or prior meningitis, then management decisions should be based on knowledge of the natural history of these conditions. If an identified etiology carries a high risk of seizure recurrence and a guarded prognosis, starting an AED after a FUS may be indicated. In contrast, in the absence of other risk factors and with a normal EEG, a FUS that does not fit into a particular syndrome may not require treatment with an AED. Withholding treatment in this situation may be justified based on the fact that the majority of children with FUS will not suffer a recurrence, antiepileptic medications are themselves not without risk, and treatment has not been shown to alter the long-term outcome.
When considering starting an AED for a FUS, the general risks and benefits of the medication must also be discussed with the family and, if appropriate, the child. Side effects of medication can be considerable and potentially life-threatening. Monitoring blood levels can be painful for the child and inconvenient for the busy family. On the other hand, the risk of seizure recurrence poses a potential danger to the child, both physically and psychologically, particularly for older children who might participate in activities that put them at jeopardy for injury. The family’s ability to cope with uncertainty, their financial resources, and the support system available to them may also impact the decision to begin treatment. In the end, this decision should be individualized to meet each child’s specific situation.
Regardless of whether a patient is treated with medication, all patients with a FUS should receive appropriate education about seizures. It can be helpful to provide the family with written materials describing their child’s type of seizure. Safety precautions should allow the child to lead as normal a life as possible while keeping him safe. First aid measures to institute should another seizure occur should be thoroughly explained, including when to seek emergency care. An appropriate amount of time is required to adequately discuss these and other issues with the family, and address their concerns and questions. A telephone call a few days after the evaluation is complete can address misunderstandings and clear up misconceptions about their child’s diagnosis, prognosis and treatment. If necessary, appropriate follow-up, especially if medication was started, should be arranged.
The FUS is a disturbing event for any family, and creates anxiety and uncertainty. Many parents relate that they thought their child was dying, and that the feeling of helplessness was overwhelming. Their first thought is to prevent any future episodes at all costs. By carefully and thoughtfully exploring the meaning of the event, the rationale behind and the results of the tests performed, and the concept of risks for recurrence and treatment, the family can be assisted in achieving a reasonably comfortable understanding of the situation.
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- Quality Standards Subcommittee of the American Academy of Neurology. Practice parameter: evaluating a first nonfebrile seizure in children. Neurology 2000;55:616-623.