Volume 17, Issue 7 , Pages 583-587, October 2008
The frequency of non-epileptic spells in children: Results of video–EEG monitoring in a tertiary care center
Article Outline
Summary
Rationale
The diagnosis of non-epileptic spells (NES) in children can be challenging, even for experienced clinicians. Our objective was to describe the characteristics of such events.
Methods
This was a retrospective study conducted from January 2004 to December 2006. Inclusion criteria were age >1 month and <18 years and the diagnosis of NES established by video–EEG monitoring.
Results
Among 746 monitored children (1203 recorded video–EEG sessions), 109 (14.6%) had NES. The mean age of patients with NES was 6.6 years (range 0.1–18). Seventy patients were diagnosed with NES alone; the remaining 39 with both NES and epilepsy. Developmental delay was more frequent among patients with a co-morbid diagnosis of epilepsy (p
<0.001). Similar clinical events were reported in both of these groups, save for crying spells/irritability which was more common in children with epilepsy. Frequent manifestations of NES included staring spells in preschool children, crying/irritability, tremor and eye deviation in young children and preschoolers, and limb shaking in adolescents. All of the patients with epilepsy and 19 (27%) of those without epilepsy were receiving antiepileptic drugs.
Conclusion
Our data highlights the importance of accurate diagnosis of NES toward the appropriate treatment of affected children.
Keywords: Epilepsy, Childhood, Non-epileptic spells
Introduction
Seizure diagnosis is often based on the clinical description of an event made by parents or other caretakers. A seizure in a child is a sudden, dramatic and frightening event; it is therefore inevitable that a lay description of a seizure is framed by parental anxiety and clouded by an inability to attend to important and specific details of the event. In this setting, an inaccurate description may lead to an inaccurate diagnosis.1, 2 Moreover, non-epileptic spells (NES) are common in childhood. The differentiation of these spells from epileptic seizures can be challenging, even for experienced epileptologists.3, 4, 5, 6
The ramifications of an inaccurate diagnosis of epilepsy are significant. Restriction of activities, such as participation in many sports and driving an automobile, and the emotional cost of managing a chronic illness, can have important long-term repercussions. Of additional concern are the potentially deleterious effects of unnecessary long-term exposure to antiepileptic drugs (AED). Video–EEG monitoring is the gold standard to differentiate NES from electrographic seizures. The objective of this study was to evaluate the characteristics of non-epileptic events in children seen at a tertiary center for such monitoring.
Methods
This was a retrospective study conducted at the Pediatric Epilepsy Monitoring Unit of the Columbia University Comprehensive Epilepsy Center. We evaluated patients who underwent video–EEG monitoring between 1 January 2004 and 31 December 2006. All studies were reviewed and reported by board certified epileptologists. Non-epileptic seizures were established by video–EEG monitoring based on the clinical features and absence of paroxysmal activity or changes in baseline EEG pattern. Children between age >1 month and <18 years who received the diagnosis of NES were included in the study. Patient clinical information was collected through chart review and included age, gender, preexisting medical and neurological conditions, seizure history, and AED usage. The type of epileptic seizure and syndrome was described in accordance with the classification guidelines of the International League Against Epilepsy.7, 8
Video–EEG monitoring was performed on all patients. Electrodes were placed according to the 10–20 international electrode system. Additionally, if appropriate, inferior temporal electrodes (F9, T9, P9, F10, T10, and P10) were utilized. EEG activity was digitally recorded referentially to P1/P2 or A1/A2 electrodes. The family and patient were instructed to activate a push-button alarm at the onset of any event.
Patients with NES were divided into two groups based on the presence or absence of coexistent epilepsy. Statistical analysis was performed using the Student's t and Fisher Exact test with a level of significance of 0.05.
Results
A total of 746 patients were admitted to EEG/video monitoring for evaluation (1203 video–EEG monitoring sessions). Epilepsy was the admitting diagnosis in 548 children (73%). The other 198 children (26%) did not have history of epilepsy. One hundred and nine patients (13%) met the inclusion criteria; 70 patients had NES alone, while 39 had both NES and epilepsy.
Age ranged from 1 month to 18 years (mean=6.6 years; ±5.2), 52 were girls and 57 were boys. Among 39 patients with epilepsy, 18 had a generalized epilepsy syndrome, 15 localization-related epilepsy, and in six the type of epilepsy could not be established. Twenty patients had symptomatic epilepsy, 12 probable symptomatic epilepsy and six idiopathic epilepsy.
From the group of 70 patients which presented with isolated NES, 19 patients (27%) were in use of at least one AED: clonazepam in six, phenobarbital in three, topiramate in two, levetiracetam in two, oxcabazepine in two, carbamazepine in two, and gabapentin, diazepam, valproic acid and lamotrigine in one each. Only one patient was on polytherapy. The EEG was abnormal in 8/19 (42%) patients in use of AEDs, and in 14/51 (27%) patients who were not in use of any AED (p=0.260).
Fig. 1 shows the type of NES; staring spells and shuddering attacks were the most common paroxysmal events; 16% and 12%, respectively. When the patients with NES were grouped as with or without history of epilepsy; irritability and crying spells (17%, 7/39) were more common in the group of children with epilepsy whereas staring spells (22%, 16/70) in the group without epilepsy. Developmental delay was more frequent among patients with a co-morbid diagnosis of epilepsy (p<0.001). Regarding the type of non-epileptic event; staring spells/unresponsiveness, eye deviation, shudder/tremor and limb shaking were equally present in both groups. However, crying spells/irritability was more frequent in the group of patients with epilepsy (p=0.032). Table 1 shows the characteristics of both cohorts. There was no difference in the type of non-epileptic event according to the presence of developmental delay (Table 2; p>0.05).
Figure 1.
Type of NES by predominant activity *.
Table 1. Characteristics of the patients according to each group
| Characteristics | Patients with epilepsy (n=39) | Patients without epilepsy (n=70) | p value |
|---|---|---|---|
| Age | |||
| (Mean±SD) | 6.1 (±4.3) | 6.8 (±5.6) | 0.427 |
| Gender | |||
| Boys | 23 | 34 | 0.323 |
| Girls | 16 | 36 | |
| Days on EMU | |||
| (Mean±SD) | 2.9 (±1.2) | 2.7 (±1.2) | 0.469 |
| Developmental delay | |||
| n (%) | 31 (79.5%) | 26 (37%) | <0.0001 |
| Type of non-epileptic eventa | |||
| Crying/irritability | 7 | 3 | 0.032 |
| Staring spell | 7 | 16 | 0.629 |
| Eye deviation | 5 | 8 | 1 |
| Shudder/tremor | 5 | 13 | 0.592 |
| Limb shaking | 3 | 10 | 0.371 |
aOnly the most common NES were included in the analysis. |
Table 2. Type of non-epileptic event according to the presence of developmental delay
| Type of non-epileptic event | Patients with DD | Patients without DD | p value |
|---|---|---|---|
| Crying/irritability | 8 | 2 | 0.096 |
| Staring spell | 16 | 7 | 0.098 |
| Eye deviation | 6 | 7 | 0.769 |
| Shudder/tremor | 9 | 9 | 1 |
| Limb shaking | 5 | 7 | 0.545 |
Common manifestations of NES in both cohorts included staring spells in preschool children, limb shaking in adolescents and crying/irritability, tremor and eye deviation in young children and preschoolers (Fig. 2).
Figure 2.
Type of non-epileptic spell according to each age (year).
Discussion
Our data showed that NES are frequent and easily misdiagnosed as epileptic spells in childhood. An interesting aspect of our finding is that NES was equally frequent in children with or without co-morbid diagnosis of epilepsy.
Failure to recognize the presence of NES can lead to over-treatment and possible morbidity related to AED toxicity. This may well hinder misdiagnosed children from achieving their maximal cognitive potential.9 Moreover, the clarification of the true nature of a NES often provides relief for parents, who often believe the event to be the initial manifestation of a serious underlying disorder.10
When the description of a paroxysmal event is vague and does not fit a recognizable pattern, it is important for the physician to acknowledge the uncertainty of the diagnosis.10 Additional investigation is often necessary to clarify the nature of the event; however, an abnormal EEG can be misleading, suggesting a potentially incorrect diagnosis of epilepsy.10, 11 Interictal findings should be interpreted with caution, especially in children with autism, in whom epileptiform abnormalities are typically found.9 Among our group of patients that presented with isolated NES, 31.5% (22/70) of the patients had an abnormal EEG. Although abnormal EEG findings were more frequently seen in patients in use of AED; an abnormal EEG was also seen in many patients not in use of AEDs.
It is well known that some epileptic discharges might be missed if no extra electrodes are added in the 10–20 system. However, due to the retrospective nature of our study, no extra electrode was added routinely in the evaluation of our patients. We also were unable to determine the possible selection bias which might occur before children entered EEG/video monitoring unit in our center. The major limitation for such evaluation was the absence of uniform database between various outpatient clinics in the center. Although we were unable to compare the number of children who presented to our center and referred for EEG–video monitoring; only 13% received the diagnosis of NES. Most importantly, 36% of these children had also epilepsy. This observation supports the importance of EEG–video monitoring to differentiate the paroxysmal events from habitual seizures to prevent over medication.
It is interesting to note that, although a careful clinical history will often allow differentiation of NES from epileptic seizures in most patients,12 there are no reliable clinical features that enable the differentiation of these events in all patients. Moreover, although the stereotypic presentation of motor seizures can usually be identified during the evaluation of video–EEG monitoring, these characteristics are difficult to recognize from history or clinical descriptions.13 Therefore, based on clinical description alone it is often impossible to determine whether the event is truly an epileptic seizure.1, 14
Although the clinical description of NES is similar in children regardless of the presence of epilepsy or development delay, the etiology of the NES may be different. Due to the retrospective nature of our study, the etiology of the spells could not be established in some patients, especially for those with conversion disorder. Conversion disorder does exist in childhood, and it is more frequent in children with normal development.3 Prospective studies are needed in order to better assess these findings.
It has been shown that conversion disorder and staring spells were the most frequent NES.2 In our series; we also noted that staring spells were the most common non-epileptic events in the group with and without epilepsy. Overall frequency was 16% in our cohort which was consistent with the earlier reports.6, 12 It is interesting to note that the type of NES was similar in both groups of patients, independent of the presence of epilepsy or developmental delay. The only exception was the identification of crying or irritability as a more frequent manifestation of NES among patients with epilepsy. Perhaps following the diagnosis of epilepsy, some parents became more observant and suspicious of any paroxysmal behavior; conversely, parents of children without epilepsy are less likely to become alarmed by episodes of crying and irritability. With the absence of other accompanying clinical features such discoloration, eye deviation or limb shaking; irritability and cry alone may suggest NES rather than an epileptic event.
The description of the clinical manifestations of NES is often difficult to distinguish from epileptic seizures. In addition, epileptic seizures and NES might co-exist in the same patient. Given the potential adverse effects associated with long-term AED usage and the ramifications of a diagnosis of epilepsy, the utilization of video–EEG monitoring should be a consideration in order to clarify the nature of the clinical events, establish accurate diagnosis and provide appropriate medical care when indicated.
References
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PII: S1059-1311(08)00055-1
doi:10.1016/j.seizure.2008.02.010
© 2008 British Epilepsy Association. Published by Elsevier Inc. All rights reserved.
Volume 17, Issue 7 , Pages 583-587, October 2008
