Febrile seizures in patients with complex partial seizures

Febrile seizures: current views and investigations

Febrile seizures (FSs) are seizures that occur during fever, usually at the time of a cold or flu, and represent the most common cause of seizures in the pediatric population. Up to 5% of children between the ages of six months and five years-of-age will experience a FS. Clinically these seizures are categorized as benign events with little impact on the growth and development of the child. However, studies have linked the occurrence of FSs to an increased risk of developing adult epileptic disorders. There are many unanswered questions about FSs, such as the mechanism of their generation, the long-term effects of these seizures, and their role in epileptogenesis. Answers are beginning to emerge based on results from animal studies. This review summarizes the current literature on animal models of FSs, mechanisms underlying the seizures, and functional, structural, and molecular changes that may result from them.

Cortical hyperexcitability and epileptogenesis: Understanding the mechanisms of epilepsy - part 2

Epilepsy encompasses a diverse group of seizure disorders caused by a variety of structural, cellular and molecular alterations of the brain primarily affecting the cerebral cortex, leading to recurrent unprovoked epileptic seizures. In this two-part review we examine the mechanisms underlying normal neuronal function and those predisposing to recurrent epileptic seizures starting at the most basic cellular derangements (Part 1, Volume 16, Issue 3) and working up to the highly complex epileptic networks and factors that modulate the predisposition to seizures (Part 2). We attempt to show that multiple factors can modify the epileptic process and that different mechanisms underlie different types of epilepsy, and in most situations there is an interplay between multiple genetic and environmental factors.

Progressive hippocampal and extrahippocampal atrophy in drug resistant epilepsy

PURPOSE OF REVIEW

This article reviews recent experimental and clinical evidence for seizure-related progressive brain damage and discusses possible mechanisms of ongoing brain atrophy in epilepsy.

RECENT FINDINGS

Experimental data indicate that seizures induce brain plasticity that may result in either damage or protection. Brief seizures or status epilepticus may promote resistance to additional damage but also induce cumulative neuronal loss and increase susceptibility to network synchronization. Some experimental studies indicated that, following the initial damage caused by status epilepticus, further brief seizures may not produce significant continuing neuronal loss and hippocampal atrophy, whereas other studies showed the contrary. There is recent evidence that progressive damage and atrophy may occur after an acute insult but are not directly associated with recurrent seizures. Clinical research data continue to show discrepancies regarding whether ongoing seizures cause progressive atrophy. Some cross-sectional and longitudinal magnetic resonance imaging studies in patients with partial epilepsies have shown progressive hippocampal and extrahippocampal atrophy, the severity of which correlated with the duration of epilepsy, seizure frequency, or lifetime seizure number, whereas others have failed to show a clear association.

SUMMARY

Experimental data indicate that epileptogenesis in developing brain may not require significant neuronal loss, which is in keeping with clinical observations that progressive cognitive and behavioural impairment may occur in patients with no detectable brain atrophy. A better understanding of why, when and how progressive brain atrophy occurs will lead to better clinical management, earlier surgical intervention when necessary and, ultimately, prevention of epileptogenesis.

A retrospective analysis of patients with febrile seizures followed by epilepsy

This study was performed to investigate some clinical parameters of febrile seizures (FSs) in patients with epilepsy, testing any possible correlation between those parameters and the type of subsequent epilepsy. One hundred and nine patients with epilepsy having a history of FSs were evaluated for age at onset of FSs, interval between first FS and first afebrile seizure, recurrence rate, type of FSs, incidence of febrile status, family history for epilepsy and for FSs and the neurological status of the patient. The epilepsy that developed subsequently, were classified as generalised versus partial and also according to their syndromic subgroups. In temporal lobe epilepsy with mesial temporal sclerosis (TLE-MTS), statistical analyses revealed a younger age at onset of FSs, and a high incidence of episodes of febrile status and of complex FSs. Clinical characteristics of FSs followed by partial epilepsies were younger age at onset, presence of focal features and of febrile status, longer interval between the first FS and the first afebrile seizure, and a high incidence of FSs in the family history. In generalised epilepsies, however, a shorter interval between the first FS and the first afebrile seizure, a high incidence of single FS and of a family history of epilepsy were predominating characteristics. Results suggest that certain features of FSs may be predictive of a particular type of subsequent epilepsy.

Clinical features and surgical outcome of medial temporal lobe epilepsy with a history of complex febrile convulsions

PURPOSE

Temporal lobe epilepsy (TLE) is frequently associated with hippocampal sclerosis (HS) and complex febrile convulsions (CFC). The causal relationship between TLE, HS, and CFC is unclear. There is also contradictory data whether CFC-associated TLE is a distinct epilepsy syndrome and has different surgical outcome than other medial TLEs.

METHODS

We investigated 133 patients (aged 16-59 years) with HS-associated TLE. Thirty-six patients with CFC (CFC group) versus 97 patients without febrile convulsions (NFC group) were compared for clinical history, video-EEG recorded seizure semiology, and surgical outcome.

RESULTS

In the CFC group the right-sided HS (67% versus 32%) occurred more frequently than in the NFC group (P<0.001). The two groups did not differ according to the clinical features, both groups share the typical symptoms and findings of the medial TLE. In the CFC group, seizure-freedom 2 years after surgery was 91%, while in the NFC group it was only 64% (P=0.023). This difference was significant even after considering the other known predictive factors for medial TLE.

CONCLUSIONS

Medial TLE with CFC is not a distinct epilepsy syndrome. The surgical outcome, however, is much more favorable in these patients in comparison with medial TLE patients who had no history of febrile convulsions.

Childhood febrile convulsions--which factors determine the subsequent epilepsy syndrome? A retrospective study

To analyze the spectrum of epilepsy syndromes which follow childhood febrile convulsions (FC) and to examine whether retrospective analysis of clinical features of the FC enables discrimination of patients who develop temporal lobe epilepsy (TLE) from those who develop generalized epilepsy (GE). One hundred and thirteen patients with epilepsy and antecedent FC were retrospectively analyzed. We inquired in detail about the clinical characteristics of FC (age, duration, number, focal symptoms) as well as family history, birth history, neurological status, and psychomotor development before onset of FC. Forty five (39.8%) patients had TLE, 41 (36.6%) GE, and 27 (23.9%) had extratemporal epilepsy (ETE). Patients with TLE had a significantly longer duration of FC (P< or =0.001), more often focal features (P< or =0.001), and febrile status epilepticus (P< or =0.001) than patients with GE. Age at FC, Number of FC, family history, birth history and neurological status at FC did not differ between groups. A stepwise discriminant model allowed correct assignment after cross validation in 84.2% to TLE and in 100% to GE. A broad spectrum of epilepsy syndromes follow FC. We found a strong association of prolonged and focal FC with later development of TLE. Short generalized FC were associated with GE.

Treatment of febrile seizures with intermittent clobazam

Fifty children, 24 female and 26 male, with ages varying from 6 to 72 months (mean = 23.7 m.) that experienced at least one febrile seizure (FS) entered a prospective study of intermittent therapy with clobazam. Cases with severe neurological abnormalities, progressive neurological disease, afebrile seizures, symptomatic seizures of other nature, or seizures during a central nervous system infection were excluded. Seizures were of the simple type in 25 patients, complex in 20 and unclassified in 5. The mean follow-up period was 7.9 months (range = 1 to 23 m.), and the age at the first seizure varied from 5 to 42 months (mean = 16.8 m.). Clobazam was administered orally during the febrile episode according to the child's weight: up to 5 kg, 5 mg/day; from 5 to 10 kg, 10 mg/day; from 11 to 15 kg, 15 mg/day, and over 15 kg, 20 mg/day. There were 219 febrile episodes, with temperature above 37.8 degrees C, in 40 children during the study period. Twelve children never received clobazam and 28 received the drug at least once. Drug efficacy was measured by comparing FS recurrence in the febrile episodes that were treated with clobazam with those in which only antipyretic measures were taken. Ten children (20%) experienced a FS during the study period. Of the 171 febrile episodes treated with clobazam there were only 3 recurrences (1.7%), while of the 48 episodes treated only with antipyretic measures there were 11 recurrences (22.9%), a difference highly significant (p < 0.0001). Adverse effects occurred in 10/28 patients (35.7%), consisting mainly in vomiting, somnolence and hyperactivity. Only one patient had recurrent vomiting which lead to drug interruption. These effects did not necessarily occurred in every instance the drug was administered, being present in one febrile episode and not in the others. We conclude that clonazepam is safe and efficacious in preventing FS recurrence. It may be an alternative to diazepam in the intermittent treatment of FS recurrence.

Atrophy of mesial structures in patients with temporal lobe epilepsy: cause or consequence of repeated seizures?

We studied 70 epileptic patients by using magnetic resonance imaging volumetric measurements of amygdala (AM) and hippocampal formation (HF). Fifty patients presented with intractable temporal lobe epilepsy (TLE), 10 patients had focal extratemporal lobe epilepsy, and 10 had generalized epilepsy. In 91% of the 45 TLE patients without foreign tissue lesions, there was significant smallness of the AM and/or HF coinciding with the side of electroencephalographic seizure onset. No significant smallness or asymmetry was demonstrated in patients with focal extratemporal or generalized epilepsy. We performed a linear regression analysis, plotting the number of years of recurrent seizures and the estimated seizure frequency against the volumes of the AM and HF. There was no correlation between either of these two parameters and AM or HF volume (p > 0.9). There was also no correlation between the patient's age and volumetric measurements of AM or HF, nor did these measurements correlate with the occurrence of generalized seizures. On the other hand, patients with antecedent prolonged febrile convulsions in early childhood had significantly smaller AM and HF, compared with those without such a history (p < 0.001). The findings indicate that repeated seizures or longer duration of epilepsy do not cause increased atrophy of AM or HF that is measurable by volumetric magnetic resonance imaging.

Temporal lobe epilepsy after prolonged febrile convulsions: excellent outcome after surgical treatment

We studied 47 consecutive patients who underwent temporal resection for seizure control. Nineteen (40%) had febrile convulsions preceding onset of their habitual seizures. In 17 of 18 patients whose disease duration was known, the febrile convulsions were prolonged (mean 4 h). As compared with patients without preceding febrile convulsions, patients with antecedent febrile convulsions had a significantly higher prevalence of positive family history of febrile convulsions, an increased incidence of retrospectively identified gestational or perinatal complications, and no foreign tissue lesions. Pathologic studies showed gliosis and cell loss in mesiotemporal structures, usually moderate, in addition to usually mild gliosis in lateral temporal cortex. These patients had an excellent outcome after temporal resection: 84% were seizure-free, had residual auras only, or occasional convulsions with medication discontinuation. One patient (5%) had > 90% improvement. Two patients (11%) in whom the hippocampus was totally spared continued to have complex partial seizures: in both, seizures stopped after reoperation and hippocampal resection. Thus, 95% of these patients had an excellent result. Only 16% required invasive preoperative studies to confirm lateralization. These results were significantly better than those of the group without preceding febrile convulsions (p = 0.0013).

Benign epilepsy of children with complex partial seizures following febrile convulsions

Among the partial epilepsies with complex partial seizures (CPS) following febrile convulsions (FC), there is an idiopathic epilepsy with extremely benign outcome, characterized by: 1) no past history suggesting brain insult, no underlying brain lesions, no neurological abnormalities, no mental retardation; 2) a high incidence of a positive family history of FC or benign epilepsy; 3) no past history of prolonged febrile convulsions; 4) EEG spike foci other than anterior temporal ones; 5) CPS easily controlled with full recovery.

Seizure prognosis and EEG evolution in complex partial seizures of childhood onset

We studied the clinical course and seizure prognosis of 126 children with complex partial seizures regularly followed up for more than 4 years in our clinic. Clinical and EEG features of 63 seizure-free patients were compared with those of 63 patients with persistent seizures. The features contributing to poor prognosis were 1) mental retardation, 2) a history of status epilepticus and 3) abnormal basic rhythm in EEG. CT abnormality, a history of febrile convulsions (FC), the clustering of seizures and association with other types of seizures did not influence prognosis. We divided the patients into four groups according to the evolutionary pattern of seizure discharges: Group A, 55 (43.7%) patients with spike focus always fixed in the same region; Group B, 20 (15.9%) patients with wandering foci; Group C, 10 (7.4%) patients with multifocal spikes; and group D, 41 (32.5%) patients with no focal discharges. There was no difference in seizure prognosis among these four groups, but the patients with a focus in the anterior temporal region in Group A evidenced the worst prognosis.

Seizure prognosis for partial epilepsies in India

The long-term prognosis and factors associated with good and poor prognosis were studied in 95 patients with partial seizures. Thirty-nine per cent of the patients became seizure free. Significant prognostic factors were: male sex, most attacks while awake, attacks precipitated by a hot-water bath, presence of autonomic phenomena and complex symptoms, chronicity and severity of the illness, and seizure activity and the presence of symmetric synchronous EEG foci in the initial EEG records. Regularity of medication, duration of illness and autonomic phenomena were 3 predictive factors for long-term prognosis.

Factors prognostic of unprovoked seizures after febrile convulsions

We evaluated the risk of unprovoked seizures after febrile convulsions and the factors prognostic of them in a cohort of 687 children who had an initial febrile seizure while residing in Rochester, Minnesota. Overall, children with febrile convulsions had a fivefold excess of unprovoked seizures, and the risk until the age of 25 was 7 percent. The risk ranged from 2.4 percent among children with simple febrile convulsions to 6 to 8 percent among children with a single complex feature--i.e., focal or prolonged seizures or repeated episodes of febrile convulsions with the same illness. For children with any two of the complex features, the risk was 17 to 22 percent, and for those with all three features, 49 percent. The occurrence of subsequent partial unprovoked seizures was strongly associated with all three of the complex features, whereas the occurrence of subsequent unprovoked seizures of generalized onset was associated with the number of febrile convulsions and a family history of unprovoked seizures. These results are consistent with the view that the increased risk of generalized-onset unprovoked seizures reflects a predisposition to both simple febrile convulsions and generalized-onset unprovoked seizures. The association between complex febrile convulsions and partial seizures, on the other hand, may reflect either a causal association or the presence of preexisting brain disease that is responsible for both the complex febrile seizures and later partial seizures.