Sci. Med. J. Cai. Synd. Vol. 4, No. 3, July 1992 161 -

FEBRILE CONVULSION: PROGNOSTIC CRITERIA FOR RECURRENCE

Tarkhan, M.N. Magda Y. Hussein and Fathalla, M.F.

Form the Departments of Neurology, Assiut University and Pediatrics, Ain Shams Universify.

ABSTRACT

49 infants and children (29 boys and 20 girls) between the ages ~f 3 nlonthes and 5 Years, fulfilling the criteria of Fc were studied dus- ing the acute phase of the illness; both clinically and electroencephal- ographically and were followed up fox I2 nzonths with the main airn of defining the inlportant risk factors for recurrence of F.C. Recur- rence was reported if2 13 cases (26.5%) during that period s f follow up. Various clinical and EEG findings were correlated statistically the following 5 risk factors for recurrence identified: I . Positive neurological findings. 2. Type of seizures. 3. Duration of fits. 4. Family history of FC, and 5. Positive EEC findings.,

INTRODUCTION AND AIM OF WORK

Febrile convulsion is not synon- ~ I I I O U S with convulsion with fever. In the concensus statement (Nelson and Ellenberg, 1981) a febrile con- vulsion is defined as an event in in- fancy or childhood, usually occur- ring between 3 months and 5 years ot' age associated with fever but without evidence of intracranial in- fection or defined cause. Seizures

with fever in children who have suffered a previous non febrile sei- zures are excluded. This definition could be criticized according to Aicardi (1986). Wallace (1988) de- fined Febrile ~ o n v u l s i o n as any seizure of cerebral origin which oc- curs in association with any febrile illness. However, inclusion of chil- dren with seizures suffering from

Tarkhan, M. N. et a1 ...

Meningitis, Encephalitis, Reyes Syndrome or cerebral Malaria seems questionable. The diagnosis is justified only if the body temper- ature is 38"C, rectal temperature or more. Simple FC are generalized and last less than 15 minutes and do not recur within 24 hours and do not exhibit post-ictal neurological abnormalities. Complex or conipli- cnted FC are focal or longer than 15 minutes or recur within 24 hours. Simple FC are always generalized, conlplex FC are partial or general- ized, (Knudsen, 1990). FC are now recognized as a benign condi- tion and the long term prognosis is excellent for the vast majority of children.

Most of the studies done showed that the risk of epilepsy subsequent to FC ranges from 2-7% (Knudsen, 1990). The most common secluela of a 1st FC is recurrent FC, occur- ring i n about 40% of cases, (Kn udsen, 1990).

Regarding the role of EEC in the acute phase of the febrile convul- sion, the literature showed some controversy about the value of EEG in giving a real indication of the lik- elihood of of recurrence of febrile seizures or expectancy of epilepsy (Lennox, 1949; Lerique, 1955).

Laplane et a1 (1959) and Frant- Zen et a1 (1968) reported that, dur-

ing the I st week after febrile con- vulsion between 30% and 70% of children have nomial EEG.

Slowing of the background rhythm was in one third of the pa- tients in some studies (Laplan et al, 1958; Baniberger and Matthes, 1959 amd Frantzen et al, 1968), rind In 88% of the patients in one study (Gregory stores, 1990). The last author reported that, this activi- ty is predominantly posterior in dis- tribution and although mostly bilat- eral, is often asymmetrical or even unilateral. When EEG changes were related to changes in tempera- ture over a 24 hours period of con- tinuous recording, Minchom and Wallace (1984) were unable to demonstrate any relationship be- tween the frequency of the back- ground rhythm and the height of pyrexia.

Spikes or spike and slow wave discharges, localized or generalized are rare in the early post-ictal period in febrile convulsion as reported by Gregory stores (1990). Frantzen et a1 ( 1968) gave a figure of 1.4% and kajitrtni et a1 (1981) reported 3% of their patients. Both these figures are close to the 1.9% given by Eeg- Olofsson (197 1) as the incidence of fmal sharp activity in normal young children.

In the lights of the previous liter-

atures this current study was carried to describe the EEG changes seen out with 2 aims. The first was the in those cases during the acute re-evauation of some clinical as- phaseof the illness, correlating them pects of children with febrile con- clinically and assessing the prog- vi~lsion and defining the group at nostic value of EEG at that early risk of recurrence. The second was stage of the illness.

SUBJECTS AND METHODS

This study was carried out on 49 infants and children who presented to the pediatric and Neurology department of A 1 Salama Hospital, Jeddah, Saudi Arabia i n the duration between April 1989 to March 1990, fulfilling the above mentioned criteria of febrile convulsion.

On presentation, all of them had the convulsion for the first time in their life and were brought to the hospital within few hours from de- veloping the seizures.

They were 29 boys and 20 girls with their age ranging between 3 months up to 5 years. Cases which had previous history of a febrile fits were not included in the study.

Each patient was submitted to full clinical assessment carried out by the pediatrician and neurologist. Temperature was taken rectally and routine blood test as well as other necessary investigations as chest X- ray were done. Analysis of the his-

tory data including perinatal histo- ry, seizures description, history of febrile as well as afebrile seizures in the family members weretaken. The aim of the clinical assessment was the diagnosis of underlying cause of fever aided by the necessary in- vestigations, and to search for any neurological or developmental ab- normality. During their hospital stay, the patients were managed aiming at reducing body tempera- ture and giving the specific medica- tion for the underlying cause of fe- ver. Following discharge from the hospital, patients' parents were in- structed to bring their kids at regu- lar intervals to the Outpatient Department. Some of the patients had more than one year duration of follow up, all of them had at least 6 months duration of follow up with the main aim of recording any febrile seizure recurrence.

All patients had an awake interic- tal EEG done maximallywithin 12 hours from developing the fits. This EEG was carried out using 16

164 Tarkhan, M. N. et a1 ...

channel EEG machine with the ap- No provocation was carried out, plication of small sized rubberhead mostly, due to lack of cooperation cap and saline electrodes through of the kids. Filter used was 60 Hz, the standard 10-12 placement sys- speed was 30m/sec., average sensi- tern using different transverse, lon- tivity was SOuv/cm and time con- gitudinal and Gasteau montages. stant was 0.53 Hz 0.3 second.

RESULTS

Age of children included in this study ranged between 3 months and 5 years with mean of 22.6 + 14.4 months. Most of these children (40 cases, i.e. 8 1.6%) were boys with male to female ratio 3:2. Three types of fits were encountered : 1. Generalized convulsive in 73.5% (36 cases). 2. Partial, secondary generalized in 18.4% (9 cases). 3. Focal in 8.1% (4 cases). Nearly thirth nine patients (79.6%) had their seizures lesting for 4 minutes or less. In 10 cases only (20.4%) seizures lasted more than 4 min- utes, but the maximum was 7 min- utes (mean duration was 3.15 -+ 1.7 minutes). In 45% of cases (22patients), the seizure took place in the 1st 12 hours of the illness and i n around 80% (39 patients) the fits started on the 2nd day of the illness but maximal was within 126 hours starting from the rise of temperature. The highest fever re- ported was 40.5"C and the lowest was 38.S°C with a mean of 39.4"C ;t 0,56, Twenty one patients (42.9%) had their fever ranging

from 39 to 39.goC, 30.6% with fe- ver above 40°C, and 26.6% with fever ranging from 38.S°C to 38.9"C. A diagnosis for the cause of the febrile illness could be reached in 39 cases (around 80%) with the viral URT infection on the top of the diagnosed cases (18 pa- tients) followed by the chest infec- tion or pneumonia (7 cases), tonsil- litis (6 cases), gastroenteritis (4 cases). Post-vaccination febrile convulsions were reported in 2 ca- sess and otitis media in 2 cases. Neuro-examination was negative in the majority of cases (41 patients, ie. 83.7%), while 6 patients (12.2%) showed an evidence for delayed milestones of development, and 2 cases (4.1 %) showed infan- tile hemiparesis. Perinatal history was surveyed in all patients with negative reporting in 38 patients (77.6%). Eleven patients gave dif- ferent postitive history data : La- bour was difficult in 3 cases, neo- natal jaundice was reported in 3 cases, low birth weight in 2, Cae- sarean section in 2, and eclampsia

in one case. Regarding the family history of febrile seizures 9 patients (18.4%) gave positive history of fe- brile seizures in their relatives while 4 only (8.2%) reported afebrile sei- zures in their family members. (Table 1).

In order to study and investigate the important factors for recurrence of febrile convulsions, recurrence rate was observed during the one year duration of follow up. In 13 cases (26.5%) recurrence of FC was reported within this period. Various clinical items were correlat- ed statistically between the recurrent and non recurrent groups with the following results being reached :

A- Insignificant factors : Neither sex nor age had a prog-

nostic value in recurrence of FC (mean age in recurrence group was 28.84 + 16.15 months, while in non recurrent it was 24.05 + 13.27) (P>0.05). Also, underlying cause of fever had nothing to do with the possibility of recurrence. Time of occurrence of fits in relation to the strut of fever was also found to be statistically insignific'mt. Difference between both groups in the height of fever was found also to be insig- nificant (recurrent mean+ SD 39.78 +_ 0.48 and non recurrent mean + SD 39.55 + 0.54) (P>O.OS). Also the history of afebrile seizures in the relatives was found to be insig-

nificant (one case in the recurrent group, 3 cases in the non recurrent group). Positive perinatal history was also compared in the two groups, the differnce between them was statistically insignificant (P> 0.0s).

B-Significant factors : Mean duration of fits i n the re-

current group was higher (mean + SD in recurrent group 3.96 + 1.26 minutes and mean + SD in non re- current 2.88 _+ 1.85). The differ- ence was statistically significant (P<0.05). Type of fits was found to be highly significant (P<0.01) as an indicator of recurrence. Focal as well as partial fits with secondary generalization had a significantly higher rate of recurrence if com- pared to the generalized fits (table 2). Positive neuro-findings on ex- amination were found to be an im- portant risk factor for recurrence (table 2). Delayed milestones of mental development and hemipare- sis were found to be significantly higher in the group of recurrent fe- brile seizures (P<0.001). Also, his- tory of FC in the relatives of the pa- tient was significantly high in the recurrent group (P<0.01) (table 2).

EEG Results EEG was found to be normal in

35 cases (7 1.4%) while in 14 cases (28.6%) it showed various abnor- mal findings. Diffuse slowing was

reported in 5 cases, asymmetric slowing in 2 cases, 3 cases showed focal sharp waves or spikes and 4 cases showed generalized bursts formed by high voltage slow waves with and without spike activities. Positive versus negative EEG find- ings were correlated between the re-

current and non recurrent groups (table 3), the difference between them was statistically significant (P<0.05 to P < 0.001) indicating that, patients having one of the pos- itive EEG findings described above, had a significantly higher tendency for recurrence of FC.

FEBRILE CONVULSION: PROGNOSTC ...

Table ( 1 ) Evaluation of the patients.

Percen tag5

48.9% 32.7% 18.4%

59.2% 40.8%

26.5% 42.9% 30.6%

79.6% 20.4%

73.5% 18.4% 8.1%

83.7% 16.3%

26.5% 73.5%

18.4% 8.2%

(1) Age : Below 1 year 1-3 years 3-5 years

(2) Sex : Boys Girls

(3) Range of fever : 38.5 - 38.9"C. 39 - 39.9"C Above 40°C

(4) Duration of fit : Below 4 mintes 4 minutes and more

(5) Seizure type : Generalized Partial Focal

(6) Neurological Exam. Nom~al Abnormal

(7) Recurrence rate : Positive Negative

(8) Family history of seizures : Febrile Afebrile

Number of cases

24 16 9

29 20

13 2 1 15

39 10

3 6 9 4

4 1 8

13 36

9 4

Table (2) Significant factors for FC recurrence.

b) Partial sec.

P < 0.05 = Significant. P < 0.81 = Highly significant. P < 0.001 = Highly significant.

EBRILE CONVULSION: PROGNO

Table (3) EEG in relation to FC recurrence.

Non recurrent Recurrenr EEG Findings I group (N=36) group (N=13) Significance

Ne~at ive EEG : Positive EEG : 1. Focal spikes . 2. G. bursts 3. Diffuse slowing 4. Asymmetric siowing

I-' > 0.05 = Non significant. P < 0.05 = Significant P < 0.01 = Highly significant. P < 0.001 = Highly signif~cant.

DISCUSSION AND CONCLUSION

Febrile convulsion is one of the most common seizure disorders in early childhood, about 3% of a11 children are likely to have at least one FC (Knudsen, 1990). The cur- rent study tried to focus on some clinical aspects and EECi changes In the acute phase and the prognostic value of each. Most of our cases were beiow 3 years of age; a find- ing being conlpatible with marly previous studies (Verity et al, 1979 and Jacqueline, 1990). The inci- dence of FC in m:iles in our series of cases was greater than in fe- males. This also came in agreement with other authors (Ohtahara, 198 1: Jacqueline, 1990 and Knudsen,

1990). Generalized convulsion is the most common presentation (73.5% current study, 82% Jacque- line, 1990) and mostly occurs with- in the 1 st 24 hours of the febrile ill ness (80% current study, 81% Jacquel ine, 1990). Knudsen (1990), In his study, identified 5 significant risk factors for recur- rence of FC, namely : 1. Young age at onset (less than 15

months). 2. Epilepsy in 1st degree relatives. 3. FC in 1st degree relatives. 4. One or more complex features of

the 1;t FC. 5. Many subsequent febrile epi-

sodes.

Tarkhan, M. N. et a1 ...

In our study there were some common criteria of recurrence with those of knudsen (1990), however, young age at onset and history of febrile convulsions in the relatives mentioned by him were found in our study to be statistically insignif- icant. On the other hand, the signif- icance of neuro-findings and EEG changes done for our patients were not included in his study. These differences could be attributed to differences in environmental fac- tors, number of patients and follow up periods in both studies.

'There is a lot of controversy in the literature as regards the value of EEG recording during the acute phase of FC in giving a real indica- tion of recurrence. While some au- thors reported that when recording in the acute phase EEG does not provide any useful information for prognosis (Nelson and Ellenberg, 1981 and Gregory stores, 1990), other authors found that EEG changes during the acute stages of febrile illness reflect changes related to the underlying infection than the seizures (Wallace and Zeally, 1970).

The current study showed that,

EEG even done during the acute phase of illness does have predic- tive value for further recurrence of FC. The reason of this difference can not be pinpointed because of the difference in the recording pro- cedures, time of recording and also the variation in the concepts of nor- mality versus abnormality in EEG. However it is important to state that there is a serious risk of misdiag- nosing epilepsy on the basis of such EEG findings alone. Serial and follow up EEG are needed in those patients with abnormal EEG findings for better electrophysiolog- ical evaluation.

In conclusion, this study tried to highlighten the risk factors for re- cilrrence of FC and they were found as follows :

1. Positive neurological findings on exiiniination.

2. Type of seizures (focal and par- tial with secondary generaliza- tion).

3. Family history of FC.. 4. Duration of the fit (the longer the

duration the more tendency of recurrence).

5. Positive EEG findings in the acute phase of illness.

171 FEBRILE CONVULSION: PROGNOSTC ... -

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