mill, S

Child's Nerv Syst (1989) 5:160-162

© Springer-Verlag 1989

EEG findings in minor head trauma as a clue for indication to CT scan* G . L i g u o r i , L. F o g g i a , A . B u o n a g u r o , M . C o l u c c i , G . C a n t o n e , a n d A . A m b r o s i o Ospedate Pediatrico Santobouo,. Divisione di Neurochirurgia, Via Mario Fiore 6, 1-80129 Napoli, Italy

Abstract. In order to investigate the role of E E G in m i n o r head t r a u m a t a in the pediatric age, E E G and CT scan findings were c o m p a r e d in a series of 103 consecutive cases of children hospitalized within 24 h after head trauma. The E E G s were classified as normal in 50 patients, borderline in 10 patients, and a b n o r m a l in 43 patients. CT scan showed contusion in 6 patients and extracerebral h e m a t o m a in 4. All cases o f a b n o r m a l CT scans were reported for patients with frankly a b n o r m a l E E G findings. In contrast, no pathological findings were found in CT scans for patients with normal EEG. The data suggest that E E G findings can play a major role in the diagnostic w o r k u p o f patients with minor head traumata. Specifically, in the case of asymptomatic patients with n o r m a l E E G findings, it is likely that the CT scan will also be normal. Key words: M i n o r head injury scan.

Pediatric age - E E G - CT

In the pediatric age group, there is a high prevalence o f head trauma. Only a few evolve into true medical and surgical emergencies. Luckily, the vast majority have a quite benign outcome. On the other hand, even minor head t r a u m a can be a real medical p r o b l e m because the final outcome can be unpredictable in the individual patient at the very beginning of the disease. In head t r a u m a with frank neurological symptoms and diagnostic signs, the therapeutic guidelines are not controversial; in minor head traumata, however, the physician has to weigh the medical and legal benefits against the psychological and iatrogenic costs o f his diagnostic and therapeutic actions. In particular, m o d e r n neurological and neurosurgical services have profited greatly from the widespread use of CT scans, which are consequently of great usefulness also in the m a n a g e m e n t o f patients with head trauma. Specifically, * Presented at the 11th Meeting of the European Society for Paediatric Neurosurgery, Naples 1988 Offprint requests to: G. Liguori

in the case of head t r a u m a with loss of consciousness (either immediate or after a lucid interval) or with neurological deficit (either stable or worsening), the value of the CT scan cannot be overemphasized. On the other hand, considering the prevalence o f m i n o r head t r a u m a and the usually benign outcome of the vast majority, the indiscriminate use of CT scan m a y be unjustified, particularly in an apparently healthy patient. Unfortunately, although most children with head trauma are free o f sequelae, we must not forget that some patients m a y develop major problems that m a y even be lifethreatening. In other words, the final outcome of the individual patient cannot be reliably predicted on the basis of the clinical evaluation alone. Therefore, in order to minimize the use of the CT scan in m i n o r head trauma, it is necessary to supplement the d a t a gathered from clinical observations with those offered by other methods such as EEG. In fact, E E G is a time-honored clinical method with some clear advantages: noninvasiveness, its wide availability, and the avoidance of exposure to ionizing radiation. In light of these considerations, we have studied the possible correlation of E E G and CT scan findings in children with minor head trauma.

Materials and methods We studied a series of 103 consecutive cases of children (aged fi'om 4 months to 13 years) hospitalized at our institution within 24 h after a minor head trauma. All of the cases of patients who were free of neurological signs and symptoms on admission were classified as having minor head trauma. The etiology of head injuries is reported in Table 1. The patients were classified into two groups: the first included patients with transient unconsciousness and the second unimpaired consciousness; in the second group non-specific signs and symptoms such as vomiting, headaches, convulsions, and ohtundation may or not have been present. At least three neurological evaluations were performed during hospitalization and all patients were reported as asymptomatic. EEG and CT scans were performed by physicians who were unaware of the study protocol. EEG was performed within 12 h after admission, using a 10-20 montage system and, when possible, with the usual method of activation; also, CT scan was performed within 12 h after admission. Data were evaluated using the Chisquare test, with the "fates correction, when recommended. Confi-

161 Table

1. Etiology in 103 cases of minor head injury

60

No. Accidental falls while playing Falls from tables, beds, etc. Falls from bicycles Road accidents Falls from balconies Blunt instrument Other

%

18 28 2 41 4 7 3

Totals

17.47 27.18 1.94 39.80 3.89 6.80 2.92

103

30 20 10

100

Table 2. Symptoms in 103 cases of minor head injury

.--

"~n

•

"=

o-~

z

~, m

No a_~

N

e~

:

m

~ CL

Fig. 1. EEG findings (n = 103)

No. 1. Transient unconsciousness

40

%

25

24.27 100

2. Integral conscious level a. Asymptomatic b. Aspecific symptoms

31 47

Totals

30.09 45.64

103

100

90 80 70 60

Non-specific symptoms in 47 cases Vomiting Obturation Headache Convulsions

33 28 5 2

70.21 59.57 10.63 4.25

50 40 30 20 10

Table

3. EEG findings in relation to symptomatotogy groups pa-

i

tients o

EEG

Normal Borderline Pathological Diffuse slowing Lateralization Focal slowing Paroxysms

Transient unconsciousness 12 1 12 2 6 3 1

Integrat conscious level Asymptom- Symptoms atic 14 2 13 2 2 8 1

25 1 23 2 6 14 1

dence limits were calculated using Cornfield's method; a Chi-square test for trend was performed. All data were analyzed with computer-based programs.

Results

The E E G s were classified as n o r m a l in 51 patients and pathological in 48; in 4 other cases, they were classified as borderline because o f the presence of non-specific backg r o u n d activity (Fig. 1). Twenty patients with pathological E E G s showed diffuse slowing o f the electric activity; in 14 o f them, a focal dominance o f slow waves was also present.

~

.--Q 4--

Fig. 2. CT findings (n = 103)

F o c a l slow waves, with a variable degree and without background abnormalities, were found in 25 patients. In two, a focal depression was also found. In most patients the localization of focal slow waves is not correlated with the area of injury because they were mostly found in the occipital region, which was unilateral in 18 cases and bilateral in 2 cases. Three patients, furthermore, showed focal paroxystic activity. In Table 3, the E E G findings are correlated with symptomatological groups. A m o n g the 103 cases, only 10 had a relevant pathological finding u p o n CT scan; extradural effusion was found in 4 cases, focal concussion in 4 cases, and subarachnoidal hemorrhage in 2 (Fig. 2). The relationship between the E E G and CT scan findings is shown in Fig. 3. The statistical analysis of results showed a highly significant relation (P < 0.01) between the pathological E E G findings and the lesion findings on CT, but we were not able to find a significant relationship between individual E E G pathological findings and lesions found on CT.

162 6O 50

4O

40 30 20

ive

10

Fig. 3. EEG and CT correlation

Discussion Silverman [4] has analyzed E E G findings in children with head trauma, and his data have been confirmed by other authors [1-3]. The most frequent abnormality is slowing of the cerebral activity, especially in the occipital region. This finding is also c o m m o n after minimal trauma. Diffuse or focal slowing of the cerebral activity is usually found in less trivial injuries. In general, head trauma, even minor, is often associated with detectable E E G abnormalities. In our series, such abnormalities were present in 46% of the patients with minor head trauma who were free of neurological signs and symptoms upon admission. These data are in accordance with those reported by others [1]. In this study, a significant association between definite lesions demonstrated on CT scan and pathological findings on E E G tracings was found. In contrast, we were not able to correlate the type of E E G abnormality with other data, either from the clinical evaluation or the CT scan. A correlation between E E G findings and clinical conditions has been described by Mizrahi and Kellaway [3], but while such a correlation is evident in the case of frank head injuries, in minor

head trauma the usual observation is slowing of cerebral activity in the occipital region. Therefore, it is not surprising that in our series there was no clear correlation between the type of E E G findings and clinical data: we studied only patients with lesser head injuries. In keeping with this hypothesis, the slowing of cerebral activity in the occipital areas is, by far, the most frequent E E G abnormality. This finding is known to be a non-specific sign of minor head trauma. It seems worthwhile to point out that not all patients with pathological EEGs also show definite anatomical lesions that are detectable on CT scans. These data are in accordance with those reported by E n o m o t o et al. [1]. The latter authors also affirm that the functional data evaluated with E E G are different in nature from the anatomical study performed with CT scan. On this basis, it is not surprising that there is an occasional discordance between E E G and CT scan signs in some patients. Presumably, the functional study is more sensitive than the anatomical one, as suggested by the greater number of patients classified as pathological on EEG. In conclusion, since our data suggest that pathological E E G findings are found in patients with anatomical lesions that are detectable on CT scan, it seems worthwhile to perform EEGs in patientswith minor head trauma who are free of neurological symptoms and signs. The aim is to identifity a subgroup of patients with a higher probability of surgically correctable lesions.

References 1. Enomoto T, Ono Y, Nose T, Maki Y, Tsukada K (1986) Electroencephalography in minor head injury in children. Child's Nerv Syst 2:72 79 2. Landau-Ferey J, Bour F (1980) Inter~t pronostique de I'EEG dans les jours suivant certains traumatismes craniens de l'enfant et de l'adolescent. Electroencephal Clin Neurophysio149:173 180 3. Mizrahi EM, Kellaway P (1984) Cerebral concussion in children: assessment of injury by electroencefalography. Pediatrics 73:419-425 4. Silverman D (1962) Electroencephalographic study of acute head injury in children. Neurology 12:273-281 Received December 5, 1988