Computerised tomography (ct) and electroencephalography (eeg) in the immediate evaluation of term infants with symptomatic birth asphyxia – what is anoxic encephalopathy

Indian I pediat 51: 327-332, 1984

Computerlsed tomography (CT) and

Electroencephalograph]/(EEG) in the

Immediate evaluation of term infants with

Symptomatic birth asphyxia

R. Merchant. M.D., V. Chablani, M.D., B. Parekh, M.D.,

N. Goudinho, M.B.B.S., and N.P. Vas, M.D.

Twelve full term asphyxiated neonates who exhibited evidences of hypoxic-ischemlc

Encephalopathy (HIE) were subjected to computerised tomography (C’F) and electroen-

Cephalography (EEG), in order to evaluate the immediate prognostic values of these two,

Noninvaslve techniques. CTscan was also done in one normal term newborn and’EEG in ten

Normal term neonates to serve as controls. CT flndlngs revealed normal scans in two, bor-

Derline normal scans in two, tentorial hemorrhages with hydrocephalus but without

what is anoxic encephalopathy

Parenchymal bleeds in two, gross cerebral edema in ,four, cerebral atrophy and hyd-

Rocephalus in one each. Repeat scans done in both in,fan ts with tentortal hemorrhages, at 2

Months, revealed complete resolution of bleeds and decrease in yen tricular size. EEG were

Within normal limits in ,four and abnormal in the rest. Four in,rants died, three o,f asphyxia

And one o,f pyogenic meningitis. The three who died o,f asphyxia had clinical evidences oj a

Severe enoephalopathy along with significant abnormalities on scan (gross cerebral edema)

And on EEG (very low amplitude). O,f the eight surviving in,rants, six are neurologically nor.

Real so,far, while two have evidences o,f spastic cerebral palsy. Both neonates with tentorial

what is anoxic encephalopathy

Bleeds are normal at 6 months, although both had a moderately severe neonatal neurologi-

Cal syndrome.

Key words: birth asphyxia; computer ised tomography; electro-


Asphyxia is the single most important

Perinatal cause of brain damage in term

Infants. In an attempt to determine the

Extent of cerebral injury and to predict the

Immediate and long term outcome, a num-

Ber of clinical and laboratory efforts have

Been made. The much utilized apgar score

Is an unreliable screening test for predicting

Bai jerbai wadia hospital for children and institute of

Child health and B. Nanavati hospital and bombay

Medical centre, bombay.

Reprint requests: dr. R, merchant, pediatrician, B.J.

Wadia hospital for children, pard, bombay 400 012.What is anoxic encephalopathy

Cerebral damage, l as it is a highly subjective

Parameter, is not always recorded accurately

And may be influenced by maternal seda-

Tion. Both computerised tomography (CT)

And electroencephalography (EEG) are now

Accepted as routine diagnostic procedures in

Conjunction with neurological evaluation to

Detect brain damage in neonates. They have

The advantage of being non-invasive and

Reflect structural and electrophysiological

Integrity of the cerebral neurones.

This preliminary study was undertaken

To determine the immediate prognostic

Value of these two procedures in infants with

Symptomatic birth asphyxia.


Material and methods

From august 1982 through may 1983, 12

Term neonates admitted with evidence of

what is anoxic encephalopathy

Hypoxic-ischemic encephalopathy (HIE)

Were prospectively diagnosed and studied.

Only those neonates who met at least two of

The underlying criteria were included in the

Study: (i) evidences of perinatal asphyxia i.E.

Fetal distress clinically detectable-fetal heart

Irregularities/abnormalities; (ii) apgar

Score less than 6 at 1 or 5 min; (iii) need for

Resuscitation either mechanical or phar-

Macological; (iv) abnormal neurological

Findings such as altered tone or sensorium,

Abnormal neonatal reflexes or seizure

Activity. CNS examination was done on

Admission and then daily to ascertain pro-

Gress ofencephalopathy. Patients were then

Graded into mild (stage I), moderate (stage

II) or severe (stage III) encephalopathy as

what is anoxic encephalopathy

Per sarnat’s classification. No infant with

Confirmed CNS malformation, chromo-

Somal anomaly or intrauterine infection was


Most CT scans were done on an

Omnimedical 4001 dedicated head scanner

Unit, while only two were done on a siemens

Somatone D II body scanner unit. Contrast

Studies using conray 280 were done in 5

Cases. Scans were performed in all but one

Infant within first 2 wk of life. Infants were

Transported to the scanner when their condi-

Tion had stabilised. Most neonates were well

Sedated with 5-7 drops of trimeprazine

(vallergan forte) syrup, while a few required

Injectable diazepam I.M. For proper seda-

Tion. Repeat scans at 2 months were done in

Only two cases with tentorial hemorrhages.What is anoxic encephalopathy

All scans were analysed by the same

Individual (VC) who was aware of condition

Of the patients. One normal neonate was

Subjected to a CT scan to serve as a control.

Ventricular size was measured in all

Vol. 51, no. 410

Patients and classified into 6 categories. 2 (i)

Ventricles not seen; (ii) slit-like ventricles;

(iii) normal ventricles le. Lateral ventriclar

Ratio (LVR)=less than .3; where LVR=max.

Width of body of lateral ventricles at level of

Caudate nucleus divided by 1/2 biparietal

Diameter; (iv) LVR .3-.4; (v) LVR between

.4-.5 (moderate dilatation of ventricles); (vi~

LVR above .5 (marked ventricular dila’


Electroancephalograms were done

Without sedation using the standard inter

National 10-20 system of electrode place

what is anoxic encephalopathy

Ment with a chart speed of 30 mm/sec, on an

Eight channel OTE. Biomedica EEG model

E 8 d machine with calibration of 50 ~V/7

Mm. All movement artefacts were noted dur-

Ing the recording, which was done during

Active sleep in most neonates. Initial eegs

Were performed in 11 infants within the first

Two weeks of life. Repeat eegwere done in 5

To 8 surviving infants at 3 months. Ten nor,

Mal term neonates were also subjected to

EEG in order to serve as controls.

A systematic treatment protocol was not

Planned for this study and the treatment was

Left to the discretion of the attending

Neonatologists. However, there was consen-

Sus in favour of treating cerebral edema,

With fluid restriction and mannitol and

Treating convulsions with phenobarbitone

what is anoxic encephalopathy

With conventional recommended dosage.

The period of follow-up ranged from 3 to 9



There were 6 males and 6 females, all were

More than 37 wk gestation, as calculated

From maternal dates and dubowitz criteria.

Six infants were delivered normally, three by

Breech, two by cesarean section and one by

Outlet forceps. Seizure activity either frank

Or subtle was noted in ten newborns. Six


Table. Relationship of clinical status to CT and EEG results and outcome


Clinical status no. Of cases CT results EEG results outcome

Mild HIE (stage it 3 normal -2 normal -2 all 3 normal

Mild periventricalar neuronal

Hypodensity -1 hyperexcitability -1

Moderate il IE 3 mild periventricular normal -1 normal -2

what is anoxic encephalopathy

-C.~=age 11) hyprodensity -I low amplitude -i expired -i*

Tentorial bleed -I neuronal

Dilated ventricles -I hyperexcitability -1

Severe HIE (stage ili) 6 tentorial bleed -1 normal -1 normal -1

Severe periventricular low amplitude -3 cerebral palsy -2

Hypodnsity -4 neuronal expired -3

Cerebral atrophy -i hyperexcitability -2

*expired of pyogenic meningi!Is

HlE–hypoxic-ischemic encephalopathy.

Babies exhibited evidence of severe HIE of

Which 3 died, 2 developed spastic cerebral

Palsy and one is normal; 3 had moderate

Symptoms while 3 had a mild HIE. Four

Patients died, two of asphyxia, one of

Pyogenic meningitis and one of a combined

Effect of asphyxia and meningitis. Eight

Infants recovered, six of them were neuro-

what is anoxic encephalopathy

Logically normal on follow up, these

Included both cases with intracranial

Bleeds. Two infants developed spastic cereb-

Ral palsy (CP).

CT-results (table) of the total 12, only 2

Newborns had normal CT-scan. Both of

These had normal EEG recording as well.

Half of the newborns had periventricular

Hypodensities, all these had abnormal EEG

As well (fig. 1). In two babies, who had

Fig. I. A. Scan showing gross cerebral oedema with b. Corresponding EEG abnormality (case no.

Hypodense areas and slit-like ventricles. 12).


Byperdc~l~.E ar~ ~.

Evidence of tentorial bleed i~ the ~e.Wborr~

Period, repeat CT-oscans at 2 months of age

Were normal (fig, 2a b). In a single new-

what is anoxic encephalopathy

Born ventricular dilatation (INR-0.4) was

~een in~CT scan. This child subsequently

Died of pyogenic meningitis, three patients

With extensive cerebral edema also died.

EEG results: four newborns (33%) had

Normal EEG recordings, one of whom died

Of pyogenic meningitis (table). Low or very

Low delta and theta activity (


Observations by sarnat and sarnat 4 as there

Was a demonstrable relationship between

Severity of encephalopathy and outcome. In

Their study five of 21 had a severe disease

(HIE), two died and three were abnormal, in

Our study six had a severe HIE, three died,

Two have developed spastic CP and one was

Normal. Both infants who developed

Apnoeic spells, one of whom also developed

what is anoxic encephalopathy

A hemorrhagic diathesis expired, suggesting

That these are ominous signs in infants with

HIE. S,6 subtle convulsions as described by

Volpe 7 were seen in two cases, both are nor-

Mal on follow up.

Since the initial description of CT scan-

Ning by hounsfield, s CT has been found to

Be sensitive, accurate and safe technique to

Investigate all neurological disorders in

Children, and is highly reliable within first

Few days of life. 9 tentorial area bleeds were

Detected and diagnosed only because these

Two infants were subjected to CT scan, as

There was no specific feature in their clinical

Findings to distinguish these from the other

Patients. As both these bleeds and the

Accompanying hydrocephalus resolved

Completely without sequelae on follow up it

what is anoxic encephalopathy

Seems that some of the initial pessimism

Related to intracranial bleeds may be unjus-

Tified and the prognosis may after all not be

So gloomy.

Hypodense areas were seen in six, in two,

These were periventricular with minimal

Extension into the frontal areas. It has been

Suggested that these findings in the neonatal

Brain are due to premyelinated white matter

Rather than to cerebral edema, l~ most

Infants with these changes when followed up

Are normal, as were the two infants in the

Present study. Generalised cerebral edema

Defined as diffuse moderate to severe

Hypodensity with diminished ventricular

Size was noted in four, of whom three died

And hence this seems to correlate well with

Severity of hypoxic insult. 2 it may be con-

what is anoxic encephalopathy

Cluded that (i) mild periventricular hypo-

Densities are essentially normal in new-

Horns; (ii) severely low densities have an

Unfavourable outcome; (iii) bleeds in areas

Other than the cerebral parenchyma or

Intraventricular areas have a satisfactory


It has been shown by many workers 12.13

That a grossly abnormal EEG is associated

With a bad outcome, however limits of nor-

Mality of the neonatal EEG must first be

Ascertained 3 and must be correlated in

Reference to states of wakefulness, active

Sleep and quiet sleep, la an inactive record-

Ing which carries a very bad prognosis, was

Not seen in any of our cases, however low to

Very low amplitude with intermittent burst

Activity is also known to be associatedwith

what is anoxic encephalopathy

Severe neuronal necrosis 15 and carries a bad

Immediate prognosis, as was noted in our

Cases with these recordings..Many EEG

Changes are transient, and tend to disappear

Within few weeks as was noted in our cases,

Wherein all repeat EEG done at 3 months

Were within normal limits, including the two

Who had initial abnormal recordings. Con-

Tinuous EEG monitoring of infants with

HIE may provide a clearer understanding of

The role and prognostic significance of this

Procedure. 16

In conclusion the preliminary obser-

Vations suggest that in conjunction with a

Detail clinical evaluation, CT and EEG

Studies may be of significant immediate pro-

Gnostic value in HIE. Clearly what is needed

Is a larger systematic study with a proper

what is anoxic encephalopathy

Treatment protocol and a longer period of

Follow up. We also wish to mention that

Limits of normality of EEG and CT patterns

In the neonate are difficult to describe with

Precision and hence a note of caution is to be

Made in the interpretation of their results.



We wish to thank drs. CJ. Vaz and K.N.

Shah for their valuable assistance in inter-

Pretation of the EEG and ms. Hamida sid-

Diqui who very patiently recorded the EEG

For us. We also wish to thank dr. S.M.

Merchant, dean, bai jerbai wadia hospital

For children, bombay, for permission to

Publish this material.


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