This document discusses seizures in neonates. It begins by defining seizures, convulsions, and epilepsy. It then notes that seizures are most common in neonates, occurring in 0.5-0.8% of term babies and 6-12% of babies under 1500g. Common causes of neonatal seizures include hypoxic ischemic encephalopathy, intracranial hemorrhage, infections, inborn errors of metabolism like hypoglycemia and hypocalcemia, and epilepsy syndromes. The immature neonatal brain is more excitable and prone to seizures due to reduced connectivity, an imbalance toward excitatory processes, and the excitatory effect of GABA in some regions. The document describes different seizure types and discusses

1. Dr G Ravali.

2.  SEIZURES: A seizure is a transient occurrence
of signs and/or symptoms resulting from
abnormal excessive or synchronous neuronal
activity in the brain.
 CONVULSIONS: Motor component of seizures.
 EPILEPSY: It is a disorder of the brain
characterised by an enduring predisposition
to generate seizures and by the
neurobiologic, cognitive, psychological and
social consequences of this condition.

3.  Seizures occur more frequently in the
neonatal period than at any other time of life.
 Neonates are at risk for development of
seizures because, metabolic, toxic, structural
& infectious diseases are more likely to
manifest during this period.
 Incidence: 0.5-0.8% in term babies & 6-12%
in babies weighing < 1500g
 85% occur during first 15 days with 65%
between 2-5th day of life.

4.  The immature brain has many differences
from the mature brain that render it more
excitable and more likely to develop seizures.
1. REDUCED CONNECTIVITY OF NEONATAL BRAIN-
GENERALISED TYPE OF SEIZURES RARE.
Arborization of axons and dendritic process as
well as myelination is incomplete.
Neonatal cortex has near complete neuronal
component but relative paucity of dendrites and
synaptic connections.

5. Neuronal membranes are leaky & allow Na+ and
K+ to move easily across cell membrane. Thus they
remain hyperpolarized, making it more difficult for
the epileptic neuron to have rapid and repetitive
firing and to permit recruitment of other neurons
for synchronous discharge.
 2. THE BALANCE OF EXCITATORY AND INHIBITORY
PROCESSES IN IMMATURE BRAIN IS MORE TOWARDS
EXCITATION.(More glutamate synapses with
increased NMDA and AMPA receptor density.)

6. 3. IN SOME REGIONS OF THE NEONATAL BRAIN,
GABA TEMPORARILY ACTS AS AN EXCITATORY
NEUROTRANSMITTER.

7. Repeated seizures
Hypoventilation ↑ BP ↓ ATP, ↑ ADP ↑ EAA
↓ Po2 ↑ PCo2
↓ CBF ↑ CBF
Brain injury
Glycolysis
Lactate
H+ ion

8.  Seizure with consistent EEG event:
 Focal clonic, focal tonic and some myoclonic seizures.
 They are clearly epileptic and are likely to respond to
treatment
 Clinical seizures with inconsistent EEG events:
 All GTCS, subtle seizures and some myoclonic seizures.
 These infants tend to be neurologically depressed of
comatose &are associated with HIE. Seizures are non
epileptic in origin and do not Require or respond to
conventional antiepileptics.
 Electrical seizures with absent clinical seizures:
 May occur in encephalopathic infants not on AED
 Persistent electrical changes after initiation of AED

9.  Subtle
 Clonic
 Tonic
 spasms
 Myoclonic

10. Subtle seizures: Most common type of neonatal
seizures. More common in preterms.
Chewing, blinking, nystagmus, peddling,
bicycling, hyperopnea, tachycardia, hypertension
episodes, apnea.
Oral, facial and lingual phenomenon are common due
to advanced maturation of the limbic system.

11.  Clonic seizures: focal/ multifocal.
Stereotypic, repeated biphasic movements
with fast contraction & slow relaxation
Unifocal -infarct
-SAH
-metabolic
Multifocal: nonjacksonian, migrating
Generalised clonic seizures are uncommon in
neonatal period.

12.  Tonic seizures: Rigid posturing with tonic eye
deviation
 Focal :sustained posturing of a limb
 Generalized: mimic decorticate / decerebrate
posturing
 MC in premature infants with diffuse neurologic
dysfunction or IVH; kernicterus.
 Poor prognosis

13.  Myoclonic seizures: sudden jerky movements
produced by episodic contractions of a group
of muscles.
Rapid jerks and non rhythmic
Focal: MC flexor group of upper limbs
Multifocal: asynchronous twitching of several
parts of body
Generalized: commonly associated with EEG
changes.

14.  Spasms: sudden generalized jerks lasting 1-2
sec.
Distinguished from generalized tonic spells by
their shorter duration and usually associated
with a single, very brief, generalized
discharge.

16.  CNS:
Hypoxic ischemic encephalopathy
Intracranial haemorrhage
CNS infections
CNS malformations:
Neuronal migration disorders
Cerebral dysgenesis
Neurocutaneous disorders
Maternal drug withdrawl
Local anaesthetic intoxication into infant scalp
Kernicterus

17.  Metabolic
1. Hypoglycemia
2. Hypocalcaemia
3. Hypomagnesaemia
4. Hypo / Hypernatremia
5. Hypoxemia
6. Pyridoxine deficiency
 Inborn errors of metabolism
Aminoacidurias
Urea cycle defects
Organic acidurias
Peroxisomal and mitochondrial
disorders
 Epilepsy syndromes

18.  First day: HIE, cerebral contusion,
hypocalcaemia, pyridoxine deficiency,
accidental injection of LA.
 1-3rd day: ICH, hypoglycemia, narcotic
withdrawal, IEM
 4-7th day: Meningitis, TORCH infection,
developmental anomaly, Kernicterus

19.  Commonest cause- 50% of the cases
 Can be global as in perinatal asphyxia/
focal ischemia (MCA stroke)
 In perinatal asphyxia, history s/o difficult
labour, decreased umbilical artery ph, APGAR
score of <5 at 5 mins.
 Focal seizures <1 min,very frequent esp in 1st
24 hrs of life.

20.  10 to 15% of the cases
 Subarachnoid :
May be the result of trauma, deliveries with
instrumentation.
More common in premature.
Seizures on 2nd day of life
good prognosis.
 Intraventricular / parenchymal:
more common among prematures
Tonic type, occur within day 3 of life.
poor prognosis

21.  Subdural:
More likely due to trauma in a large baby and
after breech delivery.
Occur due to tear of falx, tentorium, or
superficial cortical veins.
Bleeding occurs during first few days of life.

22. 5% of the cases
Postnatal sepsis:Bacterial/ fungal/viral
TORCH infections

23.  Ionised calcium: <4.4mg/dl-term & >1.5kg
<4mg/dl- preterms <1.5kg
 Early: <3 days of life
associated with prematurity, IUGR,
asphyxia, infants of diabetic mothers
 Late: >10 days of life
 may be d/t cow milk feeding,
hypoparathyroidism, DiGeorge syndrome,
hypomagnesemia.

24.  Seizures usually occur once the feeds are
introduced.
 Convulsions may be intractable to Rx.
 H/O affected previous sibling may be present.
 Associated features like vomiting, severe
jaundice, Hepatospleenomegaly, virilization &
malodorous urine, hypotonia, metabolic
acidosis ( anion gap) may be present.
 HYPERGLYCENEMIA: Myoclonic events
d/t defect in glycine cleavage, glycine
acts as co agonist with glutamate.

25.  PYRIDOXINE DEPENDENCY:
Rare cause of Seizure in NB.
Prolonged maternal intake of B6.
decreased levels of Pyridoxal-5-phosphate
in CSF and increased serum pipecolic acid.
Deficiency in binding of coenzyme to GABA
may be the primary cause.
 Present as intractable seizures within 1st 12
hrs.(may occur in utero)
 Responds to 50-100mg of pyridoxine.

26.  BENIGN FAMILIAL NEONATAL SEIZURES
 BENIGN INFANTILE NEONATAL SEIZURES-
FIFTH DAY FITS
 EARLY MYOCLONIC EPILEPSY
 EARLY INFANTILE EPILEPTIC
ENCEPHALOPATHY- Ohtahara syndrome
 MALIGNANT MIGRATING PARTIAL SEIZURES IN
INFANCY- Coppola syndrome

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