Convulsions and Neonatal Convulsions: Diagnostic Approach and Management

Introduction to Convulsions

Convulsions are uncontrolled electrical discharges of neurons in the brain that manifest as violent contractions of muscles, typically with generalized movements and unresponsiveness reflecting excessive synchronous cortical electrical activity 1, 2
The term "convulsions" is best reserved for epileptic seizures, distinguishing them from other paroxysmal events 3
A seizure is defined as a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain 4
Convulsive seizures affect large areas or both sides of the brain and manifest as full-body rhythmic jerking with alterations in consciousness 1
The mere presence of myoclonic movements (brief jerking) does not confirm epileptic seizures, as these can occur in syncope; the distinction depends on synchrony, rhythmicity, and number of movements (many movements in seizures vs. few in syncope) 3, 5

Diagnostic Approach

The diagnostic approach must prioritize immediate stabilization, rapid exclusion of treatable metabolic causes, and systematic evaluation to identify the underlying etiology in approximately 95% of cases 6, 7
Essential immediate labs include electrolytes (sodium, calcium, and magnesium), blood gas analysis 5, complete blood count, and blood culture if infection is suspected 6
Correct hypocalcemia and hypomagnesemia before initiating anticonvulsants 6
Imaging algorithm based on clinical stability includes head ultrasound as initial bedside imaging if the infant is unstable or MRI unavailable, and MRI with diffusion-weighted imaging as the gold standard for identifying etiology 6, 7

Management

Immediate stabilization includes ensuring patent airway, adequate breathing, and circulation, continuous monitoring of heart rate, blood pressure, temperature, and oxygen saturation, and establishing IV/IO access immediately 6
Point-of-care glucose testing is mandatory to exclude hypoglycemia, and if hypoglycemic, correct with D10%-containing isotonic IV solution at maintenance rate 6
When infection is suspected, treat with empirical antibiotics immediately, and perform blood culture, urine culture, and lumbar puncture if necessary, but avoid lumbar puncture in comatose infants due to risk of herniation 6
Do not delay metabolic correction, as hypocalcemia and hypomagnesemia must be corrected before anticonvulsants, and hypoglycemia requires immediate correction 6

Causes of Neonatal Convulsions

Hypoxic-ischemic encephalopathy (HIE) is the dominant cause of neonatal seizures, accounting for 46-65% of cases, with 90% of these seizures occurring within the first 2 days of life 6, 7
Other causes include intracranial hemorrhage and perinatal ischemic stroke (10-12% combined), metabolic derangements such as hypoglycemia, hypocalcemia, hypomagnesemia, and hyponatremia, infection, genetic disorders, and malformations of cortical development 6, 7

Diagnostic Approach to Neonatal Seizures

Lumbar Puncture Indications

The American Academy of Pediatrics recommends performing a lumbar puncture if clinical signs of meningism are present, after a complex convulsion, if the child is unduly drowsy, irritable, or systemically ill, or if the age is less than 12-18 months, especially in infants less than 12 months 8

Neuroimaging Algorithm

The American College of Radiology suggests that head ultrasound is used as initial bedside imaging to identify intraventricular hemorrhage, hydrocephalus, white matter changes, and cystic periventricular leukomalacia, although it has limitations in detecting hypoxic-ischemic injury and small infarctions 9
MRI with diffusion-weighted imaging is the gold standard and most sensitive for hypoxic-ischemic encephalopathy, and it provides additional information beyond ultrasound in 39.8% of patients 9, 10
CT head has a limited but specific role in detecting hemorrhagic lesions in encephalopathic infants with a history of birth trauma, low hematocrit, or coagulopathy 11, 10

Electroencephalography

The American Academy of Neurology recommends continuous video-EEG monitoring as essential to recognize seizures, assess prognosis, and understand that not all clinical movements have an EEG correlate, and not all EEG seizures have clinical manifestations 8

Neonatal Seizure Signs

Clinical Manifestations

Many neonates with seizures present with additional neurological symptoms such as hemiparesia or altered level of consciousness, and in the context of neonatal infectious endocarditis, seizures can be accompanied by apnea as a neurological manifestation 12
The presence of brief myoclonic movements does not confirm epileptic seizures, as these can occur in syncope; distinction depends on synchrony, rhythmicity, and number of movements, according to the European Society of Cardiology 13

Diagnostic Considerations

The American Academy of Neurology and the International League Against Epilepsy classify autonomic signs, including apneas, as non-motor seizures, which can be the only clinical manifestation of seizure activity 12
The diagnosis of neonatal seizures is not reliable, as most seizures are subclinical or lack apparent clinical correlation, and many seizures present as exclusively electroencephalographic events without clinical signs 12

Seizures in Congenital Asphyxiation

Epidemiology and Timing

Hypoxic-ischemic injury from perinatal asphyxia is the dominant cause of neonatal seizures, accounting for 46-65% of all neonatal seizure cases, according to the American College of Radiology 14, 15, 16, 17, 18
Approximately 90% of infants with hypoxic-ischemic encephalopathy experience seizure onset within the first 2 days after birth, as reported by the American College of Radiology 14, 15, 16, 17, 18

Diagnostic Approach

The American College of Radiology recommends head ultrasound as initial bedside imaging if the infant is unstable or MRI unavailable, which identifies intraventricular hemorrhage, hydrocephalus, and white matter changes, though it has low sensitivity for hypoxic-ischemic injury 15
The American College of Radiology suggests an imaging algorithm based on clinical stability, including head ultrasound and MRI with diffusion-weighted imaging, which is the gold standard for identifying hypoxic-ischemic encephalopathy 14, 15, 16, 17, 18

Prognostic Implications

The American Heart Association, as reported in Circulation, notes that when perioperative seizures occur in infants with congenital heart disease who also experienced perinatal asphyxia, seizures in the postoperative period are the medical variable most consistently related to adverse neurodevelopmental outcome 19, 20
The absence of major cerebral lesions on MRI is highly predictive of normal neurological outcome, making neuroimaging valuable for prognostication, according to the American College of Radiology 14, 15, 16, 17, 18

Hypoxic-Ischemic Encephalopathy (HIE) in Newborn Babies: Diagnosis and Treatment

Definition and Epidemiology

The American Heart Association recommends that HIE occurs in term and near-term infants (≥36 weeks gestational age) who experience perinatal asphyxia, affecting 1.5 per 1000 live births in developed countries 21

Treatment

The American Heart Association recommends therapeutic hypothermia (cooling to 33-34°C for 72 hours) as the only evidence-based treatment for moderate-to-severe HIE, which must be initiated within 6 hours of birth, reducing mortality from 35% to 27% and permanent neurological disability from 48% to 27% 21, 22
The treatment protocol requires initiation within 6 hours of birth, strict temperature control to 33-34°C, duration of 72 hours, slow rewarming over at least 4 hours, and multidisciplinary neonatal intensive care with capabilities for respiratory support, pulse oximetry, IV therapy, antibiotics, antiseizure medications, and comprehensive monitoring 21, 22

Prognosis and Long-term Outcomes

The American Heart Association states that survivors of HIE face significant risks of cerebral palsy, with the absence of major cerebral lesions on MRI being highly predictive of normal neurological outcome 22