Chapter 40. Neurology

Hypoxic–ischemic encephalopathy

• Leading cause of neonatal seizures in full-term infants.
• This diagnosis should never be one of exclusion.
• Data supporting this diagnosis (history of prolonged labor, perinatal depression, prolonged resuscitation) should be obtained and documented.

Focal ischemia/infarction

• Second most common cause of neonatal seizures in full-term infants.
• Most common presentation is right-sided clonic seizures due to infarction in the left middle cerebral artery territory.
• Cerebral vein thromboses can lead to venous infarcts.

Intracranial hemorrhage

• In term infants, subarachnoid hemorrhage is more associated with subsequent seizure than subdural hemorrhage.
• Infratentorial subdural hemorrhages require urgent evaluation due to risk of brainstem compression.
• In preterm infants, intraventricular hemorrhage is the most common type of ICH (see below).

Infections of the CNS

• Can occur in utero (CMV, toxoplasmosis) or perinatally (herpes simplex, bacterial meningitis with GBS or Escherichia coli being most common).
• Prognosis can be very grim.

Metabolic derangement

• Transient causes (hypoglycemia, hypocalcemia, hyponatremia); see Chapter 34 for further information.
• Inborn errors of metabolism (pyridoxine dependency, nonketotic hyperglycinemia, urea cycle defects, glutaric aciduria (type II), maple syrup urine disease, organic acidurias, cofactor deficiencies, mitochondrial defects , Zellweger Syndrome).

Structural defects

• Defects of neuronal migration (heterotopias).
• Defects of neuronal organization (polymicrogyria).
• Cerebral malformation (holoprosencephaly).
• Usually will display associated dysmorphic features on physical examination.

1

Hypoxic ischemic encephalopathy

Infection

Hypocalcemia

Maternal drug use

Hypoglycemia

2–3

All of the above

Inborn errors of metabolism

Drug withdrawal

CNS malformation

Hypernatremia

Hyponatremia

Seizure Type

Clinical Manifestation

Subtle

Oral–buccal–lingual or ocular movements

Autonomic dysfunction (Δ in HR, BP, Spo2)

Stereotypical stepping/swimming

Clonic

Rhythmic, slow jerking

Facial, extremity, or axial involvement

Focal or generalized

Tonic

Sustained limb posturing

Asymmetric position of trunk/neck

Focal or generalized

Myoclonic

Rapid isolated jerks

Limb/trunk involvement

Generalized, multifocal, or focal

Seizure Mimic

Clinical Manifestation

Jitteriness

Spontaneous or provoked by stimulus

Flexion/extension are equivalent

Diminished by repositioning

Abolished with containment

Benign neonatal sleep myoclonus

Bilateral or unilateral

Synchronous or asynchronous

Occurs during sleep

Not due to a stimulus

Stimulus-evoked myoclonus

Focal or generalized

Severe CNS dysfunction

EEG may show cortical spike-wave discharge

Hyperekplexia (stiff-man syndrome)

Generalized stiffness

Autosomal dominant and recessive forms

Excessive startle responses to unexpected stimuli

Excessive stiffness following startle response

Benzodiazepines reduce symptoms