Skip to Main Content

++

I. DEFINITION

++

A seizure is defined clinically as a paroxysmal alteration in neurologic function (ie, behavioral, motor, or autonomic function).

++

II. INCIDENCE

++

Neonatal seizures are relatively common and occur in 0.15–1.5% of all neonates.

++

III. PATHOPHYSIOLOGY

++

The neurons within the central nervous system (CNS) undergo depolarization as a result of inward migration of sodium. Repolarization occurs via efflux of potassium. A seizure occurs when there is excessive depolarization, resulting in excessive synchronous electrical discharge. Volpe (2001) proposed the following 4 possible reasons for excessive depolarization: failure of the sodium-potassium pump because of a disturbance in energy production, a relative excess of excitatory versus inhibitory neurotransmitter, a relative deficiency of inhibitory versus excitatory neurotransmitter, and alteration in the neuronal membrane, causing inhibition of sodium movement. The basic mechanisms of neonatal seizures, however, are unknown.

++

IV. ETIOLOGY

++

There are numerous causes of neonatal seizures, but relatively few account for most cases (Table 129–1). Therefore, only common causes of seizures are discussed here.

++
Table Graphic Jump Location
Table 129–1.CAUSES OF NEONATAL SEIZURES
++

  1. Perinatal asphyxia is the most common cause of neonatal seizures. These occur within the first 24 hours of life in most cases and may progress to overt status epilepticus. In premature infants, seizures are of the generalized tonic type, whereas in full-term infants they are of the multifocal clonic type. Accompanying subtle seizures are usually present in both types.

  2. Intracranial hemorrhage, whether subarachnoid, periventricular, or intraventricular, may occur as a result of hypoxic insults that can lead to neonatal seizures. Subdural hemorrhage, usually a result of trauma, can cause seizures.

    1. In primary subarachnoid hemorrhage, convulsions often occur on the second postnatal day, and the infant appears quite well during the interictal period.

    2. Periventricular or intraventricular hemorrhage arising from the subependymal germinal matrix is accompanied by subtle seizures, decerebrate posturing, or generalized tonic seizures, depending on the severity of the hemorrhage.

    3. Subdural hemorrhage over the cerebral convexities leads to focal seizures and focal cerebral signs.

  3. Metabolic disturbances

    1. Hypoglycemia is frequently seen in infants with intrauterine growth retardation and in infants of diabetic mothers (IDMs). The duration of hypoglycemia and the time lapse before initiation of treatment determine the occurrence of seizures. Seizures are less frequent in IDMs, perhaps because of the ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.

Ok

About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessPediatrics Full Site: One-Year Subscription

Connect to the full suite of AccessPediatrics content and resources including 20+ textbooks such as Rudolph’s Pediatrics and The Pediatric Practice series, high-quality procedural videos, images, and animations, interactive board review, an integrated pediatric drug database, and more.

$595 USD
Buy Now

Pay Per View: Timed Access to all of AccessPediatrics

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.