Neonatal Seizures

Recognition of neonatal epileptic seizures is problematic. Initially, the diagnosis and delineation of neona

Nonepileptic Spells in Neonates and Infants tal epileptic seizures was based on a clinical description of a paroxysmal event. However, subsequent studies of neonatal seizure evaluation with long-term electroencephalography (EEG) disclosed that some of these clinical "seizures" do not have a consistent elec-trographic ictal scalp correlate. This is particularly the case for "subtle" seizures and episodes of diffuse tonic posturing (Table 6.1) Brief descriptions of the clinical features of neonatal seizures are summarized below (1-4).

Subtle Events -/+

Tonic

Generalized Tonic Focal Tonic Myoclonic

Focal/Multifocal Generalized +/-

Subtle Seizures
FIGURE 6.1

Neonatal epileptic seizure. 7-day-old term newborn with right arm/leg focal clonic movements. EEG shows a left parasagital rhythmic discharge in association with the clinical event.

Subtle Seizures

These events are subtle alterations in the child's behavior from either a motoric or autonomic nature; these are not clearly clonic, tonic, or myoclonic. These events have been described as including abnormal eye movements (horizontal eye deviation, sustained eye opening), oral-buccal-lingual automatisms (chewing, tongue thrusting, grimacing), extremity automatisms (pedaling, boxing movements), autonomic phenomena (increase in blood pressure, heart rate), and apnea. These clinical seizures have a variable correlation with surface EEG activity (1). In one study, up to 30% of these events had no EEG correlate. Ocular events, including horizontal eye deviation or sustained eye opening or ocular fixation, were the activity most consistently associated with EEG changes.

Clonic Seizures

Clonic seizures consist of rhythmical jerking with a slow flexion phase and a faster extension phase. These clonic jerks of the neonate are typically slow (1 to 3 jerks per second). Clonic seizures are typically focal (occurring in one area of one side of the body) or multifocal (random, migratory jerks). Generalized clonic seizures, rarely, if ever, occur in the newborn. Clonic seizures in the neonate are the seizure type that most consistently is associated with an EEG correlate (Figure 6.1).

Tonic Seizures

Tonic seizures consist of episodes of stiffening or posturing of the body, or region of the body. These episodes may be generalized or focal. Generalized tonic activity involves stiffening of the entire body with either extension of the arms and legs, or flexion of the arms and extension of the legs. These events typically (85%) do not have an electrographic correlate and may reflect some form of forebrain disconnection phenomena. The generalized tonic events that are associated with surface electrographic changes typically have associated autonomic abnormalities as well. Focal tonic events are less frequent than generalized tonic episodes. Focal tonic seizures typically involve either tonic posturing of a single extremity or asymmetric, more diffuse posturing. In contrast to generalized tonic events, focal stiffening often has an ictal EEG correlate.

Myoclonic Seizures

Myoclonic jerks are characteristically very fast movements that do not recur in a rhythmic fashion. They may be epileptic in origin, may be nonepileptic but occur in patients with severe neurologic abnormalities (pathologic, nonepileptic myoclonus), or may occur in normal patients. These jerks may be focal, multifocal, or generalized. Focal and multifocal myoclonic jerks are usually not associated with EEG changes. Generalized

TABLE 6.2 Neonatal Nonepileptic Events

Apnea Jitteriness

Benign neonatal sleep myoclonus Pathologic nonepileptic myoclonus Hyperekplexia myoclonic jerks, usually involving bilateral flexion of the upper extremities, may or may not be associated with electrographic discharges.

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