Neonatal Seizure

Seizures are paroxysmal involuntary disturbance of brain function that maybe manifested as Impairment of Consciousness, abnormal motor activity, behavioral abnormality, sensory disturbance or autonomic dysfunction. Neonates are at particular risk for seizures because of: -Metabolic Disturbances. -Toxic. - Structural abnormality. - Infectious Diseases.

Neonatal seizures are dissimilar from those in children or adults because of: -Incomplete arborization of axons, and dedritic processes as well as mylenation are also incomplete. At least five seizure types are recognized in a new born infant: Focal seizure which usually involves specific group of muscles secondary to: -Structural lesions. -Infection. -Subarachnoid hemorrhage.

2- Multifocal seizure (clonic): These seizures are characterized by random clonic movements of limbs similar to those seen in normal infants under 34 weeks of gestation. The EEG is most often unifocally abnormal, the prognosis is generally good. 3- Tonic seizures: Divided into general and focal usually associated with eye deviation or apnea and most often seen in prematures and carry a poor prognosis.

4- Myoclonic Seizure: the manifestations include synchronous single or multiple slow jerks of upper or lower limbs or both and are associated with diffuse CNS pathology, the prognosis is poor. 5- Subtle seizure: 50% of seizures in both term and prematures. usually presented as: Excessive salivation. Alteration of respiratory rate. blinking. nystagmus.

-Bicycling or pedalic movements -Change in skin color. -apnea due to seizures: most often has either an: accelerated or normal heart rate while apnea due to other cause usually associated with bradycardia.

EEG Classifications of Neonatal Seizures 1- Clinical seizures with a consistent EEG events. Which includes: focal clonic. focal tonic. some myoclonic seizures. These seizures are clearly epileptic and are likely to respond to an anticonvulsants 2- Clinical seizures with inconsistent EEG events:

this is observed with all generalized tonic seizures, subtle seizures and with some myoclonic seizures. Seizures in this category are likely to be of non epileptic origin and may not require or respond to anti epileptics. 3- Electrical seizures with absent clinical seizures: may develop in comatose infant who are not on anti convulsants, conversely electrical seizures may persist in patients with focal tonic or clonic seizures without clinical signs after the introduction of an anticonvulsant.

Etiology 1-Hypoxic Ischemic Encephalopathy: represent 60% - 65% of cases of neonatal seizures, occurs in babies with severe fetal distress who are apnic at birth. Seizures usually occur in the first day of life most often beginning in the first 12 hours. 2-Intracranial hemorrhage: Subarachnoid hemorrhage. Perivetricular hemorrhage. Subdural hemorrhage. Intraventricular hemorrhage.

3- metabolic problems: -hypoglycemia. -hypocalcemia. -hypomagnesemia. -hyponatremia. -hypernatremia. -pyridoxin deficiency. -disorders of metabolism as phenylketoneurea, hyperglycinemia, urea cycle disorders and β-alanine abnormalities. -organic acidemia. -biotin responsive disorders. -fructose intolerance disorders.

-peroxisomal disorders. -mitochonderial disorders. -storage diseases. 4- Infections: -bacterial meningitis. -viral infection. -toxoplasmosis. -syphilis. 5- Developmental disorders: -cerebral dysgenesis. -fakomatosis which include: neurofibromatosis, sturge weber disease and tuberous sclerosis.

6- Drug associated seizures: -narcotic and sedative withdrawal. -local anesthesia. -theophyllin. 7- Polycythemia and hyperviscosity. 8- Familial neonatal seizures. 9- Focal infarction. 10- Hypertensive encephalopathy. 11- Idiopathic.

Treatment Treatment of the underlying cause. Anticonvulsant therapy: -phenobarbital. -phenytoin. -diazepam. -lorazepam. -medazolam.

Prognosis The overall prognosis in neonatal seizures is death in 15%. Neurologic squally such as mental retardation, motor deficit in 30%. Normal outcome in 50%. Chronic seizure disorder will develop in 15%-20% of survivors.

Prognosis is affected by the following factors: Gestational age. Etiology. Seizure pattern. EEG. Abgar score. Duration of seizures. Association of hypotonia. The presence of tonic or myoclonic seizures. Early onset of seizures. The need +ve pressure ventilation.

Good prognostic Factors Seizures free at discharge from hospital. Seizures subside within 24 hours. Neurological examination is normal with no abnormal eye movement. Return to normal routine feeding within 5 days. EEG is not persistently abnormal.

Bad prognostic Factors Prolonged and repetitive seizures (more than 30 minutes). Abnormal eye movements. Abnormal interictal EEG. Abgar score less than 7 at 5 minutes. Prematures. Early onset of convulsions.

Prognosis of Seizures by Etiology Normal outcome(%) Subarachnoid hemorrhage 90 Uncertain 75 Early Hypocalcemia 50 Late hypocalcemia 100 Hypoglycemia 33-71 Neonatal Encephalopathy 31-50 IVH 10 Meningitis 11-65 Dysgenesis zero

Prognosis of seizures by seizure pattern: Normal outcome(%) by gestational age at birth Full term(%) Premature(%) Focal clonic 100 33 Multifocal Generalized 59 41 Tonic 50 36 Myoclonic Subtle 57 44

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