Perinatal Brain Injury

Important Points

Neurologic Dysfunction Not Always Equivalent to Coincident Brain Damage

Maternal/Placental/Fetal Diseases Which Can Contribute to Dysfunction With/Without Brain Injury

Limited Clinical Repertoire of the Fetus and Neonate-Understates Severity and Chronicity of Brain Disorders

Must Frame the Neurologic Profile of the Fetus and Neonate Based on Gestational Maturity

Current Challenges for Patient Assessment

maintain careful history and exam skills
explore novel technological advances that better examine brain structure and function
apply new bench neuroscience info in a rational manner

Types of Injury

Periventricular Leukomalacia (PVL) – main ischemic lesion of the premature infant

necrosis of the white matter resulting from injury to oligodendroglia; infants as a result develop periventricular cysts at the site of injury; focal lesions are seen as white spots distributed around the anterior horns and trigones of the lateral ventricles (common sites = level of occipital radiation and around the foramen of monro)

presentation = asymptomatic or extremity hypotonia, cortical blindness if optic radiations are affected

diagnosis = cerebral ultrasound, MRI

Intracranial Hemorrhage in the Pre-Term Infant (germinal matrix – intraventricular hemorrhage (IVH)) – anterior cerebral, middle cerebral and internal carotid arteries feed an elaborate capillary bed of immature vessels in the germinal matrix; site of origin of IVH is in the subependymal germinal matrix

hemorrhage of the germinal matrix occurs from these immature capillary vessels, blood then enters the lateral ventricles and spreads throughout the ventricular system
neuropathologic consequences of IVH = germinal matrix destruction, periventricular hemorrhagic infarction, post-hemorrhagic hydrocephalus

Hypoxic Ischemic Encephalopathy (HIE) of the Term Infant – primary disturbance to neuronal tissue in HIE is deficit of O₂ supply; hypoxia and/or ischemia occur as a result of asphyxia (impairment of exchange of respiratory gases)

factors involved = prostaglandins, free radicals, thrombosis, impaired cerebral blood flow regulation, brain edema

presentation = multi system organ injury and Sarnet encephalopathy score:

stage 1 – hyperalert, jittery, tachycardia, no seizures

stage 2 – lethargy, hyperreflexia, miosis, bradycardia, seizures, weak, primitive reflexes

stage 3 – stupor, flaccidity, decreased stretch reflexes, hypothermia

diagnosis = ultrasound, CT scan, MRI, EEG

Ischemic Focal and Multifocal Brain Destruction and Cavitation – focal and multifocal cerebrovascular occlustion/insufficiency (idiopathic, vascular maldevelopment, vasculopathy, vasospasm, vascular distortion, vascular ligation/manipulation, embolus, thrombus)

generalized systemic circulatory insufficiency (intrauterine – maternal hypotension or cardiac arrest, maternal trauma, twin pregnancy, umbilical cord or placental catastrophe; neonatal – systemic hypotension or cardiac arrest, persistent pulmonary hypertension, congenital heart disease with cardiac failure)

symptoms in neonates = seizures (usually focal), hemiparesis and quadriparesis; long term sequelae = spastic hemiparesis and quadriparesis, developmental delay, seizure disorder

Fetal Brain Abnormalities

Commonly occurring fetal anomalies

Ventriculomegaly (big ventricles – may suggest hydrocephalus or brain atrophy), Copocephaly (back part of lateral ventricles are more ballooned than front part), asymmetry

Dandy-Walker cyst (cerebellar midline abnormality) vs large cisterna magna

Microcephaly

Intracranial mass or cyst – Hemorrhage/stroke/tumor/maldevelopment

Spinal Dysraphism

Holoprosencephaly – spectrum of disorders; Agenesis of the corpus callosum

Anencephaly (lack of cortex)

Hydranencephaly (necrosis of entire brain)

Coloboma Þ arrest of retinal tissue Þ indicates arrest of brain tissue

Midline facial defectsÞ chiefly cleft lip and palate; 300 multiple malformation syndromes; deficient frontonasal development

Non-neurological abnormalities of the fetus: intrauterine growth restriction; multiple-gestation pregnancy; congenital heart disease; cleft lip and palate; polyhydramnios; hydrops fetalis; fixed limbs (ie arthrogryposis); clubbed feet; asymmetry of limbs; gastroschisis/omphalocele; renal cysts; diphragmatic hernia

Caveats to Assessment of Levels of Arousal and Muscle Tone: differentiate the immediate resuscitative period; assess the clinical profile over time from the delivery period through the first 24 hours and beyond; consider the transition from fetal to neonatal life; consider the unique sleep characteristics of the neonate