Neonatal Neurology



Neonatal Neurology


Breda C. Hayes

Kalpathy S. Krishnamoorthy

Janet S. Soul



INTRACRANIAL HEMORRHAGE


Intra-axial Hemorrhage


Germinal Matrix/Periventricular-Intraventricular Hemorrhage (IVH)



  • Most common type of neonatal intracranial hemorrhage.


Incidence



  • Reported incidence in the preterm newborn ranges from 13% to 65%, but overall ˜20% to 25%.1



    • Risk of IVH correlates inversely with gestational age.


  • Varies among different hospitals and regions.


  • Newborns born to hypertensive mothers have a lower risk of IVH.2


  • Improvements in perinatal and neonatal care have led to a reduction in the overall incidence of IVH in the premature newborn; however, increased survival of the extremely premature newborn means that IVH remains a major source of mortality and morbidity in this population.


  • Incidence is much lower in term newborns than in preterm ones; the incidence of all types of intracranial hemorrhage in term newborns was 2.7/10,000 live births in one report.3,4


Pathogenesis5


Intravascular Factors



  • Ischemia and reperfusion (e.g., following treatment of hypotension or hypovolemia)


  • Impaired cerebral autoregulation


  • Fluctuating cerebral blood flow


  • ↑ Cerebral blood flow (e.g., due to hypercarbia, volume expansion)


  • ↑ Cerebral venous pressure (e.g., with pneumothorax)


  • Coagulation abnormalities


Vascular Factors



  • Germinal matrix capillaries vulnerable to rupture: thin walls with large lumen


  • Arterial development immature: acute transition from large vessels to a capillary network without gradual arborization


Extravascular Factors



  • Increased fibrinolytic activity


  • Poor vascular support in cerebral tissue


Grading of IVH (per Volpe)5



  • Grade I: Hemorrhage confined to the germinal matrix.


  • Grade II: Hemorrhage within the lateral ventricle (10%-50% of ventricular area on sagittal view).



  • Grade III: Hemorrhage within the lateral ventricle (>50% of ventricular area or distends ventricle).


  • Periventricular hemorrhagic infarction (PHI)—parenchymal echodense lesion associated with large ipsilateral IVH; often referred to as Grade IV IVH.



    • This venous infarction is caused by (usually) large IVH obstructing venous drainage of the periventricular white matter.


Management of IVH



  • Supportive care (including correction of coagulopathies, circulatory and respiratory support)


  • Daily monitoring of fontanelle and head circumference and serial head ultrasound (US) examinations in newborns with IVH ≥ Grade II to monitor for development of progressive ventricular dilation


Complications of IVH (Table 19.1)


Periventricular Hemorrhagic Infarction



  • As above, this is a complication of large IVH but is often referred to as Grade IV IVH.


Progressive Ventricular Dilation (PVD)/Posthemorrhagic Hydrocephalus



  • Occurs in 25% of preterm newborns.6


  • PVD usually caused by impaired reabsorption of the cerebrospinal fluid (CSF) by arachnoid villi.


  • Obstructive hydrocephalus rarely caused by obstruction of the aqueduct or foramen by clot.


  • PVD needs to be differentiated from stable ventricular dilation due to cerebral atrophy.


Death



  • Death may occur with catastrophic presentation of large bilateral IVH.


  • Mortality rate is higher in patients who develop PVD than in those without PVD.


Neurologic Sequelae in Survivors



  • There is a strong association between periventricular leukomalacia (PVL) and IVH. It is unknown to what degree the relationship is
    causal or whether the two entities develop in parallel because of common pathologic processes. There are data to suggest that IVH may exacerbate PVL, due to the presence of non-protein-bound iron in the CSF.7


  • The likelihood of later cerebral palsy, major neurosensory disability, and cognitive dysfunction increases with size of IVH, particularly with complications of PHI /or PVD.


  • PHI often results in mild, moderate, or severe hemiplegia.


  • Long-term cognitive impairments with school difficulties are frequent.



    • Deficits in verbal learning and verbal memory particularly common.


    • Subjects with IVH Grades III-IV score significantly lower than those with IVH Grades I-II in verbal learning, everyday memory, visuoconstructive and visuospatial abilities.


  • Sensory deficits (agnosia, tactile hypersensitivity, tactile hyposensitivity, dyspraxia) may also be associated with IVH.


  • Risk of visual impairments (strabismus, optic atrophy, retinopathy of prematurity) is increased in the presence of IVH, particularly with PHI.


  • PVD increases the likelihood of neurologic impairments and disabilities.


  • There are only a few small reports of neurologic sequelae of IVH with/without PVD in term newborns8,9; alloimmune thrombocytopenia appears to be a poor prognostic factor (may be related to size of IVH).








TABLE 19.1 Complications of Intraventricular Hemorrhage (IVH) in the Preterm Newborn




























Severity of IVH


Mortality (%)


Progressive Ventricular Dilatation (%)


Neurologic Sequelae (%)


Grade I


5


5


5


Grade II


10


20


15


Grade III


20


55


35


Periventricular hemorrhagic infarction


50


80


90



Management of PVD



  • Daily monitoring of head circumference, fontanelle, and serial head US examinations.


  • Approximately 38% of preterm newborns without treatment will have spontaneous arrest/and or resolution of PVD without treatment.6


  • Serial lumbar punctures (LPs) can be used to decrease ventricular volume ± increased intracranial pressure when there is evidence of rapidly progressive and/or persistent ventricular enlargement.



    • Sufficient CSF should be removed to decrease ventricular volume and/or ICP (10-15 mL/kg body weight at each lumbar puncture).


    • LPs should be continued until the ventricles stabilize or decrease in size on serial US studies or until surgical treatment deemed necessary and is feasible.


    • Consider ventricular tap if LPs are unsuccessful (PVD may not be communicating).


  • Trials of fibrinolytics.



    • Five randomized trials evaluated intraventricular administration of fibrinolytics in newborns with IVH and PVD, with no significant effect on rate of death or shunt dependence. Risks of treatment included meningitis and secondary IVH.


    • A high-risk therapy called DRIFT (drainage, irrigation, and fibrinolytic therapy) was tested in an international randomized clinical trial. Although it did not significantly lower the need for shunt surgery, there was decreased mortality or risk of severe disability (54% vs. 71%) and decreased severe cognitive disability
      (31% vs. 59%) at 2 y.10 Due to high risks (e.g., secondary IVH), this therapy has not been widely adopted.


Intraparenchymal Hemorrhage



  • Intraparenchymal hemorrhage (IPH) refers to bleeding into the brain parenchyma.


Causes



  • Trauma (including nonaccidental trauma)


  • Coagulation abnormalities


  • Arteriovenous malformation (AVM), aneurysm, e.g., vein of Galen


  • Venous infarction



    • Venous congestion or obstruction following large IVH.


    • Venous congestion or obstruction following sinovenous thrombosis (SVT).


Neurologic Outcome



  • Depends on the location and size of parenchymal injury


  • Could include epilepsy and motor, cognitive, and/or sensory impairments


Extra-axial Hemorrhage


Subpial Hemorrhage (a type of subarachnoid hemorrhagesee below)



  • Hemorrhage between the pial layer and cortical surface, most often around temporal lobe.


  • Appears to be related to local trauma, e.g., with instrumented delivery.11


  • On CT or MRI, appears as ribbon-like collections of blood following contours of gyri and sulci.


  • Seizures most frequent presenting sign, babies often otherwise well-appearing.


Subarachnoid Hemorrhage (SAH)



  • SAH is more commonly seen in conjugation with other types of intracranial hemorrhage, e.g., IVH, subdural hematoma, etc.


  • Primary SAH rarely leads to significant clinical signs unless large.


  • Small SAH may cause seizures in an otherwise well baby (see also subpial hemorrhage above).


  • Large SAH may result in hydrocephalus ± seizures.


Subdural Hematoma (SDH) & Epidural Hematoma



  • SDH and epidural hematoma most frequently related to trauma (e.g., birth trauma or nonaccidental injury) but epidural hematoma much less common.


  • Small SDH related to birth: common and inconsequential.


  • Rare causes of SDH are coagulation abnormalities and glutaric aciduria type 1.


  • Both large SDH and epidural hematoma may present with signs of raised intracranial pressure.



    • Lethargy, vomiting, bulging fontanel, increased head size, highpitched cry, irritability, feeding difficulties, seizures, or loss of consciousness.


  • Characterized based on size, location, and age (i.e., acute, subacute, or chronic).



  • Early surgical evacuation may be lifesaving for large hematomas with signs of raised intracranial pressure and significant neurologic compromise.


  • Size, location, and age of SDH/epidural hematoma as well as the neurologic and medical condition of the patient determine the course of treatment and outcome.


Subgaleal Hematoma (SGH)



  • Prevalence of moderate-to-severe SGH is ˜1.5 per 10,000 births.12


  • SGH may form because of preexisting risk factors (e.g., coagulopathy).


  • Vacuum extraction predisposes a newborn toward subgaleal hemorrhage.


  • SGH must be considered in any newborn with a scalp swelling and a falling hematocrit.


  • In term babies, this subaponeurotic space may hold as much as 260 mL of blood.


  • Death can result from exsanguination and hypovolemic shock, caused by massive bleeding into the subgaleal space.


  • Close monitoring of vital signs, level of consciousness, hematocrit, blood gases, head circumference, and signs of tissue hypoperfusion is recommended.


  • Coagulation studies should be performed in all newborns with a diagnosis of SGH.


Cephalohematoma



  • Very common, usually does not require treatment or diagnostic testing.


  • Collection of blood beneath the periosteum.


  • Limited by suture lines (if no associated skull fracture).


  • Due to sliding/tearing forces during the birth process.


  • More common with forceps and vacuum extraction.


  • Generally benign, but if large, may exacerbate jaundice.


  • Takes weeks to months to resolve (outer edges may calcify, so center may resolve initially, leaving a “crater”-like appearance).


  • Large cephalohematomas may occur with coagulation abnormalities (vitamin K deficiency, factor 8 deficiency, etc.).


ENCEPHALOPATHY OF PREMATURITY/WHITE MATTER INJURY/PVL



  • Classical PVL consists of focal necrotic lesions and surrounding areas of gliosis, with cyst formation detectable typically 2 to 4 wk after birth.


  • Recent MRI studies have demonstrated a more diffuse form of non-cystic white matter injury.13


  • Both cystic and non-cystic forms are usually bilateral and symmetric.


  • Histology shows microglial activation and loss of premyelinating oligodendrocytes.


  • The periventricular white matter dorsolateral to the trigones and frontal horns of the lateral ventricles are areas most commonly affected by PVL.


  • Recent MRI and neuropathology studies strongly suggest that cerebral neuronal structures, as well as cerebellum, are also frequently injured.14,15



  • Gray matter injury may reflect damage to subplate neurons, which appears early in cortical development and directs projections of afferent and efferent thalamocortical neurons.16


  • Diffuse loss of brain tissue in PVL results in ventriculomegaly, enlarged extra-axial CSF spaces, and immature gyral development.


Incidence



  • The reported incidence of cystic PVL has decreased over the past several years to ˜5% of very low birth weight newborns.


  • Diffuse non-cystic PVL is now recognized as the most common form of brain injury in preterm newborns; MRI studies at term show an incidence of up to 70%.17




Outcome—Encephalopathy of Prematurity



  • Depends on the severity and extent of PVL; however, rates of cognitive impairments, cerebral palsy or milder motor impairments, and visual perceptual or other sensory dysfunction are high.


  • Cystic PVL tends to damage more medial fiber tracts that control lower extremity function, leading to spastic diplegia, where upper extremity spasticity/dysfunction is less severe.


  • Extensive white matter involvement may result in quadriplegia and include facial weakness.


  • High incidence of subsequent cognitive deficits without prominent motor deficits may be explained in part by a reduction in the density of cerebral cortical neurons overlying areas of PVL.14


  • Cognitive and/or behavioral deficits may be very specific, such as visuomotor and perceptual disabilities, constructional dyspraxia, or attention-deficit disorders.


  • Attention deficits and impaired working memory may be associated with injury to the mediodorsal and reticular thalamic nuclei.15


  • Visual impairments: children with PVL may have visual perception difficulties or, with severe PVL, bilateral inferior visual field deficit.


  • Punctate white matter lesions and ventricular dilatation are significantly associated with cognitive and psychomotor developmental delay, motor delay, and cerebral palsy.20


NEONATAL ENCEPHALOPATHY



Etiology



  • Intrapartum asphyxia with resultant hypoxic-ischemic encephalopathy


  • Infection


  • Drug exposure


  • Perinatal arterial ischemic stroke


  • Metabolic or other genetic disorders


  • Brain malformation, epileptic encephalopathy

The clinical history will determine the need for investigation to exclude these disorders.









TABLE 19.2 Distinguishing Features of the Three Clinical Stages of Hypoxic-Ischemic Encephalopathy in the Full-Term Newborn













































































































@@


Stage 1


Stage 2


Stage 3


Level of consciousness


Hyperalert


Lethargic or obtunded


Stuporous


Neuromuscular control


Muscle tone


Normal


Mild hypotonia


Flaccid


Posture


Mild distal flexion


Strong distal flexion


Intermittent decerebration


Stretch reflexes


Overactive


Overactive


Decreased or absent


Segmental myoclonus


Present


Present


Absent


Complex reflexes


Suck


Weak


Weak or absent


Absent


Moro


Strong: low threshold


Weak, incomplete, high threshold


Absent


Oculovestibular


Normal


Overactive


Weak or absent


Tonic neck


Slight


Strong


Absent


Autonomic function


Generalized sympathetic


Generalized parasympathetic


Both systems depressed


Pupils


Mydriasis


Miosis


Variable; often unequal; poor light reflex


Heart rate


Tachycardia


Bradycardia


Variable


Bronchial and salivary secretions


Sparse


Profuse


Variable


Gastrointestinal motility


Normal or decreased


Increased; diarrhea


Variable


Seizures


None


Common; focal or multifocal


Uncommon (excluding decerebration)


Electroencephalogram findings


Normal (awake)


Early: low-voltage continuous delta and theta


Early: periodic pattern with isopotential phases




Later: periodic pattern (awake)


Later: totally isopotential




Seizures: focal 1-1½-hz spike-and-wave



Duration


<24 h


2-14 d


Hours to weeks


Sarnat HB, Sarnat MS. Neonatal encephalopathy following fetal distress. A clinical and electroencephalographic study. Arch Neurol. 1976;33(10):696-705.


Jun 20, 2016 | Posted by in NEUROLOGY | Comments Off on Neonatal Neurology

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