Intracranial Hemorrhage and White Matter Injury/Periventricular Leukomalacia
Intracranial Hemorrhage and White Matter Injury/Periventricular Leukomalacia
Janet S. Soul
KEY POINTS
A large intracranial hemorrhage (ICH) of any type is an emergency that requires prompt stabilization with volume replacement pressors and respiratory support, as needed, and urgent neuroimaging.
Due to radiation exposure, computed tomography (CT) scanning should be reserved for URGENT situations in which magnetic resonance imaging (MRI) is not available.
Neurosurgical consultation should be obtained for large ICH with mass effect, particularly if there are signs of brainstem dysfunction and/or increased intracranial pressure.
Seizures are common but may be subclinical, so electroencephalogram (EEG) monitoring should be obtained for newborns with significant intraventricular, parenchymal, subarachnoid, or subdural hemorrhage.
OVERVIEW
The incidence of intracranial hemorrhage (ICH) varies from 2% to >30% in newborns, depending on gestational age (GA) at birth and the type of ICH. Bleeding within the skull can occur in the following:
1. External to the brain into the epidural, subdural, or subarachnoid spaces
2. Into the parenchyma of the cerebrum or cerebellum
3. Into the ventricles from the subependymal germinal matrix or choroid plexus (Table 54.1)
The incidence, pathogenesis, clinical presentation, diagnosis, management, and prognosis of ICH varies according to the ICH location and size and the newborn’s GA.1, 2 There is often a combination of two or more types of ICH because an ICH in one location often extends into an adjacent compartment; for example, extension of a parenchymal hemorrhage into the subarachnoid space or ventricles, such as a thalamic hemorrhagic infarction with associated intraventricular hemorrhage.
Diagnosis usually depends on clinical suspicion when a newborn presents with typical neurologic signs, such as seizures, irritability, depressed level of consciousness, and/or focal neurologic deficits referable to either the cerebrum or brainstem. Diagnosis is confirmed with an appropriate neuroimaging study. Magnetic resonance imaging (MRI) is the optimal imaging modality for almost all types of ICH, but ultrasound (US) is typically preferred for premature newborns and critically ill newborns who are not stable for transport to MRI. To avoid exposure of newborns to the ionizing radiation associated with computed tomography (CT), CT scan should be used only for emergent imaging studies when neither MRI nor US is available/possible. The American Academy of Neurology (AAN) practice parameter states that all newborns with a birth GA of <30 weeks should undergo routine cranial ultrasound (CUS) between 7 and 14 days and optimally repeated between 36 and 40 weeks’ postmenstrual age.3 Our local practice is to obtain a CUS on every newborn with a birth GA of <32 weeks and birth weight <1,500 g.
Management varies according to the size and location of the ICH and the presenting neurologic signs. In general, only very large hemorrhages with clinical signs require surgical intervention for removal of the ICH itself. With a large ICH, pressor support or volume replacement (with normal saline, albumin, or packed red blood cells) may be required because of significant blood loss. More commonly, management is focused on treating complications such as seizures or the development of posthemorrhagic hydrocephalus. In general, although a large ICH is more likely to result in greater morbidity or mortality than a small one, the presence and severity of parenchymal injury, whether due to hemorrhage, infarction, or other neuropathology, is usually the best predictor of outcome.
Table 54.1 illustrates neonatal ICH by location, and whether each ICH type is predominantly primary1 or secondary2 source of bleeding, and the relative incidence in preterm or term newborns.
I. SUBDURAL HEMORRHAGE AND EPIDURAL HEMORRHAGE
A. Etiology and pathogenesis. The pathogenesis of subdural hemorrhage (SDH) relates to rupture of the draining veins and sinuses of the brain that occupy the subdural space. Vertical molding, fronto-occipital elongation, and torsional forces acting on the head during delivery may provoke laceration of dural leaflets of either the tentorium cerebelli or the falx cerebri. These lacerations can result in rupture of the vein of Galen, inferior sagittal sinus, straight sinus and/or transverse sinus, and usually result in posterior fossa SDH. Breech presentation also predisposes to occipital osteodiastasis, a depressed fracture of the occipital bone or bones, which may lead to direct laceration of the cerebellum or rupture of the occipital sinus. Clinically significant SDH in the posterior fossa can result from trauma in the full-term newborn, although small, inconsequential SDH (“parturitional SDH”) is fairly common in uncomplicated deliveries (the true incidence in apparently well newborns is unknown). SDH in the supratentorial space usually results from rupture of the bridging, superficial veins over the cerebral convexity. Other risk factors for SDH include factors that increase the likelihood of significant forces on the newborn’s head, such as large head size, rigid pelvis (e.g., in a primiparous or older multiparous mother), nonvertex presentation (breech, face, etc.), very rapid or prolonged labor or delivery, difficult instrumented delivery, or rarely, a bleeding diathesis. Postnatally, SDH and epidural hemorrhage (EH) are almost always due to direct head trauma or shaking; hence, nonaccidental injury needs to be suspected in cases of acute presentation of SDH or EH beyond the perinatal period. However, care should be taken not to confuse an old chronic effusion from a birth-related ICH with an acute postnatally acquired ICH. Careful interpretation of neuroimaging studies, particularly MRI, should help distinguish acute SDH or EH from chronic effusion.
B. Clinical presentation. When the accumulation of blood is rapid and large, as occurs with rupture of large veins or sinuses, the presentation follows shortly after birth and evolves rapidly. This is particularly true in infratentorial SDH where compression of the brainstem may result in nuchal rigidity or opisthotonus, obtundation or coma, apnea, other abnormal respiratory patterns, and unreactive pupils and/or abnormal extraocular movements. With increased intracranial pressure (ICP), there may be a bulging fontanelle and/or widely split sutures. With large hemorrhage, there may be systemic signs of hypovolemia and anemia. When the sources of hemorrhage are small veins, there may be few clinical signs for up to a week, at which time either the hematoma attains a critical size, imposes on the brain parenchyma, and produces neurologic signs or hydrocephalus develops. Seizures may occur in neonates with SDH, particularly with SDH over the cerebral convexity. With cerebral convexity SDH, there may also be subtle focal cerebral signs and mild disturbances of consciousness, such as irritability. Subarachnoid hemorrhage probably coexists in the majority of cases of neonatal SDH, as demonstrated by a cerebrospinal fluid (CSF) exam.4 Finally, a chronic subdural effusion may gradually develop over months, presenting as abnormally rapid head growth, with the occipitofrontal circumference (OFC) crossing percentiles in the first weeks to months after birth.
C. Diagnosis. The diagnosis should be suspected on the basis of history and clinical signs and confirmed with a neuroimaging study. MRI is the study of choice for diagnosing SDH or EH, but CT may be used for acute emergencies if MRI cannot be obtained quickly, e.g., an unstable newborn with elevated ICP who may require neurosurgical intervention.3 Although CUS may be valuable in evaluating the sick newborn at the bedside, US imaging of structures adjacent to bone (i.e., the subdural space) is often inadequate. MRI has proven to be quite sensitive to small hemorrhage and can help establish timing of ICH. MRI is also superior for detecting other lesions, such as contusion, thromboembolic infarction, or hypoxic-ischemic injury that may result from severe hypovolemia/anemia or other risk factors for parenchymal lesions. When there is clinical suspicion of a large SDH, a lumbar puncture (LP) should not be performed until after neuroimaging is obtained. An LP may be contraindicated if there is a large hemorrhage within the posterior fossa or supratentorial compartment. If a small SDH is found, an LP should be performed to rule out infection in the newborn with seizures, depressed mental status, or other systemic signs of illness because small SDH are often clinically silent.
D. Management and prognosis. Most newborns with SDH do not require surgical intervention and can be managed with supportive care and treatment of any accompanying seizures. Newborns with rapid evolution of a large infratentorial SDH require prompt stabilization with volume replacement (fluid and/or blood products), pressors, and respiratory support, as needed. An urgent head CT and neurosurgical consultation should be obtained in any newborn with signs of progressive brainstem dysfunction (i.e., coma, apnea, cranial nerve dysfunction), opisthotonus, or tense, bulging fontanelle. Open surgical evacuation of the clot is the usual management for the minority of newborns with large SDH in any location accompanied by such severe neurologic abnormalities or obstructive hydrocephalus. When the clinical picture is stable and no deterioration in neurologic function or unmanageable increase in ICP exists, supportive care and serial CT examinations instead of surgical intervention should be utilized in the management of posterior fossa SDH.5 Laboratory testing to rule out sepsis or a bleeding diathesis should be considered with large SDH, particularly if there is no history of trauma or other risk factor for large SDH. The newborn should be monitored for the development of hydrocephalus, which can occur in a delayed fashion following SDH. Finally, chronic subdural effusions may occur rarely and can present weeks to months later with abnormally increased head growth. The outcome for newborns with nonsurgical SDH is usually good, provided there is no other significant neurologic injury or disease. The prognosis is also good for cases in which prompt surgical evacuation of the hematoma is successful and there is no other parenchymal injury.
E. Epidural hemorrhage. EH is uncommon in newborns compared with older infants and children. EH appears to be correlated with trauma (e.g., difficult instrumented delivery), and a large cephalohematoma or skull fracture was found in about half the reported cases of EH. Removal or aspiration of the hemorrhage was performed in the majority of reported cases, and the prognosis was quite good except when other ICH or parenchymal pathology was present. Similar to SDH, a small EH does not necessarily require surgical treatment but should still be monitored carefully with serial imaging to ensure there is no progressive enlargement of the EH or other hemorrhage or brain injury.
II. SUBARACHNOID HEMORRHAGE
A. Etiology and pathogenesis. Subarachnoid hemorrhage (SAH) is a common form of ICH among newborns, although the true incidence of small SAH remains unknown. Primary SAH (i.e., SAH not due to extension from ICH in an adjacent compartment) is probably frequent but clinically insignificant. In these cases, SAH may go unrecognized because of a lack of clinical signs. For example, hemorrhagic or xanthochromic CSF may be the only indication of such a hemorrhage in newborns who undergo a CSF exam to rule out sepsis. Small SAH probably results from the normal “trauma” associated with the birth process. The source of bleeding is usually ruptured bridging veins of the subarachnoid space or ruptured small leptomeningeal vessels. This is quite different from SAH in adults, where the source of bleeding is usually arterial and therefore produces a much more emergent clinical syndrome. SAH should be distinguished from subarachnoid extension of blood from a germinal matrix hemorrhage/intraventricular hemorrhage (GMH/IVH), which occurs most commonly in the preterm newborn. SAH may also result from extension of SDH or a cerebral contusion (parenchymal hemorrhage). Finally, subpial hemorrhage is a focal subtype of SAH that occurs mostly in term newborns and is likely caused by local trauma resulting in venous compression or occlusion in the setting of a vaginal delivery (often instrumented).6
B. Clinical presentation. As with other forms of ICH, clinical suspicion of SAH may result because of blood loss or neurologic dysfunction. Only rarely is the blood volume loss large enough to provoke catastrophic results. More often, neurologic signs manifest as seizures, irritability, or other mild alteration of mental status, particularly with SAH or subpial hemorrhage occurring over the cerebral convexities. Small SAH may not result in any overt clinical signs except seizures in an otherwise well-appearing baby. In these circumstances, the seizures may be misdiagnosed as abnormal movements or other clinical events.
C. Diagnosis. Seizures, irritability, lethargy, or focal neurologic signs should prompt investigation to determine whether there is a SAH (or other ICH). The diagnosis is best established with a brain MRI scan, or by LP, to confirm or diagnose small SAH. CT scans may be adequate to diagnose SAH but as in the case of SDH/EH, an MRI is preferred because of the lack of radiation and to determine if there is any other parenchymal pathology. For example, SAH may occur in the setting of hypoxic-ischemic brain injury or meningoencephalitis, pathologies which are better detected by MRI than CT or US. CUS is not sensitive for the detection of small SAH so should be used only if the patient is too unstable for transport to MRI/CT.
D. Management and prognosis. Management of SAH usually requires only symptomatic therapy, such as anticonvulsant therapy for seizures (see Chapter 56) and nasogastric feeds or intravenous fluids if the newborn is too lethargic to feed orally. The majority of newborns with small SAH do well with no recognized sequelae. In rare cases, a very large SAH will cause a catastrophic presentation with profound depression of mental status, seizures, and/or brainstem signs. In such cases, blood transfusions and cardiovascular support should be provided as needed, and neurosurgical intervention may be required. It is important to establish by MRI whether there is coexisting hypoxia-ischemia or other significant neuropathology that will be the crucial determinant of a poor neurologic prognosis because a surgical procedure may not improve outcome if there is extensive brain injury in addition to the SAH. Occasionally, hydrocephalus will develop after a moderate-to-large SAH, and thus, follow-up CUS scans should be performed in such newborns, particularly if there are signs of increased ICP or abnormally rapid head growth.
III. INTRAPARENCHYMAL HEMORRHAGE
A. Etiology and pathogenesis
1. Primary cerebral hemorrhage is uncommon in all newborns, whereas cerebellar hemorrhage is found in 5% to 10% of autopsy specimens in the premature newborn. An intracerebral hemorrhage may occur rarely as a primary event related to rupture of an arteriovenous malformation or aneurysm, from a coagulation disturbance (e.g., hemophilia, thrombocytopenia), or from an unknown cause. More commonly, cerebral intraparenchymal hemorrhage (IPH) occurs as a secondary event, such as hemorrhage into a region of hypoxic-ischemic brain injury. From the venous side of the cerebral circulation, IPH may occur as a result of venous infarction (because venous infarctions are typically hemorrhagic) either in relation to a large GMH/IVH (preterm > term; see section IV) or as a result of sinus venous thrombosis (term > preterm). From the arterial side, bleeding may occur secondarily into an arterial embolic infarction or into areas of hypoxic-ischemic brain injury from global hypoxia-ischemia (term > preterm). Occasionally, there may be hemorrhage that occurs secondarily within an area of necrotic periventricular leukomalacia (PVL) (preterm > term). IPH may be found occasionally in newborns undergoing extracorporeal membrane oxygenation (ECMO) therapy. Finally, cerebral IPH may occur as an extension of a large ICH in another compartment, such as large SAH or SDH, as rarely occurs with significant trauma or coagulation disturbance, and it may sometimes be difficult to identify the original source of hemorrhage.
2. Intracerebellar hemorrhage occurs more commonly in preterm than term newborns and may be missed by routine CUS because the reported incidence is higher in neuropathologic than clinical studies. The use of mastoid and posterior fontanelle views during CUS examination increases the likelihood of detection of cerebellar hemorrhage (and posterior fossa SAH), and MRI is more sensitive for the detection of small posterior fossa IPH, SAH, or SDH.7 Intracerebellar IPH may be a primary hemorrhage or may result from venous hemorrhagic infarction or from extension of GMH/IVH or SAH (preterm > term), and small foci of cerebellar hemorrhage of unclear pathogenesis may be detected by MRI > US. It is difficult to determine the original source of cerebellar hemorrhage by US (and sometimes MRI); hence, the proportion of primary versus secondary cerebellar hemorrhage is unclear. Cerebellar IPH rarely occurs as an extension of large SAH/SDH in the posterior fossa related to a trauma (term > preterm).
B. Clinical presentation. The presentation of IPH is similar to that of SDH, where the clinical syndrome differs depending on the size and location of the IPH. In the preterm newborn, IPH is often clinically silent in either intracranial fossa, unless the hemorrhage is quite large. In the term newborn, intracerebral hemorrhage typically presents with focal neurologic signs such as seizures, asymmetry of tone/movements, or gaze preference, along with irritability or depressed level of consciousness. A large cerebellar hemorrhage (± SDH/SAH) presents as described in section I earlier and should be managed as for a large posterior fossa SDH.
C. Diagnosis. MRI is the best imaging modality for IPH, but CUS may be used in the preterm newborn or when a rapid bedside imaging study is necessary. CT can be used for urgent evaluation when MRI is not available quickly, but the radiation exposure of CT should be avoided when possible, and CT is insensitive for detection of small posterior fossa ICH because of artifact from surrounding skull bones. MRI is superior for demonstrating the extent and age of the hemorrhage and the presence of any other parenchymal abnormality. In addition, magnetic resonance (MR) angiography/venography may be useful to demonstrate a vascular anomaly, lack of flow distal to an arterial embolus, or sinus venous thrombosis. Thus, MRI is more likely than CT or CUS to establish the etiology of the IPH and to determine accurately the long-term prognosis for the term newborn. For the preterm newborn, CUS views through the mastoid and posterior fontanelle improve the detection of hemorrhage in the posterior fossa.
D. Management and prognosis
1. Acute management of IPH is similar to that for SDH and SAH, where most small hemorrhages require only symptomatic treatment and support, whereas a large IPH with severe neurologic compromise should prompt neurosurgical intervention. It is important to diagnose and treat any coexisting pathology, such as infection or sinus venous thrombosis because these underlying conditions may cause further injury that can have a greater impact on long-term outcome than the IPH itself. A large IPH, especially in association with IVH or SAH/SDH, may cause hydrocephalus, and thus head growth and neurologic status should be monitored for days to weeks following IPH. Follow-up imaging by MRI and/or CUS should be obtained in the case of large IPH, both to establish the severity and extent of injury and to rule out hydrocephalus or remaining vascular malformation.
2. The long-term prognosis largely relates to location and size of the IPH and GA of the newborn. A small IPH may have relatively few or no long-term neurologic consequences. A large cerebral IPH may result in a lifelong seizure disorder, hemiparesis or other type of cerebral palsy (CP), feeding difficulties, and cognitive impairments ranging from learning disabilities to significant intellectual disability, depending on the location and size of parenchymal injury. Focal cerebellar hemorrhage in the term newborn often has a relatively good prognosis, although it may result in cerebellar signs of ataxia, hypotonia, tremor, nystagmus, and mild cognitive deficits. There may be only minor deficits from small, unilateral cerebellar IPH in either preterm or term newborns. In contrast, an extensive cerebellar IPH that destroys a significant portion of the cerebellum (i.e., significant bilateral cerebellar injury) in a preterm newborn may result in severe cognitive and motor disability for those newborns who survive the newborn period.8
IV. GERMINAL MATRIX HEMORRHAGE/INTRAVENTRICULAR HEMORRHAGE
A. Etiology and pathogenesis. GMH/IVH is found principally in the preterm newborn, where the incidence is currently 15% to 20% in newborns born at <32 weeks’ GA but is uncommon in the term newborn. The etiology and pathogenesis are different for term and preterm newborns.
1. In the term newborn, primary IVH typically originates in the choroid plexus or in association with venous (± sinus) thrombosis and thalamic infarction and much less commonly in the small remnant of the subependymal germinal matrix. The pathogenesis of IVH in the term newborn is more likely to be related to perinatal asphyxia, venous thrombosis, trauma (i.e., from a difficult delivery), and/or other risk factors. One study suggested that IVH might occur secondary to venous hemorrhagic infarction in the thalamus in 63% of otherwise healthy term newborns with clinically significant IVH.9 In such cases, there may be thrombosis of the internal cerebral veins, but occasionally, there may be more extensive sinovenous thrombosis.
2. In the preterm newborn, GMH/IVH originates from the fragile involuting vessels of the subependymal germinal matrix, located in the caudothalamic groove. There are numerous risk factors that have been identified in the etiology of IVH, including maternal factors such as infection/inflammation and hemorrhage, lack of antenatal steroids, external factors such as mode of delivery or neonatal transport to another hospital, and increasingly recognized genetic factors that predispose some newborns to IVH. These risk factors all contribute to the pathogenesis of GMH/IVH, which is largely related to intravascular, vascular, and extravascular factors (Table 54.2). The intravascular risk factors are probably the most important and are also the factors most amenable to preventive efforts.
a. The intravascular risk factors predisposing to GMH/IVH include ischemia/reperfusion, increases in cerebral blood flow (CBF), fluctuating CBF, and increases in cerebral venous pressure. Ischemia/reperfusion occurs commonly when hypotension is corrected. This scenario often occurs shortly after birth when a premature newborn may have hypovolemia or hypotension that is treated with infusion of colloid, normal saline, or hyperosmolar solutions such as sodium bicarbonate. Rapid infusions of such solutions are thought to be particularly likely to contribute to GMH/IVH. Indeed, studies of the beagle puppy model showed that ischemia/reperfusion (hypotension precipitated by blood removal followed by volume infusion) reliably produces GMH/IVH.10 Briefer fluctuations in CBF has been demonstrated to be associated with GMH/IVH in preterm newborns. In one study, newborns with large fluctuations in CBF velocity by Doppler US were much more likely to develop GMH/IVH than newborns with a stable pattern of CBF velocity.11 The large fluctuations typically occurred in newborns breathing out of synchrony with the ventilator, but such fluctuations have also been observed in newborns with large patent ductus arteriosus or hypotension, for example. Increases in cerebral venous pressure are also thought to contribute to GMH/IVH. Sources of such increases include ventilatory strategies where intrathoracic pressure is high (e.g., high continuous positive airway pressure), pneumothorax, tracheal suctioning, and both labor and delivery, where fetal head compression likely results in significantly increased venous pressure.12 Indeed, a higher incidence of GMH/IVH is found in preterm newborns with a longer duration of labor and in those delivered vaginally compared with those delivered via cesarean section. With all of these intravascular factors related to changes in cerebral arterial and venous blood flow, the role of a pressure-passive cerebral circulation is likely to be important. Several studies have shown that preterm newborns, particularly asphyxiated newborns, have an impaired ability to regulate CBF in response to blood pressure changes (hence “pressure-passive”).13, 14 Such impaired autoregulation puts the newborn at increased risk for rupture of the fragile germinal matrix vessels in the face of significant increases in cerebral arterial or venous pressure, and particularly when ischemia precedes such increased pressure. Sustained increases in CBF may also contribute to GMH/IVH and can be caused by seizures, hypercarbia, anemia, and hypoglycemia, which result in a compensatory increase in CBF. In addition to cerebrovascular factors affecting arterial or venous flow, impaired coagulation and platelet dysfunction are intravascular factors that can contribute to the pathogenesis or severity of GMH/IVH.
Table 54.2. Factors in the Pathogenesis of GMH/IVH
Intravascular factors
Ischemia/reperfusion (e.g., volume infusion after hypotension)
Fluctuating CBF (e.g., with mechanical ventilation)
Increase in cerebral venous pressure (e.g., with high intrathoracic pressure, usually from ventilator)
Increase in CBF (e.g., with hypertension, anemia, hypercarbia)
Platelet dysfunction and coagulation disturbances
Vascular factors
Tenuous, involuting capillaries with large luminal diameter
b. Vascular factors that contribute to GMH/IVH include the fragile nature of the involuting vessels of the germinal matrix. There is no muscularis mucosa and little adventitia in this area of relatively large diameter, thin-walled vessels; all of these factors make the vessels particularly susceptible to rupture.
c. Extravascular risk factors for GMH/IVH include deficient extravascular support and likely excessive fibrinolytic activity in preterm newborns (see Table 54.2).
B. Pathogenesis of complications of GMH/IVH. The two major complications of GMH/IVH are periventricular hemorrhagic infarction (PVHI) and posthemorrhagic ventricular dilation (PVD). The risk of both complications increases with larger size of IVH. The pathogeneses of these two complications are discussed here.
1. PVHI has previously been considered an extension of a large IVH, hence is often referred to as a grade IV IVH. Although this designation is still used in much of the literature, neuropathologic studies have shown that the finding of a large, often unilateral or asymmetric, hemorrhagic lesion dorsolateral to the lateral ventricle is not an extension of the original IVH but is a separate lesion consisting of a venous hemorrhagic infarction. Neuropathologic studies demonstrate the fan-shaped appearance of a typical hemorrhagic venous infarction in the distribution of the medullary veins that drain into the terminal vein, resulting from obstruction of flow in the terminal vein by the large ipsilateral IVH. Evidence supporting the notion of venous obstruction underlying the pathogenesis of PVHI includes the observation that PVHI occurs on the side of the larger IVH, and Doppler US studies show markedly decreased or absent flow in the terminal vein on the side of the large IVH.15 Further neuropathologic evidence that PVHI is a separate lesion from the original IVH is that the ependymal lining of the lateral ventricle separating IVH and PVHI has been observed to remain intact in some cases, demonstrating that the IVH did not “extend” into the adjacent cerebral parenchyma. Hence, PVHI is a complication of large IVH, which is why some authors refer to it as a separate lesion rather than denoting PVHI to be a “higher” grade of IVH (i.e., a grade IV IVH). Risk factors for the development of PVHI include low GA, low Apgar scores, early life acidosis, patent ductus arteriosus, pneumothorax, pulmonary hemorrhage, and need for significant respiratory or blood pressure support.16
2. Progressive PVD or posthemorrhagic hydrocephalus (PHH—terminology varies) may occur days to weeks following the onset of GMH/IVH. Not all ventricular dilation progresses to established hydrocephalus that requires treatment; hence, the terms are used with slightly different meanings (see section IV.C.3 for clinical course of PVD). The pathogenesis of progressive PVD may relate in part to impaired CSF resorption and/or obstruction of the aqueduct or the foramina of Luschka or Magendie by particulate clot.17 However, other mechanisms likely play an important role in the pathogenesis of PVD. High levels of TGF-β1 are found in the CSF following IVH, particularly in newborns with PVD; TGF-β1 upregulates genes for extracellular matrix proteins that elaborate a “scar” which may obstruct CSF flow and/or CSF reabsorption.17, 18, 19 In addition, restricted arterial pulsations (e.g., due to decreased intracranial compliance) have been proposed to underlie chronic hydrocephalus in hydrodynamic models of hydrocephalus.20 The pathogenesis of the brain injury resulting from PVD is probably related in large part to regional hypoxia-ischemia and mechanical distension of the periventricular white matter based on animal and human studies.21, 22, 23, 24 In addition, the presence of non-protein-bound iron in the CSF of newborns with PVD may lead to the generation of reactive oxygen species that in turn contribute to the injury of immature oligodendrocytes in the white matter.25 The brain injury associated with PVD is principally a bilateral cerebral white matter injury (WMI) similar to PVL with regard to both its neuropathology and long-term outcome.24, 26, 27
C. Clinical presentation
1. GMH/IVH in the preterm newborn is usually a clinically silent syndrome and thus is recognized only when a routine CUS is performed. The vast majority of these hemorrhages occur within 72 hours after birth, hence the use of routine CUS within 3 to 4 days after birth in many nurseries for newborns with a GA <32 weeks. Newborns with large IVH may present with full fontanelle, anemia, decreased levels of consciousness and spontaneous movements, hypotonia, abnormal eye movements, or skew deviation. Rarely, a newborn will present with a rapid and severe neurologic deterioration with full or tense fontanelle, obtundation or coma, severe hypotonia and lack of spontaneous movements, and generalized tonic posturing thought to be seizure but does not have an electrographic correlate by electroencephalogram.
2. The term newborn with IVH typically presents with signs such as seizures, apnea, irritability or lethargy, vomiting with dehydration, or a full fontanelle. Ventriculomegaly is often present at the time of IVH diagnosis in a term newborn. IVH may be initially unrecognized such that newborns may be discharged home after birth and then present within the first week or so after birth with the earlier-listed clinical signs.
3. PVD may develop over days to weeks following IVH and may present with splitting of sutures, decreased level of consciousness, increased apnea or worsening respiratory status, feeding difficulties, increasing head growth (crossing percentiles on the growth chart), bulging fontanelle, or impaired upgaze or sunsetting sign. However, PVD is often relatively asymptomatic in preterm newborns because ICP is often normal in this population, particularly with slowly progressive dilation, and the signs of PVD are relatively nonspecific. Thus, serial CUS scans are critical for diagnosis of PVD in preterm newborns with known IVH. A retrospective study of newborns with birth weight <1,500 g who developed IVH and survived at least 14 days showed that 50% of such newborns will not show ventricular dilation, 25% will develop nonprogressive ventricular dilation (or stable ventriculomegaly), and the remaining 25% will develop PVD.28 The incidence of PVD increases with increasing severity of GMH/IVH; it is uncommon with grades I to II IVH (Table 54.3) (up to 12%) but occurs in up to 75% of newborns with grade III IVH ± PVHI. The incidence of PVD is also higher with younger GA at birth. Ventricular dilation may proceed rapidly (over a few days) or slowly (over weeks). About 40% of newborns with PVD will have spontaneous resolution of PVD without any treatment. The remaining 60% generally require medical and/or surgical therapy (˜15% of this latter group does not survive).
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