Abstract
Intracranial hemorrhage in the neonatal period is an important clinical problem. Its importance relates to a relatively high frequency of occurrence, accompanied at times by serious neurological sequelae. Over the last decade there have been changes in the relative frequency of intracranial hemorrhage owing to changes in obstetric practice, such as increased vacuum-assisted delivery and reduced rotational forceps, as well as the improved survival of preterm infants with complex intracranial hemorrhagic lesions. Moreover, systematic neuroimaging studies in otherwise asymptomatic term infants have led to a new awareness of the incidence of more clinically benign forms of intracranial hemorrhage. In this chapter, an overview of neonatal intracranial hemorrhage and the basic elements of recognition are presented. Detailed discussion is devoted to subdural hemorrhage, primary subarachnoid hemorrhage, intraventricular hemorrhage of the full-term infant, and certain unusual, miscellaneous examples of neonatal intracranial hemorrhage.
Keywords
subdural hemorrhage, subarachnoid hemorrhage, intraventricular hemorrhage, parenchymal hemorrhage, venous hemorrhage
Intracranial hemorrhage in the neonatal period is an important clinical problem. Its importance relates to a relatively high frequency of occurrence, accompanied at times by serious neurological sequelae or even death. Over the last decade there have been changes in the relative frequency of intracranial hemorrhage owing to changes in obstetrical practice, such as increased vacuum-assisted delivery and reduced rotational forceps as well as the improved survival of preterm infants with complex intracranial hemorrhagic lesions. Moreover, systematic neuroimaging studies in otherwise asymptomatic term infants have led to a new awareness of the incidence of more clinically benign forms of intracranial hemorrhage.
In this chapter, an overview of neonatal intracranial hemorrhage and the basic elements of recognition are presented. Detailed discussion is devoted to subdural hemorrhage, primary subarachnoid hemorrhage, intraventricular hemorrhage of the full-term infant , and certain unusual, miscellaneous examples of neonatal intracranial hemorrhage. The critical problem of germinal matrix–intraventricular hemorrhage of the premature infant is discussed in Chapter 24 , and cerebellar hemorrhage, in Chapter 23 . Various traumatic extracranial and intracranial hemorrhages, now generally unusual, are considered in Chapter 36 .
Overview
Classification
The major clinically important types of neonatal intracranial hemorrhages are (1) epidural hemorrhage; (2) subdural hemorrhage, including posterior fossa subdural hemorrhage; (3) primary subarachnoid hemorrhage; (4) cerebellar hemorrhage; (5) intraventricular hemorrhage; and (6) other forms of intraparenchymal hemorrhage (other than cerebellar). The approximate incidence, anatomical site of blood, relative frequency in premature versus term infants, and the usual clinical gravity are noted in Table 22.1 .
| TYPE OF HEMORRHAGE | INCIDENCE | ANATOMICAL SITE OF BLOOD | MATURATION OF INFANT | USUAL CLINICAL GRAVITY |
|---|---|---|---|---|
| Extradural (epidural)(see Chapter 36 ) | Very rare | Between skull and outside of dura | FT > PT | Variable |
| Subdural | 5%–25% | Between dura and arachnoid | FT > PT | Benign |
| Subarachnoid | 1%–2% FT 10% PT | Between arachnoid and pia | PT > FT | Benign |
| Cerebellar (see Chapter 23 ) | 0.1% FT 5% PT | Cerebellar hemispheres and/or vermis | PT > FT | Serious |
| Intraventricular (see Chapter 24 ) | 0.2% FT 15% PT | Within ventricles or including periventricular hemorrhagic infarction | PT > FT | Serious |
| Parenchymal | 0.1% FT 2%–4% PT | Cerebral parenchyma | FT > PT | Variable |
The incidence of intracranial hemorrhage has been challenging to define, because most studies have focused on symptomatic newborns. In one small study of symptomatic infants, the estimated incidence was 4.9 per 10,000 live births. The largest epidemiological data relate to the Californian Perinatal Database, with maternal and neonatal hospital discharge records on 600,000 infants (2500 to 4000 g) born to nulliparous women. These data demonstrate the following: incidences of symptomatic intracranial hemorrhage associated with spontaneous delivery (1 per 1900 births), vacuum extraction delivery (1 per 860 births), and forceps delivery (per 664 births). In contrast, more recent studies using neuroimaging, such as magnetic resonance imaging (MRI), in asymptomatic newborn infants in the first month of life have revealed a much higher frequency of intracranial hemorrhage. A large prospective MRI (0.2T) study of asymptomatic term newborns found an 8% prevalence of subdural hemorrhage. A second study of 88 asymptomatic neonates born via vaginal delivery who underwent cranial MRI (3T) between the ages of 1 and 5 weeks demonstrated 17 term infants with intracranial hemorrhage, for a study prevalence of 26%. Such findings suggest that asymptomatic intracranial hemorrhage in term newborns is much more frequent than had previously been thought.
With these limitations regarding the incidence of intracranial hemorrhage in mind, Table 22.1 provides a summary of the location, incidence, and usual clinical gravity of the main types of hemorrhages. In summary, subdural hemorrhage is more frequent in the full-term than in the premature infant and is frequently asymptomatic; if large, however, it can be clinically serious. Primary subarachnoid hemorrhage , more frequent in the premature than in the full-term infant, is, in general, common but is almost always clinically benign. Cerebellar hemorrhage , more frequent in the premature than in the full-term infant, can be serious when large. Intraventricular hemorrhage , almost exclusively a lesion of the premature infant, is, in contrast to the other three types of hemorrhages, both common and usually serious. Intraventricular hemorrhage has recently been more commonly recognized in the term infant, particularly related to sinovenous thrombosis and/or hypoxic-ischemic cerebral injury. Other forms of intraparenchymal hemorrhage , more frequent in the full-term than in the premature infant, are uncommon and are of variable clinical gravity.
Recognition of Hemorrhage
Three Major Steps
Three major steps must be taken to ensure recognition of neonatal intracranial hemorrhage. First, predisposing factors should be identified. As outlined in more detail in subsequent sections, these factors include the gestational history, the details of labor and delivery, the maturation of the baby, the occurrence of hypoxic events, the modes of resuscitation, and so forth. Second, definition of abnormal clinical features must be made early in the neonatal course. Particular attention should be given to subtle neurological signs, as outlined later. Third, visualization of the site and extent of the hemorrhage should be implemented by an imaging technique , often initially by ultrasound scan and then more definitively by MRI or computed tomography (CT) (indicated only if needed emergently). Intracranial hemorrhage may first be suspected because a lumbar puncture, often carried out to rule out sepsis, reveals cerebrospinal fluid (CSF) consistent with hemorrhage. In view of this role of the CSF examination, interpretation of the CSF findings is also discussed further on. However, lumbar puncture is not the diagnostic test of choice for intracranial hemorrhage and may potentially pose a risk to the infant if a large posterior fossa hemorrhage is present.
Neuroimaging in the Recognition of Intracranial Hemorrhage
Three key methods of neuroimaging are applied in the recognition of intracranial hemorrhage. Cranial ultrasound is portable and easily accessible in the preterm and sick term infant, making it a common choice for investigating brain injury in the encephalopathic infant. Unfortunately there is a lack of sensitivity for intracranial hemorrhage and brain injury. In a recent study analyzing 4098 term infants born between 2006 and 2010 from 95 centers, imaging was performed for 2006 with cranial ultrasound, 933 with CT, and 2690 with MRI. The number of patients with no, one, two, and all three types of imaging were 678 (16.5%), 1405 (34.3%), 1845 (45.0%), and 170 (4.1%), respectively ( N = 4098 patients). Although cranial ultrasound identified intraventricular hemorrhage well, it lacked the sensitivity of MRI and CT for identifying other types of hemorrhages and intracranial injuries. Of particular note, cranial ultrasound was particularly limited in detecting all forms of extra-axial hemorrhage (subdural, subarachnoid, and extradural) ( Fig. 22.1 and Table 22.2 ).
| ULTRASOUND VERSUS CT | ULTRASOUND VERSUS MRI | CT VERSUS MRI | ||||
|---|---|---|---|---|---|---|
| ULTRASOUND | CT | ULTRASOUND | MRI | CT | MRI | |
| Intraventricular hemorrhage | 2/43 (5) | 4/43 (9) | 3/47 (6) | 5/47 (11) | 8/70 (11) | 9/70 (13) |
| Extra-axial hemorrhage | 2/42 (5) | 10/43 (23) | 1/46 (2) | 11/47 (23) | 17/69 (25) | 14/70 (20) |
| Parenchymal hemorrhage | 5/42 (12) | 7/43 (16) | 3/46 (7) | 6/47 (13) | 10/69 (14) | 13/70 (19) |
| Subependymal hemorrhage | 1/42 (2) | 2/43 (5) | 1/46 (2) | 2/47 (4) | 0/69 (0) | 1/70 (1) |
| Deep nuclear gray matter abnormality | 1/42 (2) | 4/42 (10) | 4/46 (9) | 11/47 (23) | 8/69 (12) | 18/70 (26) |
| Cystic white matter injury | 0/42 (0) | 2/42 (5) | 0/46 (0) | 4/47 (9) | 1/69 (1) | 2/70 (3) |
| Venous or arterial occlusions | 0/42 (0) | 1/42 (2) | 0/46 (0) | 2/47 (4) | 12/69 (17) | 13/70 (19) |
| Cerebellar injury | 1/42 (2) | 3/43 (7) | 0/46 (0) | 4/47 (9) | 1/69 (1) | 5/70 (7) |
| Brain stem injury | 6/69 (9) | 6/70 (9) | ||||
CT use was recommended by the 2002 American Academy of Neurology practice parameters for infants with birth trauma and a low hematocrit or coagulopathy on the basis of data from two small studies reporting on CT diagnoses of intracranial hemorrhages leading to interventions. However, there were no comparisons with cranial ultrasound for these 31 infants. In the patients in the Barnette series, the largest published to date in term infants with encephalopathy who were examined with two imaging modalities, CT was superior to ultrasound for the detection of hemorrhage. Although the authors were unable to determine the impact of the imaging findings of the infants who needed surgical intervention, only 9 of 933 infants with CT examinations underwent any central nervous system surgery. In addition, this study documented that CT performed relatively poorly for the delineation of the common patterns of brain injury in neonatal encephalopathy, including deep nuclear gray matter and white matter injury. In comparison with MRI, CT detected less than one third of deep nuclear gray matter injuries and few brain-stem or cerebellar lesions. These findings are consistent with previous publications showing that MRI detects brain injuries and malformations in infants that are missed by CT.
Because CT scanning has inherent risks, alternative neuroimaging modalities should be considered. Major national and international organizations agree that there is probably no amount of radiation that can be considered absolutely safe. Recent data from irradiated children demonstrate small but significant increases in cancer risk, even at levels of radiation (25 to 50 milligray; 1.8 to 3.8 millisievert) comparable with those produced by neonatal and pediatric CT scans. In addition, radiation may also have harmful cognitive effects. In immature animal models, the cerebellum and cerebral cortical migration appeared to be sensitive to damage from radiation. The Image Gently campaign promotes reducing the frequency of CT imaging and minimizing medical radiation exposure.
The diagnostic accuracy of MRI is similar to that of CT in scanning for intracranial hemorrhage (see Fig. 22.1 and Table 22.2 ), with improved sensitivity for clinically important forms of cerebral parenchymal injury in both the preterm and term infant. The development of more rapid MRI sequences to allow for brief diagnostic scans for cerebral hemorrhage will enhance physician comfort with this as a first-line technique.
Cerebrospinal Fluid in the Recognition of Intracranial Hemorrhage
Traumatic Lumbar Puncture.
The finding of bloody cerebrospinal fluid (CSF) in a newborn is common (occurring in > 
of all CSF samples within a neonatal intensive care unit); it is often attributed to traumatic lumbar puncture. This conclusion primarily relates to the relative difficulty of performing the puncture in the newborn but also to the relative frequency of finding bloody CSF in infants without overt neurological signs. It is, however, likely that traumatic lumbar puncture in the newborn is much less common than is generally thought. For example, in a study in which lumbar punctures were performed on the third postnatal day in all premature infants of less than 2000 g, the 76 infants who had grossly bloody CSF with elevated protein content were evaluated by CT ( Table 22.3 ). Only 6 (8%) had no increased attenuation consistent with blood. Subarachnoid blood was detectable in 22 (29%), and intraventricular hemorrhage was noted in 48 (63%). Few studies have attempted to correlate the findings of red cells on CSF with the nature and extent of intracranial hemorrhage in either the preterm or term infant.
| BLOOD ON SCAN | NO. OF PATIENTS | PERCENTAGE OF TOTAL GROUP |
|---|---|---|
| None | 6 | 8% |
| Subarachnoid | 22 | 29% |
| Germinal matrix—intraventricular | 48 | 63% |
Cerebrospinal Fluid Findings of Intracranial Hemorrhage.
CSF findings that indicate intracranial hemorrhage are, primarily, xanthochromia of the centrifuged fluid and elevations of the number of red blood cells (RBCs) as well as the protein content. Particular emphasis should be placed on the occurrence of combinations of findings rather than on a single, isolated abnormality.
Xanthochromia of the CSF develops within several hours after hemorrhage in older children and adults. In one particularly large study of adults with subarachnoid hemorrhage, nearly 90% exhibited xanthochromia within 12 hours of the ictus. The evolution of xanthochromia in newborns has not been studied systematically, although our impression is that it appears to occur more slowly than in older patients. This slower evolution may relate to a delay in the induction of the enzyme heme oxygenase, which is located in the arachnoid and is responsible for the conversion of heme to bilirubin, the major pigment accounting for xanthochromia of the CSF. In adult rats, the activity of heme oxygenase reaches peak values 6 to 12 hours after injection of heme into the subarachnoid space. These data are closely comparable with the clinical observations of adult patients cited. Determination of the significance of xanthochromia in newborns is occasionally difficult in the presence of elevated serum bilirubin levels.
The number of RBCs that should be considered significant is difficult to state conclusively, in part because of the remarkably wide range of values considered normal (see Chapter 10 ). In studies of infants in neonatal intensive care units, median values of 100 to 200 RBC/μL have been observed. A more recent study reported even higher values for mean RBCs when the lumbar puncture was undertaken by a resident. In a study of 184 cases, 64% of infants had RBC counts below 100,000. In the only report with ultrasonographic correlates, among 43 infants of less than 1500 g birth weight, the median value was 112, but the mean value was 785, and 20% of CSF samples had more than 1000 RBCs/mm. These infants did not exhibit ultrasonographic evidence of intracranial hemorrhage. However, exclusion of minor subarachnoid hemorrhage by cranial ultrasonography is not reliable. Thus, the data indicate that findings of more than 100 RBCs/mm in the newborn are common, and in the very low-birth-weight infants, values greater than 1000 occur in a substantial minority in the absence of apparently clinically significant intracranial hemorrhage. Again, the combination of findings is important in the evaluation.
Values for CSF protein are higher in newborns in an intensive care unit than in older children. In the series of Sarff and co-workers, an average protein content in CSF of 90 mg/dL was observed for term infants and a content of 115 mg/dL for preterm infants. We have obtained similar data. In general, values for CSF protein are higher in the most premature infants; in one series, the mean value at 26 to 28 weeks of postconceptional age was 177 mg/dL; at 35 to 37 weeks, it was 109 mg/dL. Values in intracranial hemorrhage are usually severalfold higher than these. A recent study found that CSF protein concentrations increased by approximately 2 mg/dL for every 1000 CSF RBCs.
Finally, determination of the CSF glucose level may be helpful in the diagnosis. In term and preterm infants evaluated in a neonatal intensive care unit and free of intracranial infection, the ratios of CSF to blood glucose levels are relatively high (i.e., 0.81 and 0.74, respectively). As with CSF protein levels, values for CSF glucose tend to be higher in the most premature infants; in one series, the mean value at 26 to 28 weeks was 85 mg/dL; at 38 to 40 weeks, it was 44 mg/dL. After neonatal intracranial hemorrhage, the CSF glucose level is frequently low ( Table 22.4 ). Indeed, in one study in which serial lumbar punctures were performed (for therapeutic purposes) on 13 infants with intraventricular hemorrhage, the CSF glucose concentration decreased on subsequent measurements in all the infants. Of the 13 infants, 11 had CSF glucose values lower than 30 mg/dL at some point subsequent to the hemorrhage, and values of 10 mg/dL or less were common. The low values occurred as early as 1 day after the hemorrhage but usually became apparent between approximately 5 and 15 days after the hemorrhage. The depressed CSF glucose values persist for weeks and have been noted as long as 3 months after the hemorrhage.
|
| Mechanism not proved but probably related to impaired glucose transport |
The basis of hypoglycorrhachia is probably related to an impairment of the mechanisms of glucose transport into the CSF. This impairment may occur at the level of the plasma membrane glucose transporter. Other proposed pathogeneses have included glucose use by RBCs or by contiguous brain. The former is ruled out by the lack of correlation between RBC number and CSF glucose level and by the negligible rates of glucose consumption observed when the cellular CSF is incubated in vitro. The possibility of excessive anaerobic use of glucose by contiguous brain rendered hypoxic-ischemic by hemorrhage, ventricular dilation, or other insult appears unlikely in view of simultaneous serial determinations of CSF glucose and lactate. Thus, in 13 infants described with CSF hypoglycorrhachia, CSF glucose and lactate concentrations decreased pari passu; if anaerobic use of glucose had been operative, a concomitant increase in CSF lactate would have been expected. These observations favor the notion of a defect in glucose transport mechanisms.
An important practical problem arises when the low CSF glucose level is accompanied by pleocytosis and elevated protein content . This not uncommon occurrence is related presumably to meningeal inflammation from blood products and raises the question of bacterial meningitis. Although appropriate cultures are always indicated and even initiation of antimicrobial therapy may be necessary (until results of cultures are known), the CSF formula of pleocytosis, depressed glucose, and elevated protein content is not infrequent after neonatal intracranial hemorrhage.
The optimal imaging procedure for diagnosis becomes apparent in the following discussions of the respective lesions. The relative value of cranial ultrasonography, CT, and MRI in diagnosis is reviewed in Chapter 10 . Suffice it to say here that cranial ultrasonography is often used as a screening procedure, MRI is the most effective methodology, and CT is used for a more rapid emergent approach. The features of MRI signal change over the days and weeks after neonatal parenchymal hemorrhage and are reviewed in Table 22.5 . The MRI changes relate primarily to changes in hemoglobin state, which proceed from predominantly intracellular deoxyhemoglobin to intracellular methemoglobin to extracellular methemoglobin and finally to hemosiderin.
| SIGNAL CHANGES | ||
|---|---|---|
| AGE OF HEMORRHAGE | T1-WEIGHTED | T2-WEIGHTED |
| 1–3 days | Isointense | Low |
| 3–10 days | High | Low |
| 10–21 days | High | High |
| 3–6 weeks | High | High |
| 6 weeks–10 months | Isointense | Low |
Subdural Hemorrhage
The incidence of subdural hemorrhage has been underestimated because many such hemorrhages appear to be asymptomatic. Whitby et al. studied 111 term infants with a 0.2T MRI scanner and documented an 8% prevalence of subdural hemorrhage in newborns. He found that subdural hemorrhage was associated with vaginal delivery. All subdural hemorrhages resolved at follow-up imaging 4 weeks later. In both asymptomatic and symptomatic subdural hemorrhages, the supratentorial component was in a posterior location over the occipital or parietal lobes. No subdural hemorrhages were located over the frontal lobes. Of the nine infants with asymptomatic subdural hemorrhages, one had isolated supratentorial hematomas, six had isolated infratentorial hematomas, and two had subdural hemorrhages in both compartments. There were no subdural hemorrhages in the infants delivered by cesarean section. In a second study, Looney et al. studied 88 asymptomatic term infants with a 3T MRI scanner within the first month of life and identified 17 intracranial hemorrhages, of which 16 were subdural. There were nine isolated subdural hemorrhages that were mostly infratentorial or associated with occipital lobe subdural hemorrhage. The infants with subdural hemorrhages were all born by vaginal delivery. There was no proven association with instrumental delivery. The long-term outcome associated with these subdural hemorrhages remains unknown.
It is important to note that the pattern of subdural hemorrhage in asymptomatic term infants is different from that found in infants with nonaccidental head injuries. Nonaccidental head injuries typically cause subdural hematomas that are generally located in the interhemispheric fissure or over the cerebral convexities; these hematomas are often but not always of differing ages.
In contrast, symptomatic subdural hemorrhage in the newborn infant is very uncommon. However, if symptomatic, recognition of the disorder is important because therapeutic intervention can be lifesaving in patients with large hemorrhages.
Neuropathology
Anatomy of Major Veins and Sinuses
The neuropathology of neonatal subdural hemorrhage is readily understood after a brief review of the major anatomical features of the veins and sinuses involved in the production of such hemorrhage ( Fig. 22.2 ). The deep venous drainage of the cerebrum empties into the great cerebral vein of Galen at the junction of the tentorium and falx. The confluence of the vein of Galen and the inferior sagittal sinus, the latter located in the inferior margin of the falx, forms the straight sinus. This sinus proceeds directly posteriorly and joins the superior sagittal sinus, located in the superior margin of the falx, to form the transverse sinus. Blood in the transverse sinuses, located in the lateral margins of the tentorium, proceeds eventually to the jugular vein. Blood in the posterior fossa in part drains into the occipital sinus, which empties into the torcular. The superficial portion of the cerebrum is drained by the superficial, bridging cerebral veins, which empty into the superior sagittal sinus. Tears of these several veins or venous sinuses, occurring secondary to forces to be described and often accompanying laceration of the dura, result in subdural hemorrhage.
Major Varieties of Subdural Hemorrhage
The four major varieties of neonatal subdural hemorrhage include the following ( Table 22.6 ): tentorial laceration with rupture principally of the straight sinus, transverse sinus, vein of Galen, or smaller infratentorial veins; occipital osteodiastasis with rupture of the occipital sinus; falx laceration with rupture of the inferior sagittal sinus; and rupture of bridging superficial cerebral veins.
| SOURCE OF BLEEDING | LOCATION OF HEMATOMA |
|---|---|
| Tentorial laceration | Infratentorial (posterior fossa), supratentorial |
| Straight sinus, vein of Galen, transverse sinus, and infratentorial veins | — |
| Occipital osteodiastasis | Infratentorial (posterior fossa) |
| Occipital sinus | — |
| Falx laceration | Longitudinal cerebral fissure |
| Inferior sagittal sinus | — |
| Superficial cerebral veins | Surface of cerebral convexity |
Tentorial Laceration.
With major, lethal tears of the tentorium, hemorrhage is most often infratentorial. This finding is the case particularly with rupture of the vein of Galen or straight sinus or with severe involvement of the transverse sinus. The clots extend into the posterior fossa and, when large, very rapidly result in lethal compression of the brain stem. A massive infratentorial hemorrhage from a rupture of the vein of Galen also may occur without visible tear of the tentorium.
Lesser degrees of tentorial injury , with the advent of modern brain imaging techniques, are recognized now to be more common than the major lethal lacerations just described and probably are much more common than previously suspected. Thus several series, the largest and most recent described earlier, have documented a spectrum of intracranial hemorrhage, primarily subdural, associated with apparent or presumed tentorial injury. a
a References .
This spectrum, summarized in Table 22.7 , includes both infratentorial (usually retrocerebellar) subdural hemorrhage ( Fig. 22.3 ), secondary to inferior extension, and supratentorial subdural hemorrhage, secondary to superior extension. It is important to note that the infratentorial posterior fossa subdural hemorrhages may relate also to tears of cerebellar bridging veins, with or without accompanying overt tears of the tentorium. In addition to infratentorial or supratentorial extension, the hemorrhage of a tentorial tear may remain confined to the free edge of the tentorium , most often near the junction of the tentorium and falx ( Fig. 22.4 ; see also Fig. 22.3 ), or it may extend anteriorly further into the subarachnoid space, velum interpositum, or ventricular system (see Table 22.6 ). Very minor varieties of this spectrum may account for the relatively high RBC counts in CSF in normal newborns (see earlier discussion).| Anterior extension |
|
| Superior extension |
|
| Inferior extension |
|
Occipital Osteodiastasis.
A prominent traumatic lesion in some infants who die after breech delivery is occipital diastasis with posterior fossa subdural hemorrhage and laceration of the cerebellum (see Table 22.6 and Chapter 36 ). The diastasis lesion consists of traumatic separation of the cartilaginous joint between the squamous and lateral portions of the occipital bone. In its most severe form, the dura and occipital sinuses are torn, resulting in massive subdural hemorrhage in the posterior fossa and cerebellar laceration. The bony lesion may be more common than has generally been recognized because it is easily missed at postmortem examination.
Falx Laceration.
Laceration of the falx alone is distinctly less common than laceration of the tentorium and usually occurs at a point near the junction of the falx with the tentorium. The source of bleeding is usually the inferior sagittal sinus, and the clot is located in the cerebral fissure over the corpus callosum (see Table 22.6 ).
Superficial Cerebral Vein Rupture.
Rupture of the bridging superficial cerebral veins results in hemorrhage over the cerebral convexity, the well-known convexity subdural hematoma (see Table 22.6 ). The hematoma is usually more extensive over the lateral aspect of the convexity than near the superior sagittal sinus. Although convexity subdural hemorrhage is usually unilateral, bilateral lesions are not uncommon. a
a References .
Subarachnoid blood is a typical accompaniment. Convexity subdural hemorrhage is not a rare event, and, indeed, in small amounts, it is a frequent incidental finding at autopsy of the term infant. The trauma that leads to the hemorrhage may result also in cerebral contusion , which, in fact, may dominate the clinical picture.Pathogenesis
Subdural hemorrhage in the neonatal period is most commonly a traumatic lesion, especially when the lesion is large . b
b References .
Most such cases have involved full-term infants. Many of these series reported symptomatic infants. In asymptomatic infants, subdural hemorrhages are associated with vaginal delivery and not cesarean section, supporting that vaginal delivery may be associated with greater risk for trauma. However, in asymptomatic term infants with subdural hemorrhages, neither assisted vaginal delivery nor clinical evidence of neonatal birth trauma could be used to predict the presence of hemorrhage. Most (13 of 17, or 76%) of the cases were in the setting of nonassisted vaginal birth. This is in agreement with the findings of Whitby et al., who described nine neonates with asymptomatic hemorrhage; in only two of the nine neonates with subdural hemorrhages was external birth trauma an associated finding. The authors concluded that a subdural hematoma was not necessarily associated with obvious birth trauma. Holden et al. identified 4 of 11 neonates with clinically silent intracranial hemorrhage by cranial ultrasound; in all, vaginal delivery was uneventful.With regard to symptomatic subdural hemorrhages, as the incidence of grossly traumatic deliveries has decreased, the relative proportion of premature infants with subdural hemorrhage has increased as well. Indeed, in some surveys, the proportion of cases in premature and full-term infants has been approximately similar. However, most modern reports still indicate a predominance of full-term infants, especially with cerebral convexity subdural hemorrhages. c
c References .
The pathogenesis of major neonatal subdural hemorrhage is best considered in terms of predisposing factors referable to the mother, the infant, the duration and progression of labor, and the manner of delivery ( Table 22.8 ). Thus large symptomatic subdural hemorrhage is most likely to occur under the circumstances where the head of the infant is subjected to unusual or rapid deforming stresses such as compression, molding, or stresses on extraction. This can include circumstances such as (1) when the infant’s head is relatively large and/or the birth canal is relatively small; (2) when the skull is unusually compliant, as in a premature infant; (3) when the pelvic structures are unusually rigid, as in a primiparous or older multiparous mother; (4) when the duration of labor is either unusually brief, not allowing enough time for dilation of the pelvic structures, or unusually long, subjecting the head to prolonged compression and molding; (5) atypical presentations, such breech (with poor adaptation of the birth canal), face, or brow presentation; or (6) difficult vacuum extraction or challenging forceps or rotational maneuvers.
| AT RISK | PREDISPOSING FACTORS |
|---|---|
| Mother | Primipara |
| Older multipara | |
| Small birth canal | |
| Infant | Large, full term |
| Premature | |
| Labor | Precipitous |
| Prolonged | |
| Delivery | Breech extraction |
| Foot, face, or brow presentation | |
| Difficult forceps or vacuum extraction | |
| Difficult rotation |
Under the circumstances just described, excessive vertical molding and fronto-occipital elongation or oblique expansion of the head may occur (see Fig. 22.4 ). These effects can result in stretching of both the falx and one or both leaves of the tentorium, with a tendency for tearing of the tentorium, particularly near its junction with the falx, or, less commonly, tearing of the falx itself. Even if a laceration does not occur, the sinuses into which the vein of Galen drains can be stretched, and the result may be a tear of the vein of Galen or its immediate tributaries. Similarly, rupture of cerebellar bridging veins may occur in this context. Tear of the falx occurs particularly with extreme fronto-occipital elongation, especially that associated with face or brow presentation. Extreme vertical molding appears to underlie many tears of superficial cerebral veins and the formation of a convexity subdural hematoma. In the special case of occipital osteodiastasis with breech delivery, the injury results from suboccipital pressure, which most commonly occurs if the fetus is forcibly hyperextended with the head trapped beneath the symphysis. The lower edge of the squamous portion of the occipital bone is displaced in a forward direction, thus lacerating dura, occipital sinus, or cerebellum. (A roughly analogous situation in the supratentorial compartment probably occurs with difficult forceps extractions, which may result in skull fracture, convexity subdural hemorrhage, and cerebral contusion by direct compressive effects.)
Fortunately many of the aforementioned pathogenetic factors have been eliminated by vastly improved obstetrical practices in most medical centers. Indeed, subdural hemorrhage is not invariably due to trauma alone and can result from other contributing risk factors. For example, coagulation disturbances (e.g., maternal aspirin ingestion, early vitamin K deficiency secondary to maternal phenobarbital administration) may play at least a contributing role in some infants. Moreover, with the advent of intrauterine brain imaging, subdural hematoma has been identified in the fetus before intrapartum events could be responsible. In one report, maternal abuse with blunt abdominal trauma was documented in an infant with bilateral subdural hematomas identified in the first day of life. In other intrauterine cases, other forms of external abdominal pressure or coagulopathy have been important.
Clinical Features
In contrast to the considerable amount of medical writings relative to the neuropathological and radiological aspects of subdural hemorrhage, surprisingly few clinical neurological data are available. However, some important conclusions can be drawn from our own observations and from those recorded by other investigators. a
a References .
Tentorial Laceration, Occipital Diastasis, and Syndromes Associated With Posterior Fossa Subdural Hematoma
Rapidly Lethal Syndromes.
Tentorial laceration with massive infratentorial hemorrhage, an extremely rare disorder in the modern obstetrical era, is associated with neurological disturbance from the time of birth. The majority of the most severely affected infants weigh more than 4000 g at birth. Initially, the baby demonstrates signs of midbrain–upper pons compression (i.e., stupor or coma, skew deviation of eyes with lateral deviation that is not altered by the “doll’s eyes” maneuver, and unequal pupils, with some disturbance of response to light). With such infratentorial hemorrhage, nuchal rigidity with retrocollis or opisthotonos may also be a helpful early sign. When these features are associated with bradycardia, a large infratentorial clot with brain-stem compression should be suspected. Over minutes to hours, as the clot becomes larger, stupor progresses to coma, pupils may become fixed and dilated, and signs of lower brain-stem compression appear. Ocular bobbing and ataxic respirations may occur; finally, respiratory arrest ensues.
The severe clinical syndrome associated with occipital osteodiastasis resembles that described for major tentorial laceration. With occipital osteodiastasis, delivery is characteristically breech. A depressed Apgar score at 1 minute is common, and the course is one of rapid deterioration. In the six infants described by Wigglesworth and Husemeyer, the age at the time of death ranged from 7 to 45 hours.
Less Malignant Syndromes Associated With Posterior Fossa Subdural Hematoma.
Less severe clinical syndromes accompany most examples of posterior fossa subdural hematoma currently encountered on obstetrical and neonatal services. b
b References .
These syndromes appear to result from smaller tears of the tentorium than those just noted, from rupture of bridging veins from superior cerebellum without tentorial tear, or perhaps from lesser degrees of occipital diastasis. The clinical syndrome consists of three phases. First, no neurological signs are apparent for a period that varies from several hours after birth (usually a difficult vacuum, forceps, or breech extraction or all three) to as much as 3 or 4 days of age. Most commonly, the interval is less than 24 hours. Presumably, this period is associated with slow enlargement of the hematoma. Second, various signs develop referable to increased intracranial pressure (e.g., full fontanelle, irritability, lethargy ). Most of these signs appear to relate to the evolution of hydrocephalus secondary to a block of CSF flow in the posterior fossa. Third, signs referable to disturbance of brain stem develop, including respiratory abnormalities, apnea, bradycardia, oculomotor abnormalities, skew deviation of eyes, and facial paresis. These deficits relate to direct compressive effects of the posterior fossa hematoma. In addition to brain-stem signs, seizures occur in the majority of infants, perhaps because of accompanying subarachnoid blood. In infants who clearly worsen over hours or a day or more, as do approximately half, lethal brain-stem compression may develop.In more recent years, more common lesions of particularly small posterior fossa subdural hemorrhages have been identified by CT or MRI during the investigation of more subtle neurological abnormalities in term infants. In one carefully studied series of 26 small subdural hemorrhages detected by CT, 19 were infratentorial; the leading clinical features were respiratory abnormalities (apnea, dusky episodes ) in approximately 60% and neurological features (subtle seizures, hypotonia, apnea) in approximately 40%. None of the infants developed progressive neurological signs. In addition, two recent case reports describe the finding of vocal cord paralysis in infants who presented with stridor and respiratory distress and exhibited subdural hemorrhages diagnosed on subsequent MRI. Finally, as noted earlier, the most common presentation of subdural hemorrhage in the term infant is to be completely asymptomatic to the clinical providers.
Falx Laceration
No careful description of the clinical course of falx tears with major subdural hemorrhage is available. Yet in view of the locus of the hematoma, it is likely that initially bilateral cerebral signs will appear. However, striking neurological findings probably do not develop until the clot has extended infratentorially; the resulting syndrome is then similar to that described for tentorial laceration and posterior fossa subdural hematoma.
Cerebral Convexity Subdural Hemorrhage
Subdural hemorrhage over the cerebral convexities is associated with at least three neurological syndromes ( Table 22.9 ). First and probably most commonly, minor degrees of hemorrhage occur, and minimal or no clinical signs are apparent. Irritability, a hyperalert appearance, unexplained apneic episodes, or no signs have been noted.
| Minimal or no clinical signs |
| Focal cerebral syndrome: hemiparesis, deviation of eyes to side of lesion, focal seizures, homolateral pupillary abnormality |
| Chronic subdural effusion |
Second, signs of focal cerebral disturbance may occur, with the most common time of onset being the second or third day of life. With this syndrome, seizures, often focal, are common and are frequently accompanied by other focal cerebral signs (e.g., hemiparesis, deviation of eyes to the side contralateral to the hemiparesis; however, the eyes move by doll’s eyes maneuver, because this is a cerebral lesion). These focal cerebral signs are definitive, although usually not striking . The most distinctive neurological sign with major convexity subdural hemorrhage is dysfunction of the third cranial nerve on the side of the hematoma; this dysfunction is usually manifested by a nonreactive or poorly reactive, dilated pupil. The latter occurs secondary to compression of the third nerve by herniation of the temporal lobe through the tentorial notch. An excellent example of such a neurological syndrome associated with subdural hematoma was a newborn with hemophilia that we studied.
A third clinical presentation may be the occurrence of subdural hemorrhage in the neonatal period with few clinical signs and then the development over the next several months of a chronic subdural effusion. It is certainly well known that many infants presenting in the first 6 months of life with an enlarging head, increased transillumination, and chronic subdural effusions have no known cause for the lesion and that subdural hemorrhage can evolve into subdural effusion. However, the timing of the subdural hemorrhage as perinatal or postnatal may be unknown and must raise concerns for the occurrence of nonaccidental injury in the neonatal period.
Diagnosis
The diagnosis of major neonatal subdural hemorrhage depends principally on recognition of the clinical syndrome, with subsequent definitive demonstration by a brain imaging study.
Clinical Syndromes
The clinical syndromes previously reviewed are often sufficiently distinctive to raise the suspicion of a large subdural hemorrhage as well as the specific variety thereof. Neurological signs primarily referable to the brain stem should suggest infratentorial hematoma. Neurological signs primarily referable to the cerebrum should suggest convexity subdural hematoma. These signs should provoke more definitive and prompt diagnostic studies because the clinical course may deteriorate very rapidly. Lumbar puncture is not a good choice for diagnostic study in this setting because of the possibility of provoking herniation, either of cerebellar tonsils into the foramen magnum in the presence of a posterior fossa subdural hematoma or of the temporal lobe into the tentorial notch in the presence of a large unilateral convexity subdural hematoma.
Computed Tomography, Magnetic Resonance Imaging, and Ultrasound Scans
Although CT is a definitive means of demonstrating the site and extent of neonatal subdural hemorrhage, MRI is superior and currently recommended. When MRI is not available soon enough, CT is particularly useful for a rapid diagnosis and defining the location and extent of the lesions. Examples of the CT demonstration of the varieties of subdural hemorrhage just discussed are shown in Fig. 22.4 . MRI is more effective than CT in the delineation of posterior fossa subdural hemorrhage ( Figs. 22.5 to 22.7 ). This particular superiority of MRI in the evaluation of posterior fossa hemorrhage also applies to other types of lesions in this location (see Chapter 10 ). Detection of subdural hematoma by ultrasound scanning ( Fig. 22.8 ), although reported, is generally difficult. Moreover, even when these hematomas are detected, the extent and distribution of supratentorial lesions are usually demonstrated far better by MRI or CT and of infratentorial lesions by MRI. In addition, the vast majority of subdural hematomas are infratentorial, where ultrasound has even greater challenges in accurate diagnosis. The major difficulty of ultrasound scanning relates to acoustical interference by bone and to near-field transducer artifacts.
Skull Radiographs
Occipital osteodiastasis may be demonstrated by skull radiographs. The lateral view shows the lesion ( Fig. 22.9 ).
Prognosis
Infants with major symptomatic lacerations of the tentorium and falx and massive degrees of subdural hemorrhage have a very poor prognosis. Nearly all die; the rare survivor is left with hydrocephalus secondary to obstruction of CSF flow at the tentorial notch or over the convexities. Similarly, severe occipital diastasis and its complications have been associated with a poor outcome. Nevertheless it is possible that early diagnosis could lead to beneficial intervention.
Although they are often serious lesions, moderate posterior fossa subdural hematomas , frequently recognized in recent years primarily by CT and MRI, are associated with an outcome that is variable but dependent on size, rapidity of diagnosis, and, when necessary, intervention ( Table 22.10 ). a
a References .
Thus of 30 surgically treated infants, 80% either were normal or exhibited minor neurological deficits on follow-up. Approximately 15% of surgically treated patients developed communicating hydrocephalus that required shunt placement. Of 40 nonsurgically treated infants, nearly 90% had a favorable outcome (see Table 22.10 ). In earlier reports, as many as 40% to 50% of infants who did not undergo operations died, probably because of rapidly progressive lesions, the gravity of which escaped prompt detection. The small posterior fossa subdural hemorrhages described in hospital-based series are associated with no major sequelae or death.| OUTCOME | |||
|---|---|---|---|
| SURGICAL EVACUATION ( N = 81) | GOOD TO EXCELLENT | MAJOR SEQUELAE | DEATHS |
| Yes (46) | 85% | 10% | 5% |
| No (35) | 88% | 7% | 5% |
a See text for references; also includes unpublished personal cases. Lesions have been of moderate or large size.
The prognosis of patients with moderate or large convexity subdural hemorrhage is relatively good; from 50% to 90% of affected infants are well on follow-up. b
b References .
The remainder are left with focal cerebral signs and, occasionally, hydrocephalus. The deficits appear to relate to associated parenchymal lesions. The small subdural hemorrhages detected by widespread imaging in recent years have a generally favorable short-term outcome, although the longer-term prognosis remains unknown at this stage.Management
Tentorial and Falx Lacerations, Occipital Osteodiastasis, and Posterior Fossa Subdural Hematoma
The severity of the initial trauma and the rapid progression to brain-stem compromise have rendered effective treatment nearly impossible in major tears of the tentorium and falx and in overt occipital osteodiastasis with severe subdural hemorrhage. Theoretically, rapid surgical evacuation may provide some hope for salvage of the affected baby. Some support for this suggestion is obtained by the experience just reviewed with less severe posterior fossa subdural hematomas (see Table 22.10 ). Rapid detection and prompt surgical evacuation in the presence of progression of neurological signs have been of value in the management of these lesions. However, a normal outcome has been documented in posterior fossa subdural hematoma without surgical intervention (see Table 22.10 ). In summing up the available literature, several key points are apparent: Close surveillance alone is appropriate in the absence of major neurological signs, particularly brain-stem signs, or worsening neurological status. Surgery should not be delayed if clear neurological deterioration becomes apparent. With small lesions, close surveillance is almost always followed by a favorable outcome.
Cerebral Convexity Subdural Hematoma
Effective management of the infant with an acute convexity subdural hematoma requires careful sequential clinical observation. Surgery is not mandatory if the infant is stable neurologically. The need for surgery is based on large size of the lesion, signs of increased intracranial pressure, and neurological deficits, particularly if findings suggest incipient transtentorial herniation. If a stable subdural hemorrhage evolves to subdural effusion, subdural taps can be used to reduce signs of increased intracranial pressure and to prevent the development of craniocerebral disproportion, the latter serving only to perpetuate subdural bleeding. Repeated subdural taps should not be performed if the infant is asymptomatic and the head is not growing rapidly. The development of constricting subdural membranes was overestimated in the past. The smaller convexity subdural hemorrhages detected by imaging in recent years rarely require intervention.
Primary Subarachnoid Hemorrhage
Primary subarachnoid hemorrhage is hemorrhage within the subarachnoid space that is not secondary to extension from subdural, intraventricular, or cerebellar hemorrhage. Moreover, also excluded from this category are cases in which subarachnoid blood is secondary to extension from intracerebral hematoma, a structural vascular lesion (e.g., aneurysm or arteriovenous malformation), tumor, hemorrhagic infarction, or major coagulation disturbance (see later discussion of miscellaneous causes of intracranial hemorrhage). Primary subarachnoid hemorrhage, defined in this way, is a very frequent variety of neonatal intracranial hemorrhage, mostly because the category includes the many newborn infants, particularly premature infants, with a few hundred RBCs per cubic millimeter in the CSF. The frequency of clinically significant primary subarachnoid hemorrhage was overestimated in the past, particularly in the premature infant but also in the full-term infant, mostly because of the lack of brain imaging data to identify intraventricular hemorrhage. As reviewed in Table 22.3 , in our own series of infants weighing less than 2000 g with grossly bloody CSF, only 29% exhibited subarachnoid hemorrhage alone, and 63% exhibited intraventricular hemorrhage (although with blood also in the subarachnoid space). Moreover, even many term infants with bloody CSF who, in the past, would have been considered to have primary subarachnoid hemorrhage on clinical grounds, have now been shown by more detailed neuroimaging studies—including ultrasound, CT, or MRI scans—to have intraventricular hemorrhage. Finally, a localized variant of subarachnoid hemorrhage, involving the subpial space and superficial cerebral cortex, should also be recognized in this context; this lesion often occurs with subarachnoid hemorrhage and, on brain imaging, may be difficult to distinguish from typical primary subarachnoid hemorrhage (see later).
Neuropathology
Blood is usually located most prominently in the pia-arachnoid space over the cerebral convexities, especially posteriorly, and in the posterior fossa. Small amounts of subarachnoid blood are not infrequently found at postmortem examinations of newborns not suspected clinically of having sustained intracranial hemorrhage. Less commonly, large amounts of blood are observed. The source of the bleeding in primary subarachnoid hemorrhage is presumed to be small vascular channels derived from the involuting anastomoses between leptomeningeal arteries present during brain development. Origin from bridging veins within the subarachnoid space is also possible. At any rate, primary subarachnoid hemorrhage in newborn patients is unlike the dramatic large vessel, arterial hemorrhage in older patients.
Neuropathological complications of neonatal primary subarachnoid hemorrhage are very unusual. Even in major degrees of hemorrhage, significantly increased intracranial pressure with brain-stem compression is rare. The only significant, albeit very uncommon, sequela clearly related to the hemorrhage is hydrocephalus. The latter is secondary either to adhesions around the outflow of the fourth ventricle or around the tentorial notch—which result in obstruction to CSF flow—or to adhesions over the cerebral convexities, which result in impaired CSF flow or absorption.
The variant of subarachnoid hemorrhage noted earlier involves localized bleeding in the subpial region, with involvement of the most superficial aspect of cerebral cortex. Although this hemorrhage often occurs together with subarachnoid hemorrhage, in subpial hemorrhage, the blood is found beneath the pia and is contiguous with bleeding in the most superficial, largely glial-populated region of cerebral cortex. The usual location for this type of hemorrhage is in the region of the anterior temporal lobe, near the pterion (a point at the junction of the coronal, squamous sphenosquamous, and sphenofrontal sutures) or in localized cerebral regions beneath cranial sutures.
Pathogenesis
The pathogenesis of neonatal primary subarachnoid hemorrhage is not entirely understood, but most of the major hemorrhages appear to relate, on clinical grounds, to trauma or to circulatory events related to prematurity. The relationships of trauma to the genesis of major subarachnoid hemorrhage are similar in many respects to those described earlier for subdural hemorrhage. The relationships to prematurity are similar to those described in Chapter 24 for germinal matrix–intraventricular hemorrhage of the premature infant. Common to both pathogenetic themes is the substrate of maturation-dependent involution of leptomeningeal anastomotic channels. The pathogenesis of the common smaller subarachnoid hemorrhages is unclear because most of these hemorrhages occur without any apparent traumatic or circulatory abnormality.
The interesting subpial hemorrhages may relate to local trauma with resulting disruption of small veins because the lesions occur at sites in proximity to cranial sutures and to likely movement of bone during normal delivery. Thus, in one series of seven cases, four occurred in proximity to the pterion and the remainder occurred beneath the coronal or squamosal sutures.
Clinical Features
Three major syndromes with primary subarachnoid hemorrhage can be distinguished ( Table 22.11 ). First, and undoubtedly most commonly , minor degrees of hemorrhage occur, and minimal or no signs develop. Second, primary subarachnoid hemorrhage can result in seizures , especially in full-term infants (see Chapter 12 ). The seizures usually have their onset on the second postnatal day. In the interictal period, these babies usually appear remarkably well, and the description “well baby with seizures” often seems appropriate. In the subpial variant, the seizures are often focal, reflecting the localized nature of these lesions.
| Minimal or no clinical signs |
| Seizures in full-term infant; considered well during interictal period |
| Catastrophic deterioration |
A third and rare syndrome is massive subarachnoid hemorrhage with catastrophic deterioration and a rapidly fatal course. The infants have usually sustained severe perinatal asphyxia, sometimes with an element of trauma at the time of birth. The neurological syndrome is similar to the catastrophic deterioration described in Chapter 24 for some patients with large intraventricular hemorrhage.
Diagnosis
The diagnosis of primary subarachnoid hemorrhage is usually made by MRI or CT; on rare occasions it is made by ultrasound (see earlier discussion of neuroimaging). On CT, distinction from the normal, slightly increased attenuation in the region of the falx and major venous sinuses in the newborn may be difficult. Sometimes the possibility of primary subarachnoid hemorrhage is raised initially by the findings of an elevated number of RBCs and an elevated protein content in the CSF, usually obtained for another purpose (e.g., to rule out meningitis). Exclusion of another cause of blood in the subarachnoid space (e.g., extension from subdural, cerebellar, or intraventricular hemorrhage) or from certain unusual sources (e.g., tumor, vascular lesions) is made best by MRI or CT. The localized subpial hemorrhages, often with superficial cortical hemorrhage, are observable both by MRI or CT ( Fig. 22.10 ).
Ultrasonography is insensitive in detecting subarachnoid hemorrhage per se because of the normal increase in echogenicity around the periphery of the brain. A large subarachnoid hemorrhage occasionally distends the sylvian fissure and thus becomes detectable, but care must be taken not to confuse a sylvian fissure distended with blood from the wide fissure seen consistently in premature infants and resulting from the normal separation of the frontal operculum and superior temporal region until late in gestation ( Fig. 22.11 ).
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