Cerebellar hemorrhagic injury in premature infants occurs during a vulnerable developmental period and is associated with wider neuropathology
© Haines et al.; licensee BioMed Central Ltd. 2013
Received: 26 September 2013
Accepted: 16 October 2013
Published: 21 October 2013
Cerebellar hemorrhagic injury (CHI) is being recognized more frequently in premature infants. However, much of what we know about CHI neuropathology is from autopsy studies that date back to a prior era of neonatal intensive care. To update and expand our knowledge of CHI we reviewed autopsy materials and medical records of all live-born preterm infants (<37 weeks gestation) autopsied at our institution from 1999–2010 who had destructive hemorrhagic injury to cerebellar parenchyma (n = 19) and compared them to matched non-CHI controls (n = 26).
CHI occurred at a mean gestational age of 25 weeks and involved the ventral aspect of the posterior lobe in almost all cases. CHI arose as a large hemorrhage or as multiple smaller hemorrhages in the emerging internal granule cell layer of the developing cortex or in the nearby white matter. Supratentorial germinal matrix hemorrhage occurred in 95% (18/19) of CHI cases compared to 54% (14/26) of control cases (p = 0.003). The cerebellar cortex frequently showed focal neuronal loss and gliosis (both 15/19, 79%) in CHI cases compared to control cases (both 1/26, 4% p < 0.0001). The cerebellar dentate had more neuronal loss (8/15, 53%) and gliosis (9/15, 60%) in CHI cases than controls (both 0/23, 0%; p < 0.0001). The inferior olivary nuclei showed significantly more neuronal loss in CHI (10/17, 59%) than in control cases (5/26, 19%) (p = 0.0077). All other gray matter sites examined showed no significant difference in the incidence of neuronal loss or gliosis between CHI and controls.
We favor the possibility that CHI represents a primary hemorrhage arising due to the effects of impaired autoregulation in a delicate vascular bed. The incidences of neuronal loss and gliosis in the inferior olivary and dentate nuclei, critical cerebellar input and output structures, respectively were higher in CHI compared to control cases and may represent a transsynpatic degenerative process. CHI occurs during a critical developmental period and may render the cerebellum vulnerable to additional deficits if cerebellar growth and neuronal connectivity are not established as expected. Therefore, CHI has the potential to significantly impact neurodevelopmental outcome in survivors.
Cerebellar injury is a frequent complication of premature birth that is receiving more attention due, in part, to the emergence of improved imaging techniques with enhanced sensitivity to detect posterior fossa lesions [1–3]. Often these injuries have a significant hemorrhagic component and the term cerebellar hemorrhagic injury (CHI) has been applied [3, 4]. The actual incidence of CHI is difficult to estimate as it has likely been underdiagnosed clinically . Previous autopsy studies suggest an incidence of 10 to 25%, although this is likely high  as recent neuroimaging based studies indicate a much lower incidence [3, 4, 7–13]. The largest series reported an overall incidence of approximately 3%, which increased to 8.7% in infants with a birth weight less than 750 gm, and decreased in infants of greater birth weight suggesting that the smallest and most premature infants are at greatest risk to develop CHI [4, 13].
During this developmental period the human cerebellum is undergoing rapid growth and many complex developmental processes are taking place that are essential to proper cerebellar function . In this period cerebellar growth is rapid and mostly due to the massive increase in external granule cell number. Other critical developmental events occurring in this time period include granule cell migration and the early establishment of cerebellar neuronal circuitry. Because all of these important events occur within this time frame it is considered to represent a critical period of cerebellar development when the cerebellum is vulnerable to injury. An injury at this time could have consequences beyond the direct impact of the damaged cerebellar tissue if the injury impairs or arrests later developmental processes and takes the cerebellum off its developmental trajectory. Because CHI tends to affect the most premature infants during a time when the cerebellum is developmentally vulnerable, CHI could have significant neurodevelopmental impact on survivors, and there is a critical need to learn as much as possible about the neuropathology of CHI.
The number of CHI autopsy studies is limited and most were performed in a previous era of neonatal intensive care and therefore may not be directly applicable to contemporary standards of care and technology [6, 15–18]. Autopsy data have suggested that CHI is a primary hemorrhage  or possibly due to alterations in venous drainage , however, the goal of the latter study was to test the potential impact of a type of ventilation mask attachment that is no longer in use, rather than study CHI itself. Previous autopsy studies indicate that CHI often coexists with a supratentorial germinal matrix hemorrhage (GMH)/ intraventricular hemorrhage (IVH) and suggest that CHI and GMH share common pathogenetic factors [6, 15–18]. In one study, 34% of the CHI cases had periventricular leukomalacia (PVL) . Aside from this, the available autopsy studies are mostly silent on whether or not CHI is associated with injury to other neuroanatomic structures such as the pre- and post-cerebellar nuclei, which are of critical importance to cerebellar function. Nonetheless, there are data to suggest that CHI is indeed associated with such injury. Takashima approached the issue from the standpoint of inferior olivary nuclear injury in his study of 15 premature infants who sustained neuronal loss and gliosis to this structure; he observed “a close relationship between lesions of the inferior olivary nuclei and the presence of cerebellar hemispheric lesions such as cerebellar hemorrhage…” . Other autopsy studies indicate that premature infants sustain diverse types of injury to the cerebellar cortex, cerebellar dentate, basis pontis, and inferior olivary nuclei, which is often, but not always, associated with PVL . The impact and extent of CHI on the cerebellum and its associated nuclei are likely of significant clinical importance to survivors and our knowledge of CHI needs to be updated by studying a contemporary CHI patient autopsy dataset.
The cerebellum is known to integrate sensory information and function in motor control, however it also appears to have roles in cognition, learning, behavior and language domains [21–24]. The success of innovations in neonatal critical care means that infants who are most at risk to develop CHI frequently survive and are at increased risk to bear the long-term consequences of CHI, which may contribute to the cognitive, learning and behavioral issues known to affect survivors of premature birth [3, 7, 10, 25]. The high frequency of CHI in premature infants and the vulnerable nature of the cerebellum in this developmental period need to be considered with emerging concepts of cerebellar function as we update our knowledge of CHI neuropathology.
In this study we examined a modern cohort of premature infants with CHI, we sought to determine: 1) the extent and region of the cerebellum involved by CHI; and 2) if CHI is associated with additional neuropathology, especially gray matter lesions that may provide insight into the neurodevelopmental impairments encountered in surviving premature infants. To address these aims we reviewed autopsy materials and medical records of all live-born preterm infants (< 37 weeks gestation) autopsied at our institution from 1999–2010 and identified 19 premature infants who had CHI as defined by the presence of a destructive hemorrhage located in cerebellar parenchyma. The CHI group was compared to a matched control group of 26 premature infants who did not have CHI and were autopsied in the same time frame. We hypothesized that CHI has a characteristic pattern of distribution, and that infants with CHI have a significantly greater incidence of injury to pre- and post-cerebellar nuclei critical to cerebellar processing, i.e. inferior olivary nuclei, basis pontis and cerebellar dentate, compared to control infants who did not sustain CHI.
The autopsy records and pathology materials of all premature infants (<37 gestational weeks at birth) autopsied in 1999–2010 at Nationwide Children’s Hospital were retrospectively reviewed. CHI was defined as a destructive lesion of cerebellar parenchyma that was predominately hemorrhagic in nature and appeared to arise from the cerebellum. A group of gender and age-matched subjects who did not have CHI and were autopsied in the same year as a CHI subject were also identified as a control group. Subjects with chromosomal aberrations or other genetic conditions and patients with significant malformations were excluded. To prevent bias all potential control cases meeting these criteria were included. Parental consent for autopsy was granted in each case and the study was performed after approval of the project by the Institutional Review Board at Nationwide Children’s Hospital.
Medical chart review
The medical chart of each subject was reviewed for key demographic data as well as maternal and neonatal clinical factors. Basic demographic data including maternal age, gestational age, postnatal age, postconceptional age, birth weight, birth length, head circumference, 1 and 5 minute Apgar scores, gender, and race (African-American, Caucasian and Biracial) were recorded. The occurrence of important pregnancy complications such as pregnancy induced hypertension, pre-ecclampsia, ecclampsia, maternal infection around the time of delivery and antibiotic use, prolonged rupture of membranes, preterm labor, chorioamnionitis, abruption, administration of prenatal corticosteroids, and multiple gestation were recorded. Delivery conditions such as the performance of a caesarian section or an emergent delivery were documented. The medical record was also reviewed for neonatal treatment measures such as resuscitation, positive pressure ventilation (PPV), conventional mechanical ventilation (CMV) and intubation, chest compressions and epinephrine administration, high frequency oscillatory ventilation (HFOV), continuous positive airway pressure (CPAP), nasal cannula (NC), intravenous nitrous oxide (iNO), volume expanders (normal saline), vasopressors (dopamine, dobutamine, epinephrine), blood transfusions (packed red blood cells, platelets, plasma) hydrocortisone, sodium bicarbonate, acidosis (< pH 7.20), furosemide and renal failure. The medical record was reviewed for the occurrence of complications of prematurity such as respiratory distress syndrome, bronchopulmonary dysplasia, pneumonia, pneumothorax, pulmonary hemorrhage, sepsis (clinical blood cultures positive for microbial growth and clinical signs), disseminated intravascular coagulation, intestinal injury (small intestinal perforation (SIP), necrotizing enterocolitis (NEC)), surgery (exploratory laparotomy for SIP or NEC) and hyperbilirubinemia. A patent ductus arterious (PDA) was associated with CHI in a previous multivariate analysis, so the identification of PDA on echocardiogram and management measures such as indomethacin prophylaxis and treatment and ibuprofen administration, and the need for surgical intervention to close a PDA was noted from the medical record . The need for pain medication (fentanyl, morphine) or sedatives (Ativan, versed) and the occurrence of seizures were recorded. Body weight, body length, head circumference, and brain mass were recorded from the autopsy reports.
Review of pathology materials
A mean of 10 hematoxylin-eosin (H&E) stained histopathologic sections were examined from each case. Our institution routinely samples the brain to include neocortex from the frontal lobe (watershed areas) and triple watershed area, the thalamus (at the level of the lateral geniculate nucleus and dorsal medial nucleus), caudate, putamen, globus pallidus, hippocampus (at the level of the lateral geniculate nucleus), cerebellar cortex, cerebellar dentate, midbrain, pons, rostral and caudal medulla and spinal cord.
Autopsy reports and gross photographs were reviewed for the presence of primary hemorrhagic lesions of the cerebellum and to assess the laterality and extent of CHI. Hemorrhages from a supratentorial source could be reliably discerned from a primary cerebellar parenchymal hemorrhage as blood from the former formed a cast of the cerebellomedullary cistern, whereas blood from the later adopted the shape of the cerebellum and was often at least partially covered by leptomeninges. Histopathologic sections were assessed to determine the relative age of the hemorrhage. Acute lesions were defined by the presence of recent hemorrhage with relatively intact red blood cells. Subacute hemorrhages had macrophages that often contained hemosiderin and early organization with tissue fragmentation; chronic lesions were defined as those with cyst-like cavities.
Histopathologic sections were examined for acute neuronal necrosis, neuronal loss and gliosis in the most severely affected high power fields of each gray matter site. Acute neuronal necrosis was defined as neuronal hypereosinophilia with nuclear pyknosis or as karyorrhexis in the case of immature neurons with relatively less cytoplasm. The CHI and control cases all had varying degrees of acute neuronal necrosis in a number of neuroanatomic structures. We considered these findings to represent agonal changes developing in the 24 to 48 hour period prior to death and, instead focused our analysis on neuronal loss and gliosis, which are changes indicative of an injury occurring 3 to 5 days or more prior to death and may more appropriately represent the neuropathology encountered in CHI survivors . Gliosis was defined as the occurrence of 11 or more reactive astrocytes with abundant eosinophilic cytoplasm and an eccentrically situated nucleus with delicate chromatin in a high powered field. Neuronal loss was recognized as focal or confluent areas of neuronal drop out in gray matter structures and was often accompanied by reactive gliosis. We selected these parameters for gliosis and neuronal loss because we felt that they are readily evident using standard histopathological techniques and because they likely represent significant injury as has been shown previously . Gliosis and neuronal loss were evaluated in the entire gray matter structure that appeared in the section and we assessed the mostly severely affected area.
The cerebral white matter of all lobes, corpus callosum, internal capsules and cerebellum was reviewed for evidence of PVL, which was defined as the presence of focal white matter necrosis and diffuse reactive gliosis of the surrounding white matter . The presence of GMH and supratentorial IVH were also analyzed. Pontosubicular necrosis was defined as the presence karyorrhectic neurons in the basis pontis and subiculum of the hippocampus.
The 45 cases were divided into a CHI group (n = 19) and a control group (n = 26) that did not have CHI. Categorical data were compared between the groups by using likelihood ratio Chi-Square test or Fisher’s Exact test when it was appropriate. Continuous data were compared using either a t test or the nonparametric Wilcoxon two-sample test as appropriate. Significance was defined as a p value < 0.05 in all statistical tests. All tests were conducted using SAS 9.3 (SAS Institute Inc., Cary, NC, USA).
Demographic, maternal, and neonatal clinical data
Gestational Age (weeks)
Postnatal Age (weeks)
Postconceptional Age (weeks)
Birth weight (gm)
Birth length (cm)
Birth head circumference (cm)
Apgar 1 minute
Apgar 5 minutes
Postmortem body weight (gm)
Postmortem body length (cm)
Postmortem head circumference (cm)
Postmortem brain weight, fixed (gm)
Maternal Age (years)
Pregnancy induced hypertension
Prolonged rupture of membranes
Chest compressions and/or epinephrine
Positive pressure ventilation (PPV) and intubation
High frequency oscillatory ventilation (HFOV)
Continuous positive airway pressure (CPAP)/nasal cannula
Respiratory distress syndrome (RDS)
Bronchopulmonary dysplasia (BPD)
PDA on ultrasound
Surgical ligation of PDA
Disseminated intravascular coagulation
Total parental nutrition
Acidosis (pH < 7.20)
Germinal matrix hemorrhage
Intraventricular hemorrhage Grades 3 or 4
Frontal cortex - neuronal loss
Frontal cortex - gliosis
Parietal cortex - neuronal loss
Parietal cortex - gliosis
Temporal cortex - neuronal loss
Temporal cortex - gliosis
Occipital cortex - neuronal loss
Occipital cortex - gliosis
Putamen – neuronal loss
Putamen – gliosis
Caudate – neuronal loss
Caudate – gliosis
Globus pallidus – neuronal loss
Globus pallidus – gliosis
Thalamus – neuronal loss
Thalamus – gliosis
Hypothalamus- neuronal loss
Hypothalamus – gliosis
Hippocampus – neuronal loss
Hippocampus – gliosis
Midbrain, tectum – neuronal loss
Midbrain, tectum – gliosis
Midbrain, tegmentum – neuronal loss
Midbrain, tegmentum – gliosis
Pons, tegmentum – neuronal loss
Pons, tegmentum – gliosis
Rostral medulla, tegmentum – neuronal loss
Rostral medulla, tegmentum – gliosis
Inferior olivary nucleus – neuronal loss
Inferior olivary nucleus - gliosis
Cerebellar cortex – neuronal loss
Cerebellar cortex – gliosis
Dentate nucleus – neuronal loss
Dentate nucleus - gliosis
Spinal cord – neuronal loss
Spinal cord - gliosis
Associated neuropathologic findings
The CHI cases had a higher incidence of PVL (5/19, 26%) than controls (1/26, 4%) but the difference was not significant (p = 0.0687) (Table 2). At autopsy, 95% (18/19) of CHI cases had a GMH compared to 54% (14/26) of controls, which was a significant difference (p = 0.003) (Table 2) . Grade 3 and 4 intraventricular hemorrhages occurred in 12 of the 18 CHI cases (67%) and in 10 of the 14 control cases that had a GMH (71%) (p = 1.0) (Table 2). Pontosubicular necrosis is a common pattern of injury in this age group and it occurred in 69% (11/16) of CHI cases compared to 27% (7/26) of controls, a difference that was significant (p = 0.0073) (Table 2).
This case-controlled neuropathologic autopsy study of CHI in premature infants shows that CHI tends to be bilateral and involve the ventral surface of the posterior lobe of the cerebellum. CHI is often multifocal and appears to arise in the deep cerebellar cortex or adjacent white matter. We found that CHI occurs in association with significant pathology in the inferior olivary and dentate nuclei, which are critical input and output structures, respectively, of the cerebellar cortex. CHI occurs during a critical period of cerebellar development when the cerebellum may be particularly vulnerable to injury and may account for a component of the adverse neurodevelopmental outcomes of premature birth.
At autopsy, CHI frequently involved the ventral surface of one or both hemispheres and vermis, which is consistent with the pattern observed in severely affected survivors [30, 31]; however, unilateral involvement tends to be more common in survivors [4, 8], and was only observed in five of our autopsy cases. This may simply reflect the fact that subjects who come to autopsy were generally more severely affected than survivors. The frequency of PVL in this series was 26%, which is similar to that reported in a prior autopsy study (34%), although each study used a slightly different definition of PVL . Nonetheless, the frequency of PVL in CHI subjects at autopsy is likely higher than that reported in survivors [4, 17]. A novel finding in this study is the significantly higher incidence of pontosubicular necrosis (69%) in CHI patients compared to controls (27%). Pontosubicular necrosis is rarely noted in isolation, but rather tends to coexist with other hypoxic-ischemic lesions . It is possible that our patient population may not be completely representative of the brain pathology of premature infants with CHI who survive beyond the perinatal period, but nonetheless it still provides important information about CHI itself and may help guide future research into the neuropathologic substrate of the neurological sequelae encountered in CHI survivors.
Nearly all of the infants with CHI also had supratentorial hemorrhage, an association which has been recognized previously [4, 6, 8, 18]. CHI and GMH/IVH commonly coexist, which suggests that these hemorrhagic lesions share common pathogenetic mechanisms. In our series CHI tended to be multifocal and frequently consisted of multiple variably sized hemorrhages of different histopathologic age. This multifocality and heterogeneous histopathologic picture suggests that CHI may develop as a series of recurrent hemorrhagic episodes occurring over a period of time. It is possible that the large main hemorrhage grossly evident in many cases of CHI actually originated from a number of smaller bleeds that coalesced together. If this is indeed the case then CHI may represent an evolving process, rather than a single event. More work is needed on the temporal pace of CHI, but this could be important to take into consideration when instituting future therapeutic or preventative measures.
We were unable to reproduce many of the recently identified risk factors associated with CHI, likely because these studies, unlike ours, were conducted in surviving infants. However, our findings are in accordance with previously noted themes that CHI patients are critically ill and require intense supportive therapy [4, 11]. A multivariate analysis indicated that emergency caesarean section, PDA and acidosis were independent risk factors for CHI . At autopsy we observed no statistically significant difference in the frequency of acidosis, caesarean section or emergent delivery between CHI and control infants. Sepsis and renal failure were significantly more frequent in the CHI group compared to controls. The presence of sepsis may indicate a role for infection and the inflammatory cascade, while renal failure could further substantiate the role of poor perfusion in severe CHI cases. At autopsy we noted no difference in the incidence of PDA between the CHI and control cases, or in the frequency of measures taken to close a PDA. Pulmonary hemorrhage, however, is indicative of a hemodynamically significant PDA , and it was significantly more frequent in CHI patients than in controls at autopsy and has been reported to be increased in CHI survivors . Middle cerebral artery blood flow velocity is reduced in association with a PDA, so it seems possible that the presence of a PDA could also impair cerebellar perfusion . While the direct effect of a PDA on the posterior cerebral circulation has not been formally evaluated, PDA has been associated with cerebellar infarcts . Overall, hemodynamic factors such as impaired autoregulation and a significant PDA seem to be important in CHI pathogenesis, as they are in GMH and IVH [34, 35].
CHI could arise from a number of intra- or extracerebellar sources and likely has a complex, multifactorial pathogenesis with hematologic and vascular factors potentially playing important roles. Donet et al. suggested that cerebellar hemorrhage in premature infants is due to the dissection of blood from either the fourth ventricle or from the subarachnoid space that originates from an IVH . We found no parenchymal tract that would be consistent with this mechanism, but we also made an effort to include only primary cerebellar hemorrhages. It has been suggested that primary cerebellar hemorrhages arise from either the subependymal germinal matrix of the fourth ventricle or from the external granule layer which has a superficial venous anastomoses [6, 16, 17]. We found little evidence to support either of these sites as a substantial source of hemorrhage. None of our cases showed significant hemorrhage in these locations and those that did were always accompanied by other larger, more deeply situated hemorrhages. The hemorrhages we observed occurred in the deep cortex and in the white matter near the internal granule layer. The internal granule layer is one of, if not the, most highly vascularized region of the human brain ; however, the dense vascularity of this region would only enhance the probability of hemorrhage, and other factors must contribute. We suspect that the vessels in the region of the white matter-internal granule layer interface are immature and relatively weak in this developmental period due to the rapid angiogenesis that may be occurring in order to accommodate the quickly expanding internal granule cell population. We are currently testing this hypothesis.
Although it is plausible that CHI represents hemorrhagic conversion of a thromboembolic infarct CHI was often bilateral and infarcts were not noted in other brain vascular distributions, making hemorrhagic conversion of an infarct an unlikely cause of CHI. Autoregulation of cerebral perfusion is impaired in critically ill premature infants and limits their ability to maintain uniform cerebral blood flow across a range of perfusion pressures. Impaired autoregulation renders the brain susceptible to episodes of hypoperfusion/ischemia, which can weaken blood vessels making them prone to rupture during episodes of hyperperfusion leading to hemorrhage. Interestingly, nearly all of the hemorrhages we studied involved the ventral posterior lobe of the cerebellum, which is largely supplied by the PICA. The autoregulatory capacity of the cerebellum is even narrower than that of the cerebrum . Whether the PICA is more susceptible to the hemodynamic perturbations typical of prematurity is unknown; however, the cerebella of CHI cases often demonstrated focal cerebellar cortical loss and gliosis, which is consistent with hypoperfusion (Figure 3a and d).
The ventral cerebellum not only has a distinct arterial supply, it also has a distinct venous return. The superior cerebellar veins drain superior hemispheric and vermal areas to the great cerebral vein of Galen or to the proximal straight sinus. The posterior inferior veins drain the inferior hemispheres into the transverse sinus and the inferior vermis drains into the confluens . The premature infant has a compliant skull and external forces causing occipital compression can displace the squamous portion of the occipital bone under the parietal bones distorting the venous sinuses at the confluens thereby increasing venous pressure, which would preferentially affect the ventral cerebellum [5, 39]. This raises the possibility that CHI could arise from a venous source, as some have suggested . The venous drainage of the deep zone of the cerebellar cortex principally occurs via vessels Duvernoy et al. term V5 veins, which have extensive ramifications that drain the internal granule layer and subcortical white matter . The location of many of the hemorrhages in this series corresponds to the location of the V5 veins. It is possible that some cases of cerebellar hemorrhage are due to a venous source; however, the frequent coexistence of CHI with cortical injury that is likely hypoxic-ischemic in nature speaks against a venous source underlying all cases. More research is needed to elucidate the vascular source of CHI.
The cerebellum undergoes a lengthy developmental process that extends well into the postnatal period so cerebellar injury in premature infants can potentially alter the developmental trajectory of the cerebellum. Quantitative MRI studies have indeed demonstrated that premature birth is associated with impaired cerebellar growth . In this series CHI occurred at a mean gestational age of approximately 25 weeks, at which time the cerebellum has achieved only 20 to 25% of its term volume . From 24 gestational weeks to term birth cerebellar growth peaks mostly due to proliferation, migration and differentiation of external granule precursor cells . The death of external granule cells (or their limited proliferation) would reduce the number of internal granule cells and decrease excitatory input to Purkinje cells resulting in defects in cerebellar circuitry. CHI can directly destroy a significant amount of cerebellar tissue and impair cerebellar growth and the establishment of proper neuronal connectivity patterns. However, CHI could also exert indirect effects that are capable of impacting neurodevelopment and outcome. For example, CHI exposes external granule precursor cells on the surface of the molecular layer to non-heme iron and hemosiderin, which can produce free radicals, reactive oxygen species and pro-inflammatory cytokines [42–46]. Subarachnoid blood in premature infants can decrease glutamate transporter expression in Purkinje cells and Bergman glia, leading to excitotoxic cell death via increased extracellular glutamate . Subarachnoid blood can induce vasoconstriction of pial vessels at the surface of the cerebellum in experimental animals, which would further potentiate ischemic injury . Experimental models indicate that meningeal cells over the cerebellar surface are important for proper foliation, neurogenesis and cortical lamination [48–50], therefore hemorrhages disrupting the leptomeninges could impact cerebellar tissue that is not directly involved by CHI. Free radicals, reactive oxygen species, cytokines, excitotoxicity and altered meningeal-cortical interactions are potentially important pathogenetic factors that warrant further study.
We observed significant neuronal loss and gliosis in the dentate and inferior olivary nuclei in association with CHI at autopsy, but not in other gray matter sites (Table 2). This dentate and inferior olivary nuclear pathology likely represents a transsynaptic degenerative phenomenon; as tissue adjacent to these nuclear structures was intact and their overall architecture was recognizable. This is in accordance with a study by Takashima who examined 15 cases with inferior olivary nuclear pathology and observed an association with lesions in the cerebellar hemisphere and further suggested that the olivary pathology is due to transsynaptic degeneration . The dentate and inferior olivary nuclei, like the cerebellar cortex, are in a critical developmental period at 25 weeks gestation [51–54]. Dentate neurons increase in size and dendrites start to branch extensively and acquire spines from 20 to 25 weeks . Extensive infolding of the early dentate nucleus begins at 24 weeks and continues until the mature serpentine configuration is attained at 35 weeks gestation . A slower phase of maturation extends into the neonatal period, during which time the neurons acquire an even more complex dendritic tree . The olivary nuclei are the main origin of climbing fibers, which extend into the cerebellum at about 20 weeks gestation and synapse with Purkinje cells around 28 weeks. At 34 weeks the climbing fibers ascend the Purkinje cell dendrites and this process continues into postnatal life [51, 52]. The long developmental period of the cerebellar cortex and its associated nuclei may enable the interconnections between these structures to become more complex or larger in number, and this could increase cerebellar processing capacity [52, 53, 55]. Since these intricate interconnections are established over an extended period of the time, the cerebellum and its associated nuclei are not only impacted by the immediate destructive effects of CHI, but may also be vulnerable to any potential effects CHI may have on later developmental events, which would be expected to delay or prevent the establishment of critical neuroanatomic connections and contribute to long term neurodevelopmental deficits in survivors. More research is needed to determine specifically how CHI can alter the developmental trajectory of the cerebellum and its associated nuclei.
Survivors of premature birth are at risk for deficits in motor function as well as in cognitive, language, socialization and behavioral domains [21, 31, 56, 57]. The long-term effects of CHI are not fully understood, but there is mounting evidence to support the role of cerebellar injury in the pathogenesis of the non-motor deficits in survivors [3, 8, 9, 21, 25, 58]. The largest study retrospectively compared CHI patients to age-matched controls and uncovered a significant incidence of non-motor deficits, including disorders in language and cognition as well as social and behavioral issues independent of those associated with supratentorial cerebral injury . Studies report that bilateral CHI as we encountered at autopsy is associated with more severe adverse neurodevelopmental outcomes [10, 25]. In terms of topography, hemispheric injury is associated with more severe neurological abnormalities while global pervasive developmental deficits were far more common in patients with injuries to the vermis . The mechanism underlying these associations is unknown and although they may be due to a primary cerebellar defect, cerebellar lesions can exert a negative impact on cerebral development. Limperopoulos et al. demonstrated a relatively symmetric decrease in cerebral volume following bilateral cerebellar hemorrhage, while unilateral cerebellar hemorrhage resulted in a significant reduction in contralateral cerebral volume . Although it seems likely that CHI plays an important role in the neurologic morbidity of premature neonates these disabilities can evolve over time so long-term longitudinal follow-up studies are essential to determine if the deficits associated with CHI endure.
In conclusion, this study establishes the neuropathology of CHI in an autopsy case controlled cohort of premature infants. Our results indicate that CHI tends to involve the ventral cerebellum and may arise in the deep cerebellar cortex or adjacent white matter. We favor the possibility that CHI arises as a primary bleed due to the impact of impaired autoregulation in a delicate vascular bed. The high frequency of cortical neuronal loss and gliosis further suggests the presence of cerebellar hypoxia-ischemia and is in keeping with this possible mechanism. CHI occurs during a key period of development when the cerebellum and its associated pre- and post-cerebellar cortical nuclei are vulnerable to injury. CHI likely has long-term consequences on future neurodevelopment may account for a significant component of the neurological deficits encountered in survivors of premature birth. These deficits are due not only to the direct damage to the cerebellum, but also to potential indirect effects such as injury to cerebellar rely nuclei and possibly, to the cerebrum, via impaired trophic effects.
The authors thank Dr. Hannah C. Kinney, Department of Pathology Children’s Hospital, Boston for helpful discussions.
- Di Salvo DN: A new view of the neonatal brain: clinical utility of supplemental neurologic US imaging windows. Radiographics 2001,21(4):943–955.PubMedGoogle Scholar
- Johnsen SD, Tarby TJ, Lewis KS, Bird R, Prenger E: Cerebellar infarction: an unrecognized complication of very low birthweight. J Child Neurol 2002,17(5):320–324. 10.1177/088307380201700502PubMedGoogle Scholar
- Merrill JD, Piecuch RE, Fell SC, Barkovich AJ, Goldstein RB: A new pattern of cerebellar hemorrhages in preterm infants. Pediatrics 1998,102(6):E62. 10.1542/peds.102.6.e62PubMedGoogle Scholar
- Limperopoulos C, Benson CB, Bassan H, Disalvo DN, Kinnamon DD, Moore M, Ringer SA, Volpe JJ, du Plessis AJ: Cerebellar hemorrhage in the preterm infant: ultrasonographic findings and risk factors. Pediatrics 2005,116(3):717–724. 10.1542/peds.2005-0556PubMedGoogle Scholar
- Volpe JJ: Intracranial hemorrhage: subdural, primary subarachnoid, intracerebellar, intraventricular (term infnat) and miscellaneous. In Neurology of the newborn. 4th edition. Edited by: Volpe JJ. Philadelphia: Elsevier; 2004:408–413.Google Scholar
- Martin R, Roessmann U, Fanaroff A: Massive intracerebellar hemorrhage in low-birth-weight infants. J Pediatr 1976,89(2):290–293. 10.1016/S0022-3476(76)80470-2PubMedGoogle Scholar
- Dyet LE, Kennea N, Counsell SJ, Maalouf EF, Ajayi-Obe M, Duggan PJ, Harrison M, Allsop JM, Hajnal J, Herlihy AH, Edwards B, Laroche S, Cowan FM, Rutherford MA, Edwards AD: Natural history of brain lesions in extremely preterm infants studied with serial magnetic resonance imaging from birth and neurodevelopmental assessment. Pediatrics 2006,118(2):536–548. 10.1542/peds.2005-1866PubMedGoogle Scholar
- Hou D, Shetty U, Phillips M, Gray PH: Cerebellar haemorrhage in the extremely preterm infant. J Paediatr Child Health 2012,48(4):350–355. 10.1111/j.1440-1754.2011.02232.xPubMedGoogle Scholar
- Muller H, Beedgen B, Schenk JP, Troger J, Linderkamp O: Intracerebellar hemorrhage in premature infants: sonographic detection and outcome. J Perinat Med 2007,35(1):67–70.PubMedGoogle Scholar
- O’Shea TM, Kuban KC, Allred EN, Paneth N, Pagano M, Dammann O, Bostic L, Brooklier K, Butler S, Goldstein DJ, Hounshell G, Keller C, McQuiston S, Miller A, Pasternak S, Plesha-Troyke S, Price J, Romano E, Solomon KM, Jacobson A, Westra S, Leviton A, Extremely Low Gestational Age Newborns Study I: Neonatal cranial ultrasound lesions and developmental delays at 2 years of age among extremely low gestational age children. Pediatrics 2008,122(3):e662-e669. 10.1542/peds.2008-0594PubMed CentralPubMedGoogle Scholar
- Sehgal A, El-Naggar W, Glanc P, Asztalos E: Risk factors and ultrasonographic profile of posterior fossa haemorrhages in preterm infants. J Paediatr Child Health 2009,45(4):215–218. 10.1111/j.1440-1754.2008.01456.xPubMedGoogle Scholar
- Steggerda SJ, Leijser LM, Wiggers-de Bruine FT, van der Grond J, Walther FJ, van Wezel-Meijler G: Cerebellar injury in preterm infants: incidence and findings on US and MR images. Radiology 2009,252(1):190–199. 10.1148/radiol.2521081525PubMedGoogle Scholar
- Zayek MM, Benjamin JT, Maertens P, Trimm RF, Lal CV, Eyal FG: Cerebellar hemorrhage: a major morbidity in extremely preterm infants. J Perinatol 2012,32(9):699–704. 10.1038/jp.2011.185PubMedGoogle Scholar
- Volpe JJ: Cerebellum of the premature infant: rapidly developing, vulnerable, clinically important. J Child Neurol 2009,24(9):1085–1104. 10.1177/0883073809338067PubMed CentralPubMedGoogle Scholar
- Flodmark O, Becker LE, Harwood-Nash DC, Fitzhardinge PM, Fitz CR, Chuang SH: Correlation between computed tomography and autopsy in premature and full-term neonates that have suffered perinatal asphyxia. Radiology 1980,137(1 Pt 1):93–103.PubMedGoogle Scholar
- Grunnet ML, Shields WD: Cerebellar hemorrhage in the premature infant. J Pediatr 1976, 88: 605–608. 4 Pt. 1 10.1016/S0022-3476(76)80019-4PubMedGoogle Scholar
- Pape KE, Armstrong DL, Fitzhardinge PM: Central nervous system pathology associated with mask ventilation in the very low birthweight infant: a new etiology for intracerebellar hemorrhages. Pediatrics 1976,58(4):473–483.PubMedGoogle Scholar
- Perlman JM, Nelson JS, McAlister WH, Volpe JJ: Intracerebellar hemorrhage in a premature newborn: diagnosis by real-time ultrasound and correlation with autopsy findings. Pediatrics 1983,71(2):159–162.PubMedGoogle Scholar
- Takashima S: Olivocerebellar lesions in infants born prematurely. Brain Dev 1982,4(5):361–366. 10.1016/S0387-7604(82)80020-XPubMedGoogle Scholar
- Pierson CR, Folkerth RD, Billiards SS, Trachtenberg FL, Drinkwater ME, Volpe JJ, Kinney HC: Gray matter injury associated with periventricular leukomalacia in the premature infant. Acta Neuropathol 2007,114(6):619–631. 10.1007/s00401-007-0295-5PubMed CentralPubMedGoogle Scholar
- Allin M, Matsumoto H, Santhouse AM, Nosarti C, AlAsady MH, Stewart AL, Rifkin L, Murray RM: Cognitive and motor function and the size of the cerebellum in adolescents born very pre-term. Brain 2001,124(Pt 1):60–66.PubMedGoogle Scholar
- Gottwald B, Wilde B, Mihajlovic Z, Mehdorn HM: Evidence for distinct cognitive deficits after focal cerebellar lesions. J Neurol Neurosurg Psychiatry 2004,75(11):1524–1531. 10.1136/jnnp.2003.018093PubMed CentralPubMedGoogle Scholar
- Levisohn L, Cronin-Golomb A, Schmahmann JD: Neuropsychological consequences of cerebellar tumour resection in children: cerebellar cognitive affective syndrome in a paediatric population. Brain 2000,123(Pt 5):1041–1050.PubMedGoogle Scholar
- Riva D, Giorgi C: The cerebellum contributes to higher functions during development: evidence from a series of children surgically treated for posterior fossa tumours. Brain 2000,123(Pt 5):1051–1061.PubMedGoogle Scholar
- Limperopoulos C, Bassan H, Gauvreau K, Robertson RL Jr, Sullivan NR, Benson CB, Avery L, Stewart J, Soul JS, Ringer SA, Volpe JJ, du Plessis AJ: Does cerebellar injury in premature infants contribute to the high prevalence of long-term cognitive, learning, and behavioral disability in survivors? Pediatrics 2007,120(3):584–593. 10.1542/peds.2007-1041PubMedGoogle Scholar
- Auer RN Dunn JS, Sutherland GR: Hypoxia and related conditions. In Greenfield’s Neuropathology. Vol1. 8th edition. Edited by: Love S, Louis DN, Ellison D. London: Arnold; 2008:63–105.Google Scholar
- Kinney HC, Haynes RL, Folkerth RD: White matter lesions in the perinatal period. In Developmental neuropathology. Edited by: Golden JA, Harding BN. Basel: ISN Neuropathology; 2004:156–170.Google Scholar
- Aziz A, Ohlsson A: Surfactant for pulmonary hemorrhage in neonates. Cochrane Database Syst Rev 2008., 2: doi:10.1002/14651858 CD005254Google Scholar
- Papile LA, Burstein J, Burstein R, Koffler H: Incidence and evolution of subependymal and intraventricular hemorrhage: a study of infants with birth weights less than 1,500 gm. J Pediatr 1978,92(4):529–534. 10.1016/S0022-3476(78)80282-0PubMedGoogle Scholar
- Johnsen SD, Bodensteiner JB, Lotze TE: Frequency and nature of cerebellar injury in the extremely premature survivor with cerebral palsy. J Child Neurol 2005,20(1):60–64. 10.1177/08830738050200011001PubMedGoogle Scholar
- Messerschmidt A, Brugger PC, Boltshauser E, Zoder G, Sterniste W, Birnbacher R, Prayer D: Disruption of cerebellar development: potential complication of extreme prematurity. AJNR Am J Neuroradiol 2005,26(7):1659–1667.PubMedGoogle Scholar
- Weir FJ, Ohlsson A, Myhr TL, Fong K, Ryan ML: A patent ductus arteriosus is associated with reduced middle cerebral artery blood flow velocity. Eur J Pediatr 1999,158(6):484–487. 10.1007/s004310051125PubMedGoogle Scholar
- Argyropoulou MI, Xydis V, Drougia A, Argyropoulou PI, Tzoufi M, Bassounas A, Andronikou S, Efremidis SC: MRI measurements of the pons and cerebellum in children born preterm; associations with the severity of periventricular leukomalacia and perinatal risk factors. Neuroradiology 2003,45(10):730–734. 10.1007/s00234-003-1067-0PubMedGoogle Scholar
- Bassan H: Intracranial hemorrhage in the preterm infant: understanding it, preventing it. Clin Perinatol 2009,36(4):737–762. 10.1016/j.clp.2009.07.014PubMedGoogle Scholar
- Clyman RI, Chorne N: Patent ductus arteriosus: evidence for and against treatment. J Pediatr 2007,150(3):216–219. 10.1016/j.jpeds.2006.12.048PubMed CentralPubMedGoogle Scholar
- Donat JF, Okazaki H, Kleinberg F: Cerebellar hemorrhages in newborn infants. Amer J Dis Child 1979,133(4):441.PubMedGoogle Scholar
- Duvernoy H, Delon S, Vannson JL: The vascularization of the human cerebellar cortex. Brain Res Bull 1983,11(4):419–480. 10.1016/0361-9230(83)90116-8PubMedGoogle Scholar
- Calkins H, Seifert M, Morady F: Clinical presentation and long-term follow-up of athletes with exercise-induced vasodepressor syncope. Am Heart J 1995,129(6):1159–1164. 10.1016/0002-8703(95)90398-4PubMedGoogle Scholar
- Gillilan LA: The arterial and venous blood supplies to the cerebellum of primates. J Neuropathol Exp Neurol 1969,28(2):295–297. 10.1097/00005072-196904000-00008PubMedGoogle Scholar
- Limperopoulos C, Soul JS, Gauvreau K, Huppi PS, Warfield SK, Bassan H, Robertson RL, Volpe JJ, du Plessis AJ: Late gestation cerebellar growth is rapid and impeded by premature birth. Pediatrics 2005,115(3):688–695. 10.1542/peds.2004-1169PubMedGoogle Scholar
- Chang CH, Chang FM, Yu CH, Ko HC, Chen HY: Assessment of fetal cerebellar volume using three-dimensional ultrasound. Ultrasound Med Biol 2000,26(6):981–988. 10.1016/S0301-5629(00)00225-8PubMedGoogle Scholar
- Inder T, Mocatta T, Darlow B, Spencer C, Volpe JJ, Winterbourn C: Elevated free radical products in the cerebrospinal fluid of VLBW infants with cerebral white matter injury. Pediatr Res 2002,52(2):213–218. 10.1203/00006450-200208000-00013PubMedGoogle Scholar
- Juliet PA, Mao X, Del Bigio MR: Proinflammatory cytokine production by cultured neonatal rat microglia after exposure to blood products. Brain Res 2008, 1210: 230–239.PubMedGoogle Scholar
- Messerschmidt A, Prayer D, Brugger PC, Boltshauser E, Zoder G, Sterniste W, Pollak A, Weber M, Birnbacher R: Preterm birth and disruptive cerebellar development: assessment of perinatal risk factors. Eur J Paediatr Neurol 2008,12(6):455–460. 10.1016/j.ejpn.2007.11.003PubMedGoogle Scholar
- Savman K, Nilsson UA, Blennow M, Kjellmer I, Whitelaw A: Non-protein-bound iron is elevated in cerebrospinal fluid from preterm infants with posthemorrhagic ventricular dilatation. Pediatr Res 2001,49(2):208–212. 10.1203/00006450-200102000-00013PubMedGoogle Scholar
- Yakubu MA, Leffler CW: 5-Hydroxytryptamine-induced vasoconstriction after cerebral hematoma in piglets. Pediatr Res 1997,41(3):317–320. 10.1203/00006450-199703000-00002PubMedGoogle Scholar
- Inage YW, Itoh M, Wada K, Hoshika A, Takashima S: Glutamate transporters in neonatal cerebellar subarachnoid hemorrhage. Pediatr Neurol 2000,23(1):42–48. 10.1016/S0887-8994(00)00142-9PubMedGoogle Scholar
- Pehlemann FW, Sievers J, Berry M: Meningeal cells are involved in foliation, lamination, and neurogenesis of the cerebellum: evidence from 6-hydroxydopamine-induced destruction of meningeal cells. Dev Biol 1985,110(1):136–146. 10.1016/0012-1606(85)90071-5PubMedGoogle Scholar
- Sievers J, von Knebel DC, Pehlemann FW, Berry M: Meningeal cells influence cerebellar development over a critical period. Anat Embryol (Berl) 1986,175(1):91–100. 10.1007/BF00315459Google Scholar
- von Knebel DC, Sievers J, Sadler M, Pehlemann FW, Berry M, Halliwell P: Destruction of meningeal cells over the newborn hamster cerebellum with 6-hydroxydopamine prevents foliation and lamination in the rostral cerebellum. Neuroscience 1986,17(2):409–426. 10.1016/0306-4522(86)90256-3Google Scholar
- Hayaran A, Bijlani V: Polyacrylamide as an infiltrating and embedding medium for vibratome sectioning of human fetal cerebellum containing DiI-filled axons. J Neurosci Methods 1992,42(1–2):65–68.PubMedGoogle Scholar
- Marin-Padilla M: Neurogenesis of the climbing fibers in the human cerebellum: a Golgi study. J Comp Neurol 1985,235(1):82–96. 10.1002/cne.902350107PubMedGoogle Scholar
- Mihajlovic P, Zecevic N: Development of the human dentate nucleus. Hum Neurobiol 1986,5(3):189–197.PubMedGoogle Scholar
- Yamaguchi K, Goto N, Yamamoto TY: Development of human cerebellar nuclei. Morphometric study. Acta Anat 1989,136(1):61–68. 10.1159/000146799PubMedGoogle Scholar
- Zecevic N, Rakic P: Differentiation of Purkinje cells and their relationship to other components of developing cerebellar cortex in man. J Comp Neurol 1976,167(1):27–47. 10.1002/cne.901670103PubMedGoogle Scholar
- Peterson BS, Vohr B, Staib LH, Cannistraci CJ, Dolberg A, Schneider KC, Katz KH, Westerveld M, Sparrow S, Anderson AW, Duncan CC, Makuch RW, Gore JC, Ment LR: Regional brain volume abnormalities and long-term cognitive outcome in preterm infants. JAMA 2000,284(15):1939–1947. 10.1001/jama.284.15.1939PubMedGoogle Scholar
- Srinivasan L, Allsop J, Counsell SJ, Boardman JP, Edwards AD, Rutherford M: Smaller cerebellar volumes in very preterm infants at term-equivalent age are associated with the presence of supratentorial lesions. AJNR Am J Neuroradiol 2006,27(3):573–579.PubMedGoogle Scholar
- Tam EW, Rosenbluth G, Rogers EE, Ferriero DM, Glidden D, Goldstein RB, Glass HC, Piecuch RE, Barkovich AJ: Cerebellar hemorrhage on magnetic resonance imaging in preterm newborns associated with abnormal neurologic outcome. J Pediatr 2011,158(2):245–250. 10.1016/j.jpeds.2010.07.049PubMed CentralPubMedGoogle Scholar
- Limperopoulos C, Soul JS, Haidar H, Huppi PS, Bassan H, Warfield SK, Robertson RL, Moore M, Akins P, Volpe JJ, du Plessis AJ: Impaired trophic interactions between the cerebellum and the cerebrum among preterm infants. Pediatrics 2005,116(4):844–850. 10.1542/peds.2004-2282PubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.