You are in: eMedicine Specialties > Radiology > PEDIATRICS Germinal Matrix HemorrhageArticle Last Updated: Jun 5, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Andrew Leung, MD, Staff Physician, Department of Diagnostic Radiology, Kingston General Hospital Andrew Leung is a member of the following medical societies: College of Physicians and Surgeons of Ontario Coauthor(s): Omar Islam, MD, FRCP(C), Assistant Professor of Diagnostic Radiology, Queen's University; Consulting Staff, Department of Diagnostic Radiology, Division of Neuroradiology, Kingston General Hospital Editors: Charles M Glasier, MD, Professor, Departments of Radiology and Pediatrics, University of Arkansas for Medical Sciences; Chief, Magnetic Resonance Imaging, Vice-Chief, Pediatric Radiology, Arkansas Children's Hospital; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Kieran McHugh, MBBCh, Honorary Lecturer, The Institute of Child Health; Consultant Pediatric Radiologist, Department of Radiology, Great Ormond Street Hospital for Children, London, UK; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Eugene C Lin, MD, Consulting Staff, Department of Radiology, Virginia Mason Medical Center Author and Editor Disclosure Synonyms and related keywords: periventricular/intraventricular/subependymal hemorrhage, hypoxic-ischemic injury, persistent ventricular enlargement, PVH, IVH, HII, PVE, GM/IVH, GMH, neonatal/fetal cerebral hemorrhage INTRODUCTIONSection 2 of 12
  BackgroundGerminal matrix hemorrhage (GMH) and intraventricular hemorrhage (IVH) are the most common and most important neurologic injuries in preterm neonates. The brain of a premature infant lacks the ability to autoregulate cerebral blood pressure. Fluctuations in cerebral blood pressure and flow can rupture the primitive germinal matrix vessels or lead to infarction of the metabolically active germinal matrix. The damage can extend into the periventricular white matter, resulting in significant neurologic sequelae, including cerebral palsy, mental retardation, and seizures. Injury to the germinal matrix has substantial mortality and morbidity rates. Ultrasonography (US) is the primary imaging modality for the screening and diagnosis of GMH/IVH, and computed tomography (CT) scanning and magnetic resonance imaging (MRI) are used as supplementary tools. PathophysiologyA common lesion that characterizes the neuropathology of GMH/IVH is bleeding into the subependymal germinal matrix, with or without subsequent rupture into the lateral ventricle. The pathogenesis of GMH is multifactorial. For simplification, the influences can be divided into intravascular, vascular, and extravascular factors. The autoregulation of blood flow and blood pressure in the germinal matrix circulation is primitive in premature infants, and the thin microvasculature of the germinal matrix is susceptible to rupture. The primitive mesenchymal and glial supportive tissues influence the extent of GMH. Large fluctuations in blood flow and blood pressure can result, leading to injury to the germinal matrix vessels and subsequent hemorrhage. Alternatively, hypotension or hypoperfusion can lead to focal or diffuse infarction; the metabolically active germinal matrix is particularly vulnerable. Hemorrhage can occur in infarcted regions after reperfusion, but hemorrhage from any cause can be confined to the subependymal layer, or it can extend into the ventricles or brain parenchyma. Sequelae of GMH/IVH include germinal matrix destruction, periventricular hemorrhagic infarction with subsequent encephalomalacia, and posthemorrhagic hydrocephalus. FrequencyUnited StatesFrequency of GMH is inversely related to the neonate's gestational age and birth weight.1 Improvements in obstetric and perinatal care have markedly decreased the incidence and severity of GMH/IVH, which was reported to be as high as 50% in 1977.2 Incidence is now 8-56% in infants; most nurseries report rates of 20-30%. The severity of GMH/IVH has decreased along with the incidence. Sheth et al observed that the rate for severe grade 3 or 4 IVH decreased from 70% in 1986 to 23% in 1995 and that the associated mortality rate decreased by 30% in the same period.2 InternationalThe incidence of GMH varies throughout the world. Rates of GMH are most dependent on the birth rates of premature infants. Mortality/MorbidityThe extent of intracranial hemorrhage and any associated parenchymal injury or hydrocephalus are the most important factors in predicting mortality and morbidity.
RaceNo significant racial predilection is known. SexGMH affects the 2 sexes equally. AgeBecause maturation of the germinal matrix vasculature occurs in the perinatal period for premature infants, most cases of GMH/IVH occur in the first week of life for these infants. Approximately 50% of cases of GMH/IVH occur in the first day of life, and about 65% occur in the first week.
AnatomyThe germinal matrix is located in the subependyma of the ventricular walls and initially extends along the ventricles. At 8-28 weeks' gestation, the germinal matrix produces neurons and glial cells, which migrate to populate the cerebral cortex. Neurons are produced earlier in gestation, and glial cells are produced later. Involution of the germinal matrix toward the caudothalamic groove begins late in the second trimester and is nearly complete by 32 weeks' gestation. The germinal matrix is metabolically active with a rich supply of blood via a thin, fragile capillary network. Arterial supply of the germinal matrix is provided by branches of the anterior cerebral artery: the arterioles from the recurrent artery of Heubner at the level of the foramen of Monro and the terminal branches of the lateral striate arteries, located more superiorly. Venous blood flows through the terminal vein, which drains via the internal cerebral vein into the vein of Galen. Clinical DetailsThe major risk factors for GMH include a young gestational age, low birth weight, acute amnionitis, and exposure to antenatal steroids for less than 48 hours. Other risk factors include the use of general anesthesia for cesarean delivery; Apgar scores that are less than 4 in the first minute or are less than 8 by 5 minutes; respiratory distress; persistent ductus arteriosus; anemia; and arterial catheterization. The grading system created by Burstein et al in 1979 relies on the detection of blood in the subependymal germinal matrix and the ventricles as follows5:
Preferred ExaminationUS is the preferred screening and diagnostic tool for GMH. The portability of US allows imaging in the nursery with minimal disturbance of the infant. US also depicts GMHs that are larger than 5 mm, with a sensitivity of nearly 100% and specificity of 91%. Smaller GMHs, however, are more difficult to identify. Power and pulsed-wave Doppler US can be used to identify preterm neonates who are at risk for GMH/IVH during their first week of life. Using this modality, clinicians can detect autoregulatory fluctuations in the preterm neonate's cerebral blood flow with examination of the lenticulostriate arteries; measurements of the peak velocity, resistive index, and coronal vascular cross-sectional area; and product of the peak velocity and vascular cross-sectional area. CT scanning and MRI are also used and have better interobserver agreement. Because these modalities more readily depict small GMHs, CT scanning and MRI have a higher sensitivity than that of US. However, these imaging modalities require that the infant be moved from the nursery; there is also the possibility that sedation would be required. Limitations of TechniquesAll imaging modalities have relatively low negative predictive values (NPVs). In a 2000 study, Blankenberg et al found NPVs of 53% and 59% (irrespective of the modality) at 2-month and at 2-year follow-up, respectively.6 However, the absence of neuroimaging abnormalities in the infant does not exclude the possibility of later neurodevelopmental problems. DIFFERENTIALSSection 3 of 12
Periventricular Leukomalacia RADIOGRAPHSection 4 of 12
FindingsPlain radiographs are not used in the evaluation of GMH. CT SCANSection 5 of 12
FindingsIVH evolves in a predictable pattern. Acutely, it appears to hyperattenuate. After 7-10 days, the hemorrhage becomes isoattenuating relative to the brain parenchyma. Later, with clot retraction, a subependymal hematoma may develop into a fluid-filled cyst. The affected brain parenchyma may undergo atrophy and gliosis (see Image 1). Degree of ConfidenceBlankenberg et al found that CT scanning had nearly twice the sensitivity of US in the detection of GMH/IVH, and interobserver agreement with this modality was also improved relative to US.6 False Positives/NegativesA normal CT scan finding for GMH/IVH does not exclude abnormal neurodevelopment; the NPV is 50-60% at age 2 years. MRISection 6 of 12
FindingsIn the first 3 days after IVH, subependymal hematomas are isointense to slightly hypointense on T1-weighted MRIs (T1WI) and markedly hypointense on T2-weighted MRIs (T2WI). In the early subacute stage during days 4-7, the signal intensity increases on T1WIs. In the late subacute stage during days 7-14, the signal intensity increases on T2WIs. Over the next several months, the hemorrhage becomes hypointense on images obtained with both sequences, and ferromagnetic effects secondary to hemosiderin and ferritin predominate (see Images 3-8). Degree of ConfidenceAs with CT scanning, Blankenberg et al found that MRI had nearly twice the sensitivity of US in the detection of GMH/IVH, and interobserver agreement with this modality was also improved relative to US.6 False Positives/NegativesA normal image finding for GMH/IVH does not exclude abnormal neurodevelopment. The NPV is 50-60% at age 2 years. ULTRASOUNDSection 7 of 12
FindingsNeurosonography is the primary modality for both screening and follow-up of GMH/IVH in neonates. US is portable, allowing imaging in the comfortable environment of the neonatal intensive care unit (NICU). US has NPVs similar to those of CT scanning and MRI. Current screening protocols recommend performing US studies on days 7-14 of life and between the fourth and sixth weeks of life. Many centers offer more frequent screening. On US, acute subependymal hemorrhage appears as a homogeneous echogenic mass, often in the caudothalamic groove (see Image 2). The hematoma becomes less echogenic over time, beginning with the central portion. Subsequent to eventual clot retraction, a subependymal cyst may develop, or a linear echo may result (see Image 9). Acutely, IVH also appears echogenic. Cerebrospinal fluid (CSF)–blood fluid levels may be observed. When large, the clot forms a cast of the ventricle (see Image 10) and may break up in the ventricle, resulting in low-level echoes that float in the CSF. The clot may also move when the patient's head position changes. With clot evolution, the hematoma becomes echolucent, starting centrally (see Images 11-12). Scanning through the posterior fontanelle may optimize visualization of occipital horn clots. Intraparenchymal hemorrhage is usually located in the frontal and parietal lobes and appears acutely as an echogenic homogeneous mass. As the hemorrhage evolves, an echogenic rim with a sonolucent center forms. After 2-3 months, a porencephalic cyst (if the lesion communicates with a ventricle) or encephalomalacia may develop (see Image 13). Power and pulsed-wave Doppler US may be useful in identifying preterm neonates who are at risk of GMH/IVH during their first week of life. The sonograms may depict autoregulatory fluctuations in cerebral blood flow. Degree of ConfidenceNeurosonography depicts GMHs that are larger than 5 mm with a sensitivity of 100% and a specificity of 91%. False Positives/NegativesIVH may blend imperceptibly with the choroid plexus, which has a similar echo texture; thus, asymmetric thickness of the choroid plexus should be viewed with suspicion. The lack of abnormality with US does not exclude the possibility of later neurodevelopmental problems. NUCLEAR MEDICINESection 8 of 12
FindingsScintigraphy is not used in the evaluation of GMH. ANGIOGRAPHYSection 9 of 12
FindingsCerebral angiography is not used in the evaluation of GMH. INTERVENTIONSection 10 of 12
Medical/Legal Pitfalls
Special Concerns
MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Germinal Matrix Hemorrhage excerpt Article Last Updated: Jun 5, 2007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
