BRAIN AWARENESS WEEK – LET’S TALK ABOUT: Intraventricular Hemorrhage (IVH)
By: Dr Namrata Todurkar, Neonatologist
The complex functions of all the muscles in the body and the unique thinking, understanding and reasoning capacity that every human being has, is due to the extremely co-ordinated actions of the nerve cells within one’s brain. In addition to this, vision, hearing, touch, taste, smell, response to stimuli, and maintenance of balance when walking or performing activities involve an almost perfectly orchestrated transfer of electrical impulse within the nervous system. Although a person’s intelligence is determined by various genetic and environmental factors, a damaged brain has a huge impact in one’s development.
The occasion of BRAIN AWARENESS WEEK seems ideal to explain ‘Intraventricular Hemorrhage’, which is a very common complication of premature birth, and can lead to consequences ranging from mild to severe.
Ventricles are the spaces within the brain which contain the cerebrospinal fluid (CSF). It is a water-like substance circulating around the brain (there are ventricles in the heart too, but in this blog post, we are referring to the ventricles in the brain). Bleeding into these fluid-filled spaces is known as an ‘Intraventricular Hemorrhage’ (IVH). IVH is most common in premature babies, especially very low birthweight babies weighing less than 1,500 grams (3 pounds, 5 ounces). It affects 13-65% of all preterm infants. The smaller and more premature the baby, the more likely IVH will occur.
It is not clear why IVH occurs. Bleeding can occur because blood vessels in a premature baby's brain are very fragile and immature, and therefore, easily rupture. Babies with respiratory problems, or other complications of prematurity, are more likely to have IVH. Nearly all IVH occurs within the first four days of life.
A cranial (head) ultrasound is usually used to diagnose IVH. This test uses sound waves to create a picture of internal structures. A cranial ultrasound can view the inside of the baby's brain through the fontanelles (the spaces between the bones of the baby's head). With the ultrasound, the amount of bleeding can be graded. Brain MRI will yield detailed images of the structure of the brain and the extent of injury, but is less commonly used in the first few weeks of life to diagnose IVH (because it requires sedation and the baby needs to be moved to an MRI machine). MRI is commonly used before discharge of a preterm baby affected with significant IVH.
IVH is often described in four grades:
Grade 1. Bleeding occurs just in a small area of the ventricles.
Grade 2. Bleeding fills the inside of the ventricles, but the ventricles are not enlarged.
Grade 3. Ventricles are enlarged by the blood.
Grade 4. Large bleeding into the ventricles resulting in decrease in blood supply to the brain tissue in the immediate vicinity of the ventricle (periventricular area), and it gives an ultrasound appearance of ‘extension of the bleeding’ into periventricular area. This is called as Periventricular haemorrhagic infarction.
The most common symptoms of IVH are listed bwlow. However, each baby may experience symptoms differently.
Stop breathing (apnea) and low heart rate
Pale or blue color
Swelling or bulging of the fontanelles, the "soft spots" between the bones of the baby's head
The symptoms of IVH may resemble other conditions or medical problems. The neonatologist may then screen for a variety of issues if a baby shows the above symptoms.
Mechanisms of IVH: The blood vessels in the brain form a blood–brain barrier, whose role is to extract vital molecules for the brain and prevent toxic substances from altering the brain functions. In the case of preterm birth, this barrier is imperfect and it therefore increases its permeability, causing the crossing of toxic substances into the brain and a higher propensity for bleeding.
The ability of a baby to maintain normal blood supply to the brain despite fluctuations in blood pressure is called ‘cerebral autoregulation’. In preterm infants, cerebral autoregulation has been found to be altered compared to neonates born at term. Furthermore, premature neonates are less capable of adaptation to extra uterine life compared to their term counterparts. Patent ductus arteriosus is a frequent condition in preterm births. In this case, the existence of a blood shunt between two large vessels emerging from the heart results in fluctuation in blood supply to the brain. Respiratory distress at birth, which is universal in all extremely preterm infants, can cause variations in blood flow and result in IVH. Hence, all these factors are responsible for intense hemodynamic fluctuations in the first days of life and lead to altered autoregulation in brain.
Nevertheless, prematurity comes with risk of infection and low platelet count, which is an independent factor of the presence and extent of bleeding. Family history of haemophilia or any type of clotting abnormality predisposes a baby to IVH. Rarely, genetic mutations may be cause for easy bleeding tendency resulting in IVH. In a few cases, IVH can occur in foetuses during pregnancy or in children born at term.
Periventricular Leukomalacia: The brain’s white matter which lies in the immediate vicinity of the ventricle is implicated in neurogenesis (multiplication of cells which give rise to brain tissue). Any injury to this crucial area results in long term consequences. On the Ultrasound and MRI, the damaged area looks liquefied and empty (cyst like), and is sometimes referred to as Cystic periventricular Leukomalacia. This condition results in long lasting problems in a child’s motor activity. Not only does a large IVH affect the process of neurogenesis, it also results in death of functional brain cells, hence the wide range of severity noted in the outcome of IVH. The overall size of brain tissue can decrease and this condition is called as cerebral atrophy.
Post-hemorrhagic hydrocephalus: Bleeding into the ventricles results in blockage of the usual CSF absorptive areas within the ventricles. It also behaves like a barrier to the flow of CSF. As a result, CSF accumulates within the ventricles and exerts distending pressure on its walls. This condition is called as Hydrocephalus. Overtime, the fluid accumulation can result in increased pressure inside the skull and threaten the integrity of the brain stem which contains vital areas controlling breathing and circulation. Therefore, serial ultrasounds are performed to detect the development of hydrocephalus and neurosurgical team is consulted to help manage the brain’s pressure by draining the excess fluid.
Prevention: The most important factors for preventing an IVH are: Prevention of prematurity, maternal transport of women in preterm labour to regional centre prior to delivery, antenatal steroids and magnesium sulphate for the mom, optimal obstetrical management, skilled resuscitation of new-born, optimal management in the NICU.
Recent research shows that, in extremely preterm neonates, simple steps like positioning the head in the middle position, elevating the head of the bed (to facilitate venous outflow from brain), avoidance of elevation of legs during diaper change, gentle administration of fluids and medicines into the baby, decreased the risk of IVH.
Management: There is no specific treatment for IVH, except to treat any other health problems that may worsen the condition. Although care of sick and premature babies has advanced greatly, it is not possible to prevent IVH from occurring.
For progressive ventricular dilatation (post-haemorrhagic hydrocephalus), the essential point is early recognition. Head circumference does not increase until after there has been considerable ventricular dilatation. Therefore, serial head U/S examinations in infants with IVH ≥grade II. Some cases of ventricular dilatation will respond to non-surgical management. Persistent, progressive ventricular dilatation requires a ventricular reservoir or ventricular peritoneal shunt by a neurosurgeon. One-third of neonates with IVH develop post-haemorrhagic hydrocephalus and 10 to 20% require shunt insertion.
Outcome: Bleeding in the brain can put pressure on the nerve cells and damage them. Severe damage to cells can lead to brain injury. Grades 1 and 2 are most common, and often there are no further complications. Grades 3 and 4 are the most serious and may result in long-term brain injury to the baby. Hydrocephalus (too much cerebral spinal fluid in the brain) may develop after severe IVH. It is commonly accepted that the onset of post hemorrhagic hydrocephalus and the need for a shunt insertion is an independent risk factor of impaired development in a child. Moreover, the shunt exposes this group of children to increased morbidity and mortality due to the risk of a shunt dysfunction and recurrent surgery exposition.
Nevertheless, in cases of severe IVH, 40% of the preterm infants die from a neurological cause. The association of prematurity, IVH and post haemorrhagic hydrocephalus is a strong determinant of impaired developmental outcomes.
The bottom line:
The incidence of IVH in preterm children remains high despite there being research on this topic and the availability of preventive measures. The cause of IVH is mainly due to impairment of autoregulation of brain’s blood flow, coagulation disorders, and genetic factors. The area surrounding the ventricles is a source of neurogenesis, and the onset of bleeding is responsible for impaired development. Presently, despite improvements in the molecular understanding of IVH, there is no single blood investigation to predict it. The therapeutic strategies derived from research are disappointing.
Best practices in neonatal care and evidence based medicine is our best bet!
Namrata Todurkar, MBBS, MD (Pediatrics), DNB (Pediatrics). Fellowship in Neonatology from National Neonatology Forum India. Fellow in Neonatal-Perinatal Medicine in University of British Columbia. Areas of interest: Neonatal nutrition, Fluid and Electrolyte Management, Inborn Errors, Neurodevelopmental followup of preterm infants. Dr. Todurkar is a volunteer blogger at CPBF.