Medical Malpractice
Our attorneys handle HIE birth injury lawsuits in all 50 states. Our birth injury attorneys focus on maximizing settlement amounts and jury payouts of these claim to provide families and children a lifetime of compensation for the harm done by hypoxic-ischemic encephalopathy injury during childbirth.
This page is about HIE during labor and delivery as the result of medical negligence. Our attorneys explain how these HIE malpractice lawsuits work, which of these ischemia cases are most viable, and the typical settlement amounts and jury compensation awards our birth injury attorneys see in these cases.
Childbirth presents risk of injury from oxygen deprivation. Some of these complications are from medical malpractice. One of the most serious is hypoxic-ischemic encephalopathy (HIE) or perinatal encephalopathy. This brain injury is caused by a lack of oxygen during birth.
HIE Is Under the Perinatal Encephalopathy Umbrella
This term perinatal encephalopathy means “brain damage of unknown etiology from the birth trauma.” It is an unbelievably broad term that includes every premature baby and infant who have low Apgar scores. It also includes a lot of children that have no significant injury that will impact their lives.
This broad term includes a ruptured uterus, obstructed or twisted umbilical cord, trauma or separation of the placenta, and a whole host of other things that we know and don’t know about. One of the big concerns is hypoxic-ischemic encephalopathy because of how important oxygen is to a newborn.
HIE – Hypoxic-Ischemic Encephalopathy
Hypoxic-ischemic encephalopathy is more specific and is cause for greater concern. The term hypoxia refers to a lack of oxygen to organs or tissues. Ischemia is a restriction of blood and the oxygen it carries that creates tissue or organ damage. Encephalopathy is a term for brain injury. Hypoxic-ischemic encephalopathy is a consequence of a deficit of oxygen supply to the brain. Potential complications from HIE run the gambit of awful: brain damage, death, and cell damage and death in an infant’s central nervous system.
HIE is a broad-based term that refers to the loss of oxygen from anything, including drowning, carbon monoxide poisoning, etc. But the focus here is the loss of oxygen when kids need it the most: before and after birth. A fetus can be permanently brain damaged or killed as a result of oxygen deprivation and lack of blood flow to the fetal brain during the antepartum, intrapartum, and postpartum periods.
Obstetricians, nurses, nurse practitioners, and nurse midwives need to be aware that conditions such as eclampsia, a prolapsed or compressed umbilical cord, ruptured uterus, or placental abruption can cause oxygen loss that can cause permanent brain injury or kill a child. Abdominal trauma, high uterine pressures, hyperstimulation of the uterus, high blood pressure, or seizures in the mother may also lead to a lack of blood and oxygen reaching the baby’s brain.
Cause and Effect with HIE
Perinatal hypoxic-ischemic encephalopathy (HIE) occurs in .3% of .full-term births.
Approximately15%–20% of these infants die. One in four develops neurological injuries that include mental development delays, learning disabilities, seizures, epilepsy, physical movement development delays, cerebral palsy, and speech problems or delays. The remaining 55%-60% of children with perinatal hypoxic-ischemic encephalopathy do quite well.
So there is no question that HIE is extremely variable from child to child. Brain insults that seem on the surface to be seemingly similar in two different children may completely spare one child and cause a lifelong injury to the other. Why is this? No one knows. Some theorize that modern medicine cannot accurately quantify the scope of the magnitude of the impairment in utero. So “seemingly similar” may not be because we just do not have the tools to measure the real extent of the brain insult with HIE.
- Answers to frequently asked HIE questions
- NEC lawsuits: NEC is more common when the child has HIE
What Causes HIE?
What causes HIE in the first place? There are a few primary causes of HIE including separation from the placenta, placental trauma, fetal stroke, eclampsia, complications with the umbilical cord, abdominal trauma, and uterine complications. It is also believed that excessive maternal sedation by anesthesia can cause or contribute to HIE.
When one of these complicating conditions occurs, oxygen is diverted from the child’s brain to the heart and lungs to keep the child alive. Once this begins, brain cells start to die; the longer the brain is without oxygen, the more cells die. As this process continues, the risk of severe and lifelong harm increases literally by the second. The timeline for HIE is short: a child can go from healthy to irreparably damaged in five minutes or less.
How Doctors and Nurses Must Manage HIE Risk
The most effective way to monitor and manage the HIE risk factors is the use of a fetal monitor. This device tells a physician about the child’s heart rate and other vital signs that show how the child is doing during contractions and labor.
The reported incidence of birth asphyxia, hypoxic-ischemic encephalopathy, or post-asphyxial encephalopathy in term or near-term infants ranges from 1 to 8 per 1000. Arguably, the real answer is probably lower, an estimated 1.6 per 10,000.
Diagnosis of HIE can be confirmed by a CT scan, MRI, EEG, EKG, or ultrasound. In the past, there has been a limited number of treatments for infants with HIE. Treatments included ventilation, NICU care, minimizing cerebral swelling, and preventing seizures.
Today, body and head cooling have been shown to decrease neurological problems caused by oxygen deprivation. This cooling process involves subjecting the infant to 72 hours of 33.5-degree temperatures. A study published in The New England Journal of Medicine found that this therapy reduced the risk of infant death and decreased the probability of long-term disability. A new study published in November 2021 indicates that cooling combined with melatonin might help ward off brain injuries from childbirth. Stem therapy may also help.
Children with HIE can require long-term care including rehabilitation, surgery, and possibly life-long aide or accommodation. Families who have child
ren with HIE might be entitled to compensation if the HIE injury resulted from a physician or hospital breach in the standard of care.
Malpractice Lawsuit Question: Was the HIE During Childbirth?
Sometimes, there is a real debate about whether a child suffered an HIE injury during childbirth. To figure this out in cases where the doctors question our belief that the child suffered this injury, our medical experts look at the baby and ask questions. Was there asphyxiation during childbirth? Did the child need resuscitation?
What were the cord and fetal blood gases and the arterial and venous pH levels? Was there a seizure? Did a brain MRI show injury in the thalamic and basal ganglia areas of the brain? Was there hypotension or metabolic acidosis? Is there an abnormality in the child’s tone, reflexes, and level of activity? These are potential markers for encephalopathy.
HIE Settlements Amounts and Jury Compensation Payouts
Below are some HIE settlements and verdicts in recent years. Keep in mind these are not meant to be representative of the average HIE case. They can be a tool for figuring out the settlement amount and jury compensation awards in HIE lawsuits. But they are just one tool.
Prior verdicts without other tools do a poor job of predicting the settlement value or jury compensation awards of future cases. That said, jury payouts and settlement amounts in successful HIE cases tend to be quite large, and these examples do reflect that.
- $35,182,818 Verdict (New York 2023): The mother, 9-months pregnant, fell on her abdomen and went to the hospital. The hospital staff told her everything was fine and discharged her with very little diagnostic work. They failed to timely diagnose the fact that the fall had triggered a placental abruption. The baby suffered HIE and was born with severe brain injuries leaving him with no independent functional movement and no vision.
- $500,000 Settlement (Kentucky 2022): The obstetrician and nursing staff at the defendant (a federally funded hospital) attempted to use a vacuum extractor to assist with the vaginal delivery. The vacuum was used in a negligent manner resulting in external damage to the baby’s head from excessive force. This caused a subgaleal hemorrhage that eventually resulted in hypoxic-ischemic encephalopathy. The birth injury malpractice case was settled for $500k.
- $1,525,000 Settlement (Nevada 2021): The baby reportedly sustained hypoxic-ischemic encephalopathy during childbirth resulting in cerebral palsy, seizures, major intellectual disabilities and impaired vision (a condition which required eye surgery). The lawsuit alleged that the defendants negligently failed to recognize the signs of fetal distress which should have prompted them to order an emergency C-section instead of continuing with a vaginal delivery.
- $6,000,000 Settlement (Michigan 2020): A baby was born at a federally funded hospital. She suffered hypoxic-ischemic encephalopathy and respiratory distress. The girl developed cerebral palsy. She suffered from seizures and permanent cognitive impairments. The girl’s parents alleged negligence against the federal government. They claimed the hospital staff failed to address fetal distress, prevent fetal injuries, and timely perform a C-section. This case settled for $6,000,000.
- $6,000,000 Settlement (New York 2019): Defendant hospital was allegedly negligent in failing to properly identify clear signs of acute fetal distress and perform an emergency C-section in response. As a result, the infant suffered significant oxygen deprivation causing hypoxic-ischemic encephalopathy. This brain injury left the child with the most severe type of cerebral palsy (spastic quadriplegia) and dependent on a feeding tube. The case eventually settled for $6 million.
- $4,200,000 Settlement (Maryland 2018): An obstetrician and a nurse are sued for failing to act on a fetal heart rate that plaintiffs believed indicated fetal distress and the need for urgent delivery. Tragically, the baby has cortical blindness, seizures, and significant developmental delays. This birth injury claim settled out-of-court for a settlement amount of $4.2 million.
- $33,153,912 Verdict (Florida 2017): A child has HIE secondary to a brain bleed during the birthing process. The blood that should have been supplying oxygen to the brain was instead stuck between the skull and the scalp. As a result, the child suffers tragically permanent brain injuries. At age 18 months, the child was being fed through a PEG-tube, could not stand, crawl or support himself; and had a tracheotomy that required suctioning every three to five minutes. The family hired a birth injury lawyers and filed a HIE lawsuit. The birth injury lawsuit alleged that a C-section would have avoided the birth trauma the child endured. The claim also alleges that excessive Pitocin to speed up the delivery was given. Plaintiff’s claimed that all of this was evident if they have properly interpreted the message the baby was sending via the fetal heart monitor. The jury obviously accepted this version of the facts, coming back from deliberations with a whopping $29,413,495.91 compensation award for the child and the balance to the parents.
- $2,500,000 Settlement (Florida 2017): A newborn suffers hypoxic-ischemic encephalopathy, seizures and respiratory failure, hearing loss and developmental delays. Plaintiff’s HIE lawsuit alleges that the doctors and nurses failed to timely and appropriately diagnose and treat the child and mother and should not have induced labor at 35 weeks.
- $4,750,000 Settlement (Florida 2016): A newborn baby born at Elmhurst Hospital Center in Queens is in immediate distress. He requires immediate resuscitation. He now has cerebral palsy. His lawyers argued that his cerebral palsy was the result of hypoxia that could have been avoided if the doctors and nurse had listened to what the child was telling them via his heart rate monitor. They hired an cerebral palsy attorney who successfully argued claim that an immediate C-section was the only reasonable choice.
- $4,250,000 Settlement (Massachusetts 2013): After presenting with contractions, a woman was admitted to a Worcester County hospital where the attending physician elected to induce labor. After about 24 hours the woman was only 4 cm dilated. Less than 12 hours later the physician determined the woman was fully dilated and should begin pushing. The physician’s decision was quickly overruled after the managing OB/GYN determined the woman was not sufficiently dilated and should stop pushing. However, the woman demanded a cesarean section be performed as she noted the infant’s head was pushing into her spine. Instead of adhering to the mother’s request, the OB/GYN spent 20 minutes trying to convince the woman to save her energy for two more hours of labor. During this predicament, the fetal heart rate monitor was disconnected for 50 minutes as the fetal heart rate variability lessened. A cesarean was not performed until four hours later. Within hours after birth, the infant began to experience seizures. She was ultimately diagnosed with hypoxic-ischemic encephalopathy. The mother sued the hospital and its physicians for negligence. Plaintiff contended that after deman
ding a cesarean section, the defendants were required to adhere as it was apparent the fetus was distressed. The defendants denied allegations, claiming their actions fell within the standard of care. Defendants also claimed the infant’s brain injury was inflicted before the time, Plaintiff came under their care. The parties agreed to settle for $4,250,000. - $3,141,825 Verdict (Maine 2012): A soon-to-be mother was admitted to a hospital for labor and delivery. Upon her arrival, she began experiencing contractions in more than normal frequency and the fetal monitor was demonstrating fetal distress and lack of oxygen. The nurse midwife spent 45 minutes attempting to deliver the infant before consulting the on-call OB/GYN. It was determined that an emergency cesarean section was necessary. Unfortunately, due to the lack of oxygen, the infant was diagnosed with hypoxic-ischemic encephalopathy, resulting in cerebral palsy and cortical blindness. The mother and father sued the hospital, and the nurse midwife and her practice for failing to consult the OB/GYN when it became apparent the fetus was in distress. Defendant Midwife denied allegations, claiming the infant suffered a condition called Kabuki Syndrome that results in mental retardation. Defendant Hospital denied liability, claiming Defendant Midwife and her practice rented the space from the hospital and are not monitored as if they were employees. The jury found midwife 100% liable for the infant’s injuries and rendered a $3,141,825 verdict.
- $144,000,000 Verdict (Michigan 2011): An infant was delivered at William Beaumont Hospital in Royal Oak after her mother was induced for labor. Upon delivery, it was discovered the infant had a fractured left clavicle, was suffering from respiratory distress on top of seizures, and swelling of the scalp. She is now a paraplegic and requires permanent 24-hour care. The mother sued the hospital for malpractice, claiming the defendants failed to determine the size of the fetus before delivery as the fetus was larger than expected because of gestational diabetes. Plaintiffs alleged Defendant failed to recommend a cesarean section, resulting in the infant being crushed in the birth canal. Defendants denied liability. An Oakland County jury ruled in favor of the Plaintiff and awarded an astounding $144,000,000 verdict.
- $5,500,000 Settlement (Maryland 2011): An infant, who after delivery weighed just under three pounds and was showing normal APGAR and chord PH scores, had to have umbilical artery and venous catheters inserted. A chest X-ray was taken to confirm placement. But a follow-up X-ray revealed the catheter had advanced into the heart. A third X-ray was performed three hours later showing the catheter had advanced further. An additional X-ray was performed the following morning and confirmed the inappropriate position of the catheter. Soon the infant became hypotensive, but it was not until 20 minutes later that a doctor was called to assess the hypotension. By the time the catheter was removed, the infant had suffered hypotension, bradycardia, and a decrease in cerebral profusion, resulting in hypoxic-ischemic encephalopathy. The mother sued the hospital on the infant’s behalf for failing to reposition the catheter after multiple X-rays revealed the improper location. Defendant denied liability, claiming all actions were within the standard of care. The matter proceeded to trial where a Baltimore City jury ruled a $5,500,000 verdict for the Plaintiff.
- $800,000 Settlement (Virginia 2010): A woman was admitted to Reston Hospital for induction of labor. However, there were difficulties in delivery and the physicians elected to use a vacuum extractor. About six hours after delivery the infant began to develop seizures. He was soon after diagnosed with hypoxic-ischemic encephalopathy, resulting in right arm paresis and cognitive deficits. His parents sued the hospital and its physicians for malpractice, claiming they failed to timely perform a cesarean section after excessive use of a vacuum extractor. Plaintiff claimed that due to the failure to perform a cesarean section, the infant suffered insufficient oxygen and blood flow. Defendants disputed liability, claiming the child’s injuries were caused by a perinatal stroke before birth. The parties agreed to settle for $800,000.
Understanding HIE
There is a great deal of confusion about HIE, particularly in the malpractice litigation context. These are some of the most common questions our birth injury lawyers get about this brain injury:
What is HIE?
HIE is an acronym for hypoxic ischemic encephalopathy. The term encephalopathy refers generally to any condition or disease that involves impairment of the brain. Hypoxic-ischemic encephalopathy is an acquired syndrome characterized by clinical and imaging studies that show a brain injury from lack of oxygen.
Hypoxic ischemic encephalopathy or HIE is a particular type of damage to the brain that results when the brain is temporarily deprived of oxygenated blood. HIE often occurs during childbirth because babies are particularly vulnerable to this type of injury during labor.
HIE is one of the most severe types of birth injuries. It can cause permanent, debilitating brain injuries and even death. The incidence rate of HIE in the U.S. is between 2-20 cases per 1000.
How Do I Know If HIE Was Caused by Malpractice?
It is hard to know without reviewing the medical records if your child’s HIE was caused by malpractice. But a large percentage of HIE cases are caused by malpractice. The best advice is if your child has HIE call a lawyer to discuss your child’s injuries and a potential claim.
This way, you understand your legal options and have the peace of mind of getting to the real truth of what happened and whether a mistake during the birthing process caused your child’s brain injury.
How Does HIE Cause Injury?
The neurological insult from HIE comes from tissue perfusion. This means that the oxygen and nutrients is not being adequately transmitted by blood to the child’s tissues. This can lead to injury to all of the vital organs. At greatest risk is the brain.
The extend of the injury to the brain depends on the nature, severity, and time duration of the loss of oxygen. The injury comes in two phases. Following the initial asphyxia injury, the cerebral metabolism recovers only to fall again in the second phase of injury that occurs between 8 and 24 hours after the initial insult.
This new phase of neuronal destruction is a delayed injury that may persist for weeks. One newer development in recent years is cooling as treatment to slow the cellular damage caused by this second phase of brain insult caused by HIE.
How Much Is an HIE Birth Injury Case Typically Worth for Settlement?
The value of an HIE birth injury cases is going to depend on two things: (1) the extent of the child’s injuries and, (2) the strength of the case against the health care providers.
These is no typical HIE birth injury settlement value. But there is no question as you see on the verdicts and settlements on this page that these are very large malpractice cases. The claims are for lifelong injuries and care for a child which is how the value of these cases can quickly get to the tens of millions of dollars.
What Causes HIE?
The human brain needs a continuous supply of blood in order to maintain itself. The heat pumps blood which is continuously circulated to the brain. The main function of this blood circulation is to deliver oxygen to the brain which is needs at all times. HIE occurs when the brain is deprived of oxygenated blood for an extended time causing cells in the brain to rapidly decay and die.
Babies in the womb are particularly vulnerable to HIE because there are a number of complication or adverse events that can occur during pregnancy or childbirth that can interrupt the supply of oxygenated blood to the baby’s brain. Events during pregnancy and childbirth that can potentially cause HIE include but are not limited to
- Placental abruption: placental abruption is a dangerous complication during pregnancy in which the placenta (the organ responsible to delivering oxygen and nutrients from mother to baby) becomes fully or partially detached from the wall of the uterus and disrupting the supply of oxygen to the baby.
- Uterine rupture: a uterine rupture is an event that typically occurs during labor where the uterine wall ruptures and tears (often along a scar line from a prior C-section site).
- Pitocin misuse: Pitocin is a synthetic form of the hormone oxytocin which stimulate the muscles of the uterus to start contractions during labor. Pitocin is used by doctors to induce or speed up labor but it sometimes triggers over stimulation causing contraction that are too strong and/or too frequent which can disrupt the supply of oxygen to the baby during delivery.
- Umbilical Cord Prolapse: this complication occurs when the umbilical cord (which connects the baby to the placenta for delivery of oxygen and nutrients) abnormally drops down into the birth canal in front of the baby and gets compressed during delivery. This type of umbilical compression can restrict and even cut off blood and oxygen circulation to the baby.
- Maternal Infection: untreated maternal infections during pregnancy can disrupt the ability of the placenta to delivery oxygen and nutrients to the baby.
- Delayed C-Section: when obstetric emergencies occur during childbirth the appropriate response is often an emergency C-section which is often the only way to avoid harm to the baby. However, doctors frequently fail to recognize the signs of fetal distress or are not prepared to perform an emergency C-section. Failure to intervene and preform a timely C-section is a leading cause of preventable HIE injuries.
Defense lawyers who represent the hospitals, doctors, and nurses in these cases desperately argue that HIE is caused long before childbirth. But there reality is that while hypoxic-ischemic injury certainly can occur during the prenatal period, the incidence rate of antepartum HIE is very low.
What are the Possible Consequences of HIE?
Although some cases of HIE can have comparatively mild results, HIE is a usually a very damaging and life threatening injury. HIE is not a very common event, occurring in just 3 out of every 1,000 births in the U.S.
Even with this very low occurrence rate, HIE still ranks as one of the top causes of infant death during childbirth. Almost a quarter of all babies who suffer HIE during childbirth die within the first week of life. Another 30% of babies born with HIE are eventually diagnosed with major neurologic disabilities such as cerebral palsy.
Does HIE Cause Cerebral Palsy?
Yes. Cerebral palsy includes a group of movement disorders caused by neurologic injury during pregnancy or child birth. The neurologic injury that results in CP is most often triggered by asphyxiation or oxygen deprivation during childbirth.
Hypoxic ischemic encephalopathy or HIE is the most common types of neurologic oxygen deprivation during labor and delivery. Like all type of oxygen deprivation brain injuries, HIE can potentially result in a diagnosis of cerebral palsy. In fact, approximately 10-15% of cerebral palsy cases are caused by HIE.
What Does an MRI Show?
An MRI of the head shows the severity and duration of HIE. It helps doctors better diagnose the status of myelination, white-grey tissue injury, and to identify developmental defects of the brain. HIE will not always appear on an MRI.
Some doctors question whether an MRI is sensitive enough to pick up all of the delicate brain injuries likely to result in behavioral problems and learning difficulties. But no one doubts that the correlation between neonatal HIE and subsequent neurologic injury is made much more definitively if the child has an abnormal MRI.
Ultrasounds and computed tomography (CT-scans) are sometimes useful in diagnosing brain injuries but the gold standard for uncovering the damage done by HIE is an MRI.
What are Treatment Options for HIE?
Sadly there really are no effective options for “treating” HIE. Hypoxic ischemic encephalopathy cannot be cured. Once cells in the brain are damaged and die they cannot be medically regenerated or repaired.
All brain damage, including HIE, is more or less permanent. Treatment options for HIE are mostly limited to therapy and other techniques that are designed to help manage the condition and improve the child’s functionality. Most babies with moderate to severe HIE injuries will require a life time of medical assistance and therapy.
What Are the Symptoms of HIE?
From a parent’s perspective, initial symptoms of HIE can vary significantly from case to case depending on the extent of neurologic damage involved. Symptoms of a moderate level HIE injury can include
- significant hypotonia or lack of muscle tone (baby feels like a “rag doll”)
- unable to suck or grasp
- apnea
- seizures.
Symptoms of more severe cases of HIE will include
- major seizures that increase in frequency
- coma or total lack of response to external stimulus
- abnormal respiration
- hypotonia (rag doll feel)
- abnormal eye movements, and highly abnormal heart rate.
A formal diagnosis of HIE will begin with clinical exams with confirmation made by lab and imaging testing.
In malpractice litigation, there are a variety of markers that our medical experts – obstetricians, neonatologists, pediatric neurologists, maternal-fetal medicine physicians, etc. – look for when trying to determine whether there is a causal relationship between hypoxia during childbirth and a newborn’s brain damage.
These factors include Apgar scores, the infant’s umbilical artery blood gas values (especially PH and base excess values), and evidence concerning the early onset of neonatal encephalopathy. This look back also requires the exclusion of other possible causes for the child’s neurological injuries.
If there is some genetic disorder, infection, stroke, infection, genetic disorder, stroke, aneurysm, etc., these could all be other reasons for a child’s brain injury. So it is important to rule them out.
The fetal heart tracings are also going to be critical in determining whether the fetus was at risk for hypoxic-ischemic brain damage. Our experts at trial need to be able to correlate non-reassuring fetal heart rate with the condition of the child during the birthing process to properly perform a medical causation analysis and reach conclusions as the time within which the HIE injury likely occurred.
This is also important in determining whether a doctor was negligent. If the fetal heart monitor tracings show the fetus is at risk for hypoxia and ischemia, the path is clear. a reasonable obstetrician knows that if the fetus is not delivered quickly, the child is at risk for lifelong injuries from brain damage as a result of oxygen deprivation.
How a Malpractice Lawyer Help Your HIE Lawsuit
These awful birth injuries are not always the result of a doctor or nurse’s mistake. Awful tragedies sometimes happen and no one is to blame Bad things happen to good people. But, sometimes, far too often, a doctor’s error caused the child lifelong injuries.
What happens? Sometimes, the doctors, nurses, and midwives who are responsible for a safe delivery of these infants into the world do not adequately monitor the condition of the fetus. Sometimes they wait too long to perform a C-section.
When these things happen, the child can suffer lifelong injuries or death. Harm to any child is awful. But, in some ways, this harm is worse. Because it so easily could have been avoided. Parents and families can stay mad forever. And it is impossible to blame them.
Ultimately, what we may be able to do for you is get you and your child compensation for a horrific loss. That is all we can do. But the settlements and verdicts in these cases can be extremely high. Does that make it all better? Of course not. But money can help make a difference for your child.
How a Malpractice Lawyer Help Your HIE Lawsuit
If you want to investigate your potential child injury claim or if you are a lawyer looking for help evaluating your client’s claim, call our birth injury malpractice lawyers at 800-553-8082 or get a free online consultation.
More Information
- HIE Frequently Asked Questions
- Medical Malpractice Overview (information on malpractice cases generally)
- An Overview of Birth Injury Lawsuits
- Malpractice During Pregnancy That Causes Birth Injuries
- Herpes Encephalitis Lawsuits (an overview)