Spina bifida

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Spina_bifida
 

Spina bifida
Illustration of a child with spina bifida
Specialty	Pediatrics, neurosurgery, rehabilitation medicine
Symptoms	Hairy patch, dimple, dark spot, swelling on the lower back
Complications	Poor ability to walk, problems with bladder or bowel control, hydrocephalus, tethered spinal cord, latex allergy
Causes	Genetic and environmental factors
Risk factors	Lack of folate during pregnancy, certain antiseizure medications, obesity, poorly controlled diabetes
Diagnostic method	Amniocentesis, medical imaging
Prevention	Folate supplementation
Treatment	Surgery
Frequency	15% (occulta), 0.1–5 per 1000 births (others)

Spina bifida is a birth defect in which there is incomplete closing of the spine and membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, meningocele and myelomeningocele. The most common location is the lower back, but in rare cases it may be the middle back or neck. Occulta has no or only mild signs, which may include a hairy patch, dimple, dark spot or swelling on the back at the site of the gap in the spine. Meningocele typically causes mild problems with a sac of fluid present at the gap in the spine. Myelomeningocele, also known as open spina bifida, is the most severe form. Associated problems include poor ability to walk, problems with bladder or bowel control, accumulation of fluid in the brain (hydrocephalus), a tethered spinal cord and latex allergy. Learning problems are relatively uncommon.

Spina bifida is believed to be due to a combination of genetic and environmental factors. After having one child with the condition, or if one of the parents has the condition, there is a 4% chance that the next child will also be affected. Not having enough folate in the diet before and during pregnancy also plays a significant role. Other risk factors include certain antiseizure medications, obesity and poorly controlled diabetes. Diagnosis may occur either before or after a child is born. Before birth, if a blood test or amniocentesis finds a high level of alpha-fetoprotein (AFP), there is a higher risk of spina bifida. Ultrasound examination may also detect the problem. Medical imaging can confirm the diagnosis after birth. Spina bifida is a type of neural tube defect related to but distinct from other types such as anencephaly and encephalocele.

Most cases of spina bifida can be prevented if the mother gets enough folate before and during pregnancy. Adding folic acid to flour has been found to be effective for most women. Open spina bifida can be surgically closed before or after birth. A shunt may be needed in those with hydrocephalus, and a tethered spinal cord may be surgically repaired. Devices to help with movement such as crutches or wheelchairs may be useful. Urinary catheterization may also be needed.

About 15% of people have spina bifida occulta. Rates of other types of spina bifida vary significantly by country, from 0.1 to 5 per 1,000 births. On average, in developed countries, including the United States, it occurs in about 0.4 per 1,000 births. In India, it affects about 1.9 per 1,000 births. Caucasians are at higher risk compared to Black people. The term is Latin for "split spine".

Types

Different types of spina bifida

There are two types: spina bifida occulta and spina bifida cystica. Spina bifida cystica can then be broken down into meningocele and myelomeningocele.

Spina bifida occulta

Occulta is Latin for "hidden". This is the mildest form of spina bifida. In occulta, the outer part of some of the vertebrae is not completely closed. The splits in the vertebrae are so small that the spinal cord does not protrude. The skin at the site of the lesion may be normal, or it may have some hair growing from it; there may be a dimple in the skin, or a birthmark. Unlike most other types of neural tube defects, spina bifida occulta is not associated with increased AFP, a common screening tool used to detect neural tube defects in utero. This is because, unlike most of the other neural tube defects, the dural lining is maintained.

Many people with this type of spina bifida do not even know they have it, as the condition is asymptomatic in most cases. About 15% of people have spina bifida occulta, and most people are diagnosed incidentally from spinal X-rays. A systematic review of radiographic research studies found no relationship between spina bifida occulta and back pain. More recent studies not included in the review support the negative findings.

However, other studies suggest spina bifida occulta is not always harmless. One study found that among patients with back pain, severity is worse if spina bifida occulta is present. Among females, this could be mistaken for dysmenorrhea. 

Incomplete posterior fusion is not a true spina bifida, and is very rarely of neurological significance.

Meningocele

A posterior meningocele (/mɪˈnɪŋɡəˌsiːl/) or meningeal cyst (/mɪˈnɪndʒiəl/) is the least common form of spina bifida. In this form, a single developmental defect allows the meninges to herniate between the vertebrae. As the nervous system remains undamaged, individuals with meningocele are unlikely to suffer long-term health problems, although cases of tethered cord have been reported. Causes of meningocele include teratoma and other tumors of the sacrococcyx and of the presacral space, and Currarino syndrome.

A meningocele may also form through dehiscences in the base of the skull. These may be classified by their localisation to occipital, frontoethmoidal, or nasal. Endonasal meningoceles lie at the roof of the nasal cavity and may be mistaken for a nasal polyp. They are treated surgically. Encephalomeningoceles are classified in the same way and also contain brain tissue.

Myelomeningocele

A lumbar myelomeningocele

Myelomeningocele (MMC), also known as meningomyelocele, is the type of spina bifida that often results in the most severe complications and affects the meninges and nerves. In individuals with myelomeningocele, the unfused portion of the spinal column allows the spinal cord to protrude through an opening. Myelomeningocele occurs in the third week of embryonic development, during neural tube pore closure. MMC is a failure of this to occur completely. The meningeal membranes that cover the spinal cord also protrude through the opening, forming a sac enclosing the spinal elements, such as meninges, cerebrospinal fluid, and parts of the spinal cord and nerve roots. Myelomeningocele is also associated with Arnold–Chiari malformation, necessitating a VP shunt placement.

Toxins associated with MMC formation include: calcium-channel blockers, carbamazepine, cytochalasins, hyperthermia, and valproic acid.

Myelocele

Spina bifida with myelocele is the most severe form of myelomeningocele. In this type, the involved area is represented by a flattened, plate-like mass of nervous tissue with no overlying membrane. The exposure of these nerves and tissues make the baby more prone to life-threatening infections such as meningitis.

The protruding portion of the spinal cord and the nerves that originate at that level of the cord are damaged or not properly developed. As a result, there is usually some degree of paralysis and loss of sensation below the level of the spinal cord defect. Thus, the more cranial the level of the defect, the more severe the associated nerve dysfunction and resultant paralysis may be. Symptoms may include ambulatory problems, loss of sensation, deformities of the hips, knees or feet, and loss of muscle tone.

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  X-ray image of spina bifida occulta in S-1
  
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  X-ray computed tomography scan of unfused arch at C1
  
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  Myelomeningocele in the lumbar area
  (1) External sac with cerebrospinal fluid
  (2) Spinal cord wedged between the vertebrae
  

Signs and symptoms

Physical problems

Physical signs of spina bifida may include:

• Leg weakness and paralysis
• Orthopedic abnormalities (i.e., club foot, hip dislocation, scoliosis)
• Bladder and bowel control problems, including incontinence, urinary tract infections, and poor kidney function
• Pressure sores and skin irritations
• Abnormal eye movement

68% of children with spina bifida have an allergy to latex, ranging from mild to life-threatening. The common use of latex in medical facilities makes this a particularly serious concern. The most common approach to avoid developing an allergy is to avoid contact with latex-containing products such as examination gloves and condoms and catheters that do not specify they are latex-free, and many other products, such as some commonly used by dentists.

The spinal cord lesion or the scarring due to surgery may result in a tethered spinal cord. In some individuals, this causes significant traction and stress on the spinal cord and can lead to a worsening of associated paralysis, scoliosis, back pain, and worsening bowel and/or bladder function.

Neurological problems

Many individuals with spina bifida have an associated abnormality of the cerebellum, called the Arnold Chiari II malformation. In affected individuals, the back portion of the brain is displaced from the back of the skull down into the upper neck. In about 90% of the people with myelomeningocele, hydrocephalus also occurs because the displaced cerebellum interferes with the normal flow of cerebrospinal fluid, causing an excess of the fluid to accumulate. In fact, the cerebellum also tends to be smaller in individuals with spina bifida, especially for those with higher lesion levels.

The corpus callosum is abnormally developed in 70–90% of individuals with spina bifida myelomeningocele; this affects the communication processes between the left and right brain hemispheres. Further, white matter tracts connecting posterior brain regions with anterior regions appear less organized. White matter tracts between frontal regions have also been found to be impaired.

Cortex abnormalities may also be present. For example, frontal regions of the brain tend to be thicker than expected, while posterior and parietal regions are thinner. Thinner sections of the brain are also associated with increased cortical folding. Neurons within the cortex may also be displaced.

Executive function

Several studies have demonstrated difficulties with executive functions in youth with spina bifida, with greater deficits observed in youth with shunted hydrocephalus. Unlike typically developing children, youths with spina bifida do not tend to improve in their executive functioning as they grow older. Specific areas of difficulty in some individuals include planning, organizing, initiating, and working memory. Problem-solving, abstraction, and visual planning may also be impaired. Further, children with spina bifida may have poor cognitive flexibility. Although executive functions are often attributed to the frontal lobes of the brain, individuals with spina bifida have intact frontal lobes; therefore, other areas of the brain may be implicated.

Individuals with spina bifida, especially those with shunted hydrocephalus, often have attention problems. Children with spina bifida and shunted hydrocephalus have higher rates of ADHD than children without those conditions (31% vs. 17%). Deficits have been observed for selective attention and focused attention, although poor motor speed may contribute to poor scores on tests of attention. Attention deficits may be evident at a very early age, as infants with spina bifida lag behind their peers in orienting to faces.

Academic skills

Individuals with spina bifida may struggle academically, especially in the subjects of mathematics and reading. In one study, 60% of children with spina bifida were diagnosed with a learning disability. In addition to brain abnormalities directly related to various academic skills, achievement is likely affected by impaired attentional control and executive functioning. Children with spina bifida may perform well in elementary school, but begin to struggle as academic demands increase.

Children with spina bifida are more likely than their peers without spina bifida to be dyscalculic. Individuals with spina bifida have demonstrated stable difficulties with arithmetic accuracy and speed, mathematical problem-solving, and general use and understanding of numbers in everyday life. Mathematics difficulties may be directly related to the thinning of the parietal lobes (regions implicated in mathematical functioning) and indirectly associated with deformities of the cerebellum and midbrain that affect other functions involved in mathematical skills. Further, higher numbers of shunt revisions are associated with poorer mathematics abilities. Working memory and inhibitory control deficiencies have been implicated for math difficulties, although visual-spatial difficulties are not likely involved. Early intervention to address mathematics difficulties and associated executive functions is crucial.

Individuals with spina bifida tend to have better reading skills than mathematics skills. Children and adults with spina bifida have stronger abilities in reading accuracy than in reading comprehension. Comprehension may be especially impaired for text that requires an abstract synthesis of information rather than a more literal understanding. Individuals with spina bifida may have difficulty with writing due to deficits in fine motor control and working memory.

Cause

Spina bifida is believed to be caused by a combination of genetic and environmental factors. After having one child with the condition, or if a parent has the condition, there is a 4% chance the next child will also be affected. A folic acid deficiency during pregnancy also plays a significant role. Other risk factors include certain antiseizure medications, obesity, and poorly managed diabetes. Alcohol misuse can trigger macrocytosis which discards folate. After stopping the drinking of alcohol, a time period of months is needed to rejuvenate bone marrow and recover from the macrocytosis.

Those who are white or Hispanic have a higher risk. Girls are more prone to being born with spina bifida.

Pathophysiology

Spina bifida occurs when local regions of the neural tube fail to fuse or there is failure in formation of the vertebral neural arches. Neural arch formation occurs in the first month of embryonic development (often before the mother knows she is pregnant). Some forms are known to occur with primary conditions that cause raised central nervous system pressure, raising the possibility of a dual pathogenesis.

In normal circumstances, the closure of the neural tube occurs around the 23rd (rostral closure) and 27th (caudal closure) day after fertilization. However, if something interferes and the tube fails to close properly, a neural tube defect will occur. Medications such as some anticonvulsants, diabetes, obesity, and having a relative with spina bifida can all affect the probability of neural tube malformation.

Extensive evidence from mouse strains with spina bifida indicates that there is sometimes a genetic basis for the condition. Human spina bifida, like other human diseases, such as cancer, hypertension and atherosclerosis (coronary artery disease), likely results from the interaction of multiple genes and environmental factors.

Research has shown the lack of folic acid (folate) is a contributing factor in the pathogenesis of neural tube defects, including spina bifida. Supplementation of the mother's diet with folate can reduce the incidence of neural tube defects by about 70%, and can also decrease the severity of these defects when they occur. It is unknown how or why folic acid has this effect.

Spina bifida does not follow direct patterns of heredity as do muscular dystrophy or haemophilia. Studies show a woman having had one child with a neural tube defect such as spina bifida has about a 3% risk of having another affected child. This risk can be reduced with folic acid supplementation before pregnancy. For the general population, low-dose folic acid supplements are advised (0.4 mg/day).

Prevention

There is neither a single cause of spina bifida nor any known way to prevent it entirely. However, dietary supplementation with folic acid has been shown to be helpful in reducing the incidence of spina bifida. Sources of folic acid include whole grains, fortified breakfast cereals, dried beans, leaf vegetables and fruits. However it is difficult for women to get the recommended 400 micrograms of folic acid a day from unfortified foods. Globally, fortified wheat flour is credited with preventing 50 thousand neural tube birth defects like spina bifida a year, but 230,000 could be prevented every year through this strategy.

Folate fortification of enriched grain products has been mandatory in the United States since 1998. This prevents an estimated 600 to 700 incidents of spina bifida a year in the U.S. and saves $400 - $600 million in healthcare expenses. The U.S. Food and Drug Administration, Public Health Agency of Canada and UK recommended amount of folic acid for women of childbearing age and women planning to become pregnant is at least 0.4 mg/day of folic acid from at least three months before conception, and continued for the first 12 weeks of pregnancy. Women who have already had a baby with spina bifida or other type of neural tube defect, or are taking anticonvulsant medication, should take a higher dose of 4–5 mg/day.

Certain mutations in the gene VANGL1 have been linked with spina bifida in some families with a history of the condition.

Screening

Open spina bifida can usually be detected during pregnancy by fetal ultrasound. Increased levels of maternal serum alpha-fetoprotein (MSAFP) should be followed up by two tests – an ultrasound of the fetal spine and amniocentesis of the mother's amniotic fluid (to test for alpha-fetoprotein and acetylcholinesterase). AFP tests are now mandated by some state laws (including California). and failure to provide them can have legal ramifications. In one case, a man born with spina bifida was awarded a $2-million settlement after court found his mother's OBGYN negligent for not performing these tests. Spina bifida may be associated with other malformations as in dysmorphic syndromes, often resulting in spontaneous miscarriage. In the majority of cases, though, spina bifida is an isolated malformation.

Genetic counseling and further genetic testing, such as amniocentesis, may be offered during the pregnancy, as some neural tube defects are associated with genetic disorders such as trisomy 18. Ultrasound screening for spina bifida is partly responsible for the decline in new cases, because many pregnancies are terminated out of fear that a newborn might have a poor future quality of life. With modern medical care, the quality of life of patients has greatly improved.

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  Three-dimensional ultrasound image of the fetal spine at 21 weeks of pregnancy
  
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  Ultrasound view of the fetal spine at 21 weeks of pregnancy. In the longitudinal scan a lumbar myelomeningocele is seen.
  
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  Anatomy scan of the fetal head at 20 weeks of pregnancy in a fetus affected by spina bifida. In the axial scan the characteristic lemon sign and banana sign are seen.
  

Treatment

There is no known cure for nerve damage caused by spina bifida. Standard treatment is surgery after delivery. This surgery aims to prevent further damage of the nervous tissue and to prevent infection; pediatric neurosurgeons operate to close the opening on the back. The spinal cord and its nerve roots are put back inside the spine and covered with meninges. In addition, a shunt may be surgically installed to provide a continuous drain for the excess cerebrospinal fluid produced in the brain, as happens with hydrocephalus. Shunts most commonly drain into the abdomen or chest wall.

Pregnancy

Standard treatment is after delivery. There is tentative evidence about treatment for severe disease before delivery while the baby is inside the womb. As of 2014, however, the evidence remains insufficient to determine benefits and harms.

Treatment of spina bifida during pregnancy is not without risk. To the mother, this includes scarring of the uterus. To the baby, there is the risk of preterm birth.

Broadly, there are two forms of prenatal treatment. The first is open fetal surgery, where the uterus is opened and the spina bifida repair performed. The second is via fetoscopy. These techniques may be an option to standard therapy.

Childhood

Most individuals with myelomeningocele will need periodic evaluations by a variety of specialists:

• Physiatrists coordinate the rehabilitation efforts of different therapists and prescribe specific therapies, adaptive equipment, or medications to encourage as high of a functional performance within the community as possible.
• Orthopedists monitor growth and development of bones, muscles, and joints.
• Neurosurgeons perform surgeries at birth and manage complications associated with tethered cord and hydrocephalus.
• Neurologists treat and evaluate nervous system issues, such as seizure disorders.
• Urologists to address kidney, bladder, and bowel dysfunction – many will need to manage their urinary systems with a program of catheterization. Bowel management programs aimed at improving elimination are also designed.
• Ophthalmologists evaluate and treat complications of the eyes.
• Orthotists design and customize various types of assistive technology, including braces, crutches, walkers, and wheelchairs to aid in mobility. As a general rule, the higher the level of the spina bifida defect, the more severe the paralysis, but paralysis does not always occur. Thus, those with low levels may need only short leg braces, whereas those with higher levels do best with a wheelchair, and some may be able to walk unaided.
• Physical therapists, occupational therapists, psychologists, and speech/language pathologists aid in rehabilitative therapies and increase independent living skills.

Transition to adulthood

Although many children's hospitals feature integrated multidisciplinary teams to coordinate healthcare of youth with spina bifida, the transition to adult healthcare can be difficult because the above healthcare professionals operate independently of each other, requiring separate appointments, and communicate among each other much less frequently. Healthcare professionals working with adults may also be less knowledgeable about spina bifida because it is considered a childhood chronic health condition. Due to the potential difficulties of the transition, adolescents with spina bifida and their families are encouraged to begin to prepare for the transition around ages 14–16, although this may vary depending on the adolescent's cognitive and physical abilities and available family support. The transition itself should be gradual and flexible. The adolescent's multidisciplinary treatment team may aid in the process by preparing comprehensive, up-to-date documents detailing the adolescent's medical care, including information about medications, surgery, therapies, and recommendations. A transition plan and aid in identifying adult healthcare professionals are also helpful to include in the transition process.

Further complicating the transition process is the tendency for youths with spina bifida to be delayed in the development of autonomy, with boys particularly at risk for slower development of independence. An increased dependence on others (in particular family members) may interfere with the adolescent's self-management of health-related tasks, such as catheterization, bowel management, and taking medications. As part of the transition process, it is beneficial to begin discussions at an early age about educational and vocational goals, independent living, and community involvement.

Epidemiology

About 15% of people have spina bifida occulta. Rates of other types of spina bifida vary significantly by country from 0.1 to 5 per 1000 births. On average in developed countries it occurs in about 0.4 per 1000 births. In the United States it affected about 0.7 per 1000 births, and in India about 1.9 per 1000 births. Part of this difference is believed to be due to race, with Caucasians at higher risk, and part due to environmental factors.

In the United States, rates are higher on the East Coast than on the West Coast, and higher in white people (one case per 1000 live births) than in black people (0.1–0.4 case per 1000 live births). Immigrants from Ireland have a higher incidence of spina bifida than do natives. Highest rates of the defect in the USA can be found in Hispanic youth.

The highest incidence rates worldwide were found in Ireland and Wales, where three to four cases of myelomeningocele per 1000 population have been reported during the 1970s, along with more than six cases of anencephaly (both live births and stillbirths) per 1000 population. The reported overall incidence of myelomeningocele in the British Isles was 2.0–3.5 cases per 1000 births. Since then, the rate has fallen dramatically with 0.15 per 1000 live births reported in 1998, though this decline is partially accounted for because some fetuses are aborted when tests show signs of spina bifida (see Pregnancy screening above).

Research

• 1980 – Fetal surgical techniques using animal models were first developed at the University of California, San Francisco by Michael R. Harrison, N. Scott Adzick and research colleagues.
• 1994 – A surgical model that simulates the human disease is the fetal lamb model of myelomeningocele (MMC) introduced by Meuli and Adzick in 1994. The MMC-like defect was surgically created at 75 days of gestation (term 145 to 150 days) by a lumbo-sacral laminectomy. Approximately 3 weeks after creation of the defect a reversed latissimus dorsi flap was used to cover the exposed neural placode and the animals were delivered by cesarean section just prior term. Human MMC-like lesions with similar neurological deficit were found in the control newborn lambs. In contrast, animals that underwent closure had near-normal neurological function and well-preserved cytoarchitecture of the covered spinal cord on histopathological examination. Despite mild paraparesis, they were able to stand, walk, perform demanding motor test and demonstrated no signs of incontinence. Furthermore, sensory function of the hind limbs was present clinically and confirmed electrophysiologically. Further studies showed that this model, when combined with a lumbar spinal cord myelotomy leads to the hindbrain herniation characteristic of the Chiari II malformation and that in utero surgery restores normal hindbrain anatomy by stopping the leak of cerebrospinal fluid through the myelomeningocele lesion.

Surgeons at Vanderbilt University, led by Joseph Bruner, attempted to close spina bifida in 4 human fetuses using a skin graft from the mother using a laparoscope. Four cases were performed before stopping the procedure - two of the four fetuses died.

• 1998 – N. Scott Adzick and team at The Children's Hospital of Philadelphia performed open fetal surgery for spina bifida in an early gestation fetus (22-week gestation fetus) with a successful outcome. Open fetal surgery for myelomeningocele involves surgically opening the pregnant mother's abdomen and uterus to operate on the fetus. The exposed fetal spinal cord is covered in layers with surrounding fetal tissue at mid-gestation (19–25 weeks) to protect it from further damage caused by prolonged exposure to amniotic fluid. Between 1998 and 2003, Dr. Adzick, and his colleagues in the Center for Fetal Diagnosis and Treatment at The Children's Hospital Of Philadelphia, performed prenatal spina bifida repair in 58 mothers and observed significant benefit in the babies.

Fetal surgery after 25 weeks has not shown benefit in subsequent studies.

MOMS trial

Management of myelomeningocele study (MOMS) was a phase III clinical trial designed to compare two approaches to the treatment of spina bifida: surgery before birth and surgery after birth.

The trial concluded that the outcomes after prenatal spina bifida treatment are improved to the degree that the benefits of the surgery outweigh the maternal risks. This conclusion requires a value judgment on the relative value of fetal and maternal outcomes on which opinion is still divided.

To be specific, the study found that prenatal repair resulted in:

• Reversal of the hindbrain herniation component of the Chiari II malformation
• Reduced need for ventricular shunting (a procedure in which a thin tube is introduced into the brain's ventricles to drain fluid and relieve hydrocephalus)
• Reduced incidence or severity of potentially devastating neurologic effects caused by the spine's exposure to amniotic fluid, such as impaired motor function

At one year of age, 40 percent of the children in the prenatal surgery group had received a shunt, compared to 83 percent of the children in the postnatal group. During pregnancy, all the fetuses in the trial had hindbrain herniation. However, at age 12 months, one-third (36 percent) of the infants in the prenatal surgery group no longer had any evidence of hindbrain herniation, compared to only 4 percent in the postnatal surgery group. Further surveillance is ongoing.

Fetoscopic surgery

In contrast to the open fetal operative approach performed in the MOMS trial, a minimally invasive fetoscopic approach (akin to 'keyhole' surgery) has been developed. This approach has been evaluated by independent authors of a controlled study which showed some benefit in survivors, but others are more skeptical.

The observations in mothers and their fetuses that were operated over the past two and a half years by the matured minimally invasive approach showed the following results: Compared to the open fetal surgery technique, fetoscopic repair of myelomeningocele results in far less surgical trauma to the mother, as large incisions of her abdomen and uterus are not required. In contrast, the initial punctures have a diameter of 1.2 mm only. As a result, thinning of the uterine wall or dehiscence which have been among the most worrisome and criticized complications after the open operative approach do not occur following minimally invasive fetoscopic closure of spina bifida aperta. The risks of maternal chorioamnionitis or fetal death as a result of the fetoscopic procedure run below 5%. Women are discharged home from hospital one week after the procedure. There is no need for chronic administration of tocolytic agents since postoperative uterine contractions are barely ever observed. The current cost of the entire fetoscopic procedure, including hospital stay, drugs, perioperative clinical, ECG, ultrasound and MRI-examinations, is approximately €16,000. 

In 2012, these results of the fetoscopic approach were presented at various national and international meetings, among them at the 1st European Symposium “Fetal Surgery for Spina bifida“ in April 2012 in Giessen, at the 15th Congress of the German Society for Prenatal Medicine and Obstetrics in May 2012 in Bonn, at the World Congress of the Fetal Medicine Foundation in June 2012 and at the World Congress of the International Society of Obstetrics and Gynecology (ISUOG) in Copenhagen in September 2012, and published in abstract form.

Since then more data has emerged. In 2014, two papers were published on fifty one patients. These papers suggested that the risk to the mother is small. The main risk appears to be preterm labour, on average at about 33 weeks.

Hydrocephalus

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Hydrocephalus

Hydrocephalus
Other names	Water on the brain
Hydrocephalus as seen on a CT scan of the brain. The black areas in the middle of the brain (the lateral ventricles) are abnormally large and filled with fluid.
Pronunciation	/hʌɪdrəʊˈsɛfələs/
Specialty	Neurosurgery
Symptoms	Babies: rapid head growth, vomiting, sleepiness, seizures Older people: Headaches, double vision, poor balance, urinary incontinence, personality changes, mental impairment
Causes	Neural tube defects, meningitis, brain tumors, traumatic brain injury, intraventricular hemorrhage
Diagnostic method	Based on symptoms and medical imaging
Treatment	Surgery
Prognosis	Variable, often normal life
Frequency	1.5 per 1,000 (babies)

Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary incontinence, personality changes, or mental impairment. In babies, it may be seen as a rapid increase in head size. Other symptoms may include vomiting, sleepiness, seizures, and downward pointing of the eyes.

Hydrocephalus can occur due to birth defects or be acquired later in life. Associated birth defects include neural tube defects and those that result in aqueductal stenosis. Other causes include meningitis, brain tumors, traumatic brain injury, intraventricular hemorrhage, and subarachnoid hemorrhage. The four types of hydrocephalus are communicating, noncommunicating, ex vacuo, and normal pressure. Diagnosis is typically made by physical examination and medical imaging.

Hydrocephalus is typically treated by the surgical placement of a shunt system. A procedure called a third ventriculostomy may be an option in a few people. Complications from shunts may include overdrainage, underdrainage, mechanical failure, infection, or obstruction. This may require replacement. Outcomes are variable, but many people with shunts live normal lives. Without treatment, death or permanent disability may occur.

About one to two per 1,000 newborns have hydrocephalus. Rates in the developing world may be higher. Normal pressure hydrocephalus is estimated to affect about 5 per 100,000 people, with rates increasing with age. Description of hydrocephalus by Hippocrates dates back more than 2,000 years. The word "hydrocephalus" is from the Greek ὕδωρ, hydōr, meaning "water" and κεφαλή, kephalē, meaning "head".

Signs and symptoms

Illustration showing different effects of hydrocephalus on the brain and cranium

 

The clinical presentation of hydrocephalus varies with chronicity. Acute dilatation of the ventricular system is more likely to manifest with the nonspecific signs and symptoms of increased intracranial pressure (ICP). By contrast, chronic dilatation (especially in the elderly population) may have a more insidious onset presenting, for instance, with Hakim's triad (Adams' triad).

Symptoms of increased ICP may include headaches, vomiting, nausea, papilledema, sleepiness, or coma. Elevated ICP may result in uncal or tonsillar herniation, with resulting life-threatening brain stem compression.

Hakim's triad of gait instability, urinary incontinence, and dementia is a relatively typical manifestation of the distinct entity normal-pressure hydrocephalus. Focal neurological deficits may also occur, such as abducens nerve palsy and vertical gaze palsy (Parinaud syndrome due to compression of the quadrigeminal plate, where the neural centers coordinating the conjugated vertical eye movement are located). The symptoms depend on the cause of the blockage, the person's age, and how much brain tissue has been damaged by the swelling.

In infants with hydrocephalus, CSF builds up in the central nervous system (CNS), causing the fontanelle (soft spot) to bulge and the head to be larger than expected. Early symptoms may also include:

• Eyes that appear to gaze downward
• Irritability
• Seizures
• Separated sutures
• Sleepiness
• Vomiting

Symptoms that may occur in older children can include:

• Brief, shrill, high-pitched cry
• Changes in personality, memory, or the ability to reason or think
• Changes in facial appearance and eye spacing (craniofacial disproportion)
• Crossed eyes or uncontrolled eye movements
• Difficulty feeding
• Excessive sleepiness
• Headaches
• Irritability, poor temper control
• Loss of bladder control (urinary incontinence)
• Loss of coordination and trouble walking
• Muscle spasticity (spasm)
• Slow growth (child 0–5 years)
• Delayed milestones
• Failure to thrive
• Slow or restricted movement
• Vomiting

Because hydrocephalus can injure the brain, thought and behavior may be adversely affected. Learning disabilities, including short-term memory loss, are common among those with hydrocephalus, who tend to score better on verbal IQ than on performance IQ, which is thought to reflect the distribution of nerve damage to the brain. However, the severity of hydrocephalus can differ considerably between individuals, and some are of average or above-average intelligence. Someone with hydrocephalus may have coordination and visual problems, or clumsiness. They may reach puberty earlier than the average child (this is called precocious puberty). About one in four develops epilepsy.

Cause

Congenital

A one-year-old girl with hydrocephalus showing "sunset eyes", before shunt surgery

 

Congenital hydrocephalus is present in the infant prior to birth, meaning the fetus developed hydrocephalus in utero during fetal development. The most common cause of congenital hydrocephalus is aqueductal stenosis, which occurs when the narrow passage between the third and fourth ventricles in the brain is blocked or too narrow to allow sufficient cerebral spinal fluid to drain. Fluid accumulates in the upper ventricles, causing hydrocephalus.

Other causes of congenital hydrocephalus include neural-tube defects, arachnoid cysts, Dandy–Walker syndrome, and Arnold–Chiari malformation. The cranial bones fuse by the end of the third year of life. For head enlargement to occur, hydrocephalus must occur before then. The causes are usually genetic, but can also be acquired and usually occur within the first few months of life, which include intraventricular matrix hemorrhages in premature infants, infections, type II Arnold-Chiari malformation, aqueduct atresia and stenosis, and Dandy-Walker malformation.

In newborns and toddlers with hydrocephalus, the head circumference is enlarged rapidly and soon surpasses the 97th percentile. Since the skull bones have not yet firmly joined together, bulging, firm anterior and posterior fontanelles may be present even when the person is in an upright position.

The infant exhibits fretfulness, poor feeding, and frequent vomiting. As the hydrocephalus progresses, torpor sets in, and infants show lack of interest in their surroundings. Later on, their upper eyelids become retracted and their eyes are turned downwards ("sunset eyes") (due to hydrocephalic pressure on the mesencephalic tegmentum and paralysis of upward gaze). Movements become weak and the arms may become tremulous. Papilledema is absent, but vision may be reduced. The head becomes so enlarged that they eventually may be bedridden.

About 80–90% of fetuses or newborn infants with spina bifida—often associated with meningocele or myelomeningocele—develop hydrocephalus.

Acquired

This condition is acquired as a consequence of CNS infections, meningitis, brain tumors, head trauma, toxoplasmosis, or intracranial hemorrhage (subarachnoid or intraparenchymal), and is usually painful.

Type

The cause of hydrocephalus is not known with certainty and is probably multifactorial. It may be caused by impaired CSF flow, reabsorption, or excessive CSF production.

• Obstruction to CSF flow hinders its free passage through the ventricular system and subarachnoid space (e.g., stenosis of the cerebral aqueduct or obstruction of the interventricular foramina secondary to tumors, hemorrhages, infections or congenital malformations) and can cause increases in ICP.
• Hydrocephalus can also be caused by overproduction of CSF (relative obstruction) (e.g., choroid plexus papilloma, villous hypertrophy).
• Bilateral ureteric obstruction is a rare, but reported, cause of hydrocephalus.

Based on its underlying mechanisms, hydrocephalus can be classified into communicating and noncommunicating (obstructive). Both forms can be either congenital or acquired.

Communicating

Communicating hydrocephalus, also known as nonobstructive hydrocephalus, is caused by impaired CSF reabsorption in the absence of any obstruction of CSF flow between the ventricles and subarachnoid space. This may be due to functional impairment of the arachnoidal granulations (also called arachnoid granulations or Pacchioni's granulations), which are located along the superior sagittal sinus, and is the site of CSF reabsorption back into the venous system. Various neurologic conditions may result in communicating hydrocephalus, including subarachnoid/intraventricular hemorrhage, meningitis, and congenital absence of arachnoid villi. Scarring and fibrosis of the subarachnoid space following infectious, inflammatory, or hemorrhagic events can also prevent resorption of CSF, causing diffuse ventricular dilatation.

Noncommunicating

Noncommunicating hydrocephalus, or obstructive hydrocephalus, is caused by a CSF-flow obstruction.

• Foramen of Monro obstruction may lead to dilation of one, or if large enough (e.g., in colloid cyst), both lateral ventricles.
• The aqueduct of Sylvius, normally narrow, may be obstructed by a number of genetic or acquired lesions (e.g., atresia, ependymitis, hemorrhage, or tumor) and lead to dilation of both lateral ventricles, as well as the third ventricle.
• Fourth ventricle obstruction leads to dilatation of the aqueduct, as well as the lateral and third ventricles (e.g., Chiari malformation).
• The foramina of Luschka and foramen of Magendie may be obstructed due to congenital malformation (e.g., Dandy-Walker malformation).

Other

Hydrocephalus ex vacuo from vascular dementia as seen on MRI

• Normal pressure hydrocephalus (NPH) is a particular form of chronic communicating hydrocephalus, characterized by enlarged cerebral ventricles, with only intermittently elevated cerebrospinal fluid pressure. Characteristic triad of symptoms are; dementia, apraxic gait and urinary incontinence. The diagnosis of NPH can be established only with the help of continuous intraventricular pressure recordings (over 24 hours or even longer), since more often than not instant measurements yield normal pressure values. Dynamic compliance studies may be also helpful. Altered compliance (elasticity) of the ventricular walls, as well as increased viscosity of the cerebrospinal fluid, may play a role in the pathogenesis.
• Hydrocephalus ex vacuo also refers to an enlargement of cerebral ventricles and subarachnoid spaces, and is usually due to brain atrophy (as it occurs in dementias), post-traumatic brain injuries, and even in some psychiatric disorders, such as schizophrenia. As opposed to hydrocephalus, this is a compensatory enlargement of the CSF-spaces in response to brain parenchyma loss; it is not the result of increased CSF pressure.

Mechanism

Spontaneous intracerebral and intraventricular hemorrhage with hydrocephalus shown on CT scan

 

3D cast of lateral ventricles in hydrocephalus

 

Hydrocephalus is usually due to blockage of CSF outflow in the ventricles or in the subarachnoid space over the brain. In a person without hydrocephalus, CSF continuously circulates through the brain, its ventricles and the spinal cord and is continuously drained away into the circulatory system. Alternatively, the condition may result from an overproduction of the CSF, from a congenital malformation blocking normal drainage of the fluid, or from complications of head injuries or infections.

Compression of the brain by the accumulating fluid eventually may cause neurological symptoms such as convulsions, intellectual disability, and epileptic seizures. These signs occur sooner in adults, whose skulls are no longer able to expand to accommodate the increasing fluid volume within. Fetuses, infants, and young children with hydrocephalus typically have an abnormally large head, excluding the face, because the pressure of the fluid causes the individual skull bones—which have yet to fuse—to bulge outward at their juncture points. Another medical sign, in infants, is a characteristic fixed downward gaze with whites of the eyes showing above the iris, as though the infant were trying to examine its own lower eyelids.

The elevated ICP may cause compression of the brain, leading to brain damage and other complications. Conditions among affected individuals vary widely.

If the foramina of the fourth ventricle or the cerebral aqueduct are blocked, CSF can accumulate within the ventricles. This condition is called internal hydrocephalus and it results in increased CSF pressure. The production of CSF continues, even when the passages that normally allow it to exit the brain are blocked. Consequently, fluid builds inside the brain, causing pressure that dilates the ventricles and compresses the nervous tissue. Compression of the nervous tissue usually results in irreversible brain damage. If the skull bones are not completely ossified when the hydrocephalus occurs, the pressure may also severely enlarge the head. The cerebral aqueduct may be blocked at the time of birth or may become blocked later in life because of a tumor growing in the brainstem.

Treatment

Procedures

Baby recovering from shunt surgery

Hydrocephalus treatment is surgical, creating a way for the excess fluid to drain away. In the short term, an external ventricular drain (EVD), also known as an extraventricular drain or ventriculostomy, provides relief. In the long term, some people will need any of various types of cerebral shunt. It involves the placement of a ventricular catheter (a tube made of silastic) into the cerebral ventricles to bypass the flow obstruction/malfunctioning arachnoidal granulations and drain the excess fluid into other body cavities, from where it can be resorbed. Most shunts drain the fluid into the peritoneal cavity (ventriculoperitoneal shunt), but alternative sites include the right atrium (ventriculoatrial shunt), pleural cavity (ventriculopleural shunt), and gallbladder. A shunt system can also be placed in the lumbar space of the spine and have the CSF redirected to the peritoneal cavity (lumbar-peritoneal shunt). An alternative treatment for obstructive hydrocephalus in selected people is the endoscopic third ventriculostomy (ETV), whereby a surgically created opening in the floor of the third ventricle allows the CSF to flow directly to the basal cisterns, thereby shortcutting any obstruction, as in aqueductal stenosis. This may or may not be appropriate based on individual anatomy. For infants, ETV is sometimes combined with choroid plexus cauterization, which reduces the amount of cerebrospinal fluid produced by the brain. The technique, known as ETV/CPC, was pioneered in Uganda by neurosurgeon Benjamin Warf and is now in use in several U.S. hospitals. Hydrocephalus can be successfully treated by placing a drainage tube (shunt) between the brain ventricles and abdominal cavity. Some risk exists of infection being introduced into the brain through these shunts, however, and the shunts must be replaced as the person grows.

External hydrocephalus

External hydrocephalus is a condition generally seen in infants which involves enlarged fluid spaces or subarachnoid spaces around the outside of the brain. This is generally a benign condition that resolves spontaneously by two years of age and therefore usually does not require insertion of a shunt. Imaging studies and a good medical history can help to differentiate external hydrocephalus from subdural hemorrhages or symptomatic chronic extra-axial fluid collections which are accompanied by vomiting, headaches, and seizures.

Shunt complications

Examples of possible complications include shunt malfunction, shunt failure, and shunt infection, along with infection of the shunt tract following surgery (the most common reason for shunt failure is infection of the shunt tract). Although a shunt generally works well, it may stop working if it disconnects, becomes blocked (clogged) or infected, or it is outgrown. If this happens, the CSF begins to accumulate again and a number of physical symptoms develop (headaches, nausea, vomiting, photophobia/light sensitivity), some extremely serious, such as seizures. The shunt failure rate is also relatively high (of the 40,000 surgeries performed annually to treat hydrocephalus, only 30% are a person's first surgery) and people not uncommonly have multiple shunt revisions within their lifetimes.

Another complication can occur when CSF drains more rapidly than it is produced by the choroid plexus, causing symptoms of listlessness, severe headaches, irritability, light sensitivity, auditory hyperesthesia (sound sensitivity), nausea, vomiting, dizziness, vertigo, migraines, seizures, a change in personality, weakness in the arms or legs, strabismus, and double vision to appear when the person is vertical. If the person lies down, the symptoms usually vanish quickly. A CT scan may or may not show any change in ventricle size, particularly if the person has a history of slit-like ventricles. Difficulty in diagnosing over-drainage can make treatment of this complication particularly frustrating for people and their families. Resistance to traditional analgesic pharmacological therapy may also be a sign of shunt overdrainage or failure.

The diagnosis of CSF buildup is complex and requires specialist expertise. Diagnosis of the particular complication usually depends on when the symptoms appear, that is, whether symptoms occur when the person is upright or in a prone position, with the head at roughly the same level as the feet.

Standardized protocols for inserting cerebral shunts have been shown to reduce shunt infections.

History

Skull of a hydrocephalic child (1800s)

References to hydrocephalic skulls can be found in ancient Egyptian medical literature from 2,500 BC to 500 AD. Hydrocephalus was described more clearly by the ancient Greek physician Hippocrates in the fourth century BC, while a more accurate description was later given by the Roman physician Galen in the second century AD.

The first clinical description of an operative procedure for hydrocephalus appears in the Al-Tasrif (1,000 AD) by the Arab surgeon Abulcasis, who clearly described the evacuation of superficial intracranial fluid in hydrocephalic children. He described it in his chapter on neurosurgical disease, describing infantile hydrocephalus as being caused by mechanical compression. He wrote:

The skull of a newborn baby is often full of liquid, either because the matron has compressed it excessively or for other, unknown reasons. The volume of the skull then increases daily, so that the bones of the skull fail to close. In this case, we must open the middle of the skull in three places, make the liquid flow out, then close the wound and tighten the skull with a bandage.

Historical specimen of an infant with severe hydrocephalus, probably untreated

In 1881, a few years after the landmark study of Retzius and Key, Carl Wernicke pioneered sterile ventricular puncture and external drainage of CSF for the treatment of hydrocephalus. It remained an intractable condition until the 20th century, when cerebral shunt and other neurosurgical treatment modalities were developed.

It is a lesser-known medical condition; relatively little research is conducted to improve treatment, and still no cure has been found. In developing countries, the condition often goes untreated at birth. Before birth, the condition is difficult to diagnose, and access to medical treatment is limited. However, when head swelling is prominent, children are taken at great expense for treatment. By then, brain tissue is undeveloped and neurosurgery is rare and difficult. Children more commonly live with undeveloped brain tissue and consequential intellectual disabilities and restrictions.

Society and culture

Name

The word "hydrocephalus" is from the Greek ὕδωρ, hydōr meaning "water" and κεφαλή, kephalē meaning "head". Other names for hydrocephalus include "water on the brain", a historical name, and "water baby syndrome".

Awareness campaign

Hydrocephalus awareness ribbon

September was designated National Hydrocephalus Awareness Month in July 2009 by the U.S. Congress in H.Res. 373. The resolution campaign is due in part to the advocacy work of the Pediatric Hydrocephalus Foundation. Prior to July 2009, no awareness month for this condition had been designated. Many of the hydrocephalus organizations within the U.S. use various ribbon designs as a part of their awareness and fundraising activities.

Exceptional case

One exceptional case of hydrocephalus was a man whose brain shrank to a thin sheet of tissue, due to a buildup of cerebrospinal fluid in his skull. As a child, the man had a shunt, but it was removed when he was 14. In July 2007, at age 44, he went to a hospital due to mild weakness in his left leg. When doctors learned of the man's medical history, they performed a CT and MRI scan, and were astonished to see "massive enlargement" of the lateral ventricles in the skull. Dr. Lionel Feuillet of Hôpital de la Timone in Marseille said, "The images were most unusual... the brain was virtually absent." Intelligence tests showed the person had an IQ of 75, considered "borderline intellectual functioning", just above what would be officially considered mentally challenged.

The person was a married father of two children, and worked as a civil servant, leading an at least superficially normal life, despite having enlarged ventricles with a decreased volume of brain tissue. "What I find amazing to this day is how the brain can deal with something which you think should not be compatible with life", commented Dr. Max Muenke, a pediatric brain-defect specialist at the National Human Genome Research Institute. "If something happens very slowly over quite some time, maybe over decades, the different parts of the brain take up functions that would normally be done by the part that is pushed to the side."

Notable cases

• Author Sherman Alexie, born with the condition, wrote about it in his semi-autobiographical junior fiction novel The Absolutely True Diary of a Part-Time Indian.
• Prince William, Duke of Gloucester (1689–1700) probably contracted meningitis at birth, which resulted in this condition.
• Emperor Ferdinand I of Austria (1793–1875) became emperor in 1835 despite various health issues including hydrocephalus and epilepsy.