spina bifida spina bifida spina bifida /ˌspaɪnə ˈbɪfɪdə/ (latin for 'split spine'; sb) is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. there are three main types: spina bifida occulta, meningocele and myelomeningocele. meningocele and myelomeningocele may be grouped as spina bifida cystica. the most common location is the lower back, but in rare cases it may be in the middle back or neck. spina bifidaillustration of a child with spina bifidaspecialtypediatrics, neurosurgery, rehabilitation medicinesymptomshairy patch, dimple, dark spot, swelling on the lower backcomplicationspoor ability to walk, problems with bladder or bowel control, hydrocephalus, tethered spinal cord, latex allergycausesgenetic and environmental factorsrisk factorslack of folate during pregnancy, certain antiseizure medications, obesity, poorly controlled diabetesdiagnostic methodamniocentesis, medical imagingpreventionfolate supplementationtreatmentsurgeryfrequency15% (occulta), 0.1–5 per 1000 births (others) 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. problems associated with this form include poor ability to walk, impaired 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 (vitamin b9) 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. 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. europeans are at higher risk compared to africans. types different types of spina bifida 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 in 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. 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. 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 have 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 as 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 club foot deformity, and arnold–chiari malformation, necessitating a vp shunt placement. toxins and conditions 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. x-ray image of spina bifida occulta in s-1 x-ray computed tomography scan of unfused arch at c1 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.