Spina Bifida Biology of Neurodevelopmental Disorders January 24

Spina Bifida Biology of Neurodevelopmental Disorders January 24, 2008 Chris Chapleau John Hammond

Spina Bifida • What is it? • What causes it? • How can it be prevented? • How can it be managed? • Social impact • Further information

What is spina bifida? “Split Spine” caused by incomplete closure of the neural tube, usually in the lumbar or sacral region

What is spina bifida? -Worldwide incidence is 1 -2 cases in 1000 births -US incidence is 0. 7 per 1000 live births -East coast higher than West coast -Slightly higher incidence in Caucasian population -Irish immigrants also have a higher risk -Seen more in children born in late summer and early fall

What is spina bifida? Anatomy review http: //www. fpnotebook. com/Lumbar. Spine. Anatomy. Vertebra. gif http: //thespine. net/articles/lumbardecompression_files/image 001. gif

What is spina bifida? Anatomy review Meninges Dorland’s Medical Dictionary

What is spina bifida? Several classifications that vary in severity depending on location and extent of opening Spina bifida occulta Spina bifida cystica meningocele myelomenigocele Spina bifida ventralis

What is spina bifida? Spina bifida occulta – “hidden” - The bony vertebra is open, but the spine is within the spinal canal - The skin may have a lipoma (small benign fatty tumor), some discoloration (birthmark), or a small tuft of hair overlying the spinal defect - Most patients with spina bifida occulta do not know they have it - There may be tethering of the spinal cord

What is spina bifida? Spina bifida occulta – tethered spinal cord -Often occurs later in life - Caused by limitations of movement of the spinal cord within the spinal column - Patients often have low back pain, weakness in the legs, and/or incontinence depending on the site of tethering http: //www. uwhealth. org/image s/ewebeditpro 2/upload/6144_Fig ure_1. jpg

What is spina bifida? Spina bifida cystica – meningocele -The bony vertebra is open, part of the meninges is protruding out of the spinal canal - Since the spinal cord is not protruding, there is often normal function - Some cases of tethering have been reported

What is spina bifida? Spina bifida cystica – myelomeningocele -The bony vertebra is open, part of the meninges and part or all of the spinal cord is protruding out of the spinal canal - Since the spinal cord is protruding, it is often not fully developed - Involved nerve roots are often not developed resulting in weakness, pain, and/or paralysis

What is spina bifida? Spina bifida cystica – myelomeningocele - Arnold Chiara malformation II is often associated with myelomeningocele and occurs when the cerebellum is forced downward - This can result in life-threatening situations because the build-up of cerebrospinal fluid can cause pressure on the brain - Patients with Arnold Chiari malformations often require placement of a shunt to drain the excess fluid http: //www. thefetus. net/images/article-images/central_nervous_system/arnold_chiari_files/image 001. jpg

What is spina bifida? Spina bifida ventralis – anterior opening - Much less common than other forms of spina bifida - Meningeal sac will protrude into the retroperitoneal space and impinge on retroperitoneal organs such as the duodenum, ascending/descending colon, kidneys, adrenal glands, pancreas, aorta, and inferior vena cava http: //myweb. lsbu. ac. uk/dirt/museum/margaret/871 -3398 -2082230. jpg

Spina Bifida • What is it? • What causes it? • How can it be prevented? • How can it be managed? • Social impact • Further information

What causes spina bifida? - The exact cause of spina bifida is unknown - All research to date has indicated both a genetic and environmental influence - The developmental process that results in spina bifida is well studied

Genetic Neuronal Migration White Matter Injury Lin, J. -P. J Neurol Neurosurg Psychiatry 2003;

What causes spina bifida? Developmental Biology – 6 th ed.

Stages in the closure of a xenopus neural tube Video Views and Reviews: Neurulation and the Fashioning of the Vertebrate Central Nervous System Christopher Watters

What causes spina bifida? What would prevent the neural tubes from closing properly? Folate seems to play a large role in the closing of the neural tube – but it is unknown exactly how folate works in this process. Folate influence was discovered by the increased incidence in spina bifida seen in Irish babies born in late summer and early fall. The lack of leafy green vegetables caused the mother to have low levels of folate during conception. Genetics also play a role in the development of spina bifida. - Mothers with one child with spina bifida have an increased risk of additional children having spina bifida - Studies with folate-resistant mice

What causes spina bifida? Valproic acid (Depakote) -Oral medication used to treat seizures/convulsions, migraines, and bipolar disorder - Mechanism of action – thought to increase GABA levels in the brain - Pregnant women taking Valproic acid have an increased risk of having children with spina bifida

Spina Bifida • What is it? • What causes it? • How can it be prevented? • How can it be managed? • Social impact • Further information

How can spina bifida be prevented? Education Folate intake

How can spina bifida be prevented? Education -Neural tube begins to close at day 22 after conception - Neural tube is usually fully closed by day 28 after conception

How can spina bifida be prevented?

How can spina bifida be prevented? Folate intake -Recommended that women of child-bearing age take 400 micrograms of folate per day -Pregnant women should take 600 micrograms of folate per day -Women with a previous child with spina bifida should take 4000 micrograms of folate per day - Folate can decrease the risk of spina bifida by up to 75%

How can spina bifida be prevented? Sources of folate - Vegetables and grains - Many foods are now enriched with folate - Most multi-vitamins contain folate - Some vitamins are specifically formulated for women

Spina Bifida • What is it? • What causes it? • How can it be prevented? • How can it be managed? • Social impact • Further information

How can spina bifida be managed? Treatment for spina bifida depends on the extent of spinal cord involvement - Spina bifida occulta usually requires no treatment unless pain from tethering develops - Meningocele usually requires removal and early management of the cyst - Myelomeningocele usually requires the most extensive treatment, but treatment is variable

How can spina bifida be managed? Lesion Level Spinal-related disability Above L 3 Complete paraplegia and dermatomal paraanesthesia, Bladder incontinence, Nonambulatory L 4 and below Same as for above L 3 except preservation of hip flexors, hip adductors, knee extensors; Ambulatory with aids, bracing orthopedic surgery S 1 and below Same as for L 4 and below except preservation of feet dorsiflexors, and partial preservation of hip extensors and knee flexors; Ambulatory with minimal aids S 3 and below Normal lower extremity motor function; Saddle anesthesia; Variable bladder-rectal incontinence

How can spina bifida be managed? - Detection - Antibiotics - Surgery - Careful observation - Physical therapy

How can spina bifida be managed? -Detection -Triple screening -Maternal blood test for a-fetoprotein -Ultrasound for bone defects -Amniocentesis - a-fetoprotein is elevated in 75 -80% of cases of spina bifida (myelomeningocele)

How can spina bifida be managed? Amniocentesis – using a needle to collect amniotic fluid

How can spina bifida be managed? -Antibiotics - In some cases the spinal cord is exposed to the environment - Antibiotics are essential in preventing infection of the CNS

How can spina bifida be managed? -Surgery - In some cases the spinal cord is exposed to the environment or tethered - Surgery is performed in order to cover the spinal cord with muscle and skin or to untether the spinal cord - in utero surgery has also become a viable option for some cases

How can spina bifida be managed? - Careful Observation - Children with myelomeningocele often have hydrocephalus (blockage of CSF) - Children may present with paralysis, blindness, MR, inability to speak, convulsions -Any changes in mental status or behavior should be quickly brought to the attention of the child’s physician(s)

How can spina bifida be managed? - Physical Therapy - Spinal cord damage can cause muscle weakening and wasting - Speech therapy may also be useful for some individuals

Spina Bifida • What is it? • What causes it? • How can it be prevented? • How can it be managed? • Social impact • Further information

Social impact Prognosis and any deficits are dependent upon level of involvement - Estimates from 5 -40 % of the world’s population may have spina bifida occulta - Meningocele is not very common and often has minimal impact once the cyst is removed - Myelomeningocele has the largest impact on patients and their families

Social impact Changes with time - Before antibiotics most children with myelomeningocele died because of infections in the CNS; those that survived were unlikely to ever walk - During the 1990 s, the discovery of the role of folate in neural tube closure drastically decreased the number of cases of myelomeningocele - In the late 1990 s, in utero surgery was attempted to close neural tube defects

Social impact Children born with spina bifida today require some special treatment - Multiple surgeries starting as early as 48 hours after birth - Physical therapy - Bowel and/or bladder surgery – helps prevent infection and social stigmatism - Latex allergies are often present In many cases, special centers are better equipped to treat children with spina bifida and have a variety of specialists on staff

Social impact Most children that are treated early will have normal IQ and be able to attend public schools Mobility is the biggest concern for many patients with spina bifida – lack of mobility can lead to obesity and scoliosis With proper treatment, individuals will live well into adulthood

Social impact Notable people that have spina bifida Hank Williams, Sr. (singer) John Mellencamp (singer) Buddy Winnett (horse jockey) Bruce Payne (actor) Jean Driscoll (Olympian) Rene Kirby (actor)

Further information Spina bifida association – www. sbaa. org UAB Health systems - http: //www. health. uab. edu/15521/ Local Clinic – Children's Hospital Spina Bifida Clinic #3 1600 7 th Avenue S. , Birmingham, AL 35233 Phone: 205 -939 -5281 Website: http: //www. chsys. org/

Paper Segment Spina Bifida

The Focus of the Papers • What causes Spina Bifida? – Genetic Mouse Models of Spina Bifida and Neural Tube Disorders • How can Spina Bifida be Repaired? – In utero repair in humans

Curly Tail: Brief History • Curly tail is a spontaneous mutation that was first described in the UK (1950) • The ct gene is incompletely penetrant: Some individuals fail to express the trait, even though they carry the allele. • Not sure what is the main genetic defect that leads to the curly tail phenotype

Curly Tail: The Phenotype • Curly tail mouse can demonstrate 0 -3 different phenotypes: – – Healthy Curled tail Lumbosacral spina bifida Exencephaly: Brain located outside of skull

Curly Tail: Penetrance (Incomplete) On average: 40 -50% unaffected, 50 -60% have some neural tube defects or curled tail

Curly Tail: As a Model for Spina Bifida Causative • A mouse model of common human NTDs would have to contain the following: – Have different degrees of defect – A degree of genetic complexity – Responsive to nutritional supplementation (Inositol) Mechanism Cures

Curly tail: What gene are involved? Inositol- and folate-resistant neural tube defects in mice lacking the epithelialspecific factor Grhl-3 Stephen B Ting, Tomasz Wilanowski, Alana Auden, Mark Hall, Anne K Voss, Tim Thomas, Vishwas Parekh, John M Cunningham & Stephen M Jane

Ting et al. 2003 • Based on studies in the Drosphila, the gene grainyhead (grhl) has been implicated in patterning of the nervous system • In addition mutations in the fly have shown that defects exist in epithelial closures, (which neural tube closure is) • What role does mammalian grhl have in neurulation? Are there any similarities between a knockout of grhl and the curly tail mouse?

Grhl 3 expression: Is grhl expressed in the developing mouse? In situ hybridazation shows that grhl 3 is expressed in non-neural ectoderm that is adjacent to the neural tube.

Does grhl 3 mutant mice have NTD? • All embryos had spina bifida and curled tails • 2% had exencephaly • Problems in the bone structure • In the caudal region of the neural tube, the neural folds never occurred

The relationship between grhl and ct

Can Folate or Inositol rescue NTD in grhl 3 mutant mice

Gustavsson et al. 2007 • Further investigate if grhl 3 is the gene that is defective in the curly tail mutant mice • Investigate expression of grhl 3 in ct mice • Can defects in the neural tube be rescued in curly tailed mice

Grhl 3 expression is reduced in curly tail mice… …but the expression is rescued when grhl 3 is overexpressed

Grhl 3 mutation in the promoter region exist in curly tail mice

Rescue by overexpression of grhl 3

Conclusion • Mutations in curly tail mice seem to correlate with mutations in the promoter region of the grhl 3 • Curly tail mice that overexpress grhl 3 show no defects in the neural tube • The phenotype in grhl 3 cannot be rescued by inositol • Further research: Folate has reduced the risk of spina bifida, can Inositol can be used in humans • Further research: Do mutations of grhl 3 exist in humans that have spina bifida or other defects of the neural tube

Clinical Paper • Can fetal surgery be used to correct or reduce the risk of neurological defects that are caused that exist in spina bifida? • Looking at a group of papers from the Children’s Hospital of Philadelphia

Why Fetal Surgery? • Neurological defects in patients with spina bifida are not necessarily caused by the defect in neurulation, but caused by damage from injury or chemical induced trauma when the fetal neural tissue is exposed and unprotected • Hypothesis is that surgically “covering up” the exposed neural tissue would improve neurological outcome • Fetal surgery has been used to improve neurological function in a sheep model of spina bifida

First Evidence (1998) • 27 -year old woman, with a 23 -week gestation fetus • Lesion in the thoracolumbosacral (T 11 -S 1 level) was detected at 20 weeks, in addition α-fetoprotein was raised. Arnold-Chiari II malformations were detected • Good leg movements were detected in the fetus • Surgery: A low transverse maternal laparotomy and vertical hysterotomy were performed • Cystic membrane of the spina bifida lesion was excised and skin flaps were developed to close the defect and protect the developing spinal cord

• Amniotic fluid was replaced with Ringer’s solution • Uterine and laparotomy wounds were closed

Birth • At 30 weeks gestation a baby boy was born by caesarean section • Shunt tubing was removed • Leg function was excellent, good knee and hip flexion – Except for a absent plantar and a right club foot • MRI confirmed that the lesion was repaired and the Arnold-Chiari malformation was no longer present. No hydrocephalus • All developmental milestones were reached by 6 months of age

Developmental milestones Approx. age Motor milestone 3 months Holds head up 4 -5 months Rolls front to back, sits when propped 7 -9 months Sits alone, crawls

2003 Protocol • 1998 -2002, 50 patients underwent in utero fetal closure and were delivered • To be consider for this study – Pregnancy had to be between 20 weeks and 25 weeks and 6 days – Demonstrate the presence of Arnold-Chiari malformation (type II) – Have a lesion at S 1 -level or higher • S 2 or lower lesions were excluded because outcome were usually good – Intact neurological function of lower extremities • Absence of clubfoot

Surgical Procedure and Pregnancy Management • Similar as before • After the surgery, the mother stayed in the hospital for 4 -5 days – Discharged to the Ronald Mc. Donald house and placed on bedrest with minimal physical activity • Delivery was performed at 3637 by cesarean section – There was some births that occurred before this day • After delivery, the infant was admitted to the NICU for evaluation 3 deaths, both very premature Surgery does not affect gestational ages at birth

2003 outcomes • Mean birth weight was within normal range – 2354 g (range 1100 -3490 kg) • All the surviving fetuses had reversal of Arnold-Chiari malformation (type II) Leg Function 57% better than expected 17% worse than expected

2003 Conclusions • Study suggests that fetal surgery to correct spina bifida: – Improves neurological leg function – Rescues the Arnold-Chiari malformation – Restores normal CSF hydrodynamics • 2007 paper that followed up on 51 children that went through the fetal surgery should no change or improvement of cognitive function – Shunt vs. No Shunt • Can earlier surgical prevention further improve function?