Spina bifida is a congenital spinal malformation belonging to the spectrum of neural tube defects (NTDs), arising from incomplete closure of the neural tube during early embryogenesis. Neural tube closure normally occurs between the third and fourth weeks of gestation (approximately days 21–28). Disruption of this process results in defective fusion of the vertebral arches and varying degrees of involvement of the spinal cord and surrounding structures.
The clinical presentation ranges from asymptomatic bony defects to severe forms characterized by exposure of neural elements and significant neurological impairment. Disease severity is primarily determined by the type and anatomical level of the defect.
Types of Spina Bifida
Spina bifida is broadly categorized into three principal forms:
Spina Bifida Occulta
This is the mildest and most common form. It is characterized by a small defect in the vertebral arches without herniation of neural tissue. The spinal cord typically remains in its normal position. Most individuals are asymptomatic, and the condition is often detected incidentally. Cutaneous markers such as a dermal dimple, localized hypertrichosis, or skin discoloration may occasionally be present.
Meningocele
In meningocele, the meninges protrude through the vertebral defect, forming a cystic sac filled with cerebrospinal fluid. The spinal cord itself generally remains intact and in place. Neurological deficits are usually absent or mild, and surgical correction is often associated with favorable outcomes.
Myelomeningocele
This represents the most severe and clinically significant form. Both the meninges and spinal cord herniate through the defect, leading to substantial neurological deficits. Patients frequently exhibit motor and sensory impairments, neurogenic bladder and bowel dysfunction, and are commonly associated with hydrocephalus and Arnold–Chiari type II malformation.
Symptoms of Spina Bifida
Clinical manifestations vary depending on the level and extent of the lesion:
- Weakness or paralysis of the lower extremities
- Sensory deficits below the level of the lesion
- Impaired or absent ambulation
- Urinary and fecal incontinence due to neurogenic dysfunction
- Orthopedic deformities (e.g., clubfoot, hip dislocation, scoliosis)
- Visible lumbosacral mass or open spinal defect
- Signs of hydrocephalus, including progressive head enlargement
Causes and Risk Factors
The etiology of spina bifida is multifactorial, involving both genetic and environmental influences. Key risk factors include:
- Folate deficiency (most significant modifiable factor)
- Genetic predisposition
- Maternal diabetes and obesity
- Use of antiepileptic drugs (particularly valproate)
- Maternal hyperthermia during early pregnancy
- Inadequate prenatal care
Periconceptional folic acid supplementation has been shown to significantly reduce the incidence of neural tube defects.
Diagnosis of Spina Bifida
Prenatal Diagnosis
Advances in prenatal screening have enabled early and reliable detection of spina bifida.
Maternal Serum Alpha-Fetoprotein (MSAFP)
Measured between 15 and 20 weeks of gestation, elevated MSAFP levels suggest the presence of an open neural tube defect. While sensitive, this test is not specific and requires confirmatory imaging.
Ultrasonography
Second-trimester ultrasound is the primary diagnostic modality.
- Direct findings: vertebral defects, widened spinal canal, cystic protrusion
- Indirect cranial signs: the “lemon sign” (frontal bone scalloping) and the “banana sign” (cerebellar displacement)
These findings are strongly associated with myelomeningocele and often indicate concurrent Arnold–Chiari type II malformation.
Fetal Magnetic Resonance Imaging (MRI)
Fetal MRI is utilized when ultrasound findings are inconclusive. It provides detailed evaluation of lesion level, extent, and associated central nervous system anomalies, and is particularly valuable for surgical planning.
Amniocentesis
Measurement of AFP and acetylcholinesterase (AChE) levels in amniotic fluid supports the diagnosis. The presence of AChE is highly specific for open neural tube defects.
Postnatal Diagnosis
Although diagnosis is often evident at birth, further evaluation is necessary to define the extent of involvement.
Physical Examination
Typical findings include a lumbosacral sac or open lesion, along with motor and sensory deficits in the lower extremities.
Magnetic Resonance Imaging (MRI)
MRI provides comprehensive assessment of spinal cord anatomy, tethered cord, and associated anomalies such as lipomas or split cord malformations.
Computed Tomography (CT)
CT may assist in evaluating bony structures, although its use is limited due to radiation exposure.
Urodynamic Studies
These are essential for assessing neurogenic bladder dysfunction and guiding urological management.
Treatment of Spina Bifida
Management of spina bifida requires a multidisciplinary approach combining surgical intervention and long-term supportive care.
Prenatal (Fetal) Surgery
Fetal repair is considered in selected cases of myelomeningocele.
Objectives:
- Protection of exposed neural tissue
- Reduction of secondary neurological damage
- Decrease in hydrocephalus incidence
Benefits:
- Lower need for ventriculoperitoneal shunting
- Improved motor outcomes
Risks:
- Preterm delivery
- Uterine complications
- Maternal morbidity
Postnatal Surgical Management
Early Surgical Closure
Performed within the first 24–48 hours after birth.
Goals:
- Prevent infection
- Preserve neural tissue
- Restore anatomical integrity
Management of Hydrocephalus
Hydrocephalus is common in affected patients.
- Ventriculoperitoneal (VP) shunt placement remains the standard treatment
- Endoscopic third ventriculostomy may be considered in selected cases
Long-Term Multidisciplinary Care
Neurological Rehabilitation
Focuses on improving muscle strength, mobility, and functional independence.
Urological Management
- Clean intermittent catheterization
- Anticholinergic medications
- Surgical interventions when necessary
Management of Tethered Cord Syndrome
Surgical detethering is indicated in symptomatic patients.
Outlook and Long-Term Care
Spina bifida is a complex congenital disorder that can now be managed more effectively thanks to advances in prenatal diagnostic methods and surgical techniques. A multidisciplinary approach involving neurosurgery, perinatology, pediatrics, urology, and physical medicine and rehabilitation is essential to ensure a comprehensive care plan aimed at preserving and improving quality of life.
Frequently Asked Questions
What are the three main types of spina bifida?
The three principal forms are spina bifida occulta (the mildest and most common), meningocele, and myelomeningocele (the most severe). They differ in whether the meninges and spinal cord herniate through the vertebral defect and in the degree of neurological involvement.
What causes spina bifida?
The cause is multifactorial, involving both genetic and environmental factors. Recognized risk factors include folate deficiency, genetic predisposition, maternal diabetes or obesity, certain antiepileptic drugs such as valproate, maternal hyperthermia in early pregnancy, and inadequate prenatal care.
Can spina bifida be detected before birth?
Yes. Prenatal detection may involve maternal serum alpha-fetoprotein (MSAFP) screening, second-trimester ultrasonography (including the “lemon” and “banana” signs), fetal MRI when ultrasound is inconclusive, and amniocentesis measuring AFP and acetylcholinesterase.
Can spina bifida be treated with surgery before birth?
In selected cases of myelomeningocele, prenatal (fetal) surgery may be performed to protect exposed neural tissue. Reported benefits include a lower need for ventriculoperitoneal shunting and improved motor outcomes, while potential risks include preterm delivery and maternal complications.
Is spina bifida a neural tube defect?
Yes. Spina bifida belongs to the spectrum of neural tube defects and results from incomplete closure of the neural tube during early embryonic development.
Can spina bifida be prevented?
Periconceptional folic acid supplementation has been shown to significantly reduce the incidence of neural tube defects, making folate status the most significant modifiable factor.
Updated: July 17, 2026 | Editor: info@ilhanelmaci.com.tr