Spinal dysraphism describes a group of birth differences affecting the spine, spinal cord, or nerve roots. This condition develops very early in pregnancy, around the third to sixth week of fetal development, when the neural tube, which forms the brain and spinal cord, does not close completely. These conditions are often referred to as neural tube defects and can vary significantly in severity and presentation.
Understanding the Different Forms
Spinal dysraphism manifests in open and closed types, distinguished by whether the spinal cord and its coverings are exposed. Open spinal dysraphism, or spina bifida aperta, involves a visible lesion where neural elements are exposed through a skin defect. The most common and severe form is myelomeningocele, where the spinal cord and its membranes protrude into a sac outside the body. This exposure often leads to nerve damage, impacting movement, sensation, and bladder or bowel function.
Meningocele is another open form, involving a fluid-filled sac protruding through an opening in the back. This sac contains only protective membranes and cerebrospinal fluid, without the spinal cord or nerves. Meningoceles usually result in minimal nerve damage, leading to less severe symptoms than myelomeningocele. Closed spinal dysraphism, or spina bifida occulta, means the malformation is covered by skin, though subtle external signs may be present.
Types of closed spinal dysraphism include tethered cord syndrome, where the spinal cord is abnormally attached or restricted within the spinal canal. This restriction can stretch the spinal cord as a child grows, potentially causing neurological problems like weakness, sensory loss, or issues with bladder and bowel control. Lipomyelomeningocele involves an abnormal fatty growth attached to the spinal cord, which can also lead to tethering. A dermal sinus tract is an abnormal channel from the skin surface towards the spinal canal, sometimes associated with cysts or an increased risk of infection. Less common forms include split cord malformation (diastematomyelia), where the spinal cord is divided lengthwise, often by a bony or cartilaginous septum.
Factors Contributing to Development
Spinal dysraphism development is influenced by several factors, though the exact cause often remains unknown. A primary factor is folic acid deficiency, a B vitamin. Adequate folic acid intake before and during early pregnancy significantly reduces the risk of neural tube defects. Many cases are considered “folic acid-sensitive,” emphasizing the importance of prenatal folic acid supplementation.
Genetic predispositions also play a role, as a family history of neural tube defects can increase risk. However, most affected infants are born to parents with no known family history. Environmental factors include certain medications, such as some anti-seizure drugs, which can interfere with folate use.
Other potential environmental risk factors include uncontrolled maternal diabetes and obesity during pregnancy. Elevated maternal body temperature in early pregnancy has also been suggested as a possible factor.
Identifying Spinal Dysraphism
Spinal dysraphism can be identified using various diagnostic methods, both before and after birth. Prenatal diagnosis often begins with maternal blood tests, such as maternal serum alpha-fetoprotein (MSAFP) screening, typically performed around 15 to 18 weeks of gestation. Elevated alpha-fetoprotein levels, a protein produced by the developing fetus, can indicate an increased risk of neural tube defects. If MSAFP results are abnormal, further testing is usually recommended.
Prenatal ultrasound is a common tool for visualizing spinal defects and detecting structural abnormalities in the fetal spine and spinal cord. For confirmation or more detailed assessment, amniocentesis may be performed, analyzing amniotic fluid for elevated AFP levels. Fetal magnetic resonance imaging (MRI) provides detailed images of the spinal cord and surrounding tissues, especially for conditions like meningocele or myelomeningocele.
After birth, spinal dysraphism may be identified by visible signs, particularly in open forms like myelomeningocele, which presents as a sac on the baby’s back. Closed forms may have subtle skin anomalies over the affected area, such as dimples, hair tufts, or birthmarks. Neurological symptoms like weakness, numbness in the legs, or issues with bladder and bowel function can also prompt investigation. Postnatal imaging, including MRI, CT scans, and X-rays, helps confirm and characterize the condition. MRI offers detailed visualization of soft tissues, while CT scans assess bony abnormalities.
Support and Care Approaches
Management of spinal dysraphism often involves surgical intervention to address the physical defect and prevent further damage. For open forms like myelomeningocele, surgery is performed soon after birth, or sometimes prenatally, to close the spinal defect, protect the spinal cord from further injury, and reduce infection risk. For tethered cord syndrome, surgery aims to free the spinal cord from abnormal attachments, allowing more normal movement.
A multidisciplinary team approach provides comprehensive care, involving specialists such as neurosurgeons, urologists, orthopedists, physical therapists, and social workers. This collaborative model ensures all aspects of the condition, from neurological and orthopedic issues to bladder and bowel management, are addressed. Rehabilitation and therapy are key components of long-term care. Physical therapy helps improve mobility, strength, and balance, often incorporating assistive devices as needed. Occupational therapy focuses on enhancing daily living skills and independence.
Managing complications is a significant part of ongoing care. Hydrocephalus, a buildup of fluid in the brain, often occurs with myelomeningocele and may require a shunt to drain excess fluid. Bladder and bowel dysfunction are common and require specialized management. Orthopedic problems, such as scoliosis or foot deformities, are also addressed through various interventions. Care for individuals with spinal dysraphism is often lifelong, focusing on maximizing independence, improving quality of life, and preventing neurological deterioration.