Spina Bifida Occulta and Open Spina Bifida - A Patient's Guide

Peer Reviewed

Introduction to Spina Bifida

Spina bifida is a defined as any abnormal development of the bones of the spine that display a typical pattern, with or without the involvement of the brain, nerves or covering of the nerves (meninges). It is the most common congenital spine abnormality. The term spina bifida covers a range of malformations that always include deformities of certain parts of the vertebrae, the spinous process and vertebral arch. Some have described this process as a failure of these bones to fuse during early fetal development.

spina bifida, anatomical black and white drawing indicating where deformity occurs

Most common locations are the lower thoracic, lumbar, and sacral spine. The cause behind this congenital malformation is not well understood. Data suggests that genetic factors play a predominant role, but nutritional and environmental factors may also contribute to the development of spina bifida.


Spina bifida is broken down into two categories: spina bifida occulta and open spina bifida. These subtypes are distinguished by the absence or presence of nerves, fluid that surrounds the nerves (CSF), and the meninges that are included within the deformity. See Table 1.

Table 1. Types of Spina Bifida

Type Description Incidence Examples
Spina bifida occulta
  • Bony abnormality seen by x-ray
  • Nerves may be involved when associated with skin changes or hairy patch
Relatively common (5-10% of general population) Figure 1
Open spina bifida
  • Usually seen at birth
  • Bony abnormality plus involvement of nerves, CSF, or meninges
About 10% of all patients with spina bifida Figures 2 and 3


spina bifida, hairy patch

Since there is no opening to the skin, spina bifida occulta can only be seen on x-ray or MRI. Certain clinical findings such as dimpling of the skin or a hairy patch at the base of the spine may trigger further investigation by a physician.

Underlying spinal nerve abnormalities can be seen in these situations. There is inconclusive evidence that this type of deformity is related to back pain, scoliosis, or nighttime bed-wetting. A large study showed that in patients not complaining of back pain, almost 20% had uncomplicated spina bifida occulta. If you have an abnormality on an x-ray, it does not always mean that this is causing your pain.


The diagnosis of open spina bifida is usually made at birth or during prenatal ultrasound screening. It accounts for about 10% of all patients with spina bifida. There can be a mass outside the body at the base of the spine containing nerves (myelomeningocele) or the nerves may be absent in the mass (meningocele). Usually the deformity is covered with a thin membrane (spina bifida cystica), or it can be open to the environment (spina bifida aperta) and drainage of spinal fluid is seen. mri, lipoma


spina bifida, meninges
spina bifida, meningocele


There is no specific treatment for occult spina bifida if the abnormality is limited to the bone. Usually these deformities are found at the last lumbar vertebrae (L5) or at the first sacral vertebrae (S1). However, deformities of the spine can lead to degenerative changes later in life that may require intervention.

Open spina bifida and underlying spinal abnormalities associated with occult spina bifida are treated by a neurosurgeon. The goal of surgery is to preserve the nerves, restore the normal anatomy, and close the defect. This delicate surgery is carefully performed under magnification while using special monitors to help identify the nerves. Surgery will help to reduce the risk of infection (meningitis) and reduce the progression of long-term disability.

spina bifida, surgery on a meningocele

Considerations for patients and their families

The diagnosis of spina bifida may be devastating for the parents of these children. The neurosurgeon’s role not only includes operative management but also education. Children born with a myelomeningocele (Figure 2) have a 90% chance of survival. Furthermore, they have an 80% chance of normal intelligence and around an 85% chance of walking with or without assistance. Long-term problems include: short stature, lack of leg development, scoliosis, and bowel and bladder difficulties.

There are many other conditions closely associated with open spina bifida. Approximately 80 to 90% of patients will develop hydrocephalus (increase in the size of the fluid filled spaces in the brain). This can be treated effectively, using a shunt (plastic tube under the skin from the brain to the abdomen) in the early stages of development. Children may have many other abnormalities, throughout their body, which must be recognized. Several medical and surgical specialties will contribute to the overall care of these children during their entire lives. It is essential to maintain a support network, not only for the patient, but also the family, in order to provide optimal outcomes for all patients with spina bifida.

For more information, please visit the Spina Bifida Association of America at www.sbaa.org

Updated on: 09/07/12
Randal R. Betz, MD
In this brief article, Dr. Shutack has provided a good review of Spina Bifida. Fortunately, most individuals who have spina bifida have the occult type and are asymptomatic. However, if neurologic dysfunction is associated with spina bifida then, in additional to neurosurgical follow-up, the patient will need to consult other medical specialists who will follow the patient's condition. These specialists may include a urologist for early monitoring of a neurologic (paralytic) bladder. Patients with spina bifida should be followed by a PMR physician (Physical Medicine and ) or a developmental pediatric physician so that normal function related to their age and neurologic can be monitored.

Further, a PMR physician assists the patient with activities of daily living and integration into society. In addition, the patient will need to be followed by an orthopaedic surgeon specifically for the development of scoliosis, hip subluxation and dislocation, paralytic fractures and for assistance in preventing joint contractures and maximizing function. Generally patients with spina bifida lead a productive life, but it is critical that they engage medical specialists with an interest and expertise in spina bifida in order to maximize their functional potential.