The developing nervous system forms from a sheet of cells in the embryo which fold on themselves to form a tube, the neural tube. Normally, this tube closes off completely. However, in some cases the closure and normal development of the neural tube does not proceed correctly. In general, the malformations that result from this abnormality in development are termed spina bifida. However, the resulting malformation can vary from mild and innocuous to very severe and life-threatening. Spina bifida occulta represents the most mild form of spina bifida. Occulta comes from the same word root as occult, which can mean "cut off from view by interposing something". This form of spina bifida is called occult because it is not obvious by just examining a patient. More severe forms of spina bifida are far from occult, being very obvious on physical examination of the patient's back. Therefore, this term is used to describe these most mild and hard to detect forms of spina bifida. This form of spina bifida involves just the bony part of the spine. The actual nervous system structures, the spinal cord and spinal nerves, and the coverings of the spinal cord, all develop normally. The only malformation is an incomplete closure of the bone overlaying the back side of the spinal canal. This defect in the bone generally just occurs at one small level in the lower back. Some patients who learn they have it worry that they will be paralyzed by damage to the spinal cord through the opening in the bone. They worry that pushing too hard on their back will cause injury. However, the spinal cord and spine are not right at the surface. There is muscle and other soft-tissues separating the skin of the back from the spinal column. Additionally, these openings are generally very small. As a generalization, injury associated with these malformations is very rare. In rare cases the bony abnormality may be more severe and/or associated with other abnormalities of the spine. For example, a spinal cord lipoma (a fatty tumor) or cyst can present along with the bony defect. These cases are generally termed an occult spinal dysraphism rather than spina bifida occulta. In some cases, particularly those with more severe malformations such as a spinal dysraphism, some small stigmata of the disorder will be visible on the skin of the back over the area. This can be a small dimple, a tuft of hair or other abnormality. However, in many cases of pure spina bifida occulta there is no obvious superficial mark. In the case of more severe malformations of the spine or spinal cord, treatment may be necessary to deal with the deformity or to prevent deterioration of neurological functioning. Each case should be assessed and discussed with the patient with a qualified physician. The meninges are the coverings of the brain and spinal cord, consisting of three layers, the dura mater, the arachnoid membrane and the pia mater, from outside to in. This malformation is due to the abnormal development of the outermost coverings of the spinal cord, including the arachnoid, dura and the outer bony and soft tissue parts of the spine. Normally in development, the nervous system develops from a plate of cells that folds to become a tube, the neural tube. If the lower end of the tube does not close normally, it can lead to various forms of spina bifida, including a meningocele. A meningocele represents a moderate form of spina bifida. The most severe form is a myelomeningocelewhich includes involvement of the spinal cord. The most mild form is spina bifida occulta, which does not involve any of the nervous system structures or the meninges, just the bony spine in the lower back. The most common location for this malformation is the lumbar spine, the lower back. Therefore, the primary problems with this deformity are cosmetic. However, if large, the sac on the back can interfere with normal function and development and can be quite a stigmatizing malformation. In rare cases when the skin over the sac is not fully developed, the sac can have a tendency to leak or rupture, leading to leakage of cerebrospinal fluid. This can lead to headache and, more importantly, infection such as meningitis. In these cases the diagnosis and treatment is much more urgent and a medical necessity. Each patient is different and these malformations vary in size and location somewhat. Therefore, each individual patient's treatment plan should be discussed with their own personal physicians.What Is It?
Spina Bifida Occulta is a congenital malformation of the developing spinal column which usually is asymptomatic and does not present medical problems.What Types of Symptoms Are Typical?
In true spina bifida occulta, the patient generally has no symptoms. As mentioned above, the malformation does not involve the spinal cord or spinal nerves.How Is The Diagnosis Typically Made?
Spina bifida occulta is relatively common. However, most people never know they have it unless they have imaging studies of the back for some other reason. It is often diagnosed when a patient, child or adult, has an x-ray, CT scan or MRI scan of the lower back. The opening in the bone can be visualized on most of such imaging studies.What Are Some Common Treatments?
True, pure spina bifida occulta which does not cause any symptoms generally does not require any treatment.Meningocele
What Is It?
A meningocele is a form of spina bifida. It is a congenital malformation that arises from an error in the normal development of the central nervous system, particularly the spinal cord and spine. It is an out-pouching of the coverings of the spinal cord that results in a defect in the bone and soft-tissue coverings of the back part of the spine. Therefore, this sac filled with cerebrospinal fluid can lead to a bulging mass on the back. The malformation does not include any malformation of the spinal cord itself or any of the spinal nerves.What Types of Symptoms Are Typical?
Because, by definition, a meningocele does not include any malformation of the spinal cord, typically there are not significant neurological symptoms of this malformation. The typical presentation is a bulging sac on the lower back in a newborn child. This can be associated with some deformity of the spine. Generally, if the spinal cord and/or spinal nerves are involved and cause neurological symptoms in the legs, this should be classified as amyelomeningocele, not a meningocele, which only includes the coverings of the spinal cord, not the cord itself.How Is The Diagnosis Typically Made?
Most meningocele are noticeable at birth. This generally leads to some form of imaging study such as a CT scan or MRI scan. These, particularly the MRI, can help to identify which parts of the spinal column are involved in the malformation and distinguish it from other forms of spina bifida such as a myelomeningocele. If any of the spinal cord and spinal nerves are involved in the sac, it is termed a myelomeningocele.What Are Some Common Treatments?
Most cases of meningocele are recommended for treatment as soon after birth as possible. In the case of a sac which is leaking fluid, the treatment is more urgent. Generally, treatment includes a surgical procedure to close and remove the bulging sac of meninges and to re-construct the soft-tissue covering of the back.
Wednesday, March 31, 2010
Labels: Spina Bifida Occulta Meningocele
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