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There are various types of spinal malformations which in most cases are the result of a disorder during the development of the spinal cord. The spectrum of different types of spinal malformations ranges from those with no or minimal impairment to severe neurological symptoms.
During the formation of the central nervous system, the nerve tissue invaginates so that a tube-shaped structure (neural tube) is formed from a surface tissue layer. This process starts in the chest region and continues toward the head and leg. Finally, between the 23rd and 26th day of pregnancy, the newly formed lower end of the future spinal cord fuses in the area of the sacral bone. This explains the fact that the vast majority of malformations are found at the lower end of the spinal column (in the lumbar or sacral region).
In most spinal malformations, closure of the the bony spinal column is impeded. This disorder is referred to by the umbrella term spina bifida. A further subdivision can be made based on whether, in the scope of the malformation, spinal cord tissue is exposed on the body's surface (spina bifida aperta) or covered by skin (spina bifida occulta).
Spina Bifida Aperta - Myelomeningocele
A part of the spinal malformation occurs when the spinal cord does not invaginate and the spinal cord tissue is exposed with its sheaths at birth on the body's surface (myelomeningocele, spina bifida aperta). Cerebrospinal fluid regularly leaks out of an open spinal malformation. Because spinal cord tissue is exposed on the body's surface and due to the CSF leakage there is a connection to the ventricles with the risk of meningitis, all children born with an open spinal malformation should be operated on as soon as possible. This is done, as soon as the baby's condition allows, within the first few days of life. The goal of the operation is to reconstruct the spinal cord and its sheaths in as anatomically correct a manner as possible and to cosmetically cover the skin defect. Currently, a controlled study is being carried out on the possibility of prenatal treatment for myelomeningoceles (In Utero Treatment during Pregnancy – MOMS-tria).
Spina Bifida Occulta
The term spina bifida occulta refers to all types of spinal malformations which are covered by skin. The term covers a broad spectrum of various types which can range from simple osseous vertebral arch closure disorders without clinical significance to complex malformations which can also affect the spinal cord and its sheaths. In most instances, changes in the skin covering the malformation (e.g. hair growth, pit-shaped retraction of the skin, birthmarks, lipomas) are visible. Some representative types of these are described below.
Split Cord Malformation - Diastematomyelia
Split cord malformation refers to a rare malformation of the spinal cord in which the spinal cord is split into two halves by a strand of connective tissue or a bony spur. As a result of the strand running through both halves of the spinal cord, there is also a local fixation of the spinal cord which can lead to neurological symptoms. In general, surgery is indicated for diagnosed split cord malformations. In this procedure, the corresponding strand is cut out, all other anchors of the spinal cord removed and the spinal meninges are reconstructed.
Spinal Lipoma - Lipomyelomeningocele
Spinal lipomas are accumulations of fatty tissue in the spinal canal (the canal inside the spinal column through which the spinal cord runs in its meninges) which directly communicate with the the spinal cord and the nerves originating therein. Often there is also a circumscribed defect in the spinal meninges across which the fatty tissue in the spinal canal directly connects to the surrounding fatty tissue. These spinal fatty tissue buildups are usually associated with more and less severe malformations of the lower end of the spinal cord or displacement of segments of the spinal cord out of the spinal canal (lipomyelomeningoceles). As a result of the direct contact with the fatty tissue, there is necessarily a local fixation of the spinal cord (see tethered cord) which can be significant during the child's development and can lead to neurological symptoms. For this reason, a microsurgical procedure may indicated whose goal is the complete removal of the anchorage of the spinal cord and the reconstruction of the spinal meninges. The fatty tissue portions are removed to the greatest possible extent.
Dermal sinus refers to a pathway covered in skin which stretches from a small pit on the surface of the back to the deeper structures. There it extends all the way to the spinal canal, passes through the spinal meninges and is usually anchored to the conus (the bottom end) of the spinal cord. Since, through this sinus, there is a direct connection to the cerebrospinal fluid, affected children may become prone to meningitis. For this reason, an operation in which the pathway is followed to its fixation point on the spinal cord, separated and completely removed.
Tethered Cord is an umbrella term which refers to all clinical conditions in which the spinal cord is tethered to its sheaths or surrounding tissue. This is particularly significant in children since a tethered cord becomes subjected to mechanical stress as the child grows which can bring about mechanical symptoms. Generally we differentiate between primary and secondary tethered cord syndrome. Primary tethered cord syndrome comprises the above-mentioned clinical situations (split cord malformation, spinal lipoma, lipomyelomeningocele, dermal sinus, thickened filum terminale) in which there is a congenital fixation of the spinal cord. Secondary tethered cord syndrome describes conditions in which, due to prior operations (often after closure of an open myelomeningocele) or regrowth after injuries, the spinal cord is fixed (tethered). The need for neurosurgical treatment of patients with tethered cord arises when neurological symptoms occur. In some forms of primary tethered cord syndrome, a preventative microsurgical operation is indicated. The aim of the surgical procedure is to remove all "anchors" of the spinal cord to surrounding tissue and reconstruct the spinal meninges to prevent future regrowths. All types of tethered cord syndrome are routinely and frequently treated and microsurgically operated in the pediatric neurosurgery department. In order to increase safety for the children receiving treatment, electrophysiological monitoring is used during the operation.