Congenital malformations of the spine are defects or disorders of the spine that are present from birth. These malformations may be mild or severe and are often corrected by surgery.
Chiari malformation is a congenital anomaly whose acquired forms are also known. The anomaly is categorized in order of severity as; types I, II, III, and IV. These malformations are closely associated with syringomyelia and hydromyelia. The majority of these cases are asymptomatic and are often detected coincidently among patients who have undergone diagnostic imaging for unrelated reasons.
This malformation is characterized by further downward displacement of the lower brain and brain stem into the cervical spinal canal, as well as elongation of the upper brain stem. This type occurs almost exclusively in patients with myelomeningocele which is a congenital condition in which the spinal cord and column do not close properly during fetal development, resulting in an open spinal cord defect at birth. Other abnormalities commonly associated with myelomeningocele include hydrocephalus, cardiovascular abnormalities, as well as gastrointestinal abnormalities, and genitourinary abnormalities.
This includes a form of dysraphism with a portion of the cerebellum and/or brainstem pushing out through a defect in the back of the head or neck.
This is the most severe form and the rarest. The cerebellum fails to develop normally. There may be other associated malformations of the brain and brainstem.
Encephalocele: a congenital malformation characterized by herniation of the brain and/or meninges through a defect in the skull.
Arachnoid Cysts are congenital lesions that occur as a result of the splitting of the arachnoid membrane. The cysts are fluid-filled sacs, not tumors, appearing in one of the three layers of tissue covering the central nervous system.
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Although most of the people with Chiari I malformation has no symptoms some may show any of the following symptoms:
This is a surgical emergency needing a multidisciplinary approach in Neonatal ICU.
There are several tests that can help diagnose and determine the extent of Chiari malformation and syringomyelia including:
Almost all types of congenital malformations need surgical treatment if they are in the symptomatic stage. Asymptomatic malformations should not be operated.
Surgical treatment of Chiari malformations and syringomyelia
Treatment of Chiari malformations and syringomyelia depends upon the type of malformation and its progression in the form of anatomy changes or symptoms. Asymptomatic Chiari malformations should not be operated. If the malformation is symptomatic or is causing a syrinx, treatment is usually recommended by an urgent multidisciplinary approach.
Goals of Surgery for Chiari malformations and syringomyelia
Correct the physical defects or malformations present in the spine
Relieve the symptoms
Stop the progression of the syrinx or symptoms
Maximizing the functionality of the individual
Surgical treatment of Chiari malformations include
Only local decompression of the overlying bones
Decompression of the bones and release of the dura
Decompression of the bone and dura
Duraplasty
The objective of surgery Chiari malformation is:
Optimal decompression of nerve tissue
Reconstruction of normal CSF flow around and behind the cerebellum
Decompression is performed under general anesthesia. It consists of removing the back of the foramen magnum and often the back of the first vertebrae to the point where the cerebellar tonsils end. This provides more space for the brainstem, spinal cord, and descended cerebellar components. A tissue graft is often spliced into this opening to provide even more room for the unimpeded passage of CSF. Care is taken to avoid a breach of the arachnoid membrane. Occasionally, the cavity within the spinal cord resulting from hydromyelia can be drained with a diverting shunt tube. This tube can divert the fluid from inside the spinal cord to outside the cord, or be directed to either the chest or abdominal cavity. These procedures can be done together or separately.
Surgical Treatments :
Almost all types of congenital malformations need surgical treatment if they are in the symptomatic stage. Asymptomatic malformations should not be operated.
Treatment of Chiari malformations and syringomyelia depends upon the type of malformation and its progression in the form of anatomy changes or symptoms. Asymptomatic Chiari malformations should not be operated. If the malformation is symptomatic or is causing a syrinx, treatment is usually recommended by an urgent multidisciplinary approach.
Decompression is performed under general anesthesia. It consists of removing the back of the foramen magnum and often the back of the first vertebrae to the point where the cerebellar tonsils end. This provides more space for the brainstem, spinal cord, and descended cerebellar components. A tissue graft is often spliced into this opening to provide even more room for the unimpeded passage of CSF. Care is taken to avoid a breach of the arachnoid membrane. Occasionally, the cavity within the spinal cord resulting from hydromyelia can be drained with a diverting shunt tube. This tube can divert the fluid from inside the spinal cord to outside the cord, or be directed to either the chest or abdominal cavity. These procedures can be done together or separately.
The benefits of surgery should always be weighed carefully against its risks. Although some patients experience a reduction in their symptoms, there is no guarantee that surgery will help every individual. Nerve damage that has already occurred usually cannot be reversed. Some patients may need repeated surgeries, while others may not achieve symptom relief.
Surgery is the most commonly recommended treatment for encephaloceles. It is usually done within a few months of birth. A craniotomy is performed to remove a piece of bone from the skull, followed by the removal of dura mater. Meanwhile, any membrane, or brain tissue, or fluid that is out of the skull is replaced. The sac surrounding the skull is also removed. Then the dura mater is closed. If possible, the skull is closed up using the removed piece of bone. Any large hole in the skull may be treated using an artificial plate.
Asymptomatic arachnoid cysts do not require treatment. But in the case of symptomatic cysts treatment is necessary. Various methods used to treat arachnoid cysts are:
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