Spina Bifida

Spina bifida is a group of congenital defects of the spine developed during fetal stage. During the first month after conception, the embryonic structure called neural tube is formed which eventually develops into the baby's brain, spinal cord and the surrounding bony structure. In case of spina bifida, the lower part of the neural tube does not develop or fuse fully leading to abnormalities in brain or spinal cord. When the spinal column does not close properly around the baby's spinal cord the nerves start to protrude through the opening causing spina bifida.

Spina bifida is a broader term used for various conditions of the spine. The defect may range from very mild form which may not present itself with any symptoms to a severe one causing disability and disrupting the patient's normal life. There are broadly three types of spina bifida which are discussed below.

Spina bifida occulta

It is a very mild and most common form of spina bifida in which one or two vertebrae are left unfused. The portion of the spinal cord that is not enclosed by vertebrae is covered by skin. Occulta means 'hidden' and since the opening is hidden under the skin, the condition is referred as spina bifida occulta. However, in such cases, nerve roots and the spinal cord are not affected and hence, the person remains asymptotic.

Meningocele

In meningocele, the meninges (membranes that surround and protect the spinal cord) protrude through the spinal opening without affecting the spinal cord. Sometimes a layer of skin is formed over the opening. In few cases of meningocele, when the membranes push through the opening, they get filled with the spinal fluid forming a cyst. With this type of spina bifida, one may experience only mild symptoms or in few cases the damage may be very severe.

Myelomeningocele

Myelomeningocele is the most severe form of spina bifida. Myelomeningocele, almost certainly leads to mental and physical disabilities. The severity of the damage depends upon the site of the opening on the spine as the portion that is below the opening becomes dysfunctional. The higher the location of the opening, the greater will be the impact on the functioning of the body.

Symptoms

The symptoms vary depending upon the type of the spina bifida. In case of spina bifida occulta, the child remains largely asymptotic and there may be a birthmark, a patch, a dimple or hair growth on the skin under which the vertebrae is not joined properly. This condition is usually diagnosed during an ultrasound performed for some other purpose.

Meningocele may or may not show any symptoms. Partial paralysis with urinary and bowel problems are usually associated with meningocele. This condition is diagnosed before birth through fetal ultrasound and other tests. This condition is diagnosed when a test called maternal serum alpha-fetoprotein is performed on pregnant woman.

Treatment

Spina bifida occulta doesn't require any treatment; however other two conditions are always treated surgically. In case of meningocele, surgery involves pushing back the membranes into the place and closing the vertebrates. Babies born with Myelomeningocele are operated within 24 to 48 hours of their birth. The surgery is mainly performed to prevent infection and further damage to the spinal cord. If the baby develops too much cerebrospinal fluid which is known as hydrocephalus, a shunt will be placed as part of the treatment. In recent times spina bifida is also treated through fetal surgery, wherein the uterus is surgically opened to correct the spine defect and immediately closed back. Spina bifida, particularly Myelomeningocele type, requires lifelong medical support as children with such a condition continue to suffer from neurological, orthopaedic and bladder and bowel related problems.

Kyphoplasty

Kyphoplasty is similar to Vertebroplasty with a bit of variation in the technique used in injecting cement into the collapsed vertebral bones. Both methods aim at alleviating the pain caused by recent vertebral fracture which has stopped responding to conventional treatment of pain medication and bed rest. Kyphoplasty makes use of an inflatable balloon to create a cavity inside the collapsed vertebrae and is eventually filled with special bone cement to stabilize the fracture.

Percutaneous Balloon Kyphoplasty (BKP) is primarily used to treat vertebral compression fractures arising out of issues like osteoporosis, metastases or trauma.

Kyphoplasty is believed to be a superior procedure/ Interventional radiologic technique when compared to vertebroplasty as it claims the additional advantage of correcting the kyphosis (stooped back) and regaining the height lost, to some extent. A balloon (bone tamp) that can withstand high pressures is inserted and inflated to achieve the height. When the height and alignment of spine are corrected, the stress in the adjacent vertebral segments is reduced. Then there are lesser chances of adjacent vertebral fractures.

Taking the aid of image guided X-Ray machine, a hollow needle called Trocar is passed through the spinal muscle and positioned at the fractured back bone. This needle is inserted at an angle to avoid the spinal cord. Once the needle reaches the right position, the balloon is inflated to help gain the normal height of the vertebrae. Most often, two balloons are used to provide good support while lifting the collapsed vertebrae back to its normal position.

Inflated balloons, create a cavity/space inside vertebra while raising the collapsed bone. The balloons are slowly deflated and withdrawn. Bone cement (such as polymethylmethacrylate (PMMA)) is then carefully injected into the cavity under pressure filling the deeper side to the upper side of the cavity. Filling cement needs lot of care and skill as excess pressure or quantity may cause the cement to leak into adjacent areas. Cement hardens within 10 to 20 minutes forming an internal cast that holds the vertebral body. The needle is pulled off carefully before the cement hardens. The incision is closed with sterilized strips. The procedure takes about an hour to complete and is carried out both as inpatient or outpatient procedure. The patient is advised to take rest for a day even though he is discharged the same day after a brief period of observation. Some patients have reported Transient Hyperalgesia (abnormal sensitivity to pain) due to polymerization of the acrylic cement used in the procedure.

Vertebroplasty

Vertebroplasty is a medical procedure that is employed to treat compression fractures in the vertebrae. The procedure involves injecting medical grade bone cement into the vertebral bones that have been damaged or collapsed. This procedure offers support. Osteoporosis is the most common cause for fractured spine bones. Spinal tumors, traumatic injuries and rarely Hemangioma are some of the other causes for vertebral compression fractures (VCF) of the spine. However osteoporosis-led vertebral fracture is the most common clinical situation in which vertebroplasty is used. These fractures cause severe pain and reduce the mobility of the patient. Vertebroplasty is a recently developed image-guided surgical procedure with minimum invasion that promises faster pain relief. Vertebroplasty becomes the best alternative choice when conservative pain management does not provide relief to the patient. It is a simple day-care procedure that not only helps in stabilizing the broken bone but also prevents further compression of the affected vertebral area.

Vertebroplasty Procedure

An MRI scan is performed on the patient prior to the procedure to confirm the fracture. If MRI scan is not recommended for the patient due to any specific medical condition, CT scan is carried out to assess the exact location of the fracture. If the patient is on any kind of medication, it should be informed to the doctor. Anticoagulation medicines or blood thinners have to be stopped at least five days before the surgery. Vertebroplasty is performed under local anesthesia with sedation by an Interventional radiologist or neuroradiologist. He should be well trained in fluoroscopically guided needle placement and should be able to deliver the cement to the exact position skillfully.

The patient is made to lie face down during the procedure. A small hollow point needle is positioned into the crushed bone. The doctor navigates the needle into position using a . Once the needle is in position, bone cement is directly injected into the collapsed bone to secure it. It is a special cement called polymethylmethacrylate (PMMA) that hardens within 10 to 20 minutes and restores the strength and shape of the vertebrae alleviating the pain caused due to compression. Though PMMA cement is the most widely used ingredient to repair vertebral fractures, other new substances such as cortoss (an injectable, non-resorbable, polymer composite that is designed to mimic cortical bone) are being explored in place of PMMA cement as excess polymethylmethacrylate cement can become toxic in the body. More than one fracture can be fixed at the same sitting. Vertebroplasty reduces the pain instantly and helps the patient to return to normal activity in a short period of time. Few hours of rest is recommended soon after the procedure; however the patient can be discharged the same day.

Vertebroplasty is generally a safe procedure. But in rare cases, the cement may leak into adjacent areas leading to complications. If the leaked cement enters the vein and travels to the lungs, it will cause serious pulmonary problems. In worst cases, cement leak may press upon the spinal cord or compress nerves leading to nerve damage. It may also require further surgery to treat the condition. Possibility of infection, allergy and bleeding are some of the other risks associated with Vertebroplasty. Vertebroplasty is not a recommended treatment for herniated disks or arthritis related back pain.

Tags: #Spina Bifida #Kyphoplasty #Vertebroplasty