Vertebral problems in TOF/OA and VACTERL Text created in association with Robert Dickson, Professor and Head of the Department of Orthopaedic Surgery, the University of Leeds.
What is a vertebra? A vertebra is is one of many bones making up the spinal column or backbone. Our vertebrae are divided up into five types according to their location:
Cervical vertebrae are found below the base of the skull, in the neck Thoracic vertebrae are in the chest and each carry an articulation with a rib Lumbar vertebrae are designed to allow the flexibility that we have in the small of the back Sacral vertebrae are fused together to form the sacrum, which forms a joint with our pelvis Coccygeal vertebrae make up our ‘coccyx.’ Between the vertebrae are found structures which are commonly referred to as the ‘discs’ – more correctly ‘invertebral discs.’ These form the joints between the ‘vertebral bodies.’ The spine is, however, more than merely a flexible support for our torso; it houses the spinal cord through which the nerves carrying signals to and from our body run.
The cord runs through the spinal canal, within the vertebrae, and nerves emerge from it to our muscles, and return to it carrying sensory information from our skin and other body organs.
Vertebral anomalies Children are sometimes born with vertebrae which are only partly formed, (‘hemivertebrae’ or ‘wedge vertebrae’ – see illustration below) or vertebrae which are fused together (‘block vertebrae’). The so-called ‘butterfly vertebra’ is actually two hemivertebrae which have occurred at the same level.
Missing or extra vertebrae – often associated with an extra pair of ribs if located in the thoracic region of the spine – do not generally cause deformity or other problems. Another group of problems which wdo not cause a gross deformity but can be equally problematic are those which involve the shape of individual vertebrae in different ways –␣such as extra projections from the bone’s surface –␣and any abnormalities in the structures surrounding the spinal cord.
Do anomalies matter? The significance of vertebral anomalies is related to two things: their ability to cause spinal deformities, and their ability to create neurological problems.
Spinal deformities A visible deformity of the spine may be present at birth, as a direct result of the deformity causing a bend in the spine, or it may become obvious as the child grows, the unbalanced forces which the anomaly exerts on the surrounding vertebrae causing them to grow abnormally.
Types There are three categories of spinal deformity:
Scoliosis: a side-to-side curving of the spine when viewed from behind
Kyphosis: a forwards bending of the spine when viewed from the side
Lordosis: a backwards bending of the spine when viewed from the side.
These deformities may co-exist, and may be mild or severe in their appearance and effect on the individual’s life. If severe they may affect the function of organs in the chest (the heart and lungs) – however this is unlikely to develop after a child has reached the age of 5 years. An individual’s ability to sit or stand can also be affected simply due to the amount of deformity present.
Neurological problems Muscular weakness or loss of sensation may result from spinal deformities if they put pressure on the spinal cord, but can also be caused by abnormalities in the shape of individual vertebrae (either co- existant with spinal deformity or in its absence) or from various problems affecting the relationship of the spinal cord to the vertebrae (discussed under ‘spinal dysraphism’).
Spinal deformity Fortunately scoliosis is not painful at any stage throughout life. Sometimes kyphosis in adolescence can be painful but that usually settles at the end of spinal growth.
Assessing vertebral anomalies and spinal deformity In assessing a child with congenital vertebral anomalies who has a spinal deformity, several questions are asked: how bad is the deformity now? (and – if severe – is it causing neurological or cardiorespiratory signs?) and is it likely to get worse?
Whilst the current status of a deformity can be evaluated using a combination of physical examination and radiography (X-rays), it is not always possible to predict which anomalies are going to progress. Absent or additional vertebrae will not push the spine out of alignment and are therefore unlikely to cause deformity. However, multiple anomalies may either cancel one another out, or have an additive effect, and while most solitary hemivertebrae will not cause deformities which are progressive, this depends on their location in the spine – so each individual case needs to be assessed by an experienced orthopaedic surgeon.
Reassessment at regular intervals may be required for many children – and may need to be continued for many years, since the adolescent growth spurt is often a time when progression occurs rapidly.
The Cobb angle This is a measurement of the amount of deformity present, and is measured from radiographs (Xrays). A surgeon may take many views at a range of angles in order to see the deformity from different directions. An increasing Cobb angle is indicative of a worsening deformity.
Idiopathic scoliosis Scoliosis can develop in the absence of congenital vertebral anomalies; this is called ‘idiopathic scoliosis.’ TOF/VACTERL children may suffer this form of deformity – which can become apparent at varying ages and may either resolve spontaneously or progress and require treatment.
Treatment of spinal deformities Where a visible deformity is the only problem, and progression is not an issue, a decision may need to be made regarding how acceptable the deformity is to the individual (and/or the family). If it is acceptable, then no surgery will be required.
If a deformity is progressing rapidly or the underlying anomaly is of a type likely to worsen dramatically, then surgical intervention will be advised to halt this progression. The issue of acceptibility (as above) may also be relevant in order to decide whether only a halting of progression will be sufficient, or whether the spine additionally needs to be straightened from its current position. A deformity which is already causing problems for the chest organs or the spinal cord will inevitably require surgical treatment to straighten the spine. The exact surgical procedure will vary depending on the nature of the problem(s). Surgery may be required on the back or the front of the spine (or both), depending on where the anomaly lies and where it is having its effect on growth/deformity. The operation may involve removal of bone, grafting of bone from other locations in the body (often a rib or the rim of the pelvis) in order to cause vertebra to be fused together, or use of metal implants and screws. For some children, staged procedures will be necessary (i.e. one operation followed by another at an interval of a week or two afterwards) and some individuals may need to be prepared to undergo operations at different ages. Whereas body casts and splints are sometimes sufficient for the management of idiopathic scoliosis, there is no evidence that they are effective for children with congenital vertebral deformities, although they may in certain instances be useful for a short period before surgery. Traction devices may also be used for the same purpose in some patients. Bracing may be used for a while post-operatively, to support the surgical repair. Immediately after surgery, the child will require meticulous nursing care. With time, increasing movement will be encouraged and it is often surprising how quickly recovery progresses. Restriction of activities is often necessary for some months, with regular follow-up checks essential to ensure continued improvement.
Spinal dysraphism This is a term which refers to a number of different conditions with a common feature; they are all possible causes of ‘spinal cord tethering.’ After birth, the spinal cord extends further down the spinal column than it does in adulthood. This means that during a child’s growth, the end of the cord ‘migrates’ up the spinal column until it reaches its final position, between the 1st and 2nd lumbar vertebrae.
Anything which prevents this movement will put the cord under tension, and this has become known as ‘tethering.’
A small proportion of children with congenital vertebral anomalies may have a degree of tethering, so it is important to assess for this during growth – and especially important to make adequate checks prior to surgery to correct deformities, since straightening of a deformed spine may increase any tethering, with potentially serious consequences.
Causes of tethering Various problems can cause tethering, but the most common are:
Tethered conus The tapered end of the spinal cord is known as the ‘conus.’ This continues as the ‘filum terminalie’ which is attached to the coccygeal vertebrae. A shortening of the filum - usually associated with a thickening which can be seen on a special X-ray (a myelogram – where a contrast material is injected around the spinal cord so that it can be seen on a radiograph) will restrict the migration of the cord with growth. This problem is also known as ‘fatty filum.’
Diastematomyelia This is a congenital anomaly which projects into the spinal cord and may even cause it to be split into two. Since 10% of children with congenital spinal anomalies may have diastematomyelia, this must be excluded by careful examination of radiographs.
Intraspinal lipoma This is a fatty area within the spinal canal.
Dermoid cyst This is a cystic structure which is comprised of tissues originating from the skin; it may extend down to the spine.
Spinocutaneous fistula This much rarer problem is a connection between the skin and the structures around the spinal cord. It is a serious condition due to the risks of infection.
Signs of tethering Indications that a child has cord tethering may arise in various ways.
Skin An abnormally hairy patch of skin, a dimple (e.g. sacral dimple), a port wine stain or an area of scarring which is present at birth may all alert a doctor to possible causes of tethering. These problems act like a ‘warning sign’, indicating that further investigations are required and that additional signs may develop as the child grows unless corrective surgery is undertaken. Other problems usually do not present until the 2nd or 3rd year of life:
Problems VACTERL children may also have renal or anorectal problems which contribute to a lack of urinary control, however spinal cord tethering can also affect this function.
Lower limb abnormalities These either have the appearance of a ‘club foot’ or take the form of a limp due to an discrepancy in the size of the limbs. X-rays will show abnormalities of the spinal column, however a proper diagnosis cannot be made until a surgical exploration has been undertaken.
Treatment of tethering
Where the only problem is a tethered conus, this can be relatively easily released at surgery simply by cutting through the restricting filum. Other problems will require more involved sugery to remove the offending structure(s). Usually the surgeon will also inspect the filum when operating on problems further up the spine to ensure that there are not additional problems further down the cord. This can be performed using an endoscope (flexible telescope) which is inserted down alongside the spinal cord. As with spinal deformities, follow-up is important to ensure that no further problems are encountered.
Additional resources: The Scoliosis Association offers comprehensive information and a source of support for families of children with scoliosis. Scoliosis Association (UK) 2 Ivebury Court 323-327 Latimer Road London W10 6RA Tel: 020 8964 1166 Fax: 020 8964 5343 Website: http://www.scoliosis.org.uk