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The Chiari malformations type I (CMI) is a mostly congenital structural anomaly in the area of the cerebellum, brain stem and at the transition to the spinal cord. The so-called cerebellar tonsils or cerebellar tonsils are located more than five millimetres deep in the spinal canal, either with or without the brain stem (so-called cerebellar tonsil ectopia).
CMI occurs in around 1 to 3 per cent of the total population and is therefore relatively rare.
Symptoms that require treatment only occur in 10 per cent of cases. 90 per cent of CMI cases are incidental findings and do not require any treatment.
The causes of congenital CMI are not yet fully understood. There are several theories on the development of CMI. However, none of them is yet able to cover all manifestations. One of the theories attributes the occurrence of congenital CMI to a change in the genetic material (mutation) during the development of the nervous system. This spontaneous mutation would disrupt correct further development. Inheritance is not observed.
Another theory attributes the development of CMI to the confined space in the posterior fossa (back of the head) that exists during the development of the nervous system. The narrowness can lead to the brain structures there being squeezed through the opening that connects the spinal cord and the skull (foramen magnum).
Certain clinical pictures can also lead to CMI. This is referred to as secondary CMI. Brain tumours, hydrocephalus (hydrocephalus), cerebrospinal fluid loss syndrome (spontaneous loss of cerebrospinal fluid, typically in the area of the back after a lumbar puncture) and adhesion of the spinal cord to the surrounding structures (so-called tethered cord) can all lead to secondary CMI. In such cases, the cause should be treated first. CMI can also occur more frequently in combination with certain syndromes (Robin sequence, neurofibromatosis I type Recklinghausen and Noonan syndrome).
One Syringomyelia describes a fluid-filled cavity within the spinal cord and often occurs together with CMI. However, it can also be due to other causes: infectious, inflammatory, traumatic or due to hydrocephalus (hydrocephalus) or a mass (e.g. tumour). Syringomyelia in the context of CMI probably occurs when CMI leads to increased pressure in the brain, causing cerebrospinal fluid to leak into the spinal cord. This pressure builds up when the backflow of cerebrospinal fluid into the skull is blocked at the junction between the spinal cord and the brain. Over time, the accumulated fluid is pressed into the surrounding tissue. This leads to swelling of the tissue (oedema) and as a result the oedema expands the spinal cord (so-called syrinx or syringomyelia).
90 per cent of CMI cases are «incidental Chiari malformations», i.e. there are no symptoms. In symptomatic cases, the typical signs are neck pain radiating to the back of the head and numbness in the fingers and tips of the toes, for example when coughing, sneezing or straining. Other, rarer symptoms include a deformation of the back (scoliosis), the appearance of hydrocephalus and cranial nerve deficits, which manifest themselves as hoarseness, muteness, swallowing problems, repeated swallowing, abnormal eye movements, muscle weakness or sleep apnoea (cessation of spontaneous breathing during sleep).
The symptoms can appear in infancy, but also in adolescence or early adulthood.
Syringomyelia shows a wide range of symptoms. In some cases, there are no symptoms at all. However, there may also be pain or loss of pain sensation or temperature perception. Other symptoms may include unsteady gait, problems with urination or defecation (incontinence) and muscular weakness in the arms or legs. More rarely, syringomyelia can lead to breathing and swallowing problems.
If CMI or syringomyelia is suspected, magnetic resonance imaging (MRI) of the head and spine is performed. CMI or syringomyelia is often detected by chance during an MRI of the head, but if there are no symptoms, this incidental finding does not require treatment. CMI can also be detected during pregnancy with a prenatal ultrasound.
If CMI is diagnosed on MRI, possible causes for this (tumour, tethered cord, CSF loss syndrome, hydrocephalus, etc.) should be ruled out. This can be done with an MRI examination of the entire spinal axis (spinal column and head). In the case of symptomatic CMI, we will arrange for your child to undergo further examinations by our colleagues in ophthalmology, ear, nose and throat medicine, paediatric neurology and possibly sleep medicine to ensure that the symptoms are caused by the CMI.
When diagnosing syringomyelia, possible causes must also be ruled out by means of an MRI examination of the entire spinal axis. If the syringomyelia causes symptoms, we will have your child assessed by colleagues from paediatric neurology and possibly paediatric urology and nephrology, i.e. by specialists in the urinary tract and kidneys. An ultrasound examination of the bladder and/or kidneys may also be necessary.
CMI discovered by chance does not usually require treatment. The course of the disease can be monitored clinically and by MRI after one year. If the situation is stable, there is usually no need for further follow-up checks.
Surgical treatment is recommended for symptoms typical of CMI. The aim of surgical therapy is to relieve the ectopia in the transition between the brain and spinal cord. To do this, a part of the skull bone at the transition from the back of the head to the neck (so-called Extradural foramen magnum decompression) and the posterior parts of the uppermost vertebral bodies in the neck (known as a laminectomy) are removed to create additional space for the brain and brain stem. It may also be necessary to open the meninges (dura) and possibly even reduce or remove the cerebellar tonsils to create even more space. This is known as Intradural foramen magnum decompression is called. These operations reduce the pressure in the head.
The child is operated on in the prone position under anaesthetic. An incision is made at the back of the skull and upper neck at the junction with the spinal cord and an access to the junction is opened there. A hole is then made at the back of the skull (craniotomy) and the spinous process of the first cervical vertebra is removed. If necessary, the meninges are then opened to widen the confined space. When the meninges are opened, a so-called Durapatch is sutured into place. This is an artificial meninges that is sutured to the incision edges of the real, opened meninges and thus seals the meninges again. The skin is then closed again. The entire operation takes about 2 to 3 hours. Complications of a foramen magnum decompression are rare (approx. 6%) and include neck pain and headaches as well as the risk of a cerebrospinal fluid leak and a pseudomeningocele (accumulation of cerebrospinal fluid under the skin).
If there is an accompanying syringomyelia, this can also be remedied by CMI surgery. If this is not the case, syringomyelia surgery is another option for draining the excess cerebrospinal fluid from the spinal cord. This involves inserting a drainage tube (so-called «Syringo-subarachnoid shunt») is inserted into the space between the spinal cord and the meninges (subarachnoid space). The fluid can either drain through this tube into the pulmonary pleura (so-called «Syringo-pleural shunt») or into the abdominal cavity (so-called «Syringo-peritoneal shunt»).
The complication rate of syringomyelia surgery is low and occurs in around 3-5% of cases. Complications can occur due to injuries to the spinal cord, which can lead to a loss of temperature or sensory perception or to muscular deficits. There may also be a leak in the drainage tube through which cerebrospinal fluid escapes. In rare cases, the drainage tube can also become blocked and a new syringomyelia can occur, making further surgery necessary.
During the entire hospital stay, your child will be looked after by our paediatric neurosurgery team at UKBB. Your child will be admitted one day before the operation and will be examined again by our team. Your child will be operated on the next day and will then be transferred to the intensive care unit for monitoring.
On the day of the operation, a companion from the Pro UKBB Foundation's parent support service (BELOP) will be at your disposal. She will accompany you until your child has fallen asleep and show you where he or she will wake up. In between, she will help you to find your way around the hospital.
As soon as your child no longer requires close monitoring, he or she will be admitted to the paediatric surgery ward (2nd floor, ward B). During the entire hospitalisation, you may be with your child and contact the paediatric neurosurgery team, who will visit you and your child daily for rounds. As soon as your child has recovered from the operation, he or she will be allowed to return home.
The prognosis of CMI is difficult to predict and depends on the symptoms of the disease. Some patients never show symptoms, others are severely limited and some patients only develop symptoms at a very late stage. Surgery can improve symptoms in around 80 per cent of patients with CMI.
The situation is similar with syringomyelia. Here too, the symptoms can be severely restrictive or non-restrictive and patients can potentially recover after surgery. However, the longer a syringomyelia exists, the lower the potential for recovery, as the syringomyelia has more time to cause damage to the spinal cord.
The Medgate Kids Line provides quick and uncomplicated medical advice if your child is unwell. The medical team of our partner Medgate is available to you by telephone around the clock.
For emergencies abroad: Call the emergency number of your health insurance company. You will find this number on your health insurance card.
More information: On the Page of the emergency ward you will find everything you need to know about behaviour in emergencies, typical childhood illnesses and waiting times.
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