Chiari malformation
What is it?
Chiari malformation is a structural defect in the posterior cranial fossa the size of which is less than normal. To cope with it, the nerve structures (cerebellum, brain stem, inferior cranial nerves) that it contains are forced to shift up or down.
Two types can be distinguished:
- Type I. It has a more favorable course, in which syringomyelia (accumulation of cerebrospinal fluid inside the spinal cord, causing compression and damage to the nerve fibers of the spinal cord) may develop in 30-40% of cases, but signs of cranial nerve dysfunction and hydrocephalus rarely appear.
- Type II. It is very often associated with spina bifida with subsequent hydrocephalus, respiratory and swallowing dysfunction, and syringomyelia.
Causes and risk factors
Which are the symptoms?
This anatomic abnormality can cause:
- headache and pain in the back of the head and neck;
- malfunction of certain nerve structures with the occurrence of disorders of breathing (apnea), swallowing, and balance;
- obstruction of the normal circulation of cerebrospinal fluid, which can lead to hydrocephalus;
- syringomyelia; this initially causes sensory disturbances in the four limbs with formication and pain, and in the most severe cases, even paralysis.
How is it diagnosed?
Diagnostics is carried out using magnetic resonance imaging (MRI) of the brain and spinal cord, and some neurophysiological tests (somatosensory and motor evoked potentials).
Suggested exams
How is it treated?
Surgical treatment consists of enlarging the posterior cranial fossa, which is achieved by removing a small section of bone at the base of the skull and at the back of the first cervical vertebra and expanding the membrane that surrounds the nerve structures (dura mater) in that area.
It is possible to achieve a significant improvement in symptoms and a gradual disappearance of syringomyelia in more than 90% of cases of Chiari malformation type I.
In cases of Chiari malformation type II, prognosis is closely related to the associated malformations.
The duration of the postoperative hospital stay is about one week.
The patient should be re-examined in the outpatient clinic one month after surgery. Six months later, MRI of the brain and spinal cord is performed to record the regression of the syringomyelia. In the future, MRI may be done once a year.
Where do we treat it?
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