Have you heard of Arnold-Chiari malformation? If you are getting ready to become a mother and you are concerned about your future child, you most likely have.
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What Is Arnold-Chiari Malformation?
Arnold-Chiari malformation, also known as Chiari malformation, is a brain abnormality that consists of the cerebellum tonsils moving down through the foramen magnum, occasionally causing hydrocephaly due to the obstructed circulation of the cerebrospinal fluid (CSF).
It`s characterized by anomalies that occur at the junction between the marrow and the cerebral bulb, malformations of its placement and of the cerebellum (cerebral tonsils), which has a tendency of hernia through the occipital hole, occasionally leading to the occurrence of hydrocephalus due to the obstruction of the spinal fluid leak.
There are 4 types of Arnold-Chiari malformation of which, the first 2 are the most important.
- Type I – this is the most frequent one and lots of times is asymptomatic during childhood, but can manifest by headaches (frequently severe) and cerebellar signs.
- Type II – it`s accompanied by myelomeningocele and leads to the occurrence of partial or total paralysis under the spinal defect. It`s accompanied by abnormalities of development of the cerebral trunk (they`ll also hernia) and the cerebral vermix.
- Type III – the occurrence of some severe neurological defects and associates the occurrence of encephalopathy.
- Type IV – It`s characterized by global abnormalities of brain development.
Other abnormalities that may be present along with this malformation are hydrocephalus, syringomyelia or connective tissue disorders, such as Ehlers-Danlos syndrome or Marfan syndrome.
Causes & Risk Factors
An exact etiology isn`t known, but there are numerous hypotheses have been proposed that explain the mechanisms of the hernia. They include:
- Sizes of fossa, which include the cerebellum, are less than normal at birth, idiophathic (unknown);
- The upward migration of the second cervical vertebra into the cranial compartment, known as basilar invasion, may reduce the canal`s size between the spinal cord and encephalus.
- An increase in pressure in that particular compartment (for various reasons) might “push” the tonsil from its original position.
- The emergence of a suction force at the vertebral compartment`s level might “pull” the cerebellum, dislocating it.
Also, it was outlined a series of factors that may have a deleterious effect on the baby during fetal development. They only offer a general orientation, never being beneficial for the gestation period from various points of view, not only because of this syndrome:
- Infections suffered by the mother during pregnancy.
- Deficiency of essential nutritional factors and vitamins in the diet.
- Exposure to various harmful substances and agents.
- Consumption of alcohol and narcotics.
One of the most common symptoms of Arnold-Chiari malformation is headache. This starts in the neck or the base of the skull and may cover the whole back of the head. Sneezing, the bending of the spine or coughing may also be associated with headaches. A headache may last from a few minutes or a few hours and is associated with nausea. Patients with this malformation may report pain on one side, rather than on both sides.
Patients might also feel weakness in their hands or arms. They may also feel burning or stinging. Malformation may also affect the balance of a person. Some people who present this abnormality may confront with certain difficulties when swallowing.
Hoarseness is another sign of this illness. People who present this syndrome may confront with sight issues that include blurred vision, blind spots and even double vision.
Arnold-Chiari malformations are rare. There isn`t any data to show the incidence of these abnormalities. Arnold-Chiari malformations are the most common types of abnormalities that may occur at the cervico-medial junction, the region where the spinal cord and brain connect.
Around 1% of newborns present an abnormality in the cervico-medial junction.
Arnold-Chiari malformation is diagnosed based on a magnetic resonance (MRI). This examination uses magnetic radio waves to produce an image of the brain and show the clutter of space between the spinal cord and brain. There`ll also be a neurological investigation made in addition to this test.
The 2 main goals of treatment are to reduce the herniated structures and restore the normal flow of CSF between the compartments of the nervous system. Treatment may be performed strictly surgically by a method chosen by the doctor only, depending on the specific necessities of the concerned patient. Therefore, 1 or more of the following options might be chosen, most frequently during several procedures:
- Posterior femoral decompression – a procedure by which bone changes are made at the skull`s base.
- Spinal laminectomy – surgical resection of a part of the medial lamina.
- Reducing the cerebral tonsil – it can alter its size through a microsurgical intervention.
- Removal of the odontoide – part of the 2nd cervical vertebra, in the case of a basilar invasion.
- Shunt implantation – for the treatment of hydrocephalus, the CSF can be redirected to another compartment to be reabsorbed there.
- Ventriculostomy III – change in the CSF flow path.
- Spinal cord repositioning – in the case of young children.
In any neurological pathology, the prognosis can often be poor and the post-operative necessities high, but an important factors, no matter the case, will be the patient`s compliance for physician advice.