Chiari Malformation
Chiari malformation causes headaches and neurological symptoms from brainstem compression. One Brain and Spine's Melbourne neurosurgeons offer expert assessment and decompression surgery.
What is a Chiari Malformation?
Chiari malformation is a structural condition where part of the brain at the back of the head, called the cerebellar tonsils, extends downwards through the opening at the base of the skull (the foramen magnum) into the upper spinal canal. This can place pressure on the lower brain (brainstem) and upper spinal cord and may affect the normal flow of cerebrospinal fluid (CSF), which surrounds and protects the brain and spinal cord.
There are different types of Chiari malformation. Type I is the most common and is often found in adolescents or adults. In this type, only the cerebellar tonsils are displaced, and many people have no symptoms. Type II is more severe and involves both the cerebellum and brainstem and is typically associated with spina bifida.
Many people with type 1 Chiari malformation have no symptoms and do not require treatment. When symptoms are present, they can vary in severity. Management depends on symptoms, imaging findings, and whether there is evidence of disruption to CSF flow.
What Causes Chiari Malformation?
The exact cause of type 1 Chiari malformation is not always clear. It is most commonly thought to be related to a smaller than usual space at the back of the skull (the posterior fossa), which can crowd the brain and push the cerebellar tonsils downward. This may be present from birth, although symptoms can develop later in life.
In some cases, a Chiari malformation can develop due to changes in CSF pressure. For example, low CSF pressure from a spinal fluid leak or altered pressure dynamics within the spine can contribute to downward displacement of the cerebellar tonsils.
Symptoms of Chiari Malformation
Many Chiari malformations are found incidentally and do not cause symptoms. When symptoms do occur, they are often related to pressure on the brain or disruption of CSF flow.
Headache
Headache is the most common symptom. It is typically felt at the back of the head and may worsen with coughing, sneezing, straining, or bending forward (Valsalva headache). This pattern can help distinguish it from other types of headache.
Neurological Symptoms
Neurological symptoms can also occur, including numbness or tingling in the arms or legs, weakness, balance and coordination difficulties, dizziness, or problems with swallowing or speech. Eye movement abnormalities may also be present.
Syringomyelia
In some cases, a condition called syringomyelia develops. This is when a fluid-filled cavity (syrinx) forms within the spinal cord due to disrupted CSF flow. A syrinx can cause progressive symptoms such as loss of pain and temperature sensation, weakness, or stiffness in the limbs.
How is Chiari Malformation Diagnosed?
Chiari malformation is diagnosed using imaging of the brain and spine. MRI is the main test and shows the position of the cerebellar tonsils, the space at the base of the skull, and whether there is an associated syrinx.
Specialised MRI techniques can assess the flow of CSF around the brain and spinal cord. These studies may help determine whether CSF flow is obstructed and can assist in treatment planning.
Treatment of Chiari Malformation
Observation
Treatment depends on whether symptoms are present and how severe they are. Many people with Chiari malformation who have no symptoms or mild symptoms do not require treatment and can be safely monitored over time.
Surgical Decompression — Foramen Magnum Decompression
When symptoms are present and affecting quality of life, or when there is evidence of progressive neurological problems or syringomyelia, surgery may be considered. The aim of surgery is to create more space at the base of the skull and restore normal CSF flow.
The most common operation is called foramen magnum decompression. This involves removing a small section of bone at the back of the skull and, in some cases, part of the upper cervical spine. A patch is often used to expand the covering of the brain (duraplasty). This can improve CSF flow and reduce pressure on the brain and spinal cord.
Frequently Asked Questions — Chiari Malformation Melbourne
Does a Chiari malformation always need surgery?
No. Many Chiari malformations do not cause symptoms and only require monitoring. Surgery is usually considered when symptoms are significant, progressive, or associated with conditions such as syringomyelia.
What is a syrinx and does it need treatment?
A syrinx is a fluid-filled cavity within the spinal cord that can occur when CSF flow is disrupted. It may cause symptoms such as numbness, weakness, or stiffness. In many cases, treating the Chiari malformation improves or stabilises the syrinx without needing separate surgery.
What does Chiari decompression surgery involve?
Chiari decompression surgery involves creating more space at the base of the skull to relieve pressure and improve CSF flow. This is done by removing a small section of bone and often expanding the protective covering of the brain with a patch (duroplasty). The procedure is performed under general anaesthesia with a typical hospital stay of 3–5 days.
Why Choose One Brain and Spine for Chiari Malformation in Melbourne?
One Brain and Spine is a specialist neurosurgical group practice in Melbourne, bringing together extensive expertise in brain, spinal, and peripheral nerve surgery. Our team has particular strength in management of Chiari malformation delivering multidisciplinary care using the latest technology available in Australia. We are committed to providing comprehensive, patient-focused treatment through:
- Specialist cranial neurosurgeons —fellowship-trained with subspecialty cranial surgery expertise
- Advanced technology — including intraoperative navigation, neuromonitoring, and state-of-the-art microsurgical techniques
- Patient-centred approach — compassionate care with clear explanations of your diagnosis and all available treatment options
- All major health funds accepted