Chiari Facts

What is Chiari?

Hans Chiari was the Austrian pathologist born in Vienna who’s studies lead him to discover Chiari Malformation in autopsies. It was named after him and Julius Arnold. However a Scottish physician first described this condition in 1883 named John Cleland and called it Basilar Impression Syndrome.

Chiari malformations (kee-AH-ree mal-for-MAY-shuns) are a group of complex brain abnormalities that affect the area in the lower posterior skull where the brain and spinal cord connect. (National Organization for Rare Disorders, NORD)

When the indented bony space at the lower rear of the skull is smaller than normal, the cerebellum and brain stem can be pushed downward. The resulting pressure on the cerebellum can block the flow of cerebrospinal fluid (the liquid that surrounds and protects the brain and spinal cord) and can cause a range of symptoms.


What are the Symptoms

Common symptoms are but not limited to:

  • Dizziness and vertigo
  • Muscle weakness
  • Numbness and tingling in hands, legs, feet and face
  • Vision problems
  • Ringing in ears
  • Pressure and/or electrical pain headaches
  • Noise and light sensitivity
  • Neck and shoulder pain
  • Trouble swallowing
  • Problems with balance and coordination
  • Memory and concentration loss


How is Chiari Malformation Diagnosed?

There is no single test to diagnose Chiari Malformation, rather doctors look at the reported symptoms and the results from a neurological examination and an MRI (magnetic resonance imaging).  If the doctor suspects that the cerebellar tonsils are blocking the normal flow of cerebrospinal fluid (CSF), a CINE MRI (which measures the flow of CSF) may be ordered.


What causes Chiari Malformation?

While there may be a genetic component, no one really knows what causes a Chiari Malformation. Some cases are congenital (meaning you are born with it) and other cases are acquired (possibly through accidents or injuries). Some people exhibit symptoms as children, others as adults.  It is currently not well understood what triggers symptoms.


How is Chiari Malformation Treated?

Medications may ease certain symptoms, such as pain.  Surgery is the only treatment available to correct functional disturbances or halt the progression of damage to the central nervous system if symptoms are interfering with daily activities. More than one surgery may be needed to treat the condition. Some Chiari Malformations do not require surgery, e.g., when there are no noticeable symptoms. Whether or not surgery is indicated, ongoing monitoring is extremely important.


Are there associated conditions?

Yes, Chiari Malformation has many related conditions such as Syringomyelia and Ehlers-Danlos Syndrome.

Syringomyelia (sih-ring-go-my-E-lee-uh) is the development of a fluid-filled cyst (syrinx) within the spinal cord. Over time, the cyst may enlarge, damaging the spinal cord and causing pain, weakness and stiffness, among other symptoms.  Syringomyelia can be found entirely on its own or associated with Chiari Malformation. It causes nerve damage to the spinal cord and should it grow, it can lead to lack of mobility or paralysation. After a standard cervical MRI is completed and Chiari Malformation is found, a CINE MRI should be requested. According to Dr Ventureyra, and many other Neuro specialists who have conducted several Chiari Malformation related studies, the CSF flow is more important than the herniation length. A CINE MRI will tell a neurologist or neurosurgeon a great deal about the spinal cord, as it provides imaging of its entire length. They may see vertebrae issues, disc problems, alignment concerns, brain stem compression due to Chiari, and much more.

Elhers-Danlos Syndrome is defined as a group of inherited disorders that affect connective tissues — primarily skin, joints and blood vessel walls. (Mayo Clinic).  Connective tissue is a complex mixture of proteins and other substances that provides strength and elasticity to the underlying structures of the body.  Individuals with Ehlers-Danlos syndrome usually have overly flexible joints and stretchy, fragile skin. This can become a problem, for example, if a wound requires stitches often the skin often isn't strong enough to hold them.

A more severe form of the disorder, called vascular Ehlers-Danlos syndrome, can cause the walls of blood vessels, intestines or uterus to rupture. Patients diagnosed with vascular Ehlers-Danlos syndrome, may want to talk to a genetic counselor before starting a family.

Ehlers-Danlos Syndrome is closely related to Chiari Malformation. Many, but not all, patients with Chiari Malformation have positive clinical results for one of four types of EDS. This is generally done through genetic testing. A referral must be sent by a specialist and the wait can be quite long depending on where the patient lives and who the  referring doctor is. There are many other conditions associated with Ehlers-Danlos Syndrome that should be looked into should the patient receive a positive diagnosis. More information can be found through Elhers-Danlos Canada and other organizations. Some suggest that testing is important prior to deciding whether or not to go forward with decompression surgery. This is on a case by case basis and should be decided between the patient and the specialist based on several factors including the physical and mental health of the patient.

Other related conditions are, but not limited to Tethered Cord Syndrome, Hydrocephalus, Spina Bifida and Spinal Curvature/Scoliosis


All should be investigated if the patient is experiencing symptoms similar to the those noted above.

Disclaimer:  The material presented on this site is for information ONLY and does not constitute medical advice.  For diagnosis and treatment options please consult your healthcare provider.  The Canadian Chiari Association (CCA) does not recommend or endorse any one treatment, procedure or product.

The CCA aims to increase awareness of Chiari Malformation across Canada and to provide its members with information to help them in their daily lives.  As such, this site may contain third party links and/or information available as PDFs.  The CCA takes no responsibility for the accuracy or currency of these sources.  Visitors who use the information on this site do so at their own risk.