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Migraine Comorbidities: Arnold-Chiari Malformations

Migraineurs often fear MRI, CT scans and other tests their doctors frequently order for them when they receive a tentative diagnosis of Migraine, or their Migraine has become chronic or intractable.

Migraine is a diagnosis of exclusion, which means the doctor will often be doing these images and scans to rule out something more sinister such as a tumor or stroke etc. as there are actually no tests to positively confirm Migraine's presence.

Your doctors are usually not suspecting anything worse, but they are protecting you by making absolutely sure that their diagnosis is correct.

Infrequently the images a physician orders may reveal an abnormality. One of these abnormalities is called Arnold-Chiari malformation, after the physician who first described it. Other names for the same condition are cerebellomedullary malformation syndrome, or simply Chiari malformation.

What is Chiari Malformation?

Chiari malformation is a complex disorder and there are 4 types of primary Chiari malformation (See details in Diagnosis).

In most patients with Chiari, there is a congenital problem results in crowding of a portion of the brain called the cerebellum. The lower part of the cerebellum, called the cerebellar tonsils hangs too low, dropping into the spinal canal and crowding the neurological tissue.

Chiari may also be secondary — often caused by excessive removal of spinal fluid (CSF) during a lumbar puncture.


Although Chiari malformation may be present with no symptoms at all, this crowding can cause a backup of spinal fluid in the spinal canal which often results in problems which may or may not change in the adult such as:

  • Sub-occipital pressure headache, especially when coughing, sneezing or straining
  • Dizziness and balance problems
  • Eye problems including blurred vision and vertical (up/down) nystagmus
  • Neck pain
  • Abnormal feeling in arms or legs which may affect coordination and fine motor skills
  • Dysphagia (problems swallowing) and/or vomiting. Nausea may be unrelenting
  • Tinnitus (ringing or buzzing ears) and/or hearing loss
  • Fainting or “drop attacks”
  • Heart arrhythmia
  • Insomnia and/or sleep apnea
  • Brain fog
  • Endocrine symptoms including flattened pituitary gland

In Chiari II there may be additional symptoms as a result of the tethered cord which causes the Chiari. These signs and symptoms can include:

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  • Frequent urination and/or bladder problems
  • Bowel problems especially constipation
  • Low back pain
  • Numbness in legs and/or feet/and/or pelvis
  • Worsening of symptoms while walking on heels, lessening while walking on toes.
  • Depression

Symptoms of Chiari in babies and children may vary somewhat and can include:

  • Feeding problems including swallowing difficulties, excessive drooling, gagging, vomiting and irritability during feeding
  • Weak cries
  • Arm weakness
  • Breathing problems, apnea
  • Developmental delay
  • Failure to thrive, or problems gaining or maintaining weight

The occurrence of Chiari was once estimated to be about 1:1000 births, but with better imaging and diagnostic techniques physicians are finding it is actually much more common than was once thought.

Chiari can be primary (congenital) or secondary such as that caused by excessive CSF removal during lumbar puncture. Primary Chiari is found more often in females.

Because primary Chiari is a congenital problem, it is often found with other congenital issues which can include:

  • Hydrocephalus (too much fluid in the brain)
  • Spina bifida (incomplete closure of the neural tube)
  • Spinal curvature (scoliosis)
  • Syringomyelia (spinal cyst)
  • Tethered cord syndrome (spinal cord is attached to bony structures)
  • Other hereditary syndromes involving bone and neurological defects


Diagnosis of Chiari is often made as the result of routine x-ray, MRI or CT imaging of the skull and upper neck or the lumbar spine, often for Migraine or other disorders. 3D CTA and 3D MRI are preferred for the doctor’s best impression and diagnosis of Chiari malformation as well as surgical preparation. There is an art to obtaining the very specific images Chiari specialists need, and despite the fact that a patient may come to them with their own imaging results, clinics often require imaging done by them in their clinics where they are especially talented at getting the required views.

Images of both head/neck and lumbar areas are vital in an appropriate diagnosis however, the lumbar area often being forgotten by non- Chiari specialists. These images are often followed by a cine MRI CSF flow test. Other possible tests include a flip/flop MRI and/or cine MRI of the lumbar region especially when Chiari II is suspected despite *normal* imaging. There are 4 types of malformation, and knowing which type you have is vital to appropriate treatment.

Chiari 1 malformation — the defect is the *too small* bony structure and the cerebellar tonsils are being squeezed into the spinal canal. This is the most common type and management concentrates on the upper neck and skull.

Chiari 2 malformation — The defect is the spinal cord which is *stuck* to the bottom of the spine, pulling the brain into the spinal canal. This is also a common type, but management concentrates first on the lumbar spine, not the upper neck and skull.

Chiari 3 malformation and Chiari 4 are quite rare.

Additional testing will be determined based on symptoms, for example vestibular testing will be used on patients with dizziness, and a barium swallow if you have symptoms of dysphagia. It’s important for your Chiari specialist to know if your symptoms are related to your Chiari malformation or another disease or disorder.


Treatment of primary Chiari malformation is decided based on the patient’s symptoms and the type of malformation, but Chiari specialists tend to provide a multi-disciplinary approach. Asymptomatic patients may live a full life without need for treatment. For patients who do not find that medication relieves their symptoms, surgery is an option. Sometimes a single surgery may not be enough for the patient to resume their normal activities, and repeated or additional surgeries may be necessary. For patients who exhibit specific *red flag symptoms*which are considered dangerous, surgery is more of a necessity and less of an option.

Just as there are headache specialists for Migraineurs, there are specialists who concentrate almost 100% of their time and efforts on Chiari malformation and its treatment. Migraineurs who also suffer Chiari malformation are especially good candidates for these specialists as their diagnosis and treatment may be more complicated and difficult. Missing a diagnosis (which happens frequently) or receiving inappropriate or insufficient treatment for Migraine or Chiari may leave the patient and their physicians feeling helpless to find answers. Patients can find themselves disabled by their conditions and unaware that options may still be available to them.

One type of Chiari I surgery enlarges the hole at the base of the skull to eliminate crowding and restore appropriate CSF flow.

Another called Posterior Fossa Decompression surgery removes a portion of bone from the back of the skull and sometimes the spine to relieve crowding. Cauterization of the cerebellar tonsils may also be necessary to shrink them.

Spinal laminectomy removes part of the vertebrae to remove pressure on the cord and nerve roots.

The dura (covering over the brain) may be enlarged during surgery to allow for better CSF flow and less crowding.

Tethered cord surgery is available for those with Chiari II. A piece of bone at the base of the spine is cut and the filum terminal that attaches the cord to the end of the spine is released. This alone may be sufficient to relieve symptoms.

Other surgeries may be necessary for other comorbid conditions listed above.

The Migraine connection

Chiari malformation does not cause Migraine, however Chiari patients who suffer Migraine may find that their Migraine attacks can be triggered by their Chiari malformation. For these patients, treating the Chiari may lessen the incidence and/or severity of their Migraines.

Unfortunately, patients usually have several Migraine triggers however, so rarely does Chiari treatment eliminate their Migraine attacks. Proper Migraine management is still usually necessary, even after their surgery.

Research and the future

The good news is that research on Chiari malformation and its associated conditions is ongoing. With better imaging and testing, more patients are being identified and treated, leading to more productive happier lives.


For more information on Chiari malformations, I found this specialty website to be full of instructional videos with lots of great, very detailed information definitely suitable for taking to your doctor.

To read what other patients are saying about specific physicians who treat Chiari malformation and a list of questions to ask your doctor about Chiari and other helpful tips:

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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