Chiari Malformation

Causes, Symptoms, Treatment, & Other Resources

Have you ever dealt with worsening headaches, neck pain, or dizziness that make everyday tasks feel overwhelming? If so, you’re not alone, and these symptoms might point to something more serious, like a Chiari Malformation.

But what exactly is a Chiari Malformation? What types exist, what causes it, and how is it diagnosed and treated?

This article explores everything you need to know about this condition and the symptoms that come with it.

What Is a Chiari Malformation (CM)?

Chiari Malformation is a medical condition where a part of the brain at the back abnormally descends through the opening at the bottom of the skull. (1) It is named after Dr. Hans Chiari, an Austrian pathologist who, in the late 1880s, studied deformities of the brain.

The brain comprises several parts, each with a specific role. At the base of the brain are the cerebellum and the brainstem. The cerebellum is the part of the brain that helps control balance, while the brainstem manages basic functions like breathing and heart rate.

These parts normally sit just above a natural opening at the bottom of the skull called the foramen magnum. The foramen magnum is the hole at the bottom of the skull where the brain connects to the spinal cord. Understanding this layout is key to explaining Chiari Malformation.

In Chiari Malformations, the cerebellum and brainstem move below the level of the foramen magnum. This can put pressure on the lower parts of the brain (1) and affect the flow of spinal fluid around the brain and spinal cord.

Chiari malformation can occur when the opening at the base of the skull is not large enough. It can also occur when abnormal pressure in the brain pushes it downward. Chiari malformations are categorized into four major types based upon anatomical abnormality and whether congenital defects are present (2).

Chiari Type 0 Malformation

Chiari Type 0 starts early in development when the space at the back of the skull stays too small. Even though the cerebellar tonsils sit at or just below the skull opening, cramped anatomy blocks the normal flow of cerebrospinal fluid.

Over time, this extra pressure in the brain can create a fluid-filled cavity inside the spinal cord (syringomyelia or syrinx) in the spinal cord. Treating it usually means enlarging the bone opening or stabilizing the top of the neck to restore flow and let the syrinx shrink.

Having said that, for some patients who have Chiari and CCI, surgery is often not needed, as injections to stabilize the CCI can make the Chiari asymptomatic (a Chiari malformation that doesn’t cause any symptoms).

Chiari Type 0 Malformation or CTE

Chiari 0, also called cerebellar tonsillar ectopia (CTE), is a condition where the lower part of the brain (called the cerebellar tonsils) sits slightly lower than normal, near or just into the opening at the base of the skull.

Unlike more severe forms of Chiari malformation, the tonsils in Chiari 0 don’t extend far enough down to meet the typical definition of a Chiari malformation, but they can still cause symptoms.

People with Chiari 0 may experience headaches, neck pain, dizziness, balance problems, or other nervous system issues, especially if spinal fluid flow is disrupted.

Chiari Type 1 Malformation

This malformation occurs during fetal development. This first type is characterized by the downward movement of the cerebellum beneath the bony opening at the base of the skull.

It can block spinal fluid flow, leading to an increase in pressure. It can also put pressure on the lower portion of the brain with varying symptoms. Chiari Type 1 Malformation can be associated with hydrosyringomyelia, a fluid-filled cyst within the spinal cord, which is better known as a “Syrinx.”

Chiari Type II Malformation

In Chiari Type II Malformation, more tissue extends into the spinal canal than in Chiari Type 1. It is usually associated with a myelomeningocele, a form of spina bifida where part of the spinal cord and its coverings bulge outside the back. This is a condition where the baby’s spinal cord does not form or close properly during pregnancy.

Chiari Type III Malformation

This is the most severe form of Chiari Malformation. A significant amount of the brain is pushed through the opening at the base of the skull. This form of CM is diagnosed at birth or with an ultrasound during pregnancy.

Chiari Type IV Malformation

Type IV is rare and involves an incomplete or underdeveloped Cerebellum. This is also referred to as Cerebellar Hypoplasia. In this type of CM, the cerebellum is in its normal position with the foramen magnum, but parts of it are missing.

Symptoms of Chiari Malformation

Many people with Chiari Malformation have no signs or symptoms (3). Symptoms can change depending on the amount of brain and nerve compression and the increase in cerebrospinal fluid pressure. In particular, it’s thought that other things, like craniocervical instability, can take an asymptomatic Chiari and create symptoms.

The downward displaced cerebellum and brainstem restrict the flow of cerebrospinal fluid. Accordingly, it is backed up with increased pressure within the skull.

Abnormal pressure is also applied to the cerebellum and brainstem. The cerebellum controls the coordination of movement. You know the wonderful coordination that is involved with walking, talking, dancing, and running.

On the other hand, the brainstem controls many basic life functions such as heart rate, blood pressure, breathing, and level of consciousness.

Symptoms may include:

Headache
Arm and Leg weakness and numbness
Difficulty with swallowing
Breathing problems
Problems with hand coordination
Nausea and Vomiting
Balance problems

A deeper dive into each of the symptoms:

Brain Fog

Brain fog is one of the hallmark symptoms of Craniocervical instability. It is characterized by slow thinking, difficulty focusing, confusion, lack of concentration, forgetfulness, or haziness in thought. The severity of symptoms varies from patient to patient. Ever had a bad hangover or high fever and had trouble concentrating or completing simple tasks? This brain fog. Some patients describe it as a generalized haziness in thought as if cotton were stuck in the head. In addition to cognitive impairments, many patients also report generalized mental fatigue making complex tasks almost impossible. The exact cause of brain fog is unknown. Possible explanations include…

Tinnitus

Remember the ringing in your ears after a loud rock concert or highly charged sporting event? It is that ringing or buzzing sound that slowly improves the next day over several hours. Unfortunately for some individuals, the ringing in the ears is not due to an external event. Even worse is it does not resolve over time. This condition is called tinnitus. It is a medical condition characterized by ringing or other noises in one or both ears NOT caused by an external sound. Other individuals cannot hear the ringing that patients describe. It is a common problem. It affects approximately 15-20% of individuals.

Cervicalgia / Neck Pain

Cervicalgia is also known as neck pain, which is an all-too-common, unpleasant pain. Read here to learn the symptoms, diagnosis, and treatment options. We will discuss other causes for cervicalgia. What symptoms are associated with cervicalgia? How is cervicalgia diagnosed? What are the treatment options for cervicalgia? Cervicalgia is a medical term used to describe neck pain. It is very common and affects approximately 2/3 of the population at some point in their life. Cervicalgia is the 4th major cause of disability. Risk factors include injury, prior history of neck and musculoskeletal pain, jobs that require a lot of desk work, low social support, job insecurity, physical weakness, and poor computer station setup.

Chronic Fatigue

Have you ever had a challenging all-day hike, athletic endeavor, or worked a double shift and felt exhausted the next day? Later that day or the next morning, moving across the room may have seemed almost impossible and took herculean power. Now image this occurs on a daily basis without any provocation. 24/7 simple tasks are nearly impossible due to a lack of strength and energy. This is chronic fatigue, and it is one of the common symptoms associated with craniocervical instability. Severity can vary and in severe cases, patients are confined to their beds. Aggravating and alleviating factors often times can not be identified.

Chronic Headaches

Do you suffer from chronic headaches? Maybe it’s a daily issue, maybe once a week, maybe even less often, but one thing’s for sure—when a chronic headache kicks in, it can be a real pain in the neck, literally. In order to effectively address chronic headaches, you have to first determine if the pain is caused by a problem in your neck. Let’s take a look at a few neck issues that can cause headaches: Weak neck muscles – The head, on average, weighs about ten pounds, so when the neck muscles are weak, it can make your head feel a bit like a bowling ball that your neck can’t quite balance. There are many muscles that, along with the cervical spine, work together to help support the neck and aid movement…

Muscle Pain After Cervical Fusion Surgery

Cervical Fusion is a major surgery that involves joining one or more of the spinal bones together using screws, bolts, and plates (1). The hardware may be placed in the front (anterior) or the back( posterior) of the cervical spine. The disc between the spinal bones is often times removed and replaced with a bone graft or a spacer. The neck of composed of 7 boney building blocks that are numbered from 1-7. The letter C is associated with the numbers to designate the cervical spine. Hence the bones in the neck are C1 through C7. Sandwiched between neck bones are important shock absorbers called discs. A cervical fusion surgery removes…

Read More About Muscle Pain After Cervical Fusion Surgery

Neck Pain And Dizziness

Our body’s balancing system is compromised of three separate systems that work closely together to keep the body in balance: the eyes, inner ear, and upper cervical spine. The upper cervical spine contains and processes information about your position in space and communicates this information to your eyes and inner ears via nerves. There is a constant highway of electrical signals between the cervical spine, inner ear, and eyes that keep us upright, make us aware of our position and enable us to walk, move and run. This balancing system requires the inner ear, eyes and cervical spine to be operational…

Pain At The Base Of The Neck And Skull

The base of the skull is a complex area. It involves the upper cervical spine, facet joints, muscles, tendons, ligaments, and nerves. Irritation or injury to any one of these structures can result in pain at the base of the skull. Unfortunately, this area is not understood by many providers. This can lead to a delay in treatment and unnecessary pain and suffering.Treatment options depend upon the underlying cause of the pain. Conservative therapy in the form of physical therapy when appropriate is the best first-line treatment. Steroids are often recommended but should be avoided as they are toxic to orthopedic tissue and have significant side effects…

Read More About Pain At The Base Of The Neck And Skull

Symptoms of Chiari Malformation Type 0

People with Chiari Type 0 often notice brief, stabbing headaches at the base of the skull. These symptoms can flare when coughing, sneezing, or straining. Many describe a constant ache in the neck, occasional dizziness, or a sense of imbalance as the cramped area pinches the lower brain.

Symptoms of Chiari Malformation Type I

In Chiari Malformation Type 1, symptoms typically occur in late childhood or early adulthood. Headaches are the classic symptom of Chiari Malformation. They generally are in the back of the head and brought on by coughing or sneezing.

A patient may also experience any of the abovementioned symptoms, including headache and balance problems.

A syrinx can form inside the spinal cord, leading to hand numbness, weakened grip, or trouble with fine tasks like buttoning a shirt. In children, that fluid-filled cavity may slowly curve the spine into scoliosis. This can happen before any other signs appear. If pressure on the brain stem persists, swallowing can become awkward. Sleep may also be broken by gasps or snoring. Recent work also shows measurable attention- and processing-speed deficits in some adults with CM-I. (2)

Symptoms of Chiari Malformation Type II

In CM Type II, a larger portion of the brain extends through the foramen magnum into the spinal canal. Increased pressure is applied to the brain, resulting in varying symptoms. What is unique about CM Type II is its association with a form of spina bifida. Spinal Bifida is a birth defect in which the spinal column does not form properly. It has many different forms and presentations. Symptoms of CM Type II typically appear during childhood (3) and are usually caused by problems associated with Spina Bifida. These include:

Involuntary rapid eye movements
Irregular breathing
Loss of arm and leg strength.

Symptoms of Chiari Malformation Type III

Symptoms of this severe and rare condition appear at birth or in infancy. They can cause life-threatening complications. They can also be associated with severe neurologic conditions such as seizures and delayed growth.

Could Craniocervical Instability Be the Cause of Your Symptoms?

A Chiari malformation that doesn’t cause any symptoms can start causing problems if someone also develops craniocervical instability (CCI). CCI means the bones and ligaments at the top of the neck are too loose or unstable, allowing too much movement where the skull and spine meet.

This extra motion can push or pull on the brainstem and cerebellar tonsils, making a previously harmless Chiari malformation start to cause symptoms like headaches, dizziness, balance issues, or trouble swallowing. In other words, the instability at the top of the neck can “activate” a quiet Chiari malformation, turning it into something that causes real, daily problems.

Step 1

Imaging-Get movement based imaging (DMX or Upright MRI with flexion and extension).

Step 2

Get Typed via a Telemed Appointment-There are 8 different types of CCI based on which ligaments are Injured.

Step 3

Exam-If you’re a candidate for precise orthobiologic injections, you fly in for an exam and treatment. A hands-on exam refines what we need to treat.

Step 4

Treatment-Get treated with a CCI focused, orthobiologic treatment plan tailored to you. That includes ePICL or whichever image guided, precise injections are the most likely to help you.

Make an Appointment What is CCI?

Causes of Chiari Malformation

Chiari malformations are complex, with different types causing varying symptoms (4) depending on the severity of the injury. In general, there are two principal causes of Chiari Malformations:

Congenital

Otherwise known as a birth defect, these involve structural defects in the brain and spinal cord during pregnancy.

Acquired

Unlike congenital causes of Chiari Malformation, these typically occur later in life. They may be due to traumatic injury, disease, or infection. Illness or trauma may cause an increase in the pressure within the skull. The skull is a bony structure; it isn’t pliable or expandable.

The opening at the base is the only outlet. Increased pressure within the brain can therefore put downward pressure on the brain.

Diagnosis and Examination

Many patients with Chiari malformation have NO symptoms. Their malformation is also only discovered during the evaluation and treatment of another disorder.

There are several tests that can help diagnose and determine the severity of the malformation. The most common include:

Magnetic Resonance Imaging (MRI)

A powerful imaging tool that uses a strong magnetic field, a magnetic field gradient, and radio waves to create 3-D images of the body. The brain, cerebellum, brainstem, and spinal fluid are easily visualized and evaluated.

Computed Tomography Scan (CT)

Another powerful imaging tool that uses X-rays. Multiple X-rays are taken at different angles to provide detailed imaging.

Sleep Study

A dedicated study where your breathing, snoring, level of oxygenation, and seizure activity are closely monitored and recorded. Lack of breathing, called apnea, is also evaluated.

Swallowing Study

A specialized X-ray procedure that watches the swallowing process to determine if any lower brain dysfunction is present.

Common Treatments for Chiari Malformation

Chiari Malformations are classified into four major groups based upon type and severity of tissue injury. Type 1 and 2 Chiari Malformations are the most common. Treatment depends on the type of malformation, its severity, the amount of tissue involvement, and symptoms.

Nonsurgical

Most patients with Chiari 1 Malformation do not have symptoms or functional limitations and therefore only require regular follow-up with their providers. Period imaging may be required along with medications to address pain and headache.

Surgery

There are several surgical options, depending on the type of CM, its severity, and associated problems. (5) The most common surgery is called posterior fossa decompression.

It involves removing a portion of the bone at the base of the skull. (6) In this procedure, the surgeon removes a small section of bone at the skull base to give the brain more room.

The surgery creates more space for the brain, reducing the amount of pressure on the brain, which can improve spinal fluid flow. The intended goal is to improve symptoms and function.

NSAIDs

The other day I was evaluating a patient and reviewing the treatment options for their spine condition. After discussing prior treatments, we got to the topic of medications taken for pain relief. She explained that she mainly utilized anti-inflammatory (NSAID) medications and then she told me to hold much she takes and has been for many years…..she takes close to 2 grams (2000 milligrams) on a daily basis which equated to about 9-10 capsules of medication per day. I was shocked, considering she was pre-diabetic and with high blood pressure plus the kicker of it is that her PCP (primary care physician) is ok with this…

Cervical Fusion

Cervical Fusion is often recommended when chronic neck pain problems worsen over time. What exactly is it? Cervical Fusion is a major surgery that involves joining one or more of the spinal bones together using screws, bolts, and plates (1). The hardware may be placed in the front (anterior) or the back( posterior) of the Cervical spine. The disc between the spinal bones is often times removed and replaced with a bone graft or a spacer. The neck of composed of 7 boney building blocks that are numbered from 1-7. The letter C is associated with the numbers to designate the Cervical Spine.

Chiari Decompression Surgery

Chiari Decompression surgery can also called a Posterior Fossa Decompression or Craniectomy. The Cranium is that part of ther skull that contains the brain. Chiari Decompression surgery involves removing a bone at the base of the skull so as to widen the boney opening at the base of the skull. This opening is called the Foramen Magnum. The decompression surgery has four principal goals: create more space for the brain, slow or stop the progression of symptoms, relieve compression of the cerebellum and brainstem, restore normal cerebral spinal fluid flow. The Dura is one of three layers of connective tissue that…

Read More About Chiari Decompression Surgery

Occipital Cervical Fusion

An Occipital Cervical Fusion also known as Occipitocervical Susion is a Major Surgery. It is not a routine operation and is a challenging procedure due to complex anatomy of the upper neck. The procedure involves rods, plates and screws that are placed into the Cervical Spine and Occiput. A plate secured by screws are placed at the base of the Occiput. Screws are also placed into one or more Cervical bones. Rods then connect the Occipital plate to the Cervical screws as shown below. The goal of Occipital Cervical Surgery is a boney fusion between the skull and neck and to relieve…

Read More About Occipital Cervical Fusion

ePICL Procedure

CCI stands for cranial cervical instability which means that the ligaments that hold the head on are too loose. To help that problem, we developed a new procedure called PICL which stands for Percutaneous Implantation of the CCJ Ligaments. This is still an investigational procedure that has already changed many lives and helped patients avoid a complication-laden upper cervical fusion. Given the interest in the PICL procedure from patients who have CCI, there are lots of questions. Since the procedure isn’t yet covered by insurance, a few have asked why it costs more than their co-pay and deductible if they decide to have a more invasive cervical fusion.

Other Conditions Associated with Chiari Malformations

Chiari Malformation is a collection of conditions characterized by abnormal bulging or descent of the cerebellum and or brain stem through a bony opening at the base of the skull called the foramen magnum. There are other conditions associated with Chiari malformations, which include:

Tethered Cord Syndrome

A tethered cord syndrome is a group of neurologic disorders that occur due to chronic traction on the spinal cord, due to it being “tethered” or held by various structures.

Spinal Curve

Spinal curvature is common and may involve curving of the spine to the right or left, called scoliosis. Another form is where one is abnormally bent forward, which is called kyphosis. There may also be rotational curving of the spine, known as rotatory scoliosis.

Hydrocephalus

Hydrocephalus is a medical condition characterized by an excessive buildup of cerebrospinal fluid in the brain. If left untreated, the condition can become life-threatening. This can occur with CM as it blocks cerebrospinal fluid flow, which then backs up into the brain.

Syringomyelia

This medical condition is characterized by a fluid-filled cyst within the spinal cord known as a syrinx. If expanding, the syrinx can damage the spinal cord, compromise the nerves, and transmit information from the brain to the rest of the body.

Treating Chiari Malformations and Associated Symptoms

An asymptomatic Chiari malformation can become symptomatic when craniocervical instability (CCI) is also present, as the instability allows abnormal shifting of the skull and upper cervical vertebrae.

This extra motion can intermittently increase pressure at the foramen magnum or change the alignment of the brainstem and cerebellum, worsening crowding and disrupting normal cerebrospinal fluid (CSF) flow. In someone whose Chiari was not causing issues, the added mechanical stress from CCI can trigger headaches, dizziness, and neurological symptoms that were previously absent.

Because these problems are often caused by excessive movement, treating the underlying CCI can reduce Chiari-like symptoms. By stabilizing the upper cervical ligaments and restoring normal mechanics, the irritation and pressure on the brainstem, spinal cord, and cranial nerves are lessened, leading to significant symptom improvement even if a structural Chiari malformation remains.

The ePICL (percutaneous implantation of the CCJ ligaments) procedure is a non-surgical treatment that directly targets this instability. Using precise, image-guided injections of orthobiologic material into the damaged ligaments, the ePICL procedure strengthens and tightens these structures.

By eliminating the abnormal motion that aggravates the brainstem and disrupts CSF flow, the procedure can relieve the secondary effects of CCI on a Chiari malformation, often leading to significant symptom improvement without the need for decompression surgery. To learn more about Craniocervical Instability, please watch the video below.

In Conclusion

Under normal circumstances, the cerebellum and brainstem reside at the base of the skull. Chiari Malformation is a medical condition where a part of the brain bulges through a normal opening at the base of the skull. This bony opening is called the foramen magnum.

This creates abnormal pressure on the lower brain, restricts spinal fluid flow, and causes various symptoms. Chiari Malformations are categorized into four major types based on the anatomical abnormality and whether birth defects are present.

Many patients with Chiari Malformations have no signs or symptoms.Chiari Malformations can be due to birth defects or secondary causes such as trauma, disease, or infection.

Treatment of Chiari Malformations depends upon the type of malformation, the severity of tissue injury, and symptoms. Most patients with Chiari Type 1 Malformation do not have symptoms or limitations.

Other conditions associated with Chiari Malformations include tethered cord, spinal curve, hydrocephalus, and syrinx.

There are many causes of neck pain and headaches other than CM. Not all headaches and neck pain in patients with CM type 1 are due to malformation. The upper cervical spine is complex and requires a dedicated and compassionate team of experts to establish an accurate diagnosis.

If you or a loved one has ongoing neck, headache, and dizziness that has not responded to conservative treatment, please schedule a telephone candidacy discussion with a board-certified, fellowship-trained physician.

The Centeno-Schultz Clinic physicians are experts in evaluating and treating upper neck injuries. From the comfort of your home or office, learn what treatment options are available.

Our Doctors Who Treat Chiari Malformations

Christopher J. Centeno, MD

Christopher J. Centeno, M.D. is an international expert and specialist in Interventional Orthopedics and the clinical use of bone marrow concentrate in orthopedics.

Dr. Centeno is one of the few physicians in the world with extensive experience in the culture expansion of and clinical use of adult bone marrow concentrate to treat orthopedic injuries. His clinic incorporates a variety of revolutionary pain management techniques to bring its broad patient base relief and results. Dr. Centeno treats patients from all over the US who travel to Colorado to undergo innovative, non-surgical treatments. Dr. Centeno has chaired multiple international research-based conferences. He also maintains an active research-based practice, with multiple publications listed in the US National Library of Medicine. Dr. Centeno has also served as editor-in-chief of a medical research journal dedicated to traumatic injury.

Dr. Centeno trained at the Baylor College of Medicine, Texas Medical Center, and the Institute for Rehabilitation Research. He hails from both Florida and New York and currently resides in Boulder, Colorado with his wife and three children.

John Schultz, MD

John R. Schultz M.D. is a national expert and specialist in Interventional Orthopedics and the clinical use of bone marrow concentrate for orthopedic injuries. He is board certified in Anesthesiology and Pain Medicine and underwent fellowship training in both. Dr. Schultz has extensive experience with same day as well as culture expanded bone marrow concentrate and sees patients at the CSC Broomfield, Colorado Clinic, as well the Regenexx Clinic in Grand Cayman. Dr. Schultz emphasis is on the evaluation and treatment of thoracic and cervical disc, facet, nerve, and ligament injuries including the non-surgical treatment of Craniocervical instability (CCI). Dr. Schultz trained at George Washington School of…

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García M, Amayra I, Pérez M, et al. Cognition in Chiari malformation type I: an update of a systematic review. Neuropsychology Review. 2024;34:952‑973. doi:10.1007/s11065‑023‑09622‑2 SpringerLink

Saletti V, Farinotti M, Peretta P, et al. Management of Chiari malformation type 1 and syringomyelia in children: a review of the literature. Neurol Sci. 2021;42:4965‑4995. doi:10.1007/s10072‑021‑05565‑9 SpringerLink

Dhawan A, Dhawan J, Sharma AN, et al. Familial Chiari malformation: a systematic review and illustrative cases. J Neurosurg Spine. 2024;41(1):105‑114. doi:10.3171/2024.1.SPINE231277 Conquer Chiari
Silberstein H, Jackson EM, Jernigan S, et al. Congress of Neurological Surgeons systematic review and evidence‑based guidelines for patients with Chiari malformation: surgical interventions. Neurosurgery. 2023;93(4):731‑735. doi:10.1227/NEU.0000000000002635 Guideline Central
Lin W, Duan G, Xie J, et al. Comparison of results between posterior fossa decompression with and without duraplasty for the surgical treatment of Chiari malformation type I: a systematic review and meta‑analysis. World Neurosurg. 2018;110:460‑474. doi:10.1016/j.wneu.2017.10.142 ScienceDirect