Health condition
Chiari malformation
A Chiari malformation - the lower cerebellum sitting below the opening of the skull - is often an incidental finding needing no treatment; when it causes the characteristic strain-induced headache or a spinal fluid cavity, surgery can help.
Why trust this guide
- 01
Editorial team
Written by our editorial team from the UK sources listed on each page.
- 02
Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
- 03
Current for 2026
Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.
Key facts
The essentials at a glance.
The symptoms to recognise, when to seek help, which specialist to see, and what treatment usually involves.
-
The hallmark symptom is a brief occipital headache provoked by coughing, straining or laughing
-
Many Chiari I malformations found on scans cause no symptoms and need only reassurance
-
MRI of the whole spine checks for an associated fluid cavity in the cord (syringomyelia)
-
Specialist: assessment via a consultant neurologist, with neurosurgical referral for symptomatic cases
Understanding the condition
What it is and what happens next.
What causes it, how it is diagnosed, and the treatment routes available in the UK.
What it is and how it feels
In Chiari I malformation the cerebellar tonsils extend below the foramen magnum, where they can crowd the flow of cerebrospinal fluid. The typical symptom is a heavy, pressure-like pain at the back of the head lasting seconds to minutes after coughing, sneezing or straining; some people also have unsteadiness, swallowing difficulty or arm symptoms - but many have no symptoms at all, the finding surfacing on a scan done for something else.
Diagnosis and treatment routes
Assessment matches symptoms to the anatomy: incidental, asymptomatic Chiari needs no surgery, whatever the scan shows, while classic cough headache or a syrinx on spinal MRI shifts the balance. The operation - foramen magnum decompression - creates space and restores fluid flow, with good results for strain-headache and for stabilising syringomyelia, and the decision is made carefully with a neurosurgeon because headaches of other types do not improve with surgery. In many parts of the UK, routine NHS referrals for this kind of problem currently take 20-45+ weeks, whereas an initial appointment with a private consultant is typically available within around two weeks.
Seeing a specialist
Who to see, and how quickly you can be seen.
The specialist for this condition is usually a consultant neurologist. Your GP can refer you on the NHS, or you can arrange a private consultation directly.
A quiet reminder
This guide is for information, not medical advice.
Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any of the emergency symptoms described above.
Frequently asked
Common questions about Chiari malformation.
Quick, plain-English answers to what people ask us most.
-
What is a Chiari malformation?
A Chiari malformation is a structural condition in which part of the cerebellum extends down through the opening at the base of the skull into the upper spinal canal. There are different types (Chiari 1 being the most common and generally mildest), with more severe types often associated with other structural brain or spinal abnormalities. Many cases, particularly Chiari 1, cause no symptoms and are found incidentally.
-
What causes a Chiari malformation?
Most cases relate to the space at the base of the skull being smaller than needed to comfortably accommodate the cerebellum, a difference present from birth. Some more severe types are associated with other conditions such as spina bifida. The exact cause of the underlying size mismatch in Chiari 1 is not always clear.
-
What symptoms does it cause?
The most common symptom is a headache at the back of the head, particularly triggered by coughing, sneezing or straining. Other possible symptoms include neck pain, dizziness, balance problems, and, if there is spinal cord involvement, numbness, weakness, or changes in bladder or bowel function. Many people, especially with milder forms, have no symptoms at all.
-
Is a Chiari malformation dangerous?
This varies considerably by type and severity — mild, asymptomatic Chiari 1 is generally not dangerous and often simply monitored, while more significant cases, particularly with associated syringomyelia (a fluid cavity in the spinal cord) or more severe malformation types, can cause progressive neurological problems if untreated. A specialist can assess your specific situation and associated risk. Most people with mild forms live entirely normal lives.
-
Can a Chiari malformation be cured?
The underlying structural difference cannot be reversed without surgery, but surgical decompression can effectively relieve pressure and improve or stabilise symptoms in people with significant, clearly related symptoms. Many people with mild or asymptomatic Chiari malformations need no treatment at all. Ongoing monitoring helps identify if and when treatment becomes necessary.
-
How is it treated?
Treatment ranges from simple monitoring for asymptomatic or mildly symptomatic cases, to surgical decompression (creating more space at the base of the skull) for those with significant symptoms or an associated syrinx. Pain management and symptom-specific treatments can help in the meantime. Your neurosurgical team will discuss the most appropriate approach based on your specific type and symptoms.
-
When should I see a specialist?
See a neurologist or neurosurgeon if you have persistent headaches at the back of the head, particularly worsened by straining, or other neurological symptoms, especially if a Chiari malformation has been found on imaging. NHS neurosurgical referral can take several weeks; a private consultation is typically available within about 2 weeks for earlier specialist assessment.