An internist came by the general pediatric clinic to ask for help because he was seeing a young adult patient in his internal medicine clinic who had a history of an incidentally found Chiari I malformation that had been asymptomatic.
The patient currently was complaining of some new headaches and he wondered if he should be worried about the malformation as a potential cause.
The pediatrician reviewed with him that Chiari I malformations are considered congenital with caudal displacement of the cerebellar tonsils.
Patients are often asymptomatic but if symptoms occur they generally occur in adolescence or early adulthood.
The internist was going to evaluate the patient and possibly discuss his findings with one of the neurologists.
Figure 47 – Sagittal FLAIR-weighted image of the brain reveals the tip of the cerebellar tonsils to be 12 mm below the level of the foramen magnum and therefore to be low lying in position. If the tip of the cerebellar tonsils is greater than 3-5 mm below the level of the foramen magnum, the patient is considered to have a Chiari I malformation. The Chiari I malformation is best visualized on a sagittal T1-weighted image of the cervical spine.
Advances in radiology and neurosurgery have lead to improvements in the diagnosis and treatment of various congenital malformations of the nervous and skeletal system.
Magnetic resonance imaging is the best imaging procedure to evaluate the brain, posterior fossa and spinal cord for congenital abnormalities, especially as it is non-invasive and can obtain images in multiple planes.
Surgical treatment mainstays for Chiari malformation are decompression or shunting and possible laminectomy.
Historically, Hans van Chiari described 4 types of hindbrain anomalies in 1891 and 1895. Arnold described a different classification system.
The Chiari II malformation is synonymous with the Arnold-Chiari malformation. Hans van Chiari also described Budd-Chairi syndrome which is an unrelated liver problem with cirrhosis and ascites due to an obstruction of the hepatic vein by a blood clot or tumor.
Chiari I – caudal displacement of cerebellar tonsils with elongation of the 4th ventricle.
It is associated with syringomyelia in up to 80% of patients. Syringomyelia is a cyst-like formation within the spinal cord that contains altered glial elements.
This may be asymptomatic or have symptoms occurring from infancy to adulthood. Most patients present in the 3rd decade. Hydrocephalus may be present.
- Associated with brain and cranial nerves:
- Neck Pain
- Sleep apnea
- Vocal cord paralysis
- Associated with spinal cord dysfunction:
- Bowel and/or bladder dysfunction
- Extremity – weakness or spasticity
- Sensory loss
Chiari II – caudal displacement of the vermis of the cerebellum, medulla and pons with elongation of the 4th ventricle.
This is almost always associated with a lumbar meningomyelocoele. Hydrocephalus occurs because of aqueductal stenosis.
Patients are usually diagnosed at birth. Chiari II is the most common Chiari malformation.
Clinical symptoms are the same as Chiari I plus those associated with the meningomyelocoele and hydrocephalus.
Chiari III – herniation of the cerebellum into an upper cervical or occipital meningocoele. It may also be associated with a Dandy-Walker malformation.
Because of the extent of the malformation, patients present at birth and have more obvious and extensive symptoms.
Chiari IV – severe hypoplasia of the cerebellum. Because of the extent of the malformation, patients present at birth and have more obvious and extensive symptoms.
Questions for Further Discussion
1. What other congenital abnormalities may be associated with Chiari malformations?
2. What are indications for referral to a neurologist or neurosurgeon?
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
Information prescriptions for patients can be found at MedlinePlus for this topic: Neural Tube Defects.
To view current news articles on this topic check Google News.
Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:2180-2186..
Incesu L, Khosla, A. Chiari II Malformation. eMedicine.
Available from the Internet at http://www.emedicine.com/radio/topic150.htm (rev. 11/15/2002 cited 2/12/07).
Siddiqui NH, Laine FJ. Chiari I Malformation. eMedicine.
Available from the Internet at http://www.emedicine.com/radio/topic149.htm (rev.8/11/2005, cited 2/12/07).
Chiari Malformation Type I. Online Mendelian Inheritance of Man.
Available from the Internet at http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=118420 (rev.8/8/2006, cited 2/12/07).
ACGME Competencies Highlighted by Case
4. Patient management plans are developed and carried out.
9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.
10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
16. Learning of students and other health care professionals is facilitated.
19. The health professional works effectively with others as a member or leader of a health care team or other professional group.
Donna M. D’Alessandro, MD
Associate Professor of Pediatrics, Children’s Hospital of Iowa
April 2, 2007