Condition

Chiari malformations (CM) are a heterogeneous group of disorders that are defined by anatomic anomalies of the cerebellum, brainstem, and craniocervical junction, with downward displacement of the cerebellum.

Guidance at RECRUITMENT

• ACCEPTABLE if type 1 or type 2 and no symptoms. May consider for PBSC-only if associated with spina bifida occulta, other forms of spina bifida unacceptable.
• UNACCEPTABLE if treated by surgery though the skull and brain tissue, symptomatic, associated with myelomeningocele, or Types 3 or 4.

Guidance at CT/WORK-UP

• ACCEPTABLE if type 1 or type 2 and no symptoms. May consider for PBSC-only if associated with spina bifida occulta, other forms of spina bifida unacceptable.
• UNACCEPTABLE if treated by surgery though the skull and brain tissue, symptomatic, associated with myelomeningocele, or Types 3 or 4.

Individual at Risk

Donor

Justification for guidance

Data are limited regarding the natural history and clinical course. Not suitable for volunteer donation if symptomatic, required surgery, associated with myelomeningocele, or Type 3 or 4. Symptoms may include neck pain, Lhermitte phenomenon, trouble with balance, poor hand coordination, numbness, dizziness, trouble swallowing.

References

• Hidalgo JA, Tork CA, Varacallo MA. Arnold-Chiari Malformation. [Updated 2023 Sep 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK431076/