Short answer · Medically reviewed summary · Last updated: 2026-04-06
The ICD-10 code for Moyamoya disease is I67.5, while the historical ICD-9 code used for clinical classification was 437.5. As a specialist physician, I understand that navigating the diagnostic coding for Moyamoya can feel like an additional burden when you are already managing the complexities of a rare cerebrovascular condition. In the current International Classification of Diseases (ICD-10), Moyamoya is uniquely identified under code I67.5, which falls under the category of "Other cerebrovascular diseases." It is important to note that if a patient presents with secondary narrowing of the arteries due to an underlying condition like Down syndrome or neurofibromatosis, it is often classified as "Moyamoya syndrome" rather than primary Moyamoya disease, though both are frequently captured under the same diagnostic umbrella for administrative purposes. Clinical Significance of Coding While these codes may seem like mere bureaucratic labels, they are vital for ensuring that your medical records accurately reflect the progressive nature of Moyamoya.
ICD10 code of Moyamoya and ICD9 code
ICD-10 and ICD-9 codes for Moyamoya, with classification details for clinicians, coders and patients.
The ICD-10 code for Moyamoya disease is I67.5, while the historical ICD-9 code used for clinical classification was 437.5.
As a specialist physician, I understand that navigating the diagnostic coding for Moyamoya can feel like an additional burden when you are already managing the complexities of a rare cerebrovascular condition. In the current International Classification of Diseases (ICD-10), Moyamoya is uniquely identified under code I67.5, which falls under the category of "Other cerebrovascular diseases." It is important to note that if a patient presents with secondary narrowing of the arteries due to an underlying condition like Down syndrome or neurofibromatosis, it is often classified as "Moyamoya syndrome" rather than primary Moyamoya disease, though both are frequently captured under the same diagnostic umbrella for administrative purposes.
Clinical Significance of Coding
While these codes may seem like mere bureaucratic labels, they are vital for ensuring that your medical records accurately reflect the progressive nature of Moyamoya. Accurate coding helps healthcare systems track the prevalence and long-term outcomes of this condition. Because Moyamoya involves the progressive stenosis of the internal carotid arteries and the compensatory formation of fragile collateral vessels—which appear like a "puff of smoke" on an angiogram—consistent documentation is essential for justifying specialized neurosurgical interventions, such as indirect or direct revascularization procedures (like EDAS or STA-MCA bypass).
Supporting Our Community
For those of you in our community of 215 members, please remember that these codes are tools for your clinical team to facilitate access to care, insurance coverage, and specialized research. If you find discrepancies in your records, do not hesitate to ask your neurologist or neurosurgeon to clarify the coding to ensure it aligns with your specific clinical presentation. Your journey with Moyamoya is unique, and while the codes provide a standardized language for medicine, your clinical team should always treat you as an individual with specific hemodynamic needs.
Medical Disclaimer: This information is for educational purposes only and does not constitute formal medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
References
- NIH Genetic and Rare Diseases Information Center (GARD): Moyamoya disease entry.
- Orphanet: Portal for rare diseases and orphan drugs (ORPHA:2587).
- OMIM (Online Mendelian Inheritance in Man): Entry #252350.
- Moyamoya Foundation: Clinical guidelines and resource center.
