Chiari malformation type I
Findings
No curated finding names Chiari malformation type I yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Arnold-Chiari malformation type I is a central nervous system malformation characterized by caudal displacement of the cerebellar tonsils exceeding 5mm below the foramen magnum with or without syringomyelia. Symptoms vary in onset and severity and include suboccipital headache, neck pain, vertigo, tinnitus, ocular symptoms (diplopia, blurred vision, photofobia, nystagmus), lower cranial nerve signs, cerebellar ataxia, and spasticity. Some affected individuals can be asymptomatic.
Definition from the Mondo Disease Ontology (MONDO:0007316), read 2026-09-29. CC BY 4.0.
Features
44 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Chiari type I malformationHPOHP:0007099
- Obligate (100% of cases)
- HeadacheHPOHP:0002315
- Very frequent (80% to 99% of cases)
- Neck painHPOHP:0030833
- Very frequent (80% to 99% of cases)
- Recurrent paroxysmal headacheHPOHP:0002331
- Very frequent (80% to 99% of cases)
- Small posterior fossaHPOHP:0040010
- Very frequent (80% to 99% of cases)
- Abnormal clivus morphologyHPOHP:0010558
- Frequent (30% to 79% of cases)
- Abnormal vestibulocochlear nerve morphology
Show the remaining 32
- Cranial nerve compressionHPOHP:0001293
- Frequent (30% to 79% of cases)
- Cranial nerve paralysisHPOHP:0006824
- Frequent (30% to 79% of cases)
- Distal peripheral sensory neuropathyHPOHP:0007067
- Frequent (30% to 79% of cases)
- DysesthesiaHPOHP:0012534
- Frequent (30% to 79% of cases)
- DysphagiaHPOHP:0002015
- Frequent (30% to 79% of cases)
- Functional abnormality of the inner earHPOHP:0011389
- Frequent (30% to 79% of cases)
Where it sits
Other names
3 names
Resolves to: Chiari malformation type I
- Also called
- Arnold-Chiari malformation type 1Arnold-Chiari malformation type IChiari malformation type 1