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Chiari malformation and syringomyelia
In Chiari 1 the cerebellar tonsils descend 5 mm or more below the foramen magnum; the classic sign is occipital headache with coughing and straining, and surgery — posterior fossa decompression — is reserved for symptomatic patients or those with a syrinx.
Why it matters in the exam
Chiari 1 is often found incidentally on MRI, and then no surgery is needed. When symptomatic, it brings brief occipital headache triggered by coughing, laughing or straining (Valsalva), dizziness, swallowing and voice disturbances, and syrinx symptoms: loss of pain and temperature sensation in a "cape" over the shoulders and arms with preserved touch, weakness and wasting of hand muscles, and scoliosis — particularly a left-convex thoracic curve, which is not the usual idiopathic pattern. Every child with "atypical" scoliosis has an MRI to look for Chiari and a syrinx. Surgery: suboccipital craniectomy and C1 laminectomy, sometimes with dural expansion (duraplasty), to restore CSF flow.
Chiari 2 almost always comes with myelomeningocele: the vermis, brainstem and fourth ventricle are displaced downward, with a "beaked" tectum. In an infant it presents with stridor from impaired vocal cord movement, apnoeas and swallowing difficulty — and when such symptoms appear, shunt failure is excluded first and only then is decompression considered. Chiari 3 includes an occipital encephalocele. Syringomyelia can also result from an intramedullary tumour (hence contrast MRI), trauma and arachnoiditis. An arachnoid cyst is a fluid-filled space unrelated to Chiari; most are incidental and not operated on, unless they cause compression or hydrocephalus.
Key points
- Chiari 1: tonsils 5 mm or more; surgery only for symptoms or syrinx.
- Cough-induced occipital headache — the classic sign.
- Left-convex scoliosis — MRI.
- Chiari 2 — myelomeningocele; exclude shunt failure first.
- Syrinx — cape-like loss of pain and temperature.
Summary table
| Type | Anatomy | Presentation | Treatment |
|---|---|---|---|
| Chiari 1 | Tonsils 5 mm or more below the foramen magnum | Cough headache, syrinx, scoliosis | Decompression for symptoms or syrinx; incidental — follow-up |
| Chiari 2 | Vermis, brainstem and fourth ventricle descend; myelomeningocele | Stridor, apnoeas, swallowing | Exclude shunt failure first; then decompression |
| Chiari 3 | Occipital encephalocele | Severe deficits | Repair of the encephalocele |
| Syringomyelia | Cavity within the cord | Cape-like loss of pain and temperature, hand wasting | Treat the cause; contrast MRI |
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Sources
- Chiari and Syringomyelia Foundation and international consensus on Chiari malformation type 1, 2022 — Diagnosis and indications for surgery
- Congress of Neurological Surgeons guidelines on Chiari malformation in children, 2023 — Posterior fossa decompression
- Youmans and Winn Neurological Surgery, 8th edition (2022) — Chiari malformations and syringomyelia
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.