Chiari Syndrome
- Chiari
I – herniation
of tonsils below foramen magnum
- as age
increases, less herniation will produce symptoms (typically presents in
the fifth decade)
- associated
with basilar invagination, Klippel-Feil, atlanto-occipital fusion
- causes occipital/cervical
pain, occipital headache (especially with straining), exertional
headache, L’hermitte sign, long tract changes, syrinx, hydrocephalus, lower
cranial nerve palsies, ataxia, spinal cord compression
- causes downbeat
nystagmus/bulbar symptoms in very young patients
- Chiari
II –
herniation of cerebellum through enlarged foramen magnum, skull lacunae,
concave petrous bone, short clivus, thin falx, medullary kinking,
enhancing ectopic choroid, tectal beaking, enlarged massa intermedia,
elongated fourth ventricle
- most
have hydrocephalus
- always associated
with myelodysplasia
- associated
with heterotopias, polymicrogyria, corpus callosum dysgenesis
- Many are
asymptomatic; can lead to Chiari crisis (sudden onset of brainstem/cord compression
– pain, nystagmus, lower cranial nerve palsies, UE weakness, hypotonia or
spasticity)
- Chiari
III
- Caudal
displacement of cerebellum and brainstem into high cervical meningocele
- Chiari
IV
- Diagnosis:
MRI of cranio-cervical junction
- Treatment:
Posterior fossa decompression (removal of skull of posterior fossa and
foramen magnum, upper cervical laminectomies, opening of dura with
placement of dural patch graft)