A 32 year-old woman presented in increasing neck and head pain associated with dizziness. Her examination was most notable for downbeat nystagmus.

Axial T2 Weighted MRI scan (Left - Patient; Right - Normal). The dotted line shows the location of the Foramen Magnum. Note in the Chiari malformation that the brainstem and cerebellar tonsils descend below the foramen magnum. There are various types of Chiari malformations. In Type I, the malformation is limited to descent of the brainstem and cerebellum into the spinal canal. Other types may be associated with midbrain malformations, aqueductal stenosis, and myelomeningocele.

Revised 01/15/06.
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