Arnold-Chiari malformation

26 Jun


Developmental anomalies affecting the cerebellum and brainstem may present with vestibular or cerebellar symptoms in adulthood.

occurs most commonly with type I Arnold-Chiari malformation-> downward displacement of the cerebellar tonsils through the foramen magnum.

clinical manifestations of this malformation are related to cerebellar involvement, obstructive hydrocephalus, brainstem compression, and syringomyelia.

  • Cerebellar ataxia in the type I malformation usually affects the gait and is bilateral; sometimes asymmetric.
  • Hydrocephalus from blockage of CSF flow leads to headache and vomiting.
  • Compression of the brainstem by herniated cerebellar tissue may be associated with vertigo, nystagmus, and lower cranial nerve palsies. 

diagnosed by CT or MRI studies that demonstrate cerebellar tonsillar herniation.

Patients with symptoms related to compression of the cerebellum or brainstem may benefit from surgical decompression of the foramen magnum.

The treatment for this is suboccipital craniectomy, sometimes with the removal of the posterior ring of C1 vertebrae.


Submitted by J. Stone.


Sources: Pathology the Big Picture., textbook; Clinical Neurology, textbook, Posterior Fossa Malformations. Chapter 8 – disorders of equilibrium.; Schwartz’s Principles of Surgery, chapter 42 Neurosurgery, congenital and developmental anomalies.; picture 1, picture 2


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