Board Review 2 – Case 18

Neuroradiology board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case shows a patient with cerebellar tonsils which extend below the foramen magnum. They have a “peglike” or triangular configuration, and extend well below the foramen magnum. The differential for this finding includes Chiari malformation, cerebellar tonsillar ectopia, idiopathic intracranial hypertension (IIH), and spontaneous intracranial hypotension (SIH).

The diagnosis is: Chiari malformation

Chiari malformation is a congenital abnormality in which the cerebellar tonsils extend below the foramen magnum and the posterior fossa is small. Patients can have chronic headaches. CSF flow studies of the foramen magnum can be useful to determine if patients are likely to benefit from surgical decompression with suboccipital craniectomy.

When combined with other abnormalities, there are specific diagnoses, which are:

• Chiari II – cerebellar tonsillar abnormality + lumbar meningocele/myelomeningocele
• Chiari III – cerebellar tonsillar abnormality + occipital meningocele