Chiari I malformation

Case contributed by Mohamed Mahmoud Elthokapy


Chronic headache, no neurological deficits, no fits, and no history of head trauma.

Patient Data

Age: 30 years
Gender: Male

There is a mild caudal descent of the cerebellar (peg-like) tonsils about 13 mm through the foramen magnum (below the McRae line) which appears crowded.  

The CSF spaces are of average size. No hydrocephalus.

No shift of midline.

No infarction or hemorrhage.

Sagittal images of the cervical spine revealed no intrinsic cord pathology. No syringohydromyelia. No tethered cord or spinal myelomeningocele. 

Case Discussion

Chiari I is the mildest and most common form of Chiari malformations manifested by the descent of the cerebellar tonsils below the level of the foramen magnum.
Most cases are asymptomatic, however symptomatic patients complain of headache, and neck pain. 

Up to 5 mm in children and 3 mm in adult tonsillar descent is accepted as normal. 

A correct diagnosis is an MRI study that shows tonsillar descent measures on sagittal T1 or T2 WIs.

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