Makindo Medical Notes

Mild cases of Arnold-Chiari malformation are often asymptomatic and discovered incidentally during CT or MRI imaging performed for unrelated conditions.

About Arnold-Chiari Malformation

• A developmental abnormality affecting the craniocervical junction.
• The cerebellar tonsils extend downward into the foramen magnum, which can cause brainstem compression and lead to a variety of symptoms depending on severity.

Aetiology

• No definitive cause is known, but there may be a genetic predisposition.
• It may be precipitated by cerebrospinal fluid (CSF) shunt placement, particularly in cases of hydrocephalus.

Clinical Presentation

• Pain in the upper neck region.
• Dizziness or vertigo.
• Lower cranial nerve palsies may occur, affecting nerves IX (glossopharyngeal), X (vagus), and XII (hypoglossal).

Investigations

• An MRI scan is diagnostic. It shows the extent of downward displacement of the cerebellar tonsils into the upper cervical cord, along with brainstem compression and possible hydrocephalus.

Management

• Surgical intervention is recommended when there is evidence of significant brainstem compression.
• Surgery may also be needed for hydrocephalus.

Classification of Chiari Malformations