What is the treatment for Arnold Chiari malformation?

Treatment of Arnold Chiari Malformation

For symptomatic Arnold Chiari malformation, surgical intervention with posterior fossa decompression (PFD) with or without duraplasty (PFDD) is the primary treatment option to improve symptoms and address associated complications. 1

Diagnostic Evaluation Before Treatment

• Complete brain and spine MRI is recommended to evaluate for associated conditions such as hydrocephalus or syringomyelia, which significantly influence treatment decisions 1
• Phase-contrast CSF flow studies should be considered to evaluate for CSF flow obstruction, which is a primary mechanism causing symptoms in Chiari malformation 2
• Gradient echo or susceptibility-weighted sequences help fully evaluate the extent of the malformation 2

Surgical Management Options

First-Line Surgical Approaches

• Posterior fossa decompression (PFD) - Involves bone decompression at the craniocervical junction 1
• Posterior fossa decompression with duraplasty (PFDD) - Includes bone decompression plus opening and patching of the dura 1
• Both PFD and PFDD may be utilized as first-line treatments for symptomatic Chiari malformation with or without syrinx (Grade C recommendation, Class III evidence) 1

Additional Surgical Considerations

• Cerebellar tonsil reduction/resection may be performed during surgery to improve syrinx and/or symptoms (Grade C recommendation, Class III evidence) 1
• Intradural tonsil reduction or resection of intradural webs over fourth ventricle outflow may be necessary in some cases 1, 3
• Some patients with craniocervical instability may require fusion of the craniocervical junction in addition to decompression 1

Management of Associated Syringomyelia

• The main goal of surgery for syringomyelia is to reestablish CSF flow across the area of obstruction 3, 4
• Improved syrinx resolution may potentially be seen with dural patch grafting 1
• If syrinx persists after initial surgery, additional neurosurgical intervention may be considered after 6-12 months if there is no radiographic improvement (Grade B recommendation, Class II evidence) 1
• There is no strong correlation between symptom relief and syringomyelia resolution 1

Post-Surgical Monitoring

• Follow-up MRI is essential to evaluate for resolution of syrinx and CSF flow restoration 3, 4
• Patients should be monitored for at least 6-12 months before considering reoperation for persistent syringomyelia 1

Treatment Outcomes

• The majority of patients (79-90%) show improvement following surgical intervention 5, 4
• Bony decompression and establishment of CSF flow dynamics are key to successful outcomes 5
• Complications are more common with subarachnoid manipulation procedures compared to subdural decompression 4

Special Considerations

• CSF flow patterns at the cranial-vertebral junction can be classified into three patterns, which may guide surgical approach selection 4
• Intraoperative ultrasound after craniectomy can play an important role in selecting the most effective decompression procedure 4
• The goals of surgery remain constant: relieving brainstem compression, restoring normal CSF flow across the foramen magnum, and reducing the size of any associated syrinx cavity 3