What is the next step in managing a patient with a Chiari malformation and new onset diplopia, who had an MRI (Magnetic Resonance Imaging) 2 years ago?

Management of Chiari Malformation with New Onset Diplopia

A patient with known Chiari malformation presenting with new onset diplopia requires an urgent updated MRI of the brain and orbits to evaluate for progression of the condition or development of complications.

Rationale for Updated Imaging

• Diplopia is a recognized neurological manifestation that can occur in patients with Chiari malformation, often due to compression of neural structures at the craniocervical junction 1
• The previous MRI from 2 years ago is outdated for evaluating the current symptomatic state, as clinical manifestations can evolve over time 2
• MRI is the gold standard imaging modality for evaluating Chiari malformation and associated complications 3, 2

Specific Imaging Protocol Recommendations

• MRI of the head and orbits without and with IV contrast is the most appropriate initial imaging for evaluating diplopia in the context of Chiari malformation 3
• Include gradient echo or susceptibility-weighted sequences to fully evaluate the extent of the malformation 3
• The imaging should include sagittal T2-weighted sequences of the craniocervical junction to properly assess the relationship between the cerebellar tonsils and foramen magnum 1
• Consider phase-contrast CSF flow studies to evaluate for CSF flow obstruction, which is a primary mechanism causing symptoms in Chiari malformation 1

Clinical Significance of Diplopia in Chiari Malformation

• Diplopia can be a direct result of cranial nerve compression or brainstem effects from the Chiari malformation 4
• Strabismus and diplopia have been reported as presenting features of Chiari 1 malformation, with esotropia being the most common oculomotor disturbance 4
• The presence of new neurological symptoms like diplopia may indicate progression of the condition or development of complications such as syringomyelia 5

Comprehensive Evaluation Approach

• Complete brain and spine imaging is recommended to evaluate for associated conditions such as hydrocephalus or syrinx, which can influence management decisions 1, 2
• Assessment for other neurological symptoms that may have developed concurrently with diplopia is essential, as they may indicate more extensive involvement 5
• Evaluate for other common Chiari-related symptoms such as headaches (especially those exacerbated by Valsalva maneuvers), neck pain, vertigo, or nystagmus 1, 5

Management Considerations

• Surgical intervention may be necessary if imaging reveals significant progression of the Chiari malformation or development of complications 5
• Non-surgical management of the diplopia with prism glasses may be appropriate in some cases, particularly when diplopia is the primary symptom 4
• The decision for surgical decompression should be based on the severity of symptoms, presence of complications, and the degree of anatomical abnormality seen on updated imaging 2

Important Caveats

• Not all patients with radiologically diagnosed Chiari malformation require intervention; correlation between symptoms and imaging findings is crucial 2
• Surgical outcomes for ocular symptoms in Chiari malformation are variable, with some studies showing minimal improvement in strabismus following decompression 4
• The primary benefit of surgical management in Chiari malformation is often to arrest disease progression rather than completely reverse existing symptoms 5