Segmental Imaging of the Trochlear Nerve: Anatomic and Pathologic Considerations

Nivedita Agarwal, Ali Karim Ahmed, Richard H. Wiggins, Timothy J McCulley, Marinos Kontzialis, Leonardo L. MacEdo, Asim F. Choudhri, Lauren C. Ditta, Masaru Ishii, Gary L. Gallia, Nafi Aygun, Ari M Blitz

Research output: Contribution to journalArticlepeer-review


Background:The trochlear nerve (the fourth cranial nerve) is the only cranial nerve that arises from the dorsal aspect of the midbrain. The nerve has a lengthy course making it highly susceptible to injury. It is also the smallest cranial nerve and is often difficult to identify on neuroimaging.Evidence Acquisition:High-resolution 3-dimensional skull base MRI allows for submillimeter isotropic acquisition and is optimal for cranial nerve evaluation. In this text, the detailed anatomy of the fourth cranial nerve applicable to imaging will be reviewed.Results:Detailed anatomic knowledge of each segment of the trochlear nerve is necessary in patients with trochlear nerve palsy. A systematic approach to identification and assessment of each trochlear nerve segment is essential. Pathologic cases are provided for each segment.Conclusions:A segmental approach to high-resolution 3-dimensional MRI for the study of the trochlear nerve is suggested.

Original languageEnglish (US)
Pages (from-to)E7-E15
JournalJournal of Neuro-Ophthalmology
Issue number1
StatePublished - Mar 1 2021

ASJC Scopus subject areas

  • Clinical Neurology
  • Ophthalmology


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