I appreciated the valuable clinical data presented in “Posttraumatic Bilateral Abducens Nerve Palsy: Mechanism of Injury and Prognosis.” ^{Reference Fam, Baharnoori, Kassardjian and Saposnik1} However, I would like to comment on an anatomical assertion in the manuscript: the claim that the abducens nerve (CN VI) has the longest intracranial and/or subarachnoid course among the cranial nerves.

Contemporary microsurgical and microdissection literature identifies the trochlear nerve (CN IV) as having the longest intracranial and subarachnoid (cisternal) course. The trochlear nerve’s extended intracranial trajectory and unique dorsal exit are described in detail in studies such as those by Villain et al. ^{Reference Villain, Segnarbieux, Bonnel, Aubry and Arnaud2} and Tubbs and Oakes, ^{Reference Tubbs and Oakes3} which report a mean subarachnoid length of approximately 35 mm. In contrast, the abducens nerve’s mean subarachnoid length is around 15 mm.Reference Zhang, Yu and Shen ⁴ Even considering total length, the trochlear nerve remains the longest among the cranial nerves.

This distinction is not merely anatomical but has clinical relevance: understanding the true course and length of the trochlear nerve is important in interpreting nerve vulnerability in head trauma, during aneurysm surgery, and in posterior fossa and skull base approaches. Accurate anatomical knowledge assists both surgical planning and interpretation of postoperative or traumatic cranial neuropathies. Furthermore, knowing why and how the abducens nerve is affected ^{Reference Ambekar, Sonig and Nanda5} (due to its entry to Dorello’s canal and going under the Gruber’s Ligament) during high intracranial pressures not only corrects our perspective on anatomy but also our understanding of intracranial pressure and CSF flow dynamics.