Ossification of the roof of the porus trigeminus with duplicated abducens nerve.

Anat Cell Biol. 2019 Jun;52(2):211-213. doi: 10.5115/acb.2019.52.2.211. Epub 2019 Jun 30.

Dupont G, Altafulla J, Iwanaga J, Watanabe K, Tubbs RS.

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Abstract

Ossification of parts of the intracranial dura mater is common and is generally accepted as an age-related finding. Additionally, duplication of the abducens nerve along its course to the lateral rectus muscle is a known, although uncommon anatomical variant. During routine cadaveric dissection, an ossified portion of dura mater traveling over the trigeminal nerve's entrance (porus trigeminus) into the middle cranial fossa was observed unilaterally. Ipsilaterally, a duplicated abducens nerve was also observed, with a unique foramen superolateral to the entrance of Dorello's canal. To our knowledge, there has been no existing report of a simultaneous ossified roof of the porus trigeminus with an ipsilateral duplicated abducens nerve. Herein, we discuss this case and the potential clinical and surgical applications. We believe this case report will be informative for the skull base surgeon in the diagnosis of neuralgic pain in the frontomaxillary, andibular, orbital, and external and middle ear regions.

KEYWORDS:

Abducens nerve variation; Meckel's cave ossification; Microneurosurgery; Trigeminal neuralgia

Fig. 1

(A) Ossified roof of the porus trigeminus (arrow), covering the trigeminal nerve as it enters the middle cranial fossa. The boundary of the ossification is indicated by the dashed bracket. (B) A duplicated abducens nerve dural foramen is indicated by the dissector, with one part of the nerve traveling inferomedial (dashed white arrow). The trigeminal root (solid white arrow) traverses the ossified porus trigeminus into Meckel's cave (curved dashed line). More anteriorly, the optic nerve (yellow solid arrow) and internal carotid artery (yellow dashed arrow) are colored for reference.