Oculomotor Twist: Aberrant Regeneration of the Oculomotor Nerve Following Coil Embolization of a Carotid Cavernous Fistula

We describe a case of a patient with an acquired third nerve palsy and discuss potential etiologies contributing to aberrant regeneration.

Oculomotor Twist Aberrant regeneration of the oculomotor nerve following coil embolization of a carotid cavernous fistula Naira Ikram,1 Vivian Douglas,2 Konstantinos Douglas,3 Linda Dagi,4 Nurhan Torun5 3. Department of Ophthalmology, Harvard Medical School, Boston, MA 2. Athens Naval Hospital, Department of Ophthalmology, Athens, Greece 1st Athens University Eye Clinic, National and Kapodistrian University of Athens, G. Gennimatas Hospital, Athens, Greece 4. 5. 1. Department of Ophthalmology, Boston Children's Hospital/Harvard Medical School, Boston, MA Division of Ophthalmology, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA History • Chief complaint: 62 year-old woman presented with severe left-sided headaches, ptosis of right eye, and binocular oblique diplopia, referred to neuro-ophthalmology • Past Medical History: pituitary macroadenoma without demonstrable visual field defects based on Humphrey visual field testing Initial Examination • Visual acuities were 20/25 in both eyes • She had partial ptosis with mildly limited elevation in the right eye; and mildly limited abduction in the left eye • Eye exam: Anterior and posterior segment exam unremarkable, except mild nuclear sclerosis in both eyes • IOP: 12 mmg (OD), 16 mmg (OS) Impression and Plan • Patient was diagnosed with superior division third nerve palsy OD and mild abducens palsy OS, raising suspicion for a cavernous sinus etiology • Imaging studies were obtained CT/CTA showed left CCF (arrow: enlarged left superior ophthalmic vein) MRI before embolization showed abnormal flow void in the left cavernous sinus (long arrow) and distended left superior ophthalmic vein (short arrow) and orbital inflammation (short red arrow) Clinical Course • The patient underwent coil embolization • Immediately afterwards, ptosis OD improved but she developed complete ptosis OS • A month later, the superior division third nerve palsy was resolved in the right eye; however, she had a complete sixth and near complete third nerve palsies in the left eye Post-procedure CTA shows embolization coils in the left cavernous sinus and decreased size of the superior ophthalmic vein (arrow) At one-year follow-up • Both sixth and third nerve palsies had improved with stable examination for over six months. • She was also noted to have lid lag on downgaze, indicating aberrant regeneration of the left third nerve • Referred for strabismus surgery to minimize diplopia lid elevation on downgaze 9 gaze image showing left upper eyelid elevation on attempted downgaze and adduction of the left eye indicating re-routing of fibers from the inferior rectus and medial rectus, respectively, to the left levator palpebrae superioris. What is the mechanism for CN3 palsy with aberrant regeneration in this case of recently coiled CCF? Etiology in this patient’s case • Most common cause of aberrant regeneration in the context of an acquired third nerve palsy is typically due to trauma or compression rather than ischemia as ischemia does not cause axonal discontinuity • This patient developed signs of aberrant regeneration after coil embolization of a carotid cavernous fistula. This suggests that the oculomotor palsy associated with the CCF had been due to compression and not ischemia Teaching Points • Ocular motor cranial nerve palsies involving both eyes raise suspicion for a cavernous sinus pathology because of the presence of intracavernous channels, which can explain bilateral involvement • In patients with acquired third nerve palsy, remember to look for signs of aberrant regeneration such as lid lag on downgaze, miosis on adduction. Unless there is clear history of trauma, aberrant regeneration implies a compressive etiology References • 1. Bou Ghannam A, Subramanian PS. Delayed onset cranial nerve palsies after endovascular coil embolization of direct carotidcavernous fistulas. J Neuroophthalmol 2018;38:156-159. • 2. Lee SH, Cho WS, Kang HS, Kim JE, Cho YD, Yoo DH, et al. Newly occurring cranial nerve palsy after endovascular treatment of cavernous sinus dural arteriovenous fistulas. J Neurointerv Surg 2019;11:1168- 1172. • 3. Nishino K, Ito Y, Hasegawa H, Kikuchi B, Shimbo J, Kitazawa K, et al. Cranial nerve palsy following transvenous embolization for a cavernous sinus dural arteriovenous fistula: association with the volume and location of detachable coils. J Neurosurg 2008;109:208-214. • 4. Park YJ, Lee SM, No JW, Choi KD. Delayed Oculomotor Nerve Palsy After Coil Embolization of Carotid- Cavernous Fistula: Case Report and Literature Review. J Clin Neurol. 2023 Mar;19(2):207-209. • 5. 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