BACKGROUND: Intracranial carotid sympathetic plexus (CSP) nerve sheath tumors have rarely been reported in the literature. This study describes the first reported case of a CSP neurofibroma and the first case of a CSP nerve sheath tumor treated via an endoscopic endonasal approach followed by adjuvant radiosurgery.
OBSERVATIONS: A 53-year-old man presented with 3 days of headaches and diplopia and was found to have a complete left abducens nerve palsy. Computed tomography (CT) revealed a smoothly dilated left carotid canal, CT angiography revealed a superiorly displaced left internal carotid artery (ICA), and magnetic resonance imaging revealed a T2-hyperintense and avidly enhancing lesion in the left cavernous sinus encasing the ICA. The patient underwent subtotal resection via an endoscopic transsphenoidal transcavernous approach followed by Gamma Knife radiosurgery.
LESSONS: Nerve sheath tumors arising from the CSP are extremely rare but need to be considered when assessing unusual cavernous sinus lesions. The clinical presentation is dependent on the anatomical location of the tumor and its relationship to the ICA. The optimal treatment paradigm is unknown

Bhattacharjee, Meenakshi

Blackburn, Spiros L

Dawes, Bryden H

Guttenberg, Katie B

Trimble, Duncan J

Yao, William C

Zeineddine, Hussein A

English

DigitalCommons@The Texas Medical Center

Neurofibroma of the internal carotid artery cavernous sympathetic plexus:illustrative caseDuncan J. Trimble, MD,1 Bryden H. Dawes, MBBS,1 Hussein A. Zeineddine, MD,1 Katie B. Guttenberg, MD,2 William C. Yao, MD,3Meenakshi Bhattacharjee, MD,4 and Spiros L. Blackburn, MD1Departments of 1Neurosurgery, 2Endocrinology, 3Otorhinolaryngology–Head & Neck Surgery, and 4Pathology, McGovern Medical School, The University of Texas HealthScience Center at Houston, Houston, TexasBACKGROUND Intracranial carotid sympathetic plexus (CSP) nerve sheath tumors have rarely been reported in the literature. This study describesthe first reported case of a CSP neurofibroma and the first case of a CSP nerve sheath tumor treated via an endoscopic endonasal approach followedby adjuvant radiosurgery.OBSERVATIONS A 53-year-old man presented with 3 days of headaches and diplopia and was found to have a complete left abducens nerve palsy.Computed tomography (CT) revealed a smoothly dilated left carotid canal, CT angiography revealed a superiorly displaced left internal carotid artery(ICA), and magnetic resonance imaging revealed a T2-hyperintense and avidly enhancing lesion in the left cavernous sinus encasing the ICA. Thepatient underwent subtotal resection via an endoscopic transsphenoidal transcavernous approach followed by Gamma Knife radiosurgery.LESSONS Nerve sheath tumors arising from the CSP are extremely rare but need to be considered when assessing unusual cavernous sinus lesions.The clinical presentation is dependent on the anatomical location of the tumor and its relationship to the ICA. The optimal treatment paradigm isunknown.https://thejns.org/doi/abs/10.3171/CASE2375KEYWORDS cavernous sinus; sympathetic plexus; neurofibroma; carotid canal; schwannomaAlthough neurofibromas are the most common benign nervesheath tumors, they rarely present as an intracranial tumor. Theyarise from the nerve sheath and may occur along any peripheralnerve. Unlike schwannomas, which tend to be encapsulated anddisplace associated nerve fibers, neurofibromas are classically em-bedded in the axons and endoneurium. They are characterized bya germline mutation in the NF1 gene in up to 10% of patients.The internal carotid artery (ICA) sympathetic plexus containspostganglionic sympathetic fibers arising from the superior cervicalganglion. These fibers accompany the ICA throughout its petrousand cavernous segments. Nerve sheath tumors of the intracranialcarotid sympathetic plexus (CSP) are extremely rare, with only eightCSP schwannomas reported in the literature.1–8We describe the interesting case of a neurofibroma arisingfrom the cavernous CSP treated via an endoscopic endonasal ap-proach. This is the first documented case of a CSP neurofibromaas well as a CSP lesion treated via an endoscopic endonasalapproach.Illustrative CaseA 53-year-old man presented with a 3-day history of headacheand diplopia. He had experienced recurring headaches during thepreceding year. He had no significant medical history. Clinical ex-amination demonstrated a complete left abducens nerve palsy. Hehad no further cranial neuropathies and no peripheral stigmata ofneurocutaneous disorders.Imaging revealed a circumferential, heterogeneously enhancinglesion of the left ICA (Fig. 1). The lesion was located between thehorizontal segment of the petrous ICA and the anterior genu of thecavernous segment and was eccentrically located inferomedial tothe ICA. There was dilation and remodeling of the carotid canal andforamen lacerum, with the lesion abutting the lateral sphenoid sinusABBREVIATIONS CSP 5 carotid sympathetic plexus; CT 5 computed tomography; ICA 5 internal carotid artery; MR 5 magnetic resonance.INCLUDE WHEN CITING Published April 17, 2023; DOI: 10.3171/CASE2375.SUBMITTED February 7, 2023. ACCEPTED March 17, 2023.© 2023 The authors, CC BY-NC-ND 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)J Neurosurg Case Lessons | Vol 5 | Issue 16 | April 17, 2023 | 1J Neurosurg Case Lessons 5(16):CASE2375, 2023DOI: 10.3171/CASE2375wall. There was no calcification of the lesion or narrowing of theICA (Fig. 2).The patient underwent debulking of the lesion via an endoscopictranssphenoidal transcavernous approach. A modified expanded en-donasal approach was performed with a right-sided ethmoidectomy,including resection of the right middle turbinate and wide bilateralsphenoidotomies in addition to a posterior septectomy window. Wid-ening of the right nasal passageway allowed for a direct path to thecavernous sinus and lateral sphenoid wall. The anterior wall of thesella was removed on the left side, and this was extended to in-clude the floor of the sella. The bony exposure was then extendedin a medial to lateral fashion, uncovering the anterior genu of theICA and the medial cavernous sinus wall. Stereotaxis and Dopplerultrasonography were used to identify the course of the ICA. Afterthe medial wall of the cavernous sinus was widely decompressed,a dural opening was made over the tumor. The tumor was foundto be firm and fibrous. Significant resection was not possible giventhe nature of the tumor and the intimate relationship with the ICA(Fig. 3).Histopathology demonstrated a spindle cell lesion with a myxoidbackground with fascicles of spindle cells and wavy nuclei. Immuno-phenotype was positive for S100 and neurofilament and negativefor EMA, SMA, CD34, PR, and p53. The tumor was diagnosed asa neurofibroma (Fig. 4).The patient had an uncomplicated postoperative course, with thepersistence of abducens nerve palsy at the last follow-up. Heunderwent Gamma Knife radiosurgery 6 months following resectivesurgery.DiscussionWe report the first case of a CSP neurofibroma documented inthe literature. The patient was treated with subtotal resection via anendoscopic transsphenoidal transcavernous approach followed bystereotactic radiosurgery.ObservationsAnatomical ConsiderationsThe ICA sympathetic plexus arises from the superior cervicalganglion before entering the carotid canal, in association with theICA. These postganglionic sympathetic fibers derive from the gan-glion via a medial and lateral branch, contributing to the cavernousplexus and the deep petrosal nerve, respectively.9The sympathetic plexus forms two areas of increased densityalong its course: the first related to the distal petrous segment ofthe ICA and the second to the cavernous segment of the ICA.More detailed anatomical dissections have shown anterosuperiorand posteroinferior bundles along the petrous carotid. The deep pe-trosal branch originates from the anterosuperior bundle.10 In thecavernous segment, multiple smaller bundles form10 before provid-ing small branches to the abducens nerve and the ophthalmicnerve.11,12CSP schwannomas have been rarely described, with eight casesreported in the literature (Table 1). The tumor location dictates the clini-cal presentation, and distinct entities have been described. Takaseet al.7 proposed a classification scheme for CSP schwannomas basedFIG. 1. Axial T2-weighted (A) and T1-weighted with contrast (B) andcoronal T2-weighted (C) and T1-weighted with contrast (D) imagesdemonstrate a T2-hyperintense lesion with avid homogeneous contrastenhancement. The tumor is intimately related to the horizontal segmentof the cavernous ICA extending to the anterior genu.FIG. 2. Coronal CT bone window imaging (A) demonstrating remodel-ing of the carotid canal (dashed circles). CTangiography (B) showssuperior displacement of the horizontal segment of the cavernous ICA.FIG. 3. Intraoperative endoscopic images. The green dashed line indi-cates the course of the cavernous ICA. CR5 clival recess; OCR5opticocarotid recess; S5 sella; T5 tumor.2 | J Neurosurg Case Lessons | Vol 5 | Issue 16 | April 17, 2023on the anatomical location of the tumor as either type A, arising fromthe cavernous CSP, or type B, arising from the petrous CSP within thecarotid canal of the temporal bone. This anatomical classificationscheme correlates with clinical presentation and may help dictate thesurgical approach. Although originally described for schwannoma, it isapplicable in our case due to similarities in tumor behavior and ana-tomical origin.Type A tumors are intracavernous in location and arise from thecavernous plexus. Three cases, including our case, have been de-scribed, all presenting with abducens nerve palsy. Within the litera-ture, one patient underwent resection via an extradural approach tothe lateral cavernous sinus8 and one was managed without sur-gery.3 We present the first type A tumor to be approached via anendoscopic endonasal approach.Type B tumors arise from the internal carotid plexus and arelocated at the petrous apex. These lesions have been described asintraosseous. Six cases have been reported in the literature andpresent with hearing disturbance and tinnitus secondary to damageto the eustachian tube, inner ear, or tympanic cavity. The extraca-vernous location of these lesions facilitates surgical access. In theliterature, four type B tumors have been operated on via an extra-dural middle fossa approach with gross-total resection.Radiological ConsiderationsThe differential diagnosis for a cavernous sinus lesion is broad,with multiple diagnoses having nonspecific or overlapping imagingfeatures. Our patient’s computed tomography (CT) scan demon-strated dilation and remodeling of the left carotid canal without frankerosion or destruction of surrounding bone (Fig. 2). CT angiographyand magnetic resonance (MR) T2-weighted flow voids revealed asuperiorly displaced cavernous segment of the ICA. MR imagingdemonstrated a slightly hyperintense, smooth lesion on T2-weightedsequences with homogeneous, avid, postcontrast enhancement; thelesion was expanding the cavernous sinus and abutted the sphe-noid sinus while displacing the ICA superiorly and following the ICAfrom the cavernous segment to the petrous segment in the carotidcanal (Figs. 1 and 2).When reviewing the radiological features of CSP schwannomas,Hamilton et al.3 highlighted the significance of a smoothly expandedcarotid canal as compared with other pathologies that occur in theregion. This bone remodeling is attributed to the slow growth of thetumor and occurs along the axis of the ICA.Endoscopic Endonasal ConsiderationsAdvancement in endoscopic techniques, such as angled endo-scopes and image guidance, has allowed access to a broader regionof the central skull base, including the cavernous sinus. Fernandez-Miranda et al.13 defined the cavernous sinus compartments when ac-cessing them via an endonasal approach. This tumor was in the infe-rior compartment, located inferior to both the anterior genu and thehorizontal segment of the cavernous ICA. The compartment isbounded anteriorly by the anterior wall of the cavernous sinus andin anatomical dissections was found to contain the sympatheticplexus.The group proposed a transpterygoid supravidian approach tothis region,13 with exposure of the anterior and lateral wall of thecavernous sinus. This was not required in our case given the en-largement of the inferior compartment by the tumor and theFIG. 4. Histological findings consistent with neurofibroma. A: Hematox-ylin and eosin staining shows fascicles of spindle cells in a myxoidbackground. B: S100 was diffusely positive. C: Neurofilament waspositive, highlighting axons. D: Ki-67 showing a low proliferative index.Original magnification100 (A–D).TABLE 1. Summary of previous case reports.Authors & Year Pathology Age (yrs)/Sex Diplopia Hearing ICA Displacement Approach Classification Type EORSolodnik et al., 19866 S 59/M — Tinnitus Normal Suboccipital B NDHorn et al., 19954 S 46/F — Fullness Normal Postauricular B GTRS 52/M — Hearing loss Lat Middle fossa B TotalT€ure et al., 20038 S 29/M CN6 — Superolat Transcavernous A TotalHamilton et al., 20113 S 27/F CN6 Hearing loss Lat — B —S 68/M CN6 Tinnitus — NO A NOGoiney et al., 20111 S 48/F — — — Middle fossa B GTRTakase et al., 20177 S 54/M CN6 Hearing loss Superolat Middle fossa B GTRPresent case N 53/M CN6 — Superolat Endoscopic A STRCN 5 cranial nerve; EOR 5 extent of resection; GTR 5 gross-total resection; N 5 neurofibroma; NO 5 no operation; S 5 schwannoma; STR 5 subtotal resection;Superolat 5 superolateral.Adopted and updated from Takase et al.7J Neurosurg Case Lessons | Vol 5 | Issue 16 | April 17, 2023 | 3superolateral displacement of the cavernous ICA. Instead, a medialto lateral decompression approach to the medial cavernous sinuswall was performed. This approach has previously been described14and has been shown to be safe. Although exposure is limited later-ally with this approach, it was of no consequence in our case. How-ever, this is an important consideration if gross-total resection isintended.LessonsCSP nerve sheath tumors are extremely rare and may arisefrom either of the distinct sympathetic plexus bundles of the intra-cranial ICA. The location of the tumor and its relationship to thestructures at the skull base dictate the clinical presentation andguide the operative approach. We present the first case of a CSPneurofibroma and the first lesion treated with an endoscopic endo-nasal approach. Optimal management of these lesions is not yetknown because of their rarity.References1. Goiney C, Bhatia R, Auerbach K, Norenberg M, Morcos J. Intraoss-eous schwannoma of the petrous apex. J Radiol Case Rep.2011;5(11):8–16.2. Goudihalli SR, Goto T, Bohoun C, et al. Sympathetic plexusschwannoma of carotid canal: 2 cases with surgical technique andreview of literature. World Neurosurg. 2018;118:63–68.3. Hamilton JD, Demonte F, Ginsberg LE. Imaging of carotid canalsympathetic plexus schwannoma. AJNR Am J Neuroradiol.2011;32(7):1212–1215.4. Horn KL, Hankinson HL, Nissen AJ, McDaniel SL. Primary schwan-noma of the petrous apex. Skull Base Surg. 1995;5(4):261–268.5. Kim H, Hong R, Cho SI. Carotid sympathetic plexus schwannomapresenting as middle ear and external auditory canal mass. EarNose Throat J. 2023;102(3):160–163.6. Solodnik P, Som PM, Shugar JM, et al. Intraosseous petrous apexneuroma: CT findings. J Comput Assist Tomogr. 1986;10(6):1027–1029.7. Takase H, Araki K, Seki S, Takase K, Murata H, Kawahara N.Unique diagnostic features and surgical strategy for intracranialcarotid sympathetic plexus schwannoma: case report and literaturereview. World Neurosurg. 2017;98:876.8. T€ure U, Seker A, Kurtkaya O, Pamir MN. Internal carotid plexusschwannoma of the cavernous sinus: case report. Neurosurgery.2003;52(2):435–439.9. Gray H, Williams PL, Bannister LH. Gray’s Anatomy: The Anatomi-cal Basis of Medicine and Surgery. 38th ed. Churchill Livingstone;1995.10. van Overbeeke JJ, Dujovny M, Troost D. Anatomy of the sympatheticpathways in the cavernous sinus. Neurol Res. 1995;17(1):2–8.11. Bleys RL, Janssen LM, Groen GJ. The lateral sellar nerve plexusand its connections in humans. J Neurosurg. 2001;95(1):102–110.12. Iwanaga J, Anand MK, Camacho A, et al. Surgical anatomy of theinternal carotid plexus branches to the abducens nerve in thecavernous sinus. Clin Neurol Neurosurg. 2020;191:105690.13. Fernandez-Miranda JC, Zwagerman NT, Abhinav K, et al. Cavern-ous sinus compartments from the endoscopic endonasal approach:anatomical considerations and surgical relevance to adenomasurgery. J Neurosurg. 2018;129(2):430–441.14. Zhang Q, Wang Z, Guo H, et al. Direct transcavernous sinus approachfor endoscopic endonasal resection of intracavernous sinus tumors.World Neurosurg. 2019;128:e478–e487.DisclosuresDr. Yao reported personal fees from Medtronic, Inc., and Aerin Medicalfor consulting and personal fees from Optinose for the speakers'bureau, outside the submitted work.Author ContributionsConception and design: Blackburn, Trimble, Dawes, Zeineddine.Acquisition of data: Blackburn, Trimble, Dawes, Yao, Bhattacharjee.Analysis and interpretation of data: Blackburn, Trimble, Zeineddine,Yao. Drafting of the article: Blackburn, Trimble, Dawes, Zeineddine,Yao. Critically revising the article: Blackburn, Trimble, Dawes,Zeineddine, Guttenberg. Reviewed submitted version of the manuscript:all authors. Approved the final version of the manuscript on behalf of allauthors: Blackburn. Study supervision: Blackburn.CorrespondenceSpiros L. Blackburn: The University of Texas Health Science Center atHouston, TX. spiros.blackburn@uth.tmc.edu.4 | J Neurosurg Case Lessons | Vol 5 | Issue 16 | April 17, 2023

Neurofibroma of the Internal Carotid Artery Cavernous Sympathetic Plexus: Illustrative Case

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Neurofibroma of the Internal Carotid Artery Cavernous Sympathetic Plexus: Illustrative Case

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