Abducens Research Articles

Surgical anatomy of the carotid sympathetic plexus in endoscopic endonasal approaches: strategies for preventing Horner syndrome.

Endoscopic endonasal approaches (EEAs) specifically for procedures involving manipulation of the internal carotid artery (ICA), such as the transcavernous and translacerum approaches, confer a potential risk of carotid sympathetic plexus injury, potentially leading to postganglionic Horner syndrome. The primary aim of this study was to delineate the surgical anatomy of the carotid sympathetic plexus from an endoscopic endonasal perspective, offering insights to facilitate intraoperative anatomical identification and injury prevention. A comprehensive dissection was conducted on 20 silicone-injected, lightly embalmed postmortem human heads. The segments, patterns, and surgical landmarks of the carotid sympathetic plexus were investigated in a stepwise manner. In addition, 3 illustrative cases highlighting the involvement of the carotid sympathetic plexus in EEAs are included to contextualize the anatomical findings. The carotid sympathetic plexus can be categorized into 3 segments: 1) the cavernous sinus (CS) segment, beginning at the upper surface of the petrolingual ligament and ascending anterosuperiorly along the inferior compartment of the CS (mean ± SD length 5 ± 0.5 mm); 2) the lacerum segment, starting at the exit of the petrous carotid canal and ascending laterally and vertically to the upper surface of the petrolingual ligament (mean ± SD length 10 ± 1 mm); and 3) the petrous segment, originating at the external opening of the carotid canal and terminating at the foramen lacerum (mean ± SD length 18 ± 1 mm). Two primary morphological patterns of the sympathetic plexus at the CS and lacerum segments were identified: a plexus-like pattern in 12 (30%) hemispheres, and a nerve-like pattern that was subcategorized as double (18 [45%] hemispheres) or single (10 [25%] hemispheres) trunks. Surgical strategies emphasize the importance of recognizing key landmarks when approaching the carotid sympathetic plexus, including the pterygosphenoidal triangle, lingual process, petrolingual ligament, lateral parasellar ligament, and abducens nerve. This article provides a comprehensive anatomical description of the carotid sympathetic plexus in EEAs, highlighting key anatomical segments and patterns for intraoperative identification. A better understanding of anatomical landmarks for the carotid sympathetic plexus could help reduce the incidence of postganglionic Horner syndrome, augmenting the safety and efficacy of endoscopic endonasal transcavernous surgery.

Embolization of posterior fossa meningiomas supplied with meningohypophyseal trunk by using n-BCA and dual balloon protection.

Efficacy of tumor embolization for posterior fossa meningioma is controversial due to the lack of adequate embolization for dangerous feeders. Of these, a meningohypophyseal trunk (MHT) has high therapeutic value despite the high risks associated with embolization. To analyze the utility of preoperative MHT embolization for posterior fossa meningiomas using n-BCA with dual balloon protection, a single center retrospective record review was performed on eight consecutive patients who underwent preoperative tumor embolization via the MHT for posterior fossa meningiomas between 2020 and 2024. All patients successfully embolized the MHT using n-BCA. Complete obliteration was achieved in five cases, which is related to the tentorial artery alone as the feeding vessel. None of the patients had cerebral infarction associated with distal embolization. One patient experienced worsening of preoperatively observed abducens nerve palsy due to cranial nerve ischemia. Gross total resection was achieved in seven of eight cases. The mean estimated blood loss during surgical resection was 186 mL (range, 39-392 mL). The mean operative time was 431 min (range, 317-767 min). The MHT embolization of posterior fossa meningiomas by using n-BCA is technically feasible with a high success rate and an acceptable complication rate. MHT=meningohypophyseal trunk; ILT=inferolateral trunk; CPA=Cerebellopontine angle; BGC=balloon guide catheter; PVA=polyvinyl alcohol; GTR=Gross Total Resection; CN=Cranial nerve.

Sphenoclival fibrous dysplasia with cyst formation causing abducens nerve palsy in an older patient: illustrative case.

Fibrous dysplasia (FD) is typically asymptomatic but is known to occasionally cause neurological symptoms such as visual disturbances. However, FD-associated abducens nerve palsy is extremely rare. A 76-year-old woman had a left abducens nerve palsy due to mass effect on the abducens nerve at Dorello's canal caused by FD and its associated cyst, which was resolved by resection of the cyst through an endoscopic transnasal route. Although FD is generally an asymptomatic lesion occurring in younger patients, it can occasionally cause abducens nerve palsy even in older patients. In particular, cystic degeneration within FD tends to trigger a mass effect and thus can require surgical decompression. https://thejns.org/doi/10.3171/CASE24424.

Delayed Pontomesencephalic and Cervical Cord Venous Drainage Followed by Contralateral Carotid-Cavernous Fistula after Craniofacial Fractures: A Case Report.

A 24-year-old male was admitted with progressive cervical hypesthesia, tetraparesis, dyspnea, and a history of craniofacial fracture. Spinal magnetic resonance imaging (MRI) showed brainstem edema extending to the thoracic spine with multiple prominent perimedullary vascular structures. Cerebral digital-substraction angiography revealed Barrow type A carotid-cavernous fistula. Total occlusion with preservation of internal carotid artery flow was achieved using 1 detachable balloon and 6 coils. Postoperatively, immediate respiratory recovery, gradual extremities strength improvement, and right abducens nerve palsy were found. One month follow-up cervical MRI showed good recovery of spinal cord edema and perimedullary veins.

Seronegative brucella meningitis diagnosed by CSF PCR: report on seven cases

IntroductionNeurobrucellosis (NB) can be associated with meningitis and present as a headache with or without meningeal signs. Pseudotumor presentation of NB has been reported to be accompanied by lymphocytic predominant cerebrospinal fluid(CSF) pleocytosis. NB is diagnosed by means of isolation of Brucella from blood or CSF and/or the presence of anti-Brucella antibodies in the CSF. Molecular techniques have been used in chronic or challenging cases of NB.Clinical findingsWe report on seven cases of NB presenting with different types of headache and signs of meningeal involvement. In five cases, signs of intracranial hypertension were evident in the form of papilledema, sixth nerve palsy and blurred vision.DiagnosisMRIs of the brain revealed signs of intracranial hypertension in three patients, basal meningeal enhancement in one patient and white matter lesions in one patient. Brucella serology in the blood and CSF was negative in all patients. It was interesting that four patients had normocellular CSF analysis with normal glucose and protein results. The diagnosis was made by Brucella PCR in all patients.ConclusionNB should be considered in the differential diagnoses of pseudotumor cerebri syndrome in endemic areas. It is important to employ molecular techniques using sterile CSF samples in the investigation of Brucella.

Metastatic Intracranial Choriocarcinoma in the Absence of a Primary Lesion: A Case Report

AbstractIntracranial choriocarcinoma is a rare and aggressive neoplasm characterized by the proliferation of trophoblastic tissue. Although choriocarcinoma most commonly arises in the uterus as a component of gestational trophoblastic neoplasia, instances of intracranial choriocarcinoma are exceptionally uncommon. We report a case of intracranial choriocarcinoma without any evidence of a tumor elsewhere. A 25-year-old woman presented with a history of 1 month of evolution with right frontal hemicranial headache, followed by visual disturbances, otalgia, and diplopia. On neurological examination, she was conscious, cooperative, and well-oriented; a grade 1 bilateral papilledema, left homonymous hemianopsia, and sixth cranial nerve paresis, with diplopia, were detected. Neuroimaging showed a right parieto-occipital lesion with features mimicking an atypical meningioma. After surgical resection, a diagnosis of choriocarcinoma was issued. Primary intracranial choriocarcinomas are typically located in the sellar and pineal regions. The occurrence of this tumor within the occipital lobe suggested metastasis; however, a primary tumor in the thoracic or abdominal organs was not observed and a delayed metastasis was considered. This case highlights the diagnostic challenges associated with intracranial choriocarcinoma.

Cranial neuropathy following coronavirus disease 2019 vaccination in kidney transplant recipients.

Understanding of adverse reactions to coronavirus disease 2019 vaccines remains limited. Case 1: A 52-year-old woman, post-kidney transplantation, experienced sudden vision loss in her left eye after receiving a second dose of coronavirus disease 2019 vaccine. She was diagnosed with ischemic optic neuropathy.Case 2: A 53-year-old woman, post-kidney transplantation, presented with worsening diplopia and left eye pain following the second dose of coronavirus disease 2019 vaccine. She was diagnosed with left abducens nerve palsy. Vigilance is essential for recognizing the potential for delayed cranial neuropathy in immunocompromised individuals after coronavirus disease 2019 vaccination.

Differential Diagnoses for Isolated Right Sixth Nerve Palsy in the High Altitude Setting: A Case Report.

This case report describes the presentation and management of a patient with an isolated right sixth nerve palsy while trekking in Nepal. Consideration is made of the anatomy of the sixth nerve and the differential diagnoses afforded to this isolated sign, including high altitude cerebral edema. The case stresses the need to exclude life-threatening pathologies for any symptoms associated with altitude and includes decision-making processes on whether to monitor the patient in the field or evacuate them to a definitive care facility.

Persistent trigeminal artery aneurysm rupture inducing a carotid-cavernous fistula: its presentation and management. Illustrative case.

A carotid-cavernous fistula (CCF) is a well-recognized entity resulting from an abnormal connection between the internal carotid artery (ICA) or external carotid artery and the cavernous sinus. Typical CCF symptomology includes proptosis, chemosis, orbital bruit, headache, facial pain, and cranial nerve (CN) palsies. While CCFs most often occur posttraumatically, they can also occur spontaneously, secondary to cavernous ICA aneurysm rupture. Very rarely, they can occur secondary to the rupture of an anomalous persistent trigeminal artery (PTA) aneurysm. Herein, the authors describe the case of a 54-year-old woman who presented with a CN VI palsy and headache due to a CCF secondary to a PTA aneurysm rupture. The CCF was ultimately treated via coil embolization of the aneurysm and the parent PTA vessel. Though such occurrences are rare, clinicians should be vigilant in assessing for the presence of a PTA in patients with a CCF, as a PTA-associated CCF requires unique treatment considerations. In some cases where the PTA plays a crucial role in the posterior circulation supply, preservation of the parent vessel PTA is crucial. However, in cases in which an adequate posterior circulation collateral supply exists, embolization of the aneurysm and the parent vessel PTA is a reasonable treatment option for fistula closure. https://thejns.org/doi/10.3171/CASE24287.

Etiological and Prognostic Factors of Acquired Sixth Cranial Nerve Palsy

Etiological and Prognostic Factors of Acquired Sixth Cranial Nerve Palsy

Facial Colliculus and Sixth Nerve Nuclear Infarct as a Sentinel Sign of a Thrombosed Basilar Artery Aneurysm.

Facial Colliculus and Sixth Nerve Nuclear Infarct as a Sentinel Sign of a Thrombosed Basilar Artery Aneurysm.

Mullan's triangle or anteromedial triangle of the middle cranial fossa: a cadaveric study with its surgical importance.

Surgical approaches to the cavernous sinus (CS) and middle cranial fossa (MCF) can be challenging, particularly for young neurosurgeons. The anteromedial (Mullan's) triangle is a triangle by the side of the CS and constitutes part of the floor of the MCF. The contents include the sphenoid sinus, superior ophthalmic vein, and sixth cranial nerve. The literature contains very little research that has precisely defined and measured the anteromedial triangle while considering anatomical variances minimally. The present study was conducted on the skulls of 25 adult human cadavers which were dissected to expose the anteromedial (Mullan's) triangle on both sides. After precisely defining the triangle on each side, measurements of the three borders were taken, and using Heron's formula, the area of each triangle was calculated. On average, the length of the medial border was 12.5 (+ 3.1mm); the length of the lateral border was 9.9 (+ 3.1mm); the length of the base was 10.75 (+ 2.4mm) and the area of the anteromedial triangle was 43.9 (+ 15.06mm2). Precise anatomical knowledge of the Mullan's triangle enables the treatment of disorders in often deformed anatomy or difficult-to-access structures. That is the reason it is important to gain a thorough understanding of the surgical anatomy and to adopt a safe procedure.

Outcomes and Factors Associated with Successful Strabismus Surgery for Abducens Nerve Palsies: A Retrospective Study and Literature Review [Letter]

Outcomes and Factors Associated with Successful Strabismus Surgery for Abducens Nerve Palsies: A Retrospective Study and Literature Review [Letter]

Shoulder Traction as a Possible Risk Factor for C5 Palsy in Anterior Cervical Surgery: A Cadaveric Study.

Background and Objectives: Many risk factors for postoperative C5 palsy (PC5P) have been reported regarding a "cord shift" after a posterior approach. However, there are few reports about shoulder traction as a possible risk factor of anterior cervical surgery. Therefore, we assessed the stretched nerve roots when shoulder traction was applied on cadavers. Materials and Methods: Eight cadavers were employed in this study, available based on age and the presence of foramen stenosis. After dissecting the sternocleidomastoid muscle of the cadaver, the shoulder joint was pulled with a force of 2, 5, 8, 10, 15, and 20 kg. Then, the stretched length of the fifth nerve root was measured in the extra-foraminal zone. In addition, the same measurement was performed after cutting the carotid artery to accurately identify the nerve root's origin. After an additional dissection was performed so that the superior trunk of the brachial plexus could be seen, the stretched length of the fifth and sixth nerve roots was measured again. Results: Throughout the entire experiment, the fifth nerve root stretched out for an average of 1.94 mm at 8 kg and an average of 5.03 mm at a maximum force of 20 kg. In three experiments, the elongated lengths of the C5 nerve root at 8 kg and 20 kg were 1.69/4.38 mm, 2.13/5.00 mm, and 0.75/5.31 mm, respectively, and in the third experiment, the elongated length of the C6 nerve root was 1.88/5.44 mm. Conclusions: Although this was a cadaveric experiment, it suggests that shoulder traction could be the risk factors for PC5P after anterior cervical surgery. In addition, for patients with foraminal stenosis and central stenosis, the risk would be higher. Therefore, the surgeon should be aware of this, and the patient would need sufficient explanation.

Sixth cranial nerve palsy in giant cell arteritis: A systematic review

Objectives: This study aimed to review and describe isolated sixth cranial nerve or abducens nerve palsy that may present with subtle ophthalmoplegia in patients with giant cell arteritis (GCA). Materials and methods: In this systematic review following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) Extension for Scoping Reviews, MEDLINE and EMBASE were searched for all peer-reviewed articles using the keywords “cranial nerve six,” “abducens nerve,” and “giant cell arteritis” from their inception to December 22, 2022. Results: Twenty-five articles, including seven observational studies and 18 cases, were included. While the incidence and prevalence of sixth nerve palsy in GCA were variable, up to 48% of diplopia in GCA were attributed to the sixth cranial nerve palsy, according to the observational studies included. While 88.2% had a resolution of symptoms with 40-50 mg/day of prednisone-equivalent corticosteroids, it took a median of 24.5 days until the resolution of symptoms from the initiation of treatment. Conclusion: This review summarizes the current understanding of the characteristics of sixth nerve palsy in GCA. While most patients may have reversible clinical courses, a few can suffer from persistent ophthalmoplegia, which is a potentially missed yet crucial clinical finding in GCA. Increased awareness of the sixth nerve palsy in GCA is crucial.

Carotid Plexus Sympathetic Nerves as a Landmark for the Abducens Nerve Within the Cavernous Sinus During Endoscopic Endonasal Surgery: Cadaveric Anatomic Study and Surgical Consideration.

The abducens nerve (CN VI) is vulnerable to injury during endoscopic endonasal transcavernous surgery. In this study, the authors aimed to develop the surgical anatomic landmark and explore the relationship between the sympathetic nerves (SNs) around the internal carotid artery (ICA) and CN VI within the cavernous sinus (CS). The relationship and patterns between the SNs and CN VI were investigated in 15 cadaveric specimens. The intraoperative examples of anatomic landmark were presented. There were SNs around the ICA running into the CN VI, classified into ascending SNs and accessory sympathetic branches. The ascending SNs were divided into 3 types: (1) Type I had a single ascending SN. There were 2 subtypes of Type I (Type IA [17/30, 56.7%] was defined as a single ascending branch that ran into the CN VI, and Type IB [4/30, 13.3%] was defined as a single ascending branch with a terminal bifurcation before merging into the CN VI or lateral CS wall), (2) Type II (7/30, 23.3%) was defined as 2 ascending branches that ran into the CN VI and the lateral CS wall, and (3) Type III (2/30, 6.7%) was defined as 3 ascending branches that ran into the CN VIs and the lateral wall of the CS. The accessory branches of the SNs were defined by sympathetic branches from the posterior genu or horizontal ICA and found in 6/30 sides (20%). The authors propose a classification of the relationship between paraclival ICA SNs and the CN VI within the CS, as approached during endoscopic endonasal surgery. The consistent relationship of the ascending SN and CN VI within the CS provides a reliable anatomic landmark during the endonasal approach to the CS.

CHALLENGE IN TREATING OPTIC NEURITIS IN PATIENT WITH CEREBRAL TOXOPLASMOSIS RELATED TO IMMUNOCOMPROMISED CONDITION

Introduction: This study aimed to discuss the prognosis of optic neuritis in a patient with cerebral toxoplasmosis related to an immunocompromised condition. Case Report: A 28-year-old female complained of blurred vision and double vision 2 weeks before admission, accompanied by headache, low extremities weakness, dysphonia, and dysphagia. Visual acuity of both eyes was 6/30 and worsened to 6/60 in a couple of days. Anterior segment examination revealed anisocoria pupil, and RAPD was positive in the left eye. Funduscopic examination showed a blurry margin and hyperemia of the optic nerve head. There was impaired eye movement, indicating oculomotor and abducens nerve palsies. High titer of IgG Antibody Toxoplasma (264) and very low titer of CD4 (<50) with non-reactive HIV rapid test were found in laboratory findings. Multiple ring enhancement was shown in MRI finding. Unfortunately, patient passed away during hospitalization due to respiratory failure. Discussion: Toxoplasmosis-associated optic neuritis is rare and usually becomes potentially serious. Although parasite detection by microscopy and bioassay is considered the gold standard for the diagnosis of toxoplasmosis, clinical diagnosis relies more on serological examination methods. The high proportion of deaths from this disease is mostly caused by late diagnosis of the infection. Conclusion: Optic neuritis that accompanied by systemic disorders needs special attention and comprehensive treatment among multidisciplinary divisions, especially in the immunocompromised condition. Early detection and primary prevention are important to improve prognosis and survival rate.

Case Report: Tolosa-Hunt syndrome, a neuroinflammatory origin of painful ophthalmoplegia

Background Tolosa-Hunt syndrome is a rare neuroinflammatory disease that affects the cavernous sinus and superior orbital fissure, resulting in symptoms of neuropathy. Case presentation We report a case of a 35-year-old male patient with no past medical history who presented to the emergency department (ED) complaining of a four-day history of progressively increasing headaches associated with right eye pain and double vision. A physical examination showed findings suggestive of abducens nerve palsy. A computed tomography (CT) scan showed subtle asymmetric thickening of the right cavernous sinus, which prompted further investigation by magnetic resonance imaging (MRI) scan. The MRI scan showed intensely enhanced soft tissue thickening in the right cavernous sinus region, slightly extending to the right orbital apex, which caused enlargement of the cavernous sinus and appeared isointense to the adjacent muscles on T1 and T2. The diagnosis of Tolosa-Hunt syndrome was made after the exclusion of all other possible pathologies. The patient received prednisolone therapy; his symptoms improved, and he was discharged after three days. Two weeks later, the patient presented again to the ED with the same symptoms and was treated symptomatically. Conclusions This case highlights a very rare etiology for painful ophthalmoplegia, which is Tolosa-Hunt syndrome. Thickening of the cavernous sinus on MRI images with a background history of painful ophthalmoplegia and headache should raise clinician’s suspicion towards the disease. In addition, exclusion of other possible causes is very important, as Tolosa-Hunt syndrome is a diagnosis of exclusion.

Through their eyes: Navigating life with limited eyelid closure in patients with Moebius syndrome

Moebius syndrome (MoS), a rare congenital condition caused by the underdevelopment of the sixth and seventh cranial nerves, presents with uni- or bilateral facial paralysis and lateral gaze palsy. Those with MoS often have incomplete eyelid closure (lagophthalmos). This study aimed to investigate the experiences of individuals living with incomplete eyelid closure due to MoS. Participants shared their experiences in semi-structured open-ended focus groups during the 2023 MoS Foundation Conference. Data were analyzed thematically using Nvivo. The Terzis and Bruno scoring system was used to grade participant eyelid closure (range: 1 being no eyelid closure with full scleral show to 5 being complete eyelid closure with no scleral show) and blink (from 1 being no blink to 5 being synchronous and complete blink present). Marginal reflex distances 1 and 2 (MRD1 and MRD2) were measured to grade for ptosis and lid retraction, respectively. Fifteen participants participated in two focus groups, comprising adults (n=12) and adolescents (n=3). All participants had lagophthalmos with some scleral show, ptosis, and lid retraction. The median eyelid closure score was 3 (incomplete eye closure with 1/3 scleral showing). Five key themes were identified: social stigma and misunderstanding, daily life impacts, seasonal exacerbations, different attitudes toward surgical intervention between adults and adolescents, and a prevailing sense of self-acceptance regarding their condition. Incomplete eyelid closure poses significant social challenges for individuals with MoS, especially around social encounters. Our findings show the importance of developing tailored communication tools to support those living with this facial difference.

Acute abducens nerve palsy following coronavirus disease 2019 vaccination: a case report

BackgroundAbducens nerve palsy is the most common isolated ocular cranial nerve palsy. In adults, nontraumatic etiologies of isolated sixth cranial nerve palsy can include vascular disease, inflammation, tumors, and a prior history of infection.Case presentationWe present a case of a 52-year-old Asian male who developed acute abducens nerve palsy after vaccination with the AstraZeneca coronavirus disease 2019 vaccine. A complete workup including magnetic resonance imaging of the brain and orbits revealed no abnormalities. The patient experienced a gradual recovery over 10 weeks through alternative eye patching. The abducens nerve palsy is postulated to be correlated with the coronavirus disease 2019 vaccine.ConclusionDespite the recognized efficacy and cost benefits of coronavirus disease 2019 vaccines, clinicians should be aware of the possible association between cranial nerve palsies and coronavirus disease 2019 vaccines.