Internal carotid plexus schwannoma of the cavernous sinus: case report

Use of a Suction-Monopolar Stimulator for Continuous Neurophysiology Monitoring During Endonasal Resection of a Cavernous Sinus Schwannoma: 2-Dimensional Operative Video

Cavernous sinus schwannomas are exceptionally rare tumors.1,2 Although these tumors commonly originate from the trigeminal nerve, instances involving the oculomotor, abducens, trochlear nerves, and the carotid plexus have also been documented.2-7 In this operative video, we showcase a 44-year-old man with a medical history of acromegaly and schwannomatosis who presented with retro orbital pain and a growing cystic lesion in the left cavernous sinus. Genetic testing ruled out neurofibromatosis types 1 and 2. An endonasal resection was recommended considering the left side and extradural location of the lesion.8 The tumor was excised through an endonasal transpterygoid approach using 2 suctions, one of which was equipped with an electrode tip for continuous monitoring of extraocular nerves during the resection process. Imaging postoperatively demonstrated near-total resection. Institutional review board approval was not required; the patient agreed to undergo the procedure and to have his operative video published.

Carotid Sympathetic Plexus Schwannoma Presenting as Middle Ear and External Auditory Canal Mass

Schwannomas in the middle ear and external auditory canal are exceedingly rare. The facial nerve, chorda tympani nerve, and Jacobson's nerve have rarely been reported as the origins of primary schwannomas in the middle ear cavity. We experienced a case of carotid sympathetic plexus (CSP) schwannoma that arose from the carotid canal and extended into the middle ear and external auditory canal. The tumor presented bone erosion of the carotid canal, and it adhered tightly to the internal carotid artery. This report represents the first documented case of a CSP schwannoma, which involved the middle ear and external auditory canal.

Three-dimensional structure of the facial canal and related blood vessels and nerves in the temporal bone

PURPOSE

There are only limited anatomical data on nerves, veins, and arteries in the temporal bone. More detailed anatomical data are required to improve planning of treatments targeting the temporal bone region. Herein, we performed a detailed analysis of the facial canal (FC) and the related carotid artery and vein.

METHODS

We examined the bony structure of the middle ear and FC, jugular foramen, and carotid canal in 30 Japanese elderly donor cadavers. Three-dimensional reconstruction of the canal structure was achieved using cone beam computed tomography, while macroscopic and histological analyses were also performed.

RESULTS

The FC form was classified as either straight (28%) or bent (72%). There were significant differences in the diameter of the FC and the distance between the internal jugular vein, other FC branches, and the FC. Principal component analysis (PCA) was performed for the FC using 29 factors. Two principal components significantly explained 30.9% (component 1, 18.6%; component 2, 12.3%) of the FC. Histological observation showed numerous ganglion cells and shrunken neurons in the geniculate ganglion of the facial nerve of elderly samples.

CONCLUSION

FC diameter is an important contributor to the relationship between the FC and the jugular foramen. The FC and the internal jugular vein are located close to each other, which is useful information for the trans-canal surgery of the otology. Furthermore, the geniculate ganglion contains numerous ganglion cells and shrunken neurons, which may affect the FC structure during bone matrix remodeling with aging.

Endoscopic Endonasal Transpterygoid Approach for Resection of Carotid Sympathetic Plexus Schwannomas: A Cadaveric Stepwise Dissection, Technical Nuances and Surgical Outcomes

OBJECTIVE

Carotid sympathetic plexus (CSP) schwannomas are rare brain tumors located in a complex site around the cavernous sinus and carotid canal in the petrous bone. This study describes 3 cases of CSP schwannomas that underwent surgical removal of the tumor through an endoscopic endonasal transpterygoid approach.

METHODS

Between 2016 and 2021, 3 cases of CSP schwannomas were treated using an endoscopic endonasal transpterygoid approach. Preoperative tumor size, preoperative and postoperative symptoms, internal carotid artery (ICA) displacement, extent of tumor resection, intraoperative findings showing tumor origin, and surgical complications were evaluated in all patients.

RESULTS

Two tumors were in the petrous region, and the other one was in both the petrous and cavernous regions. The median tumor diameter was 41.3 mm. In the 3 cases, the ICA was displaced to the superolateral side, the anterolateral side, and the posterior side, respectively. Near-total resection was achieved in all 3 cases via an endoscopic endonasal transpterygoid approach. There were no endonasal postoperative complications, and the cranial nerve disability improved in all 3 patients at 1-year follow-up.

CONCLUSIONS

The surgical technique for CPS schwannoma using an endoscopic endonasal transpterygoid approach may be a viable option because endoscopy has been proven to offer better intraoperative visualization and reduce postoperative discomfort for patients. Tumors located medial and inferior to the ICA pars cavernous sinus or anterior, inferior, and medial to the paraclival ICA are ideal candidates for surgery using this endoscopic approach.

Abducens nerve schwannoma of the cavernous sinus: A case report and literature review

Background:

Schwannomas of the abducens nerve are a rare pathology and are encountered less within the cavernous sinus. We describe a case of sixth cranial nerve schwannoma, in the cavernous sinus.

Case Description:

A 50-year-old lady, presented with 2 years history of double vision and left facial numbness that started 6 months before presentation, found to have hyperintense lobulated mass at the left cavernous sinus extending into Meckel’s cave with bony remodeling on magnetic resonance imaging. She underwent left frontotemporal craniotomy, combined extra-intradural approach, gross total resection. She had a gradual recovery of the sixth cranial nerve function.

Conclusion:

Abducens nerve schwannoma of the cavernous sinus is a rare and challenging tumor. However amenable to surgical intervention with favorable neurological outcome.

Surgical Approach to the Cavernous Sinus for a Trigeminal Schwannoma Resection: Technical Note and Case Report

We report a rare case of schwannoma of the lateral wall of the cavernous sinus, an exceedingly rare lesion affecting this anatomical district, and discuss salient aspects of the surgical approach to the cavernous sinus, which are traditionally considered technically challenging due to the high risk of postoperative morbidity and mortality related to the presence of the cranial nerves and internal carotid artery.

Imaging of carotid canal sympathetic plexus schwannoma

One case report of a schwannoma involving the sympathetic plexus in the carotid canal has been reported previously. This article presents 2 additional cases of this rare entity with associated clinical and unique radiographic findings. All patients presented with diplopia among other symptoms, and they had enhancing masses that smoothly expanded the carotid canal on cross-sectional imaging. Comparison with the index case and differential diagnosis of more common pathologies in this area are discussed.

CELLULAR SCHWANNOMA OF THE GREATER SUPERFICIAL PETROSAL NERVE PRESENTING WITH ABDUCENS NERVE PALSY AND XEROPHTHALMIA

OBJECTIVE

Cellular schwannomas (CS) are rare in the cranial space. This report is the first of a patient with a greater superficial petrosal nerve CS presenting with abducens nerve palsy and xerophthalmia.

CLINICAL PRESENTATION

A 16-year-old female patient presented with a 1-month history of diplopia. Neurological examination was normal except for the presence of right abducens nerve palsy. Schirmer's test revealed decreased tear secretion in the right eye. Computed tomography and magnetic resonance imaging showed a mass in the right petrous apex. It was thought that the schwannoma in our patient originated from the greater superficial petrosal nerve, based on the location of the tumor in addition to the absence of partial Horner's syndrome and a persistent decrease in tear secretion. INTERVENTION: The tumor was exposed with the use of a right subtemporal extradural approach and removed entirely. Pathological evaluation of the tumor revealed a CS.

CONCLUSION

The abducens nerve palsy improved completely in the follow-up period, but the decreased tear secretion did not resolve. CS is one of the subtypes of ordinary schwannomas and exhibits malignant features on microscopic examination, although it has a good clinical prognosis. No adjuvant treatment was applied because of the tumor's benign character. The greater superficial petrosal nerve schwannoma should be considered in the differential diagnosis of the abducens nerve palsy and petrous apex mass.

Medial plantar nerve compression by a tibial artery schwannoma

✓ The authors describe the case of a patient with a novel cause of medial plantar symptoms due to extrinsic compression by a schwannoma arising within the adventitia of the tibial artery in the ankle region. Additionally they provide the operative, histological, and imaging findings.

Microanatomical architecture of Dorello's canal and its clinical implications

OBJECTIVE

We investigated the membranous architecture of the abducens nerve at the petroclival region and describe the characteristics of this area in cadaveric specimen and two children with hydrocephalus and sixth nerve palsy using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Five adult cadaver heads were used to investigate the petroclival part of the abducens nerve. The heads were injected with colored latex for microsurgical dissection, and the length of the dural sleeve of the abducens nerve and its width at the apex were measured. In one cadaver head, the area between the petroclival entrance porus of the abducens nerve and the cavernous sinus was histologically studied under light microscopy. In two patients with hydrocephalus and abducens nerve palsy, the petroclival area was screened by using the MRI fat suppression technique.

RESULTS

In the cadavers, the arachnoid membrane on the clivus extended within the dural sleeve as far as the petrous apex, as an extension of the subarachnoid space. The average length of the dural sleeve was 9.5 mm and the average width was 1.5 mm at the apex, where the nerve entered the cavernous sinus. MRI scans showed that the cerebrospinal fluid distance of the petroclival region was 5 mm in the first patient and 7 mm in the second.

CONCLUSION

The subarachnoid space inside the dural sleeve of the abducens nerve can be defined by using thin-slice MRI scans. Enlargement of the dural sleeve at the petroclival region may coexist with the abducens nerve palsy. It has been documented in this study that the arachnoid membrane forms a membraneous barrier between the subarachnoid and subdural spaces within Dorello's canal.

Non-meningeal tumours of the cavernous sinus: a surgical analysis

The popularisation of cavernous sinus approaches and subsequent experience has shaped our treatment paradigms for cavernous sinus meningiomas. However, pathologies in this region are diverse and each one requires individual consideration. The purpose of this study was first to analyse, define and summarise the individual characteristics of different non-meningeal tumours of the cavernous sinus and, secondly, to stress that their surgery can be accomplished with acceptable morbidity and rewarding results when those characteristics are considered. A retrospective analysis of 42 cases of benign non-meningeal tumours of the cavernous sinus operated on at Marmara University between April 1992 and April 2003 is presented. The patients were 15 males and 27 females aged 24-72 years. The study cohort consisted of 13 pituitary adenomas, 11 trigeminal schwannomas, seven chordomas, three chondrosarcomas, two juvenile angiofibromas, two epidermoid tumours, one plasmacytoma, one cavernous haemangioma and one internal carotid plexus schwannoma. The 42 patients underwent 46 operations aimed at radical surgical excision. Total resection was achieved in 50% and subtotal resection in 50% of cases. The majority of incompletely resected tumours were pituitary adenomas and chordomas, and 95% required further treatment. Twenty-nine percent of patients developed complications, namely cerebrospinal fluid fistula, haematoma, hydrocephalus, diabetes insipidus, cerebral infarction and cranial nerve palsies. Recurrence was seen in 7.1% of patients. At final follow up at an average of 48.2 months after surgery, the mean Karnofsky performance scale had risen from 83.4 to 87.4. Non-meningeal tumours of the cavernous sinus can be surgically resected with acceptable morbidity and mortality. In selected tumours the results are better than those for cavernous sinus meningiomas. The best surgical results are achieved with interdural tumours of the lateral sinus wall and the worst surgical results are seen in invasive tumours such as chordomas and pituitary adenomas. Individual tumour characteristics are presented in the text.

Macro Anatomical Investigations of the Cranial Cervical Ganglion in Domestic Pig (Sus scrofa domesticus)

In this study, the left and right cranial cervical ganglia (ganglion cervicale craniale) of eight young (four male, four female) domestic pigs weighing around 70-80 kg were inspected macro anatomically. The cranial cervical ganglion (CCG) was found cranio-ventrally of the distal ganglion of the vagus nerve, medial of the jugular process extremity, ventral of the atlas, dorsal of the epiglottis base and medial of the common root (CR) established by the internal carotid and occipital arteries. The internal carotid nerve and jugular nerve ramified from the cranial part of CCG. The jugular nerve gave branches that merged with the vagus and glossopharyngeal nerves. Other nerve branches originating from the cranial part of the ganglion reached to the external carotid artery and CR. The internal carotid nerve varied among cadavers in number of branches (two to four). These branches did not travel along the side of the internal carotid artery. The central part of CCG gave thin nerve branches that reached to various anatomical structures including the first and second cervical nerves, wall of the pharynx, accessory nerve, hypoglossal nerve, vagus nerve, external carotid artery and CR. The caudal part of CCG gave nerve branches that merged with the vagus, cranial laryngeal nerves, and common carotid artery. The external carotid nerves, which were two or three in number, also originated from the caudal part of CCG. In conclusion, the nerves ramifying from CCG of the pig varied in number among cadavers. Compared with literature raised in other species, there are also differences in number of nerve branches and course pattern of these nerves.