Excision of Greater Superficial Petrosal Nerve Schwannoma Via a Pure Endoscopic Endonasal Approach

Greater superficial petrosal nerve (GSPN) schwannomas are an exceedingly rare nerve sheath tumor. The current literature search was conducted using Medline and Embase database by key search terms. Only 31 cases have been reported in the literature so far. Facial palsy, hearing loss, and xerophthalmia accounted for 48.4% (15), 41.9% (13), and 29% (9) of all cases, respectively. The middle cranial fossa approach was used in all previous reports. A retrospective review of 2 GSPN schwannomas patients treated by endoscopic endonasal approach (EEA) in our center was collected. Clinical records, including clinical features, pre- and postoperative images, surgery, and follow-up information, were reviewed. In all cases, clinical features including facial numbness and headache were found, with tinnitus in case 1, hearing loss, xerophthalmia in case 2. Imaging studies showed a solid mass that originated in the anterior of the petrous bone. Two patients were treated by EEA. Furthermore, no recurrence was found during the follow-up period (15-29 months) in both of the 2 cases after the operation. Complete resection of GSPN schwannomas can be achieved via the pure EEA. Endoscopic endonasal approach for radical removal of tumors is safe and feasible.

Schwannomas of the greater superficial petrosal nerve - case series, discussion of surgical techniques, and review of literature

BACKGROUND

Facial nerve schwannomas account for about 0.8% of all petrous mass lesions. Schwannomas of the greater superficial petrosal nerve (GSPN) are a rare subtype with few case-reports up to date.

CASE PRESENTATIONS

A retrospective analysis of clinical outcomes, radiographic findings and postoperative complication between June 2007 and December 2020 was performed. Four cases of GSPN schwannomas were reported. The presenting symptoms were facial nerve palsy and hearing loss. Imaging studies showed a subtemporal mass on the anterosuperior aspect of the petrous bone, in one case with extraordinary petrous bone and mastoid infiltration and destruction. Three cases were removed through a subtemporal extra- or intradural approach, one case via a combined pre- and retrosigmoid approach. Improvement of facial nerve palsy occurred in one case; new hearing loss was observed in another case. Xeropthalmia was a short-term temporary deficit in three cases. Short- to mid-term follow-up of the patients has not shown any tumor recurrence.

CONCLUSIONS

GSPN schwannomas are rare entities presenting with heterogenous symptoms. Our surgical findings emphasize safe resection. Complete remission is possible by GTR. Since the small data set limits the expressiveness of statements regarding standard of care and alternative therapy options, additional data is needed.

Unilateral Dry Eye Due to Possible Isolated Parasympathetic Denervation of the Lacrimal Gland in a Woman With Hypothyroidism

PURPOSE

The aim of this study was to report a unique case of unilateral neurogenic dry eye disease (DED) secondary to isolated parasympathetic denervation of the lacrimal gland along with a literature review.

METHOD

This is a case report and literature review on neurogenic DED discussing its clinical presentation, etiology, and treatment options.

RESULTS

A 32-year-old woman with hypothyroidism presented with pain and a burning sensation in her left eye and dry nares for 1 week. Ocular examination revealed conjunctival congestion and inferior superficial punctate fluorescein staining in the left eye. Her unanesthetized Schirmer values were 24 and 01 mm in the right and left eyes, respectively, with no secretory activity noted in the left lacrimal gland on direct assessment. A detailed neurologic examination, autoimmune panel, and neuroimaging were unremarkable except for the dry left nasal cavity. She is currently using lubricants and did not consent to pilocarpine therapy. Her lacrimal gland activity was unchanged till 3 months of follow-up. The most common cause of neurogenic DED is idiopathic, followed by trauma. Pilocarpine therapy, in oral, topical, or combined form, has improved tear secretion in 63% of neurogenic DED seen in animal cohort.

CONCLUSIONS

Unilateral neurogenic DED can occur as an isolated parasympathetic denervation of the lacrimal glands. Pilocarpine therapy has shown some efficacy in animal cohort of neurogenic DED; however, it needs to be explored for human eyes.

Schwannoma of the Greater Superficial Petrosal Nerve: An Unusual Site for a Common Tumor

Greater superficial petrosal nerve (GSPN) schwannoma is a rare clinical entity. It forms a small subset of the larger group of facial nerve schwannomas. A thorough literature search yielded only 27 such cases reported to date in the English literature. We present one such rare case of GSPN schwannoma and discuss the clinical spectrum and management along with a review of the literature. We demonstrate the surgical steps in an operative video.

Endoscopic transorbital route to the petrous apex: a feasibility anatomic study

BACKGROUND

While the subtemporal approach represents the surgical module milestone designed to reach the petrous apex, a novel ventral route, which is the superior eyelid endoscopic transorbital approach, has been proposed to access the skull base. Accordingly, we aimed to evaluate the feasibility of this route to the petrous apex, providing a qualitative and quantitative analysis of this relatively novel pathway.

METHODS

Five human cadaveric heads were dissected at the Laboratory of Surgical NeuroAnatomy of the University of Barcelona. After proper dissection planning, anterior petrosectomy via the endoscopic transorbital route was performed. Specific quantitative analysis, as well as dedicated three-dimensional reconstruction, was done.

RESULTS

Using the endoscopic transorbital approach, it was possible to reach the petrous apex with an average volume bone removal of 1.33 ± 0.21 cm³. Three main intradural spaces were exposed: cerebellopontine angle, middle tentorial incisura, and ventral brainstem. The first one was bounded by the origin of the trigeminal nerve medially and the facial and vestibulocochlear nerves laterally, the second extended from the origin of the oculomotor nerve to the entrance of the trochlear nerve into the tentorium free edge while the ventral brainstem area was hardly accessible through the straight, ventral endoscopic transorbital trajectory.

CONCLUSION

This is the first qualitative and quantitative anatomic study concerning details of the lateral aspect of the incisura and ventrolateral posterior fossa reached via the transorbital window. This manuscript is intended as a feasibility anatomic study, and further clinical contributions are mandatory to confirm the effectiveness of this approach, defining its possible role in the neurosurgical armamentarium.

TFOS DEWS II pathophysiology report

The TFOS DEWS II Pathophysiology Subcommittee reviewed the mechanisms involved in the initiation and perpetuation of dry eye disease. Its central mechanism is evaporative water loss leading to hyperosmolar tissue damage. Research in human disease and in animal models has shown that this, either directly or by inducing inflammation, causes a loss of both epithelial and goblet cells. The consequent decrease in surface wettability leads to early tear film breakup and amplifies hyperosmolarity via a Vicious Circle. Pain in dry eye is caused by tear hyperosmolarity, loss of lubrication, inflammatory mediators and neurosensory factors, while visual symptoms arise from tear and ocular surface irregularity. Increased friction targets damage to the lids and ocular surface, resulting in characteristic punctate epithelial keratitis, superior limbic keratoconjunctivitis, filamentary keratitis, lid parallel conjunctival folds, and lid wiper epitheliopathy. Hybrid dry eye disease, with features of both aqueous deficiency and increased evaporation, is common and efforts should be made to determine the relative contribution of each form to the total picture. To this end, practical methods are needed to measure tear evaporation in the clinic, and similarly, methods are needed to measure osmolarity at the tissue level across the ocular surface, to better determine the severity of dry eye. Areas for future research include the role of genetic mechanisms in non-Sjögren syndrome dry eye, the targeting of the terminal duct in meibomian gland disease and the influence of gaze dynamics and the closed eye state on tear stability and ocular surface inflammation.

A rare case of greater petrosal nerve schwannoma

Background:

Facial nerve schwannomas include only 0.8% of all intrapetrous mass lesions, and schwannomas originating exclusively from the greater petrosal nerve (GPN) are extremely rare. To date, only 13 reports have been described. In this case, the tumor was thought to originate from the GPN on the basis of clinical, radiological, and operative findings.

Case Description:

A 23-year-old girl presented an acute left facial palsy, a disturbance in tear secretion of the ipsilateral eye, and a left-sided conductive hypoacusia. Computed tomography (CT) scan and magnetic resonance imaging (MRI) showed an extradural mass in the left middle fossa. A subtemporal approach was performed and the lesion, originating from the proximal portion of the GPN, was excised. The post-operative course was satisfactory, except for a xerophtalmia, which was treated with artificial teardrops.

Conclusion:

GPN schwannomas can originate anywhere alongside the course of the nerve, from its proximal segment near the facial hiatus to its distal segment near the foramen lacerum. For these reasons, it requires differential diagnosis with trigeminal nerve schwannomas or with injuries arising from the geniculate ganglion, because it can be easily confused with those lesions. However, in less severe cases, an early diagnosis can be able to preserve the function of the facial nerve by reducing iatrogenic injuries caused by surgical maneuvers.

Schwannoma of the greater superficial petrosal nerve

The authors report the clinical features, imaging and surgical findings, and follow-up of 5 rare cases of schwannoma of the middle fossa with possible origin from the greater superficial petrosal nerve (GSPN). All patients presented to a single neurosurgical institution. The study design was a prospective follow-up of 5 cases of schwannomas of the middle fossa that most likely originated from the GSPN. The presenting features were burning pain in the eyes in 2 cases, epilepsy and behavioral changes in 2 cases, and headache in 1 case. Imaging studies showed a subtemporal mass on the anterosuperior aspect of the petrous bone in all cases. An enhancing tail on the MR images was highly suggestive of the origin of the tumor from the GSPN. All tumors were removed through a subtemporal extra- or intradural approach.

Partial to complete peripheral facial nerve palsy was encountered after surgery in 3 cases, which recovered completely. Dry eye was the long-term permanent deficit in all cases. Mid- to long-term follow-up of the cases has not revealed any tumor recurrence. The 5 cases of schwannoma of the middle fossa with possible origin from GSPN were managed successfully, and their clinical presentation, differential diagnosis, and management are discussed.