In order to master the surgical approaches to the middle cranial fossa, the surgeon needs to understand the relevant bony anatomy. However, she/he also needs to have a clear and sound understanding of the neural and vascular anatomy because, oftentimes, the osseous anatomy (except for the optic apparatus) should be removed to expose and protect the neurovascular anatomy. This is the second of a two-part article discussing the neurovascular anatomy of the middle cranial fossa. A brief discussion of the surgical approaches follows.

UNASSIGNED: The main purpose of this study is to highlight the involvement of the facial nerve as one of the presenting symptoms in patients suspected of coronavirus disease associated mucormycosis (CAM).
UNASSIGNED: This is a retrospective observational study conducted at a tertiary care referral centre which included 300 patients with past history of being treated for coronavirus disease and who presented to our department with symptoms of invasive fungal sinusitis. All the patients were evaluated clinically and radiologically for presence of facial nerve palsy (FNP) in suspected cases of CAM. All the patients were managed with combined modality treatment with antifungal therapy and radical endoscopic debridement of the necrotic tissue and fungal debris.
UNASSIGNED: The data were analysed to assess the possible epidemiological factors linked to CAM. Diabetes mellitus was the most common associated factor identified for aggravating of CAM. FNP is also one of the common presentation seen among 53 patients with CAM.
UNASSIGNED: FNP is an unusual but significant sign in presentation of mucormycosis. It could be easily misdiagnosed as cerebrovascular accident leading to delay in the treatment. During this era of Covid-19 pandemic where wearing of masks has become mandatory, there is a high probability of this finding to be missed. Thus, our study emphasises for thorough cranial nerve examination in all cases of CAM, for an early and an immediate intervention to prevent the spread of the disease and also to improve the overall general condition of the patient.

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.

Neural insult during development results in recovery outcomes that vary dependent upon the system under investigation. Nerve regeneration does not occur if the rat gustatory chorda tympani nerve is sectioned (CTX) during neonatal (≤P10) development. It is unclear how chorda tympani soma and terminal fields are affected after neonatal CTX. The current study determined the impact of neonatal CTX on chorda tympani neurons and brainstem gustatory terminal fields. To assess terminal field volume in the nucleus of the solitary tract (NTS), rats received CTX at P5 or P10 followed by chorda tympani label, or glossopharyngeal (GL) and greater superficial petrosal (GSP) label as adults. In another group of animals, terminal field volumes and numbers of chorda tympani neurons in the geniculate ganglion (GG) were determined by labeling the chorda tympani with DiI at the time of CTX in neonatal (P5) and adult (P50) rats. There was a greater loss of chorda tympani neurons following P5 CTX compared to adult denervation. Chorda tympani terminal field volume was dramatically reduced 50 days after P5 or P10 CTX. Lack of nerve regeneration after neonatal CTX is not caused by ganglion cell death alone, as approximately 30% of chorda tympani neurons survived into adulthood. Although the total field volume of intact gustatory nerves was not altered, the GSP volume and GSP-GL overlap increased in the dorsal NTS after CTX at P5, but not P10, demonstrating age-dependent plasticity. Our findings indicate that the developing gustatory system is highly plastic and simultaneously vulnerable to injury.

Management of chronic cluster headache (CCH) remains a challenging endeavor, and the optimal surgical approach for medically refractory CCH remains controversial.
To conduct a preliminary evaluation of the efficacy and safety of vidian neurectomy (VN) in patients with medically refractory CCH.
Between March 2013 and December 2015, 9 CCH patients, all of whom had failed to respond to conservative therapy, underwent VN with a precise nerve cut and maximal preservation of the sphenopalatine ganglion. Data included demographic variables, cluster headache onset and duration, mean attack frequency, mean attack intensity, and pain disability index measures pre- and through 12-mo postsurgery.
Seven of the 9 cases (77.8%) showed immediate improvement. Improvement was delayed by 1 mo in 1 patient, after which the surgical effects of pain relief were maintained throughout the follow-up period. One patient (11.1%) did not improve after surgery. One year after VN, patients\' mean attack frequency, mean attack intensity, and pain disability index decreased by 54.5%, 52.9%, and 56.4%, respectively. No patient experienced treatment-related side effects or complications.
VN is an effective treatment method for CCH patients. Precise Vidian nerve identification and maximal preservation of the sphenopalatine ganglion may achieve good surgical outcomes and dramatically improve quality of life among patients, without significant adverse events.

BACKGROUND: Schwannoma originating from the greater superficial petrosal nerve is an extremely rare type of facial nerve schwannoma located in the middle cranial fossa around the midportion of the petrous bone. Here, we provide the first report of greater superficial petrosal nerve schwannoma presenting with contralateral facial palsy and hemiparesis due to compression of the pyramidal tract by associated intradural peritumoral cyst.
METHODS: A 69-year-old woman presented with a 6-month history of gradually worsening gait unsteadiness. Magnetic resonance imaging demonstrated a well-defined tumor occupying the right middle cranial fossa and extending into the tympanic cavity. Notably, the tumor accompanied a large cyst in the intradural space, resulting in a leftward midline shift. Extradural exploration through thinned periosteal dura mater revealed the tumor within the interdural space. After debulking of most of the tumor in a pull-out, piecemeal fashion, intradural exploration revealed the peritumoral cyst located between the meningeal dura mater and brain parenchyma. Following the disappearance of the mass effect from the tumor, fenestration of the peritumoral cyst, which had been deeper-seated than the tumor, was easily achieved while avoiding excessive retraction of the temporal lobe. Postoperatively, mild left hemiparesis involving the face resolved completely and no new symptoms such as right facial palsy, hearing disturbance, or xerophthalmia developed as postoperative complications.
CONCLUSIONS: The combination of extradural and intradural approaches in the appropriate order is essential for fenestration of an intradural peritumoral cyst along with removal of an interdural tumor.

Perineural tumor spread (PNS) substantially alters a patient\'s prognosis and treatment plan. Therefore, it is critical that the radiologists are familiar with the course of cranial nerves commonly affected by PNS and the neuronal connections to appropriately map the extent of PNS. Limited involvement of a nerve by PNS might be resectable, whereas advanced PNS may require radiation therapy.

BACKGROUND: Intracranial carotid sympathetic plexus schwannoma (CSPS) is extremely rare; thus differential diagnostic criteria, optimal surgical strategies, and even a precise definition are lacking. Here we describe a case of CSPS and propose a definition and classification for previously reported cases.
METHODS: A 54-year-old man presented with hypacusis and abducens nerve palsy. Radiologic examinations revealed a well-enhanced mass at the right medial temporal base with erosion of the petrous apex and intact perilesional cortical bone. Preoperative findings, such as spontaneous improvement of diplopia, absence of xerophthalmia or facial palsy, and laterally displaced internal carotid artery (ICA), suggested the atypical origins of the petrous apex schwannoma. The tumor was exposed using the subtemporal extradural approach and completely resected. Intact foramen ovale, rostrolateral displacement of the greater superficial petrosal nerve within the outer membrane of the tumor, eroded petrous apex and carotid canal, superolaterally displaced ICA, and lack of an obvious tumor attachment to any of the suspected nerves suggested that the tumor originated from the carotid sympathetic plexus of the petrous ICA. The patient fully recovered without neurological complications.
CONCLUSIONS: Preoperative diagnosis of petrous apex schwannoma is difficult: characteristic findings such as diplopia, hypacusis, and laterally displaced ICA may help. In addition, assessment of the relationship between the tumor and cavernous sinus could be useful in the determination of the surgical approach. Complete resection with good clinical outcome could be expected using Dolenc\'s approach (type A) and by the middle fossa extradural approach (type B) for intracavernous and extracavernous CSPS, respectively.

The purpose of this article is to explain the anatomy of the pterygopalatine ganglion (PPG), its location in the pterygopalatine fossa (PPF) in the skull, and the relationship it has to the Vidian nerve terminal branches and the fifth cranial nerve. An overview of the neuro-anatomical/clinical correlations, a spectrum of pathologies affecting the seventh cranial nerve and some therapies both medical and surgical are noted. The focus is the pterygopalatine region with discussion of the proximal courses of the seventh and fifth cranial nerves and their pathological processes. The ganglion is used as an example of neuro-anatomical model for explaining cluster headaches (CH). Radiological correlation is included to clarify the location of the PPF and its clinical importance.

Objective In the extended middle fossa approach, a portion of the petrous bone known as Kawase\'s rhomboid can be drilled to expose the posterior fossa through a middle fossa corridor. During this bony resection, the cochlea is placed at risk. The objective of this study was to objectively detail the position of the cochlea in relation to reliable surgical landmarks. Methods Eleven cadaveric specimens were dissected-including six cadaveric heads and five dry temporal bones by means of an anterior petrosectomy with skeletonization of the cochlea. Three anatomic measurements describing the location of the cochlea in relation to the extrapolated intersection of the greater superficial petrosal nerve (GSPN) and facial nerve were recorded. These measurements were then correlated with thin-cut temporal bone computed tomography scans from 25 patients with morphologically normal inner ears. Results In the cadaveric specimens, the anterior border of the membranous basal turn of the cochlea was located an average of 7.56 mm (6.4 to 8.9 mm) anterior to the extrapolated junction of the GSPN and facial nerve, as measured along the course of the GSPN. The medial border of the membranous cochlea (medial margin of basal turn) was located an average of 8.2 mm (6.9 to 8.9 mm) medial to the extrapolated junction of the GSPN and facial nerve, as measured along the course of the facial nerve. The average maximum distance from the extrapolated junction of the GSPN and facial nerve to the membranous cochlea was 9.3 mm (8.2 to 10.3 mm). These anatomic measurements correlated well with radiologic measurements of the same parameters. Conclusion When drilling Kawase\'s rhomboid, it is useful to locate the extrapolated junction of the GSPN and the facial nerve. Drilling of the anteromedial petrous bone outside of a radius of 12.5 mm from the extrapolated junction of GSPN and facial nerve appears to be associated with a low degree of risk to the cochlear apparatus.