Endoscopic endonasal approach to the middle cranial fossa through the cavernous sinus triangles: anatomical considerations.

The lateral limit of endoscopic endonasal surgery has yet to be defined. The aim of this study was to investigate the lateral limit of endoscopic endonasal surgery at the level of the sphenoid sinus. Access from the sphenoid sinus to the middle cranial fossa through the cavernous sinus triangles was evaluated by cadaver dissection. Anatomical analysis demonstrated that the medial temporal dura mater was exposed through the anterior area of the clinoidal triangle, anteromedial triangle, and superior area of the anterolateral triangle, indicating potential corridors to the middle cranial fossa. This study suggests that the cavernous sinus triangles are applicable in selected cases to manage middle cranial fossa lesions by endoscopic endonasal surgery.

Identification of the internal carotid artery at the superior part of the cavernous sinus during endoscopic endonasal cavernous sinus tumor surgery.

BACKGROUND: Identification of the internal carotid artery (ICA) is essential for successful endoscopic endonasal cavernous sinus tumor surgery. This study aimed to develop a method for identifying the ICA in cavernous sinus tumors at the superior part of the cavernous sinus. METHODS: Ten fresh cadavers were studied with a 4-mm 0° and 30° endoscope to identify surgical landmarks of the ICA in the cavernous sinus. Clinical cases of cavernous sinus tumors were surgically treated using an endoscopic transpterygoid approach. RESULTS: Anatomical study indicated the ICA at the superior part of the cavernous sinus can be identified using three steps: 1) exposure of the optic nerve sheath by drilling the optic canal; 2) identification of the proximal orifice of the optic nerve sheath at the transition of the optic nerve sheath and dura mater of the tuberculum sellae; and 3) identification of the clinoid segment of the ICA at the distal dural ring just below the proximal orifice of the optic nerve sheath. Although the ICA was encased and transposed by tumors in preliminary surgical cases, the clinoid segment of the ICA was safely exposed at the superior part of the cavernous sinus using this method. CONCLUSIONS: Dural structures around the cavernous sinus are key to identifying the ICA at the superior part of the cavernous sinus. This method is expected to reduce the risk of ICA injury during endoscopic endonasal surgery for cavernous sinus tumors.

Endoscopic endonasal approach to the middle cranial fossa through the cavernous sinus triangles: anatomical considerations.

The lateral limit of endoscopic endonasal surgery has yet to be defined. The aim of this study was to investigate the lateral limit of endoscopic endonasal surgery at the level of the sphenoid sinus. Access from the sphenoid sinus to the middle cranial fossa through the cavernous sinus triangles was evaluated by cadaver dissection. Anatomical analysis demonstrated that the medial temporal dura mater was exposed through the anterior area of the clinoidal triangle, anteromedial triangle, and superior area of the anterolateral triangle, indicating potential corridors to the middle cranial fossa. This study suggests that the cavernous sinus triangles are applicable in selected cases to manage middle cranial fossa lesions by endoscopic endonasal surgery.

Endoscopic extradural subtemporal approach to lateral and central skull base: a cadaveric study.

OBJECTIVE: Endoscopy has provided a less invasive approach to skull base surgery, mainly through endonasal routes, but has been limited in its applications due to potential complications. The aims of this study were to evaluate the feasibility of the purely endoscopic extradural transcranial approach to lateral and central skull base through a subtemporal keyhole and to better understand potential distortions of the related anatomy via endoscopy. METHODS: Ten fresh cadaver heads were studied with 4-mm 0° and 30° endoscopes to develop the surgical approach and to identify surgical landmarks. RESULTS: The endoscopic extradural subtemporal approach was divided into 3 sections after exposure of the extradural space in the middle cranial fossa: 1) exposure of the lateral wall of the cavernous sinus and the preauricular infratemporal fossa; 2) anterior petrosectomy and posterior cranial fossa exploration; and 3) unroofing of the tympanic cavity and exposure of the facial nerve. This keyhole endoscopic technique clearly visualized anatomical landmarks of the lateral and central skull base via an extradural subtemporal route. CONCLUSIONS: The endoscopic extradural subtemporal approach was feasible. This approach could display a wide range of lateral and central skull base structures with minimal invasiveness. The use of extradural space would be key to performing safe and effective endoscopic skull base surgery.

Endoscopic far-lateral approach to the posterolateral craniovertebral junction: an anatomical study.

Minimally invasive surgery to the posterolateral craniovertebral junction (CVJ) has not been sufficiently described. The aims of this study were to evaluate the feasibility of an endoscopic far-lateral approach to the posterolateral craniocervical junction and to better understand the related anatomy under distorted endoscopic view. Ten fresh cadavers were studied with 4-mm 0° and 30° endoscopes to develop the surgical approach and to identify surgical landmarks. After making a 3-cm straight incision behind the mastoid process, the superior oblique and rectus capitis posterior major muscles were partially exposed. An endoscope was then introduced and the two muscles were followed inferiorly until the posterior arch of the atlas appeared. The two muscles were removed to create ample working space without violating the posterior atlanto-occipital membrane. The vertebral artery was identified by the landmark of the posterior arch of the atlas, and the atlanto-occipital joint and foramen magnum were exposed. In addition to suboccipital craniectomy, transcondylar, supracondylar, and paracondylar extension by drilling were applicable through the narrow corridor under superb visualization. The intradural neurovascular structures from the acousticofacial bundle to the dorsal root of C2, anterolateral space of the foramen magnum, cerebellomedullary fissure, and fourth ventricle were clearly demonstrated. This endoscopic far-lateral approach offers excellent exposure of surgical landmarks around the posterolateral CVJ with minimal invasiveness. Endoscopic soft tissue dissection is key to creating the surgical corridor. This approach could offer an alternative to the conventional far-lateral approach in selected cases.

Endoscopic approaches to the trigeminal nerve and clinical consideration for trigeminal schwannomas: a cadaveric study.

OBJECT: The course of the trigeminal nerve straddles multiple fossae and is known to be very complex. Comprehensive anatomical knowledge and skull base techniques are required for surgical management of trigeminal schwannomas. The aims of this study were to become familiar with the endoscopic anatomy of the trigeminal nerve and to develop a minimally invasive surgical strategy for the treatment of trigeminal schwannomas. METHODS: Ten fresh cadavers were studied using 5 endoscopic approaches with the aid of 4-mm 0° and 30° endoscopes to identify surgical landmarks associated with the trigeminal nerve. The endoscopic approaches included 3 transcranial keyhole approaches (the extradural supraorbital, extradural subtemporal, and retrosigmoid approaches), and 2 endonasal approaches (the transpterygoid and the transmaxillary transpterygoid approaches). RESULTS: The trajectories of the extradural supraorbital, transpterygoid, and extradural subtemporal approaches corresponded with the course of the first, second, and third divisions of the trigeminal nerve, respectively. The 3 approaches demonstrated each division in intra- and extracranial spaces, as well as the Meckel cave in the middle cranial fossa. The interdural space at the lateral wall of the cavernous sinus was exposed by the extradural supraorbital and subtemporal approaches. The extradural subtemporal approach with anterior petrosectomy and the retrosigmoid approach visualized the trigeminal sensory root and its neighboring neurovascular structures in the posterior cranial fossa. The transmaxillary transpterygoid approach revealed the course of the third division in the infratemporal fossa. CONCLUSIONS: The 5 endoscopic approaches effectively followed the course of the trigeminal nerve with minimal invasiveness. These approaches could provide alternative options for the management of trigeminal schwannoma.

Endoscopic telovelar approach to the fourth ventricle: anatomic study.

The telovelar approach allows reliable access to the fourth ventricle and avoids the splitting of the vermis and its associated "posterior vermal split syndrome." Our objective was to describe the endoscopic topographical anatomy of the telovelum approach to the fourth ventricle as accessed by the cerebellomedullary corridor. A series of 20 fresh and fixed injected anatomical specimens were used. The endoscopic equipment consisted of rigid endoscopes with different lens angles, while the extradural step required the use of the microscope and/or the exoscope. All the anatomical landmarks and relationships within the fourth ventricle and the cerebellomedullary fissure were identified by means of the endoscopic microscope/exoscope-assisted telovelar approach. In conclusion, we showed that the endoscope is a valid tool to gain an anatomic understanding of the fourth ventricle reached by means of the telovelar approach.

Endoscopic reconstruction of the middle cranial fossa through a subtemporal keyhole using a pedicled deep temporal fascial flap: a cadaveric study.

BACKGROUND: Reconstruction of the skull base is essential to prevent postoperative leakage of cerebrospinal fluid (CSF). However, a reliable method of reconstructing the middle cranial fossa via a subtemporal keyhole is not available. OBJECTIVE: To determine whether less invasive reconstruction of the middle cranial fossa under endoscopic guidance with a pedicled deep temporal fascia approach via a subtemporal keyhole is feasible and useful. METHODS: The middle cranial fossa in 4 fresh cadaver heads was reconstructed with a 4-mm 0° rigid endoscope. RESULTS: A subtemporal skin incision (subtemporal incision) was followed by 2 small skin incisions (temporal line incisions) made on the superior temporal line. The endoscope was inserted through the temporal line incisions, and then the deep temporal fascia was separated from the superficial temporal fascia and temporal muscle under endoscopic view. A pedicled flap was harvested from the subtemporal incision and applied to the middle cranial fossa after subtemporal keyhole craniotomy. The pedicled deep temporal fascial flap was flexible, long, and large enough to overlay skull base defects. CONCLUSION: This purely endoscopic technique using a pedicled deep temporal fascial flap provided reliable reconstruction of the middle cranial fossa through a subtemporal keyhole. This technique would also be applicable in preventing CSF leakage or treating traumatic, acquired nontraumatic, or congenital encephalocele in the middle cranial fossa.

The subdiaphragmatic cistern: historic and radioanatomic findings.

BACKGROUND: In the past, sporadic demonstrations of the existence of a subarachnoid subdiaphragmatic cistern have been published. The aim of this study was to evaluate the anatomical characteristics of the subdiaphragmatic cistern of the pituitary gland. METHODS: After a complete review of the literature published on the topic, we report anatomical observations of the subdiaphragmatic cistern and its relationship to the pituitary gland and to the chiasmatic cistern. Ten cadaveric heads were studied using different techniques and surgical methods (plastination, plastic casts of the subarachnoid spaces, microscopic and transsphenoidal endoscopic approaches). Moreover, 3-T magnetic resonance images of ten healthy volunteers were analyzed to investigate the presence and anatomical variability of the subdiaphragmatic cistern. RESULTS: By means of our qualitative radioanatomic study, we found that the roof of the subdiaphragmatic cistern is formed by the diaphragma sellae, the floor by the superior face of the pituitary gland, the lateral walls by the arachnoidea extending laterally through the medial walls of the cavernous sinus, and the medial walls by the infundibular stem. The subdiaphragmatic cistern communicates by means of the ostium of the diaphragm with the chiasmatic cistern. CONCLUSION: We confirmed the existence of the subdiaphragmatic cistern. The overused term "suprasellar cistern" refers more to a complex of cisterns, formed by the subdiaphragmatic cistern, below the diaphragma sella, and by the chiasmatic cistern, above it, in direct communication with the lamina terminalis and carotid cisterns.

A pitfall of neuroendoscopic intraventricular hematoma removal - delayed obstructive hydrocephalus caused by a small remnant clot - case report - .

A 57-year-old female presented with a left putaminal hemorrhage, intraventricular hematoma (IVH), and acute obstructive hydrocephalus. Neuroendoscopic surgery was performed for the IVH. Three days after successful IVH removal and improvement of her consciousness, the patient lapsed into a comatose state due to hydrocephalus caused by obstruction of the mesencephalic aqueduct by a small remnant clot. The small clot was identified by constructive interference with steady state magnetic resonance imaging and was removed during a second-look operation. Even after the cerebrospinal fluid circulation improves following neuroendoscopic surgery for IVH, the patient may nevertheless develop a life-threatening condition without warning signs in the subacute phase. Awareness of this complication will lead to early diagnosis and correct management.

Intracerebral hemorrhage despite prophylactic administration of vitamin K in infants--two case reports.

The incidence of vitamin K deficiency in infancy has decreased markedly, due to prophylactic administration of vitamin K during the neonatal period. However, vitamin K deficiency bleeding may occur during or after the neonatal period despite prophylactic administration in Japan. Two cases are reported of intracranial hemorrhage associated with coagulopathy in full-term infants who had received prophylactic administration of vitamin K. More reliable methods for prophylactic administration should be established.

Purely endoscopic repair of traumatic cerebrospinal fluid rhinorrhea from the anterior skull base: case report.

A 38-year-old woman presented with a case of post-traumatic ethmoidal cerebrospinal fluid (CSF) leak that was repaired using a purely endoscopic endonasal approach. Six weeks after a mild domestic maxillofacial trauma, she started complaining of clear, watery discharge from the left nostril and headache. Neuroimaging investigations disclosed a linear fracture of the left anterior ethmoidal roof without evidence of large bony breaches or any brain tissue damage. After conservative medical treatment with carbonic anhydrase inhibitors failed, she was referred to our hospital for surgical repair of the osteodural defect. An endoscopic endonasal transethmoidal approach was successfully performed, and an overlay technique was used to reconstruct the defect. The patient was discharged without clinical evidence of CSF rhinorrhea and no leaks were apparent at the 3-month follow-up clinical and radiological examinations. Post-traumatic CSF rhinorrhea occurs in cases of dural tears associated with small bone breaks, most frequently involving the anterior skull base. Recovery is often spontaneous following only bed rest, or with medical treatments such as inhibitors of carbonic anhydrase diuretics, steroids, or eventually stool softeners to help reduce CSF pressure. Surgical repair is required when first-line conservative treatment proves ineffective. The present case shows that the endoscopic endonasal technique for the management of CSF leaks provides a less invasive surgical route to achieve valid dural repair.

Radiation-induced astrocytoma with rapid malignant transformation: case report.

A 23-year-old man was admitted with a rare case of radiation-induced astrocytoma manifesting as 3-month history of unstable gait. He had received 50 Gy of irradiation therapy for a germ cell tumor in the right basal ganglia 13 years earlier. Magnetic resonance (MR) imaging on admission showed a non-enhanced mass lesion in the right cerebellar hemisphere with expansion to the vermis. The histological diagnosis of the stereotaxic biopsy specimen was grade II astrocytoma. Two months later, he developed drowsiness, and MR imaging demonstrated that the tumor had enlarged and was enhanced after gadolinium injection. The clinical diagnosis was high-grade glioma resulting from malignant transformation. The tumor had compressed the mesencephalic aqueduct, leading to obstructive hydrocephalus. Endoscopic third ventriculostomy was performed to improve the cerebrospinal fluid circulation. He underwent chemotherapy with temozolomide postoperatively, but died 8 months after the initial diagnosis of astrocytoma. The clinical course of radiation-induced astrocytoma is not benign. The potential for malignant transformation necessitates careful postoperative follow up for patients with this tumor.

Endoscopic extradural anterior clinoidectomy via supraorbital keyhole: a cadaveric study.

BACKGROUND: Anterior clinoidectomy is an essential preliminary step for parasellar and pericavernous sinus surgery. Endoscopy is a widely accepted modality for neurosurgical strategies and is becoming more important in treating conditions involving the cranial base. OBJECTIVE: To determine the feasibility of endoscopic extradural anterior clinoidectomy via the supraorbital keyhole. METHODS: Eight fresh cadaver heads were studied using 4-mm, 0- and 30-degree rigid endoscopes to perform endoscopic extradural anterior clinoidectomy. We also evaluated a bony landmark for this technique in 36 dry craniums. RESULTS: An endoscope was introduced into the extradural space created via a supraorbital keyhole craniotomy. The periorbita and the duplication of the dura extending to the temporal lobe dura and periorbita were exposed by drilling. Anterior clinoidectomy proceeded using a diamond drill under endoscopic visualization without a dural incision. A submerged view with continuous irrigation through an endoscopic sheath maintained clear visibility while drilling. A small bony eminence at the transition between the sphenoid ridge and the anterior clinoid process, which is an anatomic landmark for endoscopic extradural anterior clinoidectomy, was identified in 57.4% of 36 adult dry craniums. CONCLUSION: The endoscopic extradural procedure can accomplish reliable anterior clinoidectomy under superb endoscopic visualization. This method would be applicable to parasellar and cavernous sinus surgery combined with keyhole or conventional craniotomy.

Endoscopic supraorbital extradural approach to the cavernous sinus: a cadaver study.

OBJECT: The cavernous sinus is a small complex structure located at the central base of the skull. Recent extensive use of endoscopy has provided less invasive approaches to the cavernous sinus via endonasal routes, although transcranial routes play an important role in the approach to the cavernous sinus. The aims of this study were to evaluate the feasibility of the purely endoscopic transcranial approach to the cavernous sinus through the supraorbital keyhole and to better understand the distorted anatomy of the cavernous sinus via endoscopy. METHODS: Eight fresh cadavers were studied using 4-mm 0° and 30° endoscopes to develop a surgical approach and to identify surgical landmarks. RESULTS: The endoscopic supraorbital extradural approach was divided into 4 stages: entry into the extradural anterior cranial fossa, exposure of the middle cranial fossa and the periorbita, exposure of the superior cavernous sinus, and exposure of the lateral cavernous sinus. This approach provided superb views of the cavernous sinus structures, especially through the clinoidal (Dolenc) triangle. The lateral wall of the cavernous sinus, including the infratrochlear (Parkinson) triangle and anteromedial (Mullan) triangle, was also clearly demonstrated. CONCLUSIONS: An endoscopic supraorbital extradural approach offers excellent exposure of the superior and lateral walls of the cavernous sinus with minimal invasiveness via the transcranial route. This approach could be an alternative to the conventional transcranial approach.

Comparison of clinical outcomes of intraventricular hematoma between neuroendoscopic removal and extraventricular drainage.

The efficacy of treatment for intraventricular hematoma by neuroendoscopic surgery and extraventricular drainage was compared in 10 patients with intraventricular hematoma and hydrocephalus who underwent neuroendoscopic surgery (endoscopic group), and eight patients with intraventricular hematoma and hydrocephalus treated with extraventricular drainage (EVD group). The outcomes in each group were assessed retrospectively using the Graeb scores on the pre- and postoperative computed tomography (CT), duration of extraventricular drainage, requirement for a shunt operation, and modified Rankin scale score at 12 months. The Graeb scores on the preoperative CT were not significantly different between the two groups, but the duration of catheter placement was significantly shorter (69.3%) in the endoscopic group (2.7 days) than in the EVD group (8.8 days). None of the patients in either group required a shunt procedure for communicating hydrocephalus 12 months after surgery. Neuroendoscopic removal is a safe and effective procedure for intraventricular hematoma. Advantages include rapid removal of hematoma in the ventricular systems and reliable improvement of non-communicating hydrocephalus in the acute phase. The procedure resulted in faster removal of the catheter in the postoperative period and earlier patient ambulation.

Endoscopic management of a traumatic meningo-encephalocele through a planum sphenoidale defect: case report.

A 37-year-old man involved in a motor vehicle accident was admitted to our hospital with disturbed consciousness. Computed tomography (CT) showed an acute, right-sided epidural hematoma and pneumocephalus. Emergency evacuation of the acute epidural hematoma was carried out, and his condition gradually recovered. However, cerebrospinal fluid (CSF) rhinorrhea continued despite conservative treatment. Three-dimensional reconstructed CT revealed a bone defect, which was approximately 20 mm in size, in the planum sphenoidale and tuberculum sellae, and magnetic resonance imaging demonstrated a traumatic meningo-encephalocele through the defect, with CSF collection in the sphenoid sinus. Endoscopic endonasal transsphenoidal surgery was performed. The 9-mm diameter dural defect was clearly visualized in the sphenoid sinus and was reconstructed with a combination of suturing and overlay with abdominal fascia, and absorbable polyglycolic acid felt. The CSF leakage from a traumatic meningo-encephalocele through the planum sphenoidale was successfully repaired by endoscopic endonasal surgery. Thorough preoperative evaluation of the feasibilities of the endoscopic and transcranial approaches should be based on the preoperative identification of the fistula, the bone defect, and vital structures.

Clinicopathological characteristics in patients presenting with acute onset of symptoms caused by Rathke's cleft cysts.

BACKGROUND: Symptomatic Rathke's cleft cyst is usually accompanied by a long history of headache, visual disturbance, and hypopituitarism; however, rare cases present with acute onset and the clinical features in such cases remain uncertain. We report herein the clinical features of Rathke's cleft cyst with acute onset and discuss the clinical significance. METHOD: In this study, we defined acute onset as the clinical course with clinical symptoms within a 7-day history. From among 35 cases of symptomatic Rathke's cleft cyst that were pathologically diagnosed at Fukuoka University Hospital between 1990 and 2009, five cases presented with acute onset. The symptoms, endocrinological findings, MR image findings, and pathological findings of these cases were analyzed retrospectively. FINDINGS: Mean age was 56.8 years. Initial symptoms included headache (n = 3), general malaise (n = 2), polyuria (n = 2), and fever (n = 1). MR imaging revealed an intrasellar cystic lesion with suprasellar extension in all cases and showed rim enhancement in three cases. All cases were treated by transsphenoidal surgery. Pathological findings included hemorrhage (n = 2), hypophysitis (n = 2), and abscess formation in the cyst (n = 1). Postoperatively, all symptoms, except for hypopituitarism, improved in all cases. CONCLUSIONS: Rathke's cleft cysts sometimes present with acute onset, and the presentation is consistent with the features of pituitary apoplexy caused by pituitary adenoma. Although pituitary apoplexy due to hemorrhage, inflammation, or infection due to an underlying Rathke's cleft cyst is difficult to diagnose pre-operatively, Rathke's cleft cyst should be included in the differential diagnosis, and early surgical treatment is needed, as for pituitary apoplexy caused by pituitary adenoma.