Microsurgical anatomy of the arteries of the pituitary stalk and gland as viewed from above

The importance of preserving the superior hypophyseal artery infundibular branch in craniopharyngioma surgery

PURPOSE

Postoperative pituitary dysfunction, a critical problem in the treatment of craniopharyngiomas, can occur even when the pituitary stalk is preserved. We hypothesized that compromise of the primary superior hypophyseal artery (pSHA) might be related to this occurrence.

METHODS

We performed a retrospective review of 131 patients with craniopharyngioma who underwent surgery from April 2009 to September 2021. The inclusion criteria were initial surgery, endoscopic transsphenoidal surgery, preoperative normal pituitary function or pituitary dysfunction in one axis, and morphological preservation of the pituitary stalk. The branches of the pSHA consist mainly of the chiasmatic branches (Cb), infundibular branches (Ib), and descending branches (Db). We analyzed the association between postoperative pituitary function and preservation of these branches.

RESULTS

Twenty patients met the criteria. Preoperative anterior pituitary function was normal in 18 patients, and there was isolated growth hormone deficiency in two patients. No patient had preoperative diabetes insipidus (DI). Anterior pituitary function was unchanged postoperatively in eight patients. Of these eight patients, bilateral preservation of pSHA Ib was confirmed in seven patients. Bilateral preservation of pSHA Ib was the only factor associated with preserved anterior pituitary function (p < 0.01). Fifteen patients were free of permanent DI, and the preservation of any given pSHA branch produced no significant difference in the postoperative occurrence of permanent DI.

CONCLUSIONS

Our study shows that bilateral preservation of pSHA Ib provides favorable postoperative anterior pituitary function in craniopharyngioma surgery; however, such preservation may have little effect on the postoperative occurrence of DI.

Pituitary stalk changes on magnetic resonance imaging following pituitary adenoma resection using a transsphenoidal approach

Objective

We aimed to investigate the magnetic resonance imaging (MRI) findings and clinical significance of position and changes in morphology of the pituitary stalk following pituitary adenoma (PA) resection using a transsphenoidal approach.

Methods

We collected clinical and MRI data of 108 patients with PA after transsphenoidal surgery. Diameter, length, and coronal deviation of the pituitary stalk were measured pre-, post-, and mid-term post-operatively, to observe pituitary stalk morphology.

Results

Of 108 patients, 53 pituitary stalks were recognisable pre-operatively. The angle between the pituitary stalk and the median line was 7.22°-50.20° (average, 25.85°) in 22 patients with left-sided pituitary stalks and 5.32°-64.05° (average, 21.63°) in 20 patients with right-sided pituitary stalks. Of 42 patients with preoperative pituitary stalk deviation, 41 had an early postoperative recovery and 1 had increased deviation. In the mid-term postoperative period, 21 of 42 patients had pituitary stalks located centrally. In 53 patients, the pituitary stalk length was 1.41-11.74 mm (mean, 6.12 mm) pre-operatively, 3.61-11.63 mm (mean, 6.93 mm) in the early postoperative period, and 5.37-17.57 mm (mean, 8.83 mm) in the mid-term postoperative period. In the early postoperative period, 58 (53.70%) patients had posterior pituitary bright spots (PPBS) and 28 (25.92%) had diabetes insipidus (DI).

Conclusion

Pre-operatively, the pituitary stalk was compressed and thinned. Post-operatively, it could be stretched to a "normal state", and its position showed a gradual centring trend. Post-operatively, the length of the pituitary stalk gradually increased. The PPBS in the early postoperative period negatively correlated with postoperative DI.

Developed Circuminfundibular Anastomosis Associated with Vascular Abnormalities

We report a 74-year-old male patient who presented with left hemiplegia and disturbance of consciousness. Computed tomography revealed diffuse subarachnoid hemorrhage, which was prominent in the right Sylvian and basal cisterns. Digital subtraction angiography revealed absence of the C2 segment of the right internal carotid artery (ICA) and a significantly developed circuminfundibular anastomosis. Occlusion of the bilateral vertebral arteries (VAs) was also seen. The upper basilar artery was supplied by the circuminfundibular anastomosis and collaterals from the VAs. Since the source of bleeding was unclear, the patient was treated conservatively. Circuminfundibular anastomosis is a potential anastomosis around the pituitary stalk. It is formed by the superior hypophyseal arteries, prechiasmal arteries, and infundibular arteries bilaterally. Agenesis of the contralateral ICA often leads to development of ICA-ICA anastomoses. In this case, the anastomosis developed due to agenesis of the C2 segment of the right ICA and occlusion of the bilateral VAs.

Contralateral vs. Ipsilateral Approach to Superior Hypophyseal Artery Aneurysms: An Anatomical Study and Morphometric Analysis

Introduction

Surgical clipping of superior hypophyseal artery (SHA) aneurysms is a challenging task for neurosurgeons due to their close anatomical relationships. The development of endovascular techniques and the difficulty in surgery have led to a decrease in the number of surgical procedures and thus the experience of neurosurgeons in this region. In this study, we aimed to reveal the microsurgical anatomy of the ipsilateral and contralateral approaches to SHA aneurysms and define their limitations via morphometric analyses of radiological anatomy, three-dimensional (3D) modeling, and surgical illustrations.

Method

Five fixed and injected cadaver heads underwent dissections. In order to make morphometric measurements, 75 cranial MRI scans were reviewed. Cranial scans were rendered with a module and used to produce 3D models of different anatomical structures. In addition, a medical illustration was drawn that shows different sizes of aneurysms and surgical clipping approaches.

Results

For the contralateral approach, pterional craniotomy and sylvian dissection were performed. The contralateral SHA was reached from the prechiasmatic area. The dissected SHA was approached with an aneurysm clip, and maneuverability was evaluated. For the ipsilateral approach, pterional craniotomy and sylvian dissection were performed. The ipsilateral SHA was reached by mobilizing the left optic nerve with left optic nerve unroofing and left anterior clinoidectomy. MRI measurements showed that the area of the prechiasm was 90.4 ± 36.6 mm² (prefixed: 46.9 ± 10.4 mm², normofixed: 84.8 ± 15.7 mm², postfixed: 137.2 ± 19.5 mm², p < 0.001), the distance between the anterior aspect of the optic chiasm and the limbus sphenoidale was 10.0 ± 3.5 mm (prefixed: 5.7 ± 0.8 mm, normofixed: 9.6 ± 1.6 mm, postfixed:14.4 ± 1.6 mm, p < 0.001), and optic nerves’ interneural angle was 65.2° ± 10.0° (prefixed: 77.1° ± 7.3, normofixed: 63.6° ± 7.7°, postfixed: 57.7° ± 5.7°, p: 0.010).

Conclusion

Anatomic dissections along with 3D virtual model simulations and illustrations demonstrated that the contralateral approach would potentially allow for proximal control and neck control/clipping in smaller SHA aneurysm with relatively minimal retraction of the contralateral optic nerve in the setting of pre- or normofixed chiasm, and ipsilateral approach requires anterior clinodectomy and optic unroofing with considerable optic nerve mobilization to control proximal ICA and clip the aneurysm neck effectively.

Quantification of Tumor Blush of Highly Vascularized Tumors with Slow Feeding System: Representative Use for Giant Pituitary Adenomas

BACKGROUND

 Modern imaging techniques can identify adverse factors for tumor removal such as cavernous sinus invasion before surgery, but surgeries for giant pituitary adenomas often reveal discrepancies between preoperative imaging and intraoperative findings because pituitary adenomas have feeding arteries with narrow diameters. Current imaging methods are not suitable for tumors with not only large vascular beds but also slow arterial filling.

PATIENTS AND METHODS

 This prospective study recruited 13 male subjects and 9 female subjects with giant pituitary adenomas between November 2011 and 2018. All the patients were investigated with three-dimensional magnetic resonance (MR) imaging, bone image computerized tomography (CT), and digital subtraction angiography (DSA) using a C-arm cone-beam CT scanner with a flat-panel detector and 50% diluted contrast medium. Fine angioarchitecture was evaluated and the tumor blush was quantified using newly developed region of interest (ROI) analysis to establish surgical strategies.

RESULTS

 Seven patients demonstrated no or very faint tumor blushes. In these patients, feeding arteries run centripetally from the surface of the tumor. Fifteen patients showed significant tumor blushes, and the feeding arteries penetrated centrifugally from the inferoposterior pole to the upper pole of the tumor. All the patients were treated according to the angiographic information with successful hemostasis. The patients showed improvement and/or disappearance of the neurologic deficits. The faint and significant blush groups showed significant differences in intraoperative bleeding (p < 0.01) and operation time (p < 0.05).

CONCLUSION

 Specialized evaluation focused on vascularization is required for successful therapy of giant pituitary adenomas.

Arterial Supply to the Pituitary Gland: A Comprehensive Review

Knowledge of the blood supply to the pituitary gland is important for clinicians and surgeons. Therefore, a good working knowledge of this anatomy is important. The goal of this article was to review current anatomic knowledge of the blood supply to the pituitary gland and its clinical relevance.

Surgical anatomy of the superior hypophyseal artery and its relevance for endoscopic endonasal surgery

OBJECTIVE

The endoscopic endonasal approach has become a routine corridor to the suprasellar region. The superior hypophyseal arteries (SHAs) are intimately related to lesions in the suprasellar space, such as craniopharyngiomas and meningiomas. Here the authors investigate the surgical anatomy and variations of the SHA from the endoscopic endonasal perspective.

METHODS

Thirty anatomical specimens with vascular injection were used for endoscopic endonasal dissection. The number of SHAs and their origin, course, branching, anastomoses, and areas of supply were collected and analyzed.

RESULTS

A total of 110 SHAs arising from 60 internal carotid arteries (ICAs), or 1.83 SHAs per ICA (range 0-3), were found. The most proximal SHA always ran in the preinfundibular space and provided the major blood supply to the infundibulum, optic chiasm, and proximal optic nerve; it was defined as the primary SHA (pSHA). The more distal SHA(s), present in 78.3% of sides, ran in the retroinfundibular space and supplied the stalk and may also supply the tuber cinereum and optic tracts. In the two sides (3.3%) in which no SHA was present, the territory was covered by a pair of infundibular arteries originating from the posterior communicating artery. Two-thirds of the pSHAs originated proximal to the distal dural ring; half of these arose from the carotid cave portion of the ICA, whereas the other half originated proximal to the cave. Four branching patterns of the pSHA were recognized, with the most common pattern (41.7%) consisting of three or more branches with a tree-like pattern. Descending branches were absent in 25% of cases. Preinfundibular anastomoses between pSHAs were found in all specimens. Anastomoses between the pSHA and the secondary SHA (sSHA) or the infundibular arteries were found in 75% cases.

CONCLUSIONS

The first SHA almost always supplies the infundibulum, optic chiasm, and proximal optic nerve and represents the pSHA. Compromising this artery can cause a visual deficit. Unilateral injury to the pSHA is less likely to cause an endocrine deficit given the artery's abundant anastomoses. A detailed understanding of the surgical anatomy of the SHA and its many variations may help surgeons when approaching challenging lesions in the suprasellar region.

The Superior Hypophyseal Arteries: Anatomical Study with an Endoscopic Endonasal Perspective

BACKGROUND

The use of high-definition endoscopes in extended transsphenoidal approaches to the suprasellar area has significantly improved visualization of its vascularization.

OBJECTIVE

To systematically examine the superior hypophyseal arteries (SHAs) anatomy from an endonasal endoscopic perspective.

METHODS

The endoscopic endonasal transsphenoidal trans-tuberculum approach was performed in 19 adult, fresh and latex injected specimens. Dissections recordings were reviewed to analyze SHAs type, number, and branches, as well as internal carotid arteries (ICA) branches that vascularized optic nerves and chiasm.

RESULTS

Identification of SHAs was possible in all specimens (37/38 sides). The number of SHAs varied from 1 to 3 per side (mean: 1.7). The anterior superior hypophyseal artery was visible in almost all cases (35/37 sides) and originated at the level of the carotid cave in 18/35 specimens; number of branches ranged from 1 to 6 (mean: 3.5), directed to the optic nerve (86%), chiasm (57%), infundibulum (86%), and/or parallel to the pituitary stalk (74%). The 4 main branches and patterns, originally described by McConnell in 1953, were confirmed. The posterior superior hypophyseal artery was evident in 28/37 sides with number of branches ranging from 0 to 4 (mean: 2.1), directed to the optic chiasm (50%), optic tract (32%), infundibulum (79%), and/or pituitary stalk (36%). The surgical implications of this study, together with anatomical and clinical videos, are also briefly discussed.

CONCLUSION

SHAs constitute a complex of anterior and posterior branches that stem from the medial ICA with different patterns, vascularizing the optic apparatus and pituitary stalk.

Role of superior hypophyseal artery in visual function impairment after paraclinoid carotid artery aneurysm surgery

OBJECT

Although a number of studies have assessed the surgical treatment of paraclinoid-segment carotid artery aneurysms and resulting visual complications, less attention has been given to the results with respect to the superior hypophyseal artery (SHA). The authors evaluated the relationship between the aneurysm, the SHA itself, and postoperative visual function in patients with ruptured and unruptured SHA aneurysms.

METHODS

From January 1991 through December 2013, 181 patients with 190 paraclinoid carotid artery aneurysms received treatment at Shinshu University Hospital and its affiliated hospitals. The authors retrospectively analyzed charts, operative records, operative videos, and neuroimaging findings for these patients with or without postoperative visual complications.

RESULTS

The authors identified 72 SHA aneurysms in 70 patients (mean age 58 years). Of 69 patients (1 patient died) evaluated, postoperative visual complications occurred in 9 (13.0%). Although the aneurysm size and SHA sacrifice did not lead to postoperative visual impairment, simultaneous treatment of bilateral aneurysms was a risk factor for postoperative visual complications.

CONCLUSIONS

Unilateral SHA impairment may be safe (i.e., it may not induce ischemia of the optic pathway) for many, but not all, patients with SHA aneurysm.

Role of craniotomy in the management of pituitary adenomas and sellar/parasellar tumors

The transphenoidal procedure has become the preferred approach in the surgical management of sellar/parasellar tumors. Nevertheless, specific indications remain for the transcranial approach and the objective of this review is to evaluate the available data on outcomes following transcranial or transphenoidal approaches to sellar/parasellar tumors. We assess the indications used for each approach and parameters that favor one over the other. Factors such as tumor size, consistency and configuration are important variables in choosing the transcranial approach. Other important considerations include persistent visual loss after incomplete decompression via the transphenoidal route, ectatic midline carotid arteries, co-existent intracranial aneurysms and sphenoid sinusitis. We review the data on visual and endocrinological outcomes following the transcranial or transphenoidal approach and provide an argument that, while there appears to be a trend towards greater visual improvement after transcranial surgery for large-to-giant pituitary adenomas, this benefit is offset by a greater risk of postoperative pituitary dysfunction. There is no difference in the rate of recurrence between the two procedures in the published literature. Overall, craniotomies will continue to play a role in the management of patients with sellar/parasellar tumors, although patient selection and careful preoperative evaluation are key elements in choosing the most appropriate approach.

Optic pathway infarct after Onyx HD 500 aneurysm embolization: visual pathway ischemia from superior hypophyseal artery occlusion

We report a case of visual deterioration after Onyx HD 500 embolization of a left 7 mm superior hypophyseal artery (SHA) aneurysm. After the procedure, the patient experienced a right incongruous homonymous hemianopia, and MRI showed an infarct of the ipsilateral optic chiasm/tract but no evidence of aneurysm mass effect or embolic cortical infarcts. The optic pathway ischemia is believed to be secondary to Onyx penetration and occlusion of an SHA branch near the aneurysm neck. Caution is advised when using liquid embolic agents to treat SHA aneurysms as SHA occlusion may lead to visual deficits.

Optic pathway infarct after Onyx HD 500 aneurysm embolization: visual pathway ischemia from superior hypophyseal artery occlusion

We report a case of visual deterioration after Onyx HD 500 embolization of a left 7 mm superior hypophyseal artery (SHA) aneurysm. After the procedure, the patient experienced a right incongruous homonymous hemianopia, and MRI showed an infarct of the ipsilateral optic chiasm/tract but no evidence of aneurysm mass effect or embolic cortical infarcts. The optic pathway ischemia is believed to be secondary to Onyx penetration and occlusion of an SHA branch near the aneurysm neck. Caution is advised when using liquid embolic agents to treat SHA aneurysms as SHA occlusion may lead to visual deficits.

The premamillary artery--a microanatomical study

BACKGROUND

The microanatomical parameters of the premamillary artery (PMA) for the different configurations of the posterior communicating artery-adult (aPComA), hypoplastic (hPComA) and foetal (fPComA) were assessed and analysed. A comparative study with relevance to the neurosurgical practice has been carried out.

METHOD

Red-coloured latex was injected in 35 human cadaver brains and a microanatomical dissection was performed. The area of emergence, the diameter, the length and the zone of penetration of the PMA were accessed.

RESULTS

Seventy PComA were found and 96 PMA were identified. In more than 85% of the cases, the diameter of the PMA largely surpassed the diameter of the other perforating vessels. In the aPComA group, the PMA was a single branch in 72.4% of the cases with mean diameter of 0.52 mm and average length of 13.22 mm. PMA was found to originate from the middle third in 60.5%. For the hPComA group, in 66.7% of the cases, one PMA with mean diameter of 0.49 mm and average length 12.41 mm was found. In 60.9%, PMA originated from the middle third. For the fPComA group, in 50.0% of the cases, one PMA was found with mean diameter of 0.39 mm, average length of 12.42 mm. PMA was found to originate from the anterior third in 41.7% of the cases. Emergence of the PMA from the internal carotid artery and from the P2 segment of the posterior cerebral artery was also documented.

CONCLUSION

For the aPComA and the hPComA groups, the typical PMA may be described as the largest and most constant perforating branch emerging from the anterior 2/3 of the PComA and reaching the paramedian perforate substance. The PMA of the fPComA generally conforms to these characteristics but it is usually thinner, frequently duplicated and with higher percent of atypical emergence. These anatomical peculiarities may facilitate the intraoperative identification and preservation of the PMA when dealing with vascular or neoplastic pathologies with parasellar or interpeduncular extension.

Transarterial embolization of traumatic carotid-superior hypophyseal arterial cavernous fistula. A case report

A 26-year-old man presented with symptoms of progressive bilateral exophthalmos and swelling of the eyelids after a severe head injury. Angiography confirmed a direct carotid-superior hypophyseal arterial (SHA) cavernous fistula with petrosal sinus and intracavernous sinus drainage. Successful transarterial coil embolization of the fistula was performed with resolution of the patient's symptoms. To our knowledge, post-traumatic arteriovenous fistula between SHA and the cavernous sinus has not been previously reported. We hereby demonstrate an effective, minimally invasive method of occluding a rare fistula by transarterial embolization.

Loss of visual evoked potential following temporary occlusion of the superior hypophyseal artery during aneurysm clip placement surgery. Case report

The authors report a case in which a 62-year-old woman with a history of subarachnoid hemorrhage due to a ruptured aneurysm was found to have a de novo paraclinoid aneurysm in the right internal carotid artery during a routine medical examination. Surgical clip placement was performed via a contralateral pterional approach under visual evoked potential (VEP) monitoring. The superior hypophyseal artery (SHA) was found to originate from the aneurysm body. The artery was temporarily occluded prior to application of the clip to the aneurysm neck. The VEP signal was lost 3 minutes after the SHA was occluded, and the potentials gradually recovered 10 minutes after the artery was released. The disappearance of VEP signal was reproducible with SHA occlusion. The clip was applied to the aneurysm body to preserve the origin of the SHA. The patient did not have any deterioration of vision after surgery. Intraoperative VEP monitoring can be used to help determine whether the SHA can be sacrificed safely.

MRI location of the distal dural ring plane: anatomoradiological study and application to paraclinoid carotid artery aneurysms

The distal dural ring plane (DDRP) separates the intradural from the extradural paraclinoid internal carotid artery. The purpose of this study was to evaluate its position with MR imaging. The protocol used a T2-weighted sequence in two orthogonal planes: diaphragmatic (DIA-P) and carotid (CAR-P). The DDRP passes through four anatomoradiological reference points (RefP). We developed on a cadaveric model a correlation method supported by correlation lines and angles (CA) projecting the RefP toward the DDRP. RefP were correlated to the DDRP in 65-84% of cases in the DIA-P and 60-76% of cases in the CAR-P. CA were identified and correlated to the DDRP, respectively, in 87% and 60% of cases in the DIA-P, and 60% and 51% of cases in the CAR-P (failure often related to a lack of visibility of just one RefP). A higher tissular contrast in living subjects allowed the identification of CA in 90% and 80% of cases, respectively, in the DIA-P and the CAR-P. We propose that CA, when identified, should be considered as an approximation of the inferior radiological limit of the DDRP curve. In difficult angiographical cases, this MRI protocol could help to locate paraclinoid aneurysms on both sides of the cavernous sinus roof.

Microanatomy of the blood supply to the optic nerve

The vascularization to the optic nerve is understood to come from the superior hypophyseal arteries and ophthalmic artery. However, anatomical studies about their detailed distribution to the optic nerve, especially its intracanalicular part, are rare. As the optic nerve is very prone to compression inside the optic canal, the vascularization here is especially at risk. This study shows that the superior hypophyseal arteries are the main source of blood supply to the intracranial and intracanalicular part of the optic nerve. The contribution of the ophthalmic artery to this part of the nerve is negligible. This artery mainly contributes to the intraorbital part of the optic nerve by means of the short and long ciliary arteries and the central retinal artery.

Expanding the boundaries of the transsphenoidal approach: a microanatomic study

The anatomic features of a transsphenoidal approach are reviewed, focusing on the microsurgical anatomy of parasellar structures. Pertinent microsurgical anatomy is described in sufficient detail for the neurosurgeon to successfully extend a standard transsphenoidal approach for treatment of lesions involving the region of the tuberculum sellae, planum sphenoidale, supradiaphragmatic intradural space, and medial cavernous sinus. The parasellar region of 50 formalin-fixed cadaveric heads was examined by using magnification 3x to 40x. The arterial and venous systems of five cadaveric specimens were injected under pressure with colored silicone rubber. The sellar region of three specimens was examined histologically. Important anatomic landmarks identified in the roof of the sphenoid sinus include a carotid and trigeminal prominence, as well as a tubercular, clival, and opticocarotid recess. The diaphragma sella is actually comprised of two layers of dura, with a venous system (circular sinus) interposed between the layers. The dura mater of the pituitary gland separates the gland from the medial compartment of the cavernous sinus. The microanatomic detail necessary to extend the transsphenoidal approach to the supradiaphragmatic intradural space and medial compartment of the cavernous sinus is described. These data are presented to facilitate the clinical application of these extended approaches.

Microsurgical anatomic features and nomenclature of the paraclinoid region

OBJECTIVE

We describe the detailed microsurgical anatomic features of the clinoid (C5) segment of the internal carotid artery (ICA) and surrounding structures, clarify the anatomic relationships of structures in this region, and emphasize the clinical relevance of these observations. Furthermore, because the nomenclature of the paraclinoid region is confusing and lacks standardization, this report provides a glossary of terms that are commonly used to descibe the anatomic features of the paraclinoid region.

METHODS

The region surrounding the anterior clinoid process was observed in 70 specimens from 35 formalin-fixed cadaveric heads. Detailed microanatomic dissections were performed in 10 specimens. Histological sections of this region were obtained from the formalin-fixed cadaveric specimens.

RESULTS

The clinoid segment of the ICA is the portion that abuts the clinoid process. This portion of the ICA can be directly observed only after removal of the clinoid process. The dura of the cavernous sinus roof separates to enclose the clinoid process. The clinoid segment of the ICA exists only where this separation of dural layers is present. Because the clinoid process does not completely enclose the ICA in most cases, the clinoid segment is shaped more like a wedge than a cylinder. The outer layer of the dura (dura propria) is a thick membrane that fuses with the adventitia of the ICA to form a competent ring that separates the intradural ICA from the extradural ICA. The thin inner membranous layer of the dura loosely surrounds the ICA throughout the entire length of its clinoid segment. The most proximal aspect of this membrane defines the proximal dural ring. The proximal ring is incompetent and admits a variable number of veins from the cavernous plexus that accompany the ICA throughout its clinoid segment.

CONCLUSION

The narrow space between the inner dural layer and the clinoid ICA is continuous with the cavernous sinus via an incompetent proximal dural ring. This space between the clinoid ICA and the inner dural layer contains a variable number of veins that directly communicate with the cavernous plexus. Given the inconstancy of the venous plexus surrounding the clinoid ICA, we think that categorical labeling of the clinoid ICA as intracavernous or extracavernous cannot be justified.

Chemotherapy with Adriamycin (doxorubicin) and CCNU (lomustine) in four children with recurrent craniopharyngioma

BACKGROUND

The prognosis of craniopharyngioma in children after subtotal surgical removal, followed by irradiation of remaining tumour with 50 Gy, is better than usually reported. In our subjects we found a relapse rate of 5% in the last 20 years. The treatment of recurrences forms a special problem because the possibilities of adjuvant radiotherapy are restricted. We report on a chemotherapeutic treatment after multiple or very rapid recurrences of craniopharyngioma in four children.

METHODS

Four children experienced their first tumour recurrence at respectively 3, 8, 50 and 59 months after the initial treatment. New neurosurgical attempts to remove the recurring tumour, and in one patient a second course of radiotherapy, were performed, but there were two or more recurrences in these children, resulting in further restriction of surgical or radiotherapeutical possibilities. Chemotherapy was given, consisting of five intravenous ambulatory courses of Adriamycin (doxorubicin) (33 mg/m2/day, continuously over 3 days) together with oral CCNU (lomustine) (80 mg/m2 at day 1) at 6-weeks intervals.

RESULTS

After the chemotherapy there was no further tumour recurrence after 12, 10, 3 and 3 years respectively. In the third patient a cystic relapse occurred after 3 years' remission. In the fourth patient a complete regression was observed of the cystic part of the tumour. The side-effects of the chemotherapy consisted of alopecia and bone marrow depression. No signs of cardiomyopathy have been found.

CONCLUSION

Treatment of recurrent craniopharyngioma in children by chemotherapy with anthracyclines and nitrourea-derivates may be effective.

Micro-anatomical study of the carotid cave

The surgical treatment of aneurysms located in the carotid cave is often hazardous and difficult. We studied the micro-anatomy of the carotid cave and its neighbourhood by microscopic observation and histological examination using 50 sides from 25 autopsy cases. The carotid caves were found in 34 out of the 50 sides (68%) examined and were usually located in the posteromedial aspect of the carotid dural ring. They were classified into three types according to the topographic micro-anatomy: the slit-type (17/50, 34%) which showed a small, thin recess of the dura mater with fine connective tissue loosely adhered to the carotid wall; the pocket-type (12/50, 24%) which had a definite dural pouch with the apex attached to the vessel wall; and the mesh-type (5/50, 10%) which formed a slit- or pocket-type dural cave covered with a mesh-like dural roof. The remaining 16 sides (32%) showed tight dural attachment without any caval structure around the dural ring. The posteromedial portion of the carotid dural ring had no contact with any bony structure, and this distinct anatomical feature thus appear to facilitate the formation of the carotid cave. Furthermore, the availability of this potential space and the closely situated origin of the superior hypophyseal artery as well as the haemodynamic effect of the internal carotid artery may allow the development of the carotid cave aneurysm.

Endovascular embolization of superior hypophyseal artery aneurysms

OBJECTIVE

Internal carotid artery aneurysms arising from the superior hypophyseal artery are frequently termed paraophthalmic or paraclinoid aneurysms, but they constitute a distinct anatomic entity. They are particularly amenable to endovascular treatment.

METHODS

Between 1991 and 1995, we attempted treatment in 11 patients with superior hypophyseal artery aneurysms with Guglielmi detachable coil embolization and were successful in 10. Surgical exploration in seven of the patients was unsuccessful, three patients were considered to be at high risk for surgery or to have poor likelihood of surgical success by the referring neurosurgeon, and one patient refused operative clipping. Two aneurysms were giant (> 25 mm), three were large (10-25 mm), and six were small (< 10 mm). Of the six small aneurysms, two had wide necks (> 4 mm) and four had narrow necks (< or = 4 mm).

RESULTS

There were no technical or clinical complications related to embolization. Immediate complete aneurysm obliteration was obtained in five aneurysms, all of which were small. Four of the remaining five aneurysms had obliteration of the dome and body, leaving only a small remnant neck. The remaining semifusiform aneurysm represented our single treatment failure. Recanalization occurred in only one patient; that patient had a giant aneurysm. Nine of the 10 patients for whom embolization was successful had good or excellent clinical outcomes; there were no clinical deteriorations attributable to embolization.

CONCLUSION

We conclude that Guglielmi detachable coil embolization of superior hypophyseal artery aneurysms is an excellent treatment alternative, especially for smaller lesions.

The microsurgical anatomy of the superior hypophyseal artery

Interest in the anatomy of the proximal segment of the intracranial internal carotid artery has been kindled by the recognition that there are multiple potential sites of aneurysm formation in this region. These various aneurysm locations have characteristic hemodynamic and clinical features as well as surgical considerations. Recently recognized as a distinct clinical and anatomical entity are aneurysms that are hemodynamically related to the superior hypophyseal artery. Although aneurysms arising in proximity to the superior hypophyseal artery are not rare, the anatomy of this vessel arising from the medial or posteromedial aspect of the proximal internal carotid artery is poorly understood. We performed a cadaveric microsurgical anatomical study of 20 internal carotid arteries between the ophthalmic and posterior communicating arteries to develop a better understanding of the anatomical relationships of the superior hypophyseal artery. There were an average of 1.8 superior hypophyseal arteries arising from each carotid artery with an average diameter of 0.22 mm. The origin of the superior hypophyseal arteries was within 5 mm of the ophthalmic artery origin in 85% of the specimens. There were two distinct patterns of superior hypophyseal artery anatomy. In 42%, a large, dominant superior hypophyseal artery branched like a candelabra with smaller branches to the pituitary stalk, optic nerve, and chiasm. The average diameter of the larger branches was 0.3 mm. In the absence of a large dominant branch, two or three medial vessels were found. In one specimen, an incidental aneurysm was discovered at the origin of the superior hypophyseal artery on the medial aspect of the internal carotid artery at the origin of a large candelabra-like branch.(ABSTRACT TRUNCATED AT 250 WORDS)

The surgical anatomy of the perforating branches of the basilar artery

The perforating branches of the basilar artery were examined in 14 brain stems injected with india ink or methylmethacrylate. Three groups of the perforators were distinguished: the caudal, the middle, and the rostral. The caudal perforators varied in number from two to five and in diameter from 80 to 600 microns. In addition to their terminal branches, which entered the foramen cecum, the perforators occasionally branched off the pontomedullary artery, the pyramidal vessels, and the hypoglossal branches. The middle perforators arose either separately from the basilar artery or along with the basilar artery collateral branches. They ranged in number from five to nine and in diameter from 210 to 940 microns. The perforators gave rise to the pontomedullary artery (8.3%), the long pontine arteries (25.0%), and the anterolateral vessels (100%). The rostral perforators originated from the terminal part of the basilar artery (91.6%), as well as from the superior cerebellar artery (91.6%) and the posterolateral artery (16.6%). They varied in number from one to five and in diameter from 190 to 800 microns. The anastomoses among various perforating vessels were noted in 41.6 to 66.6% of the cases. The authors discussed the possible clinical significance of the anatomical data observed in this study.

Carotid cave aneurysms of the internal carotid artery

In a series of 32 surgical cases of carotid-ophthalmic artery aneurysm, seven of the lesions were located in the "carotid cave." This special type of aneurysm is usually small and projects medially on the anteroposterior view of the angiogram. At surgery, it is located intradurally at the dural penetration of the internal carotid artery (ICA) on the ventromedial side, appears to be buried in the dural pouch (carotid cave), and is often difficult to find, dissect, and clip. The aneurysm extends into the cavernous sinus space, and the parent ICA penetrates the dural ring obliquely. An ipsilateral pterional approach was used in all 32 cases, and ring clips were used exclusively because the aneurysms were located ventromedially. Clipping was successful in five cases. All patients returned to their preoperative occupation, although vision worsened postoperatively in two cases. The technical steps required for successful obliteration of this aneurysm are summarized as follows: 1) exposure of the cervical ICA; 2) unroofing of the optic canal and removal of the anterior clinoid process; 3) exploration of the ICA around the dural ring and opening of the cavernous sinus; 4) direct retraction of the ICA and optic nerve; and 5) application of multiple ring clips to conform to the natural curvature of the carotid artery; a curved-blade ring clip is especially useful. The relevant topographic anatomy is discussed.

Removal of an arteriovenous malformation in the optic chiasm. A case of Bonnet-Dechaume-Blanc syndrome without retinal involvement

A rare case of an arteriovenous malformation involving the optic chiasm associated with vascular anomaly in the left maxillary region is presented. The angiogram demonstrated an arteriovenous malformation arising from the anterior circle of Willis (internal carotid, posterior communicating, and proximal anterior cerebral arteries), and located in the region of the optic chiasm and hypothalamus. The case was diagnosed as the Bonnet-Dechaume-Blanc syndrome without intraorbital and retinal arteriovenous malformations. The suprasellar arteriovenous malformation was removed, except for a small portion in the hypothalamus, with satisfactory results.