E. Knosp

The Paraclinoid Carotid Artery: Anatomical Aspects of a Microneurosurgical Approach

&NA; The paraclinoid area is investigated anatomically for possible microneurosurgical approaches to the C3 segment of the internal carotid artery and to structures in the vicinity of the anterior siphon knee. Removal of the anterior clinoid process reveals a tight connective tissue ring that fixes the internal carotid artery to the surrounding osseous structures at the point of its transdural passage. Transection of this fibrous ring opens a microsurgical pathway to the carotid C3 segment. The artery is surrounded by a loose connective tissue layer that allows blunt preparation along the C3 segment, without compromising the cranial nerves and without damaging venous compartments of the cavernous sinus. This approach provides neurosurgical access to paraclinoidal aneurysms, to partly intracavernous aneurysms, and to carotid‐ophthalmic aneurysms, allowing control of the proximal aneurysm neck and of the parent artery itself. In cases of tumors involving the medial sphenoid ridge, the apex of the orbit, or the cavernous sinus, the pericarotid connective tissue can serve as a guide layer for access along the internal carotid artery.

Direct surgical approach to infraclinoidal aneurysms

SummaryA loose connective tissue layer covering the intracavernous portion of the internal carotid artery makes the exposure of the anterior syphon knee possible without opening the cavernous sinus. The approach leads by a fronto-latero-basal craniotomy to the anterior part of the cavernous sinus roof (transversal plate). The anatomical relationships are discussed. By means of surgical cases, both the ipsilateral and the contralateral approach to infraclinoidal aneurysms are demonstrated.

Cranioplasty with individual carbon fibre reinforced polymere (CFRP) medical grade implants based on CAD/CAM technique.

Summary. Background: The authors present a new method for the reconstruction of large or complex-formed cranial bone defects using prefabricated, computer-generated, individual CFRP (carbon fibre reinforced plastics) medical grade implants. Method: CFRP is a composite material containing carbon fibres embedded in an epoxy resin matrix. It is radiolucent, heat-resistant, extremely strong and light (its weight is 20% that of steel), has a modulus of elasticity close to that of bone, and an established biocompatibility. The utilisation of a CAD/CAM (computer aided design/computer aided manufacture) technique based on digitised computed tomography (CT) data, with stereolithographic modelling as intermediate step, enabled the production of individual, prefabricated CFRP medical grade implants with an arithmetical maximum aberration in extension of less than ±0.25 mm. Between 1995 and February 2002, 29 patients (15 men and 14 women; mean age, 39.9 years; range, 16 to 67 years) underwent cranioplasty with CFRP medical grade implants at the neurosurgical department of the University of Vienna. Twenty-four patients were repaired secondarily (delayed cranioplasty) while 5 were repaired immediately following craniectomy (single stage cranioplasty). All cases were assessed for the accuracy of the intra-operative fit of the implant, restoration of the natural skull contour and aesthetics and adverse symptoms. Findings: The intra-operative fit was excellent in 93.1% and good in 6.9% of the implants. In two cases minor adjustments of the bony margin of the defect were required. The operating time for insertion ranged from 16 to 38 minutes, median 21 minutes. Postoperatively, 86.2% of the patients graded the restoration of their natural skull shape and symmetry as excellent while 13.8% termed it good. In one patient a non-space occupying subdural hygroma was found at the follow-up, but required no intervention. Two patients experienced atrophy of the frontal portion of the temporal muscle while one patient had a transient palsy of the frontal branch of the facial nerve. Over the mean follow-up period of 3.3 years (range, 0.08 to 6.8 years), there were no adverse reactions and no plate had to be removed. Interpretation: Individual, prefabricated CFRP medical grade implants may be considered as an alternative to conventionally utilised materials for cranioplasty, in particular in the challenging group of patients with extensive cranial defects or more complex-formed defects of the fronto-orbital or temporo-zygomatic region, guaranteeing short operating times and excellent functional and aesthetic results, which justifies the expense of their production.

Proliferation in Pituitary Adenomas: Measurement by MAb KI 67

The monoclonal antibody MAb KI 67 reacts with a nuclear antigen throughout the entire cell cycle and allows easy evaluation of proliferating tumour cells on routinely prepared smear and frozen sections. 120 pituitary adenomas were investigated by use of the monoclonal antibody KI 67 in a two-step avidin-biotin-peroxidase complex (ABC) technique. The KI 67 labelling index (LI) ranged in all adenomas from 0.2 to 4.6%. In 90 cases of transphenoidally operated adenomas the dura of the sella floor was investigated histologically. Adenomas with histologically proven dural infiltration showed a statistically significant higher KI 67 LI (p less than 0.001) compared to non-invasive adenomas.

Cavernous sinus surgery

SummaryThe cavernous sinus is divided from the surgical point of view into three parts. The middle part consists of the lateral sinus wall, the cranial nerves III, IV, V, VI and the posterior siphonknee of the internal carotid artery. Lesions of this region, vascular as well as tumorous, can be exposed by approaching the lateral sinus wall. The surgical dissection through the sinus wall is based on some important anatomical details, which are described here. As a consequence a modified transcavernous approach will be introduced and demonstrated by 35 clinical cases.

Microprolactinomas in males treated by transsphenoidal surgery

Summary¶Objective. To support the opinion that transsphenoidal surgery can be an effective alternative to medical treatment for microprolactinomas in men. Design. Clinical study with retrospective data analysis. Patients and methods. Of 46 men who were operated on for prolactinoma in the Department of Neurosurgery of the University of Vienna General Hospital between 1985 and 2000 a microadenoma was detected 11 times (24%). Results. Median patient age was 41 years (range 32 to 54 years). Symptoms were of endocrine nature in all patients with erectile dysfunction, infertility and gynaecomastia being the initial complaints and having lasted for a median of 13 months (range 7–68 months). Preoperative median serum prolactin (PRL) was elevated to 120 ng/ml (range 41–1000 ng/ml). Radiography by MRI revealed microadenomas with a median diameter of 8 mm (range 4–10 mm). All patients were operated on via the transsphenoidal approach. Endocrine cure as defined by a serum PRL <25 ng/ml was achieved in 8 of 11 patients (73%) after a median follow-up of 7 years (range 2–13 years). In none of the 3 patients with preoperative serum PRL levels >150 ng/ml was a normoprolactinaemia obtained after surgery: 2 require further dopamine-agonist therapy after surgery, 1 after late follow-up.Surgery and medical treatment could restore potency and libido in all but 1 patient, 2 of 3 patients remain infertile. Conclusion. Prolactinomas in males are potentially curable by surgery if detected at an early stage. They most commonly present with insidious signs and symptoms of endocrine disturbances such as loss of libido, impotence and sterility. We stress the importance of early determination of serum prolactin and high resolution magnetic resonance tomography of the sella in male patients with hyperprolactinaemia as this may prevent the possible progression to larger tumours which are rarely curable by surgery and necessitate life-long medical therapy.

Anatomical remarks on the fetal cavernous sinus and on the veins of the middle cranial fossa

Increasing surgical experience within the cavernous sinus region has generated increased interest in the region’s anatomy. Despite many attempts to understand the morphological complexity of the cavernous sinus, its description and interpretation are still controversial. Two main views oppose each other: classic textbooks of anatomy, but also recent studies (e.g. Harris and Rhoton [11], Bedford [1]), interpret the cavernous sinus as an intradural venous canal, which is more or less trabeculated by fibrous strands. Several other workers of the present century, however, interpret the cavernous sinus as a network of extradural veins (e.g. Taptas [21, 22], Bonnet [3], Parkinson [15,16, 17], a view which is not yet generally accepted. Other controversial problems of the area concern the relationship of the venous pathways with the structures that pass through the cavernous sinus area, like the internal carotid artery and the cranial nerves that run to the orbital cavity.

The blood supply of the cranial nerves in the lateral wall of the cavernous sinus

Cranial nerves III, IV, V, and VI are embedded in the deep layer of the lateral wall of the cavernous sinus, and are supplied by arteries which approach the nerves from medially. The arteries arise from two main stems of the internal carotid artery (ICA): the meningohypophyseal trunk (TMH), and the inferior lateral trunk (ILT). The ILT points towards the lateral wall of the cavernous sinus, where it supplies the cranial nerves which converge to the superior orbital fissure. The TMH points dorsally and supplies cranial nerve VI within Dorello’s canal, the Gasserian ganglion, and the dural entrance area around cranial nerve IV. Branches and anastomoses from and to the middle meningeal and ophthalmic artery system, as well as from and to the internal maxillary artery system, may in part replace the arterial supply pattern of the TMH and the ILT. In the sella and clivus area there exist anastomoses with the contralateral intracavernous branches of the ICA. Many of the anastomotic vessels observed in this study can be explained as developmental remnants of ancestral arterial patterns of the skull base.

Multiregional sampling reveals a homogenous distribution of Ki-67 proliferation rate in pituitary adenomas

Summary.Ki-67 antigen is used as a marker of proliferative activity that is linked to growth rate, invasiveness and prognosis of pituitary adenomas. So far the distribution of Ki-67 index within an individual adenoma has not been investigated. If Ki-67 antigen expression differs significantly within an individual pituitary adenoma, a sampling error may result when assessing small fragments of adenoma tissue. Such a potential error would diminish the value of Ki-67 as a tool for postoperative patient management considerations. The aim of the present study was to assess Ki-67 proliferation rates in different regions of pituitary adenomas and to statistically analyse these data for potential regional differences within each tumor.Ki-67 proliferation index was assessed in smear preparations of 100 specimens of 26 consecutive patients operated on for pituitary adenoma in the Department of Neurosurgery, Medical University Vienna. Depending on the size and extent of the tumor, a mean of 4 tissue samples (range 2–8) was selected intraoperatively from each adenoma from endosellar, suprasellar, parasellar, and basal sellar dural locations.Overall mean cell proliferation rate measured by Ki-67 was 1.81 ± 0.90% (range 0.33–3.43%). Histologically invasive adenomas had significantly higher mean Ki-67 proliferation index in all samples from the same tumor than non-invasive adenomas (2.01 ± 0.91% vs. 1.11 ± 0.59%; P = 0.024). Multiregional sampling revealed a homogenous distribution of Ki-67 index throughout an individual adenoma with no significant differences between any two different regions on t-test.Our data confirm that location of a biopsy does not influence Ki-67 index. Therefore, Ki-67 index of a single biopsy is representative for the whole individual adenoma. Thus Ki-67 index can be considered a reliable parameter for assessment of cell proliferation rate in adenoma biopsies and may be used for postoperative patient management considerations.

Paragangliomas of the Temporal Bone: Results of Different Treatment Modalities in 53 Patients

Summary. Background: The authors retrospectively compared the results of three different treatment modalities (surgery, conventional radiotherapy and gamma knife radiosurgery) in patients with paragangliomas of the temporal bone, in order to determine the optimal current treatment concept. Method: Between 1978 and August 2001, 53 patients (12 men and 41 women; mean age, 58.3 years; range, 17 to 84 years) with paragangliomas of the temporal bone were treated at the neurosurgery and ENT departments of the University of Vienna. According to the Fisch classification, 6 patients had class B tumours, 20 had class C, and 27 patients had class D tumours. Thirty-two patients (mean age, 57.0 years; 6 B, 14 C, 12 D) underwent surgery. In 17 cases the tumour was embolised prior to surgery. Nine patients (mean age, 73.9 years; 6 C, 3 D) received primary radiotherapy (median total dose, 46.8 Gy). Six patients (mean age, 73.5 years; 6 D) underwent primary radiosurgery (median centre dose 24, Gy) and 6 patients (6 D) admitted from other departments with recurrent tumours adjuvant radiosurgery (median centre dose, 25.5 Gy). Findings: In 20 of the surgical cases (62.5%) complete tumour resection was achieved and the patients required no further treatment over a mean follow-up period of 9.1 years. Of the 12 patients with incomplete tumour resection, 9 (5 C, 4 D) received postoperative adjuvant radiotherapy and three patients (3 D) adjuvant radiosurgery. In 15 (83.4%) of the 18 patients who underwent radiotherapy the tumours showed no signs of progression and the patients remained clinically unchanged over a mean period of 9.4 years. Three patients (16,6%) experienced progression of their tumour within an average period of 2.8 years. In the 15 patients who underwent primary radiosurgery, an objective 100% tumour control rate with no evidence of progression of disease was observed. Interpretation: The results indicate that the most effective current treatment option for patients with paragangliomas of the temporal bone is a single-stage radical tumour resection, performed in advanced tumours as an interdisciplinary neuro-otosurgical procedure. For subtotally resected or non-resectable tumours, gamma knife radiosurgery has proved to be a safe and effective treatment modality.