Angelo Pichierri

CAVERNOUS SINUS MENINGIOMAS: RETROSPECTIVE ANALYSIS AND PROPOSAL OF A TREATMENT ALGORITHM

OBJECTIVEToday, meningiomas with primary or, more commonly, secondary involvement of the cavernous sinus remain a surgical challenge. Anatomic research on cadaver specimens, together with the advances made in cranial base and microvascular surgery over the past 2 decades, have made it possible to completely resect lesions within the cavernous sinus. However, the technical complexity of some procedures, coupled with the current availability of less-invasive therapeutic options, makes the rate of complications related to surgical extirpation of intracavernous meningiomas unacceptably high, especially regarding permanent neurological morbidity and mortality. Currently, indications, timing, and multimodal treatments with surgery and radiotherapy represent the main topics of discussion concerning these lesions. METHODSOne hundred forty-seven patients underwent surgery between 1985 and 2003. The patients were retrospectively divided into 2 groups according to the type of surgical treatment: group A (open sinus surgery) and group B (closed sinus surgery). The mean follow-up time was 9.7 years. RESULTSEarly postoperative morbidity and permanent postoperative morbidity showed significant differences between the groups. At long-term follow-up, we found no statistical differences in the incidence of recurrences and progressions. Only patients treated with postoperative radiation therapy (81.5%) showed clinicoradiological stability. CONCLUSIONGrowth control and preservation of neurological functions are the primary goals in the treatment of cavernous sinus meningiomas. In most cases, surgery and radiosurgery alone do not reach the primary goals, and unresolved issues remain. Therefore, we have developed a treatment algorithm as a guide to the best therapeutic options for the most common presentations of the disease.

Frameless Stereotactic Cerebral Biopsy: Our Experience in 296 Cases

Aims: To evaluate the reliability, safety and accuracy of a the frameless stereotactic system in our clinical series and the differences between head fixation by means of a standard Mayfield head holder and the pinless FESS frame, and to evaluate the usefulness of biopsy targeting on the basis of magnetic resonance spectroscopy (MRS) data. Methods: The spectroscopic analysis was used to facilitate the targeting of the lesion. The fusion image function embedded in the Neuronavigation Unit was used postoperatively to assess the level of accuracy of the biopsy. The grading of the glioma specimens was correlated to the spectroscopic data. Results: 296 patients underwent cerebral biopsy in 8 years. The diagnostic yield was 99.7%. The spectroscopic choline/N-acetyl aspartate ratio in different areas of the same tumor correlated well with the histological grading of the lesion. Conclusion: The frameless stereotactic systems guarantee excellent biopsy results. Advanced imaging, in particular MRS, facilitates the correct targeting of nonenhancing lesions.

Endoscopic Assistance in the Epidural Subtemporal Approach and Kawase Approach: Anatomic Study

BACKGROUND Few reports exist in the literature about the use of endoscope assistance in the identification of structures in the posterior fossa. OBJECTIVE To asses the advantage of endoscopic assistance in the epidural subtemporal and Kawase approaches by studying anatomic exposure and surgical freedom in the posterior cranial fossa. METHODS Twelve epidural subtemporal approaches were performed on 6 adult cadaveric heads. On the same specimens, 6 endoscope-assisted subtemporal approaches and 6 Kawase approaches were then performed. At the end of each Kawase approach, endoscope assistance was used. The microsurgical observations were performed with a surgical microscope with magnification ranging from 4 × to 40 ×. Endoscopic observations were made with a 0°, 4-mm rod-lens endoscope. Anatomic exposure and surgical freedom were analyzed. RESULTS Endoscopic assistance during the epidural subtemporal approach increased the anatomic exposure 3 mm superiorly, 20 mm inferiorly, and 10 mm medially from the trigeminal nerve. Surgical freedom was limited in the temporal lobe, the petrous apex, and the trigeminal nerve. The amount of increased anatomic exposure obtained with endoscopic assistance during the Kawase approach was 26 mm inferiorly and medially from the trigeminal nerve. Surgical freedom was limited by the brainstem and the depth of the posterior cranial fossa. CONCLUSION The endoscope-assisted subtemporal approach can be useful in visualizing tumor in the posterior fossa. It can help the surgeon in planning further surgical steps through consideration of the size, extension, and adherence of the tumor to surrounding structures. The endoscope-assisted Kawase approach permits maximum anatomic exposure of the posterior cranial fossa, although the deepest neurovascular structures could be better addressed with more direct approaches.

Surgical exposure of lateral orbital lesions using a coronal scalp flap and lateral orbitozygomatic approach: clinical experience.

SummaryBackground. The lateral extraconal compartment is a typical localization of intra-orbital tumours. With the exception of anterior lesions, which can be reached by a transconjuntival route, most of these tumours are currently approached through the classic lateral orbitotomy originally described by Kronlein. We present here our experience in the management of lateral orbital lesions, using a coronal skin flap, followed by subfascial dissection of the temporalis muscle. The procedure was intended to overcome the potential drawbacks associated with the classic transtemporal approach.Methods. The approach was used in eleven patients harbouring bone lesions of the lateral orbital wall or intra-orbital lesion of the lateral extra-ocular compartment. The postoperative results were assessed using a simple cosmetic outcome scale, which evalutated the temporalis muscle trophism and the function of the frontotemporal branch of the facial nerve.Results. All lesions were satisfactorily exposed. The subfascial dissection of the temporalis muscle is a key manoeuvre which, at the same time, abolishes the risk of injury to the frontotemporal branch of the facial nerve and provides a wide exposure of the lateral orbital wall. The cosmetic outcome was excellent in 9 patients and good in 2 patients.Conclusions. The reported technique is a convenient surgical option to approach lateral intra-orbital lesions, with a minimal cosmetic impact.

How to set up a microsurgical laboratory on small animal models: Organization, techniques, and impact on residency training

Microsurgical training is mandatory for the optimal education of modern neurosurgeons. Even though this is a widely acknowledged statement and a lot of institutions around the world practice training in laboratory, the recent literature lacks tip and tricks on how to start a laboratory from scratch, what would be a convenient anesthesia, and what kind of exercises are appropriate. We present our experience in 16 microsurgical training courses settled up at our institutions. Two hundred eleven rodents were dissected. We will describe the organization of the laboratory and of the training courses and we will discuss its practical impact on the residency program.

Cerebellar Convexity Meningiomas

In 1938, Cushing and Eisenhard published their surgical series of meningiomas in which they describe the pathology in detail. In this book they also proposed the first classification of posterior fossa (PF) meningiomas. They encountered only three cases of pure CC meningiomas (about 1% of their entire series). In 1953, Castellano and Ruggiero categorized PF tumors into five groups: cerebellar convexity, tentorium, posterior petrous, clivus, and foramen magnum. Subsequently, different nomenclatures have been proposed by several authors, particularly regarding lesions of clivus, medial tentorium, and petrous bone. The most important and recent work on cerebellar convexity meningiomas was carried out in 1991 by Kobayashi and Nakamura, who wrote a comprehensive chapter on the topic in the book Meningiomas by Al-Mefty. Traditionally, cerebellar convexity meningiomas have been categorized according to their location into three types: medial, lateral, and superior. However, taking into consideration anatomic criteria, we prefer to classify these meningiomas into four groups.

Fourth ventricle meningiomas: a rare entity

Fourth ventricle meningiomas (FVMs) are rare, often misdiagnosed, lesions. To the best of our knowledge, 47 cases have been reported in the literature: we describe our series of three cases treated at our Institution, focusing on some diagnostic tips and intraoperative features of these tumours. Our three patients have a history of headache. Gait disturbances, vomiting and/or diplopia complicated the clinical picture before the referral at our Department. The operations were uneventful, and the patients fully recovered from neurological symptoms. They are free of recurrence at a median follow-up of 19 years. FVMs are rare lesions, which are difficult to differentiate preoperatively from the much more common ependymomas. A preoperative distinction would be extremely advantageous: indeed, although both tumours share similar radiological and clinical patterns, they clearly differ as to surgical difficulty and outcome. In fact, meningiomas are comparatively easier to remove, granting better clinical results.

Two Cystic Cavernous Angiomas after Radiotherapy for Atypical Meningioma in Adult Woman : Case Report and Literature Review

A correlation between radiation therapy and cavernoma has been suspected since 1994. Since then, only a few cases of radio-induced cavernomas have been reported in the literature (85 patients). Most of them were children, and the most frequent original tumour had been medulloblastoma. The authors report a case of two cystic cavernous angiomas after radiation therapy for atypical meningioma in adult woman. This is the first case of cavernous angioma after radiotherapy for low grade meningioma. A 39-year-old, Latin american woman was operated on for a frontal atypical meningioma with intradiploic component and adjuvant radiotherapy was delivered (6000 cGy local brain irradiation, fractionated over 6 weeks). Follow-up MR imaging showed no recurrences of the tumour and no other lesions. Ten years later, at the age of 49, she consulted for progressive drug-resistant headache. MR imaging revealed two new well defined areas of different signal intensity at the surface of each frontal pole. Both lesions were surgically removed; the histopathological diagnosis was cavernous angioma. This is the first case of cavernous angioma after radiation therapy for atypical meningioma : it confirms the development of these lesions after standard radiation therapy also in patients previously affected by non-malignant tumours.

Postoperative extradural hematomas.

Postoperative extradural hematoma (POEH) is a possible complication after head surgery, often neglected in the literature. In a single surgeon experience we found 13 cases of POEH (0.8%). We distinguished two subtypes: (1) larger hematomas (>40 cc) with typical features and overt clinical picture that always needed evacuation, and (2) smaller hematomas (<40 cc) with insidious clinical onset and different radiological features compared with traumatic and spontaneous extradural hematomas. On the basis of our experience, we propose that clinical picture and radiologic appearance lead the decision between conservative or interventional treatment of type II hematomas.

Transcallosal Approaches to Intraventricular Tumors

Walter E. Dandy pioneered the interhemispheric transcallosal routes to the lateral ventricles. He described, in 1921, the posterior transcallosal approach with division of the splenium for removal of pineal tumors, and followed this by reporting a series of third ventricle tumors in 1933 [1]. Busch performed the first interforniceal approach in 1944 for a malignant glioma [2]. Kempe and Blaylock reported their series of paratrigonal lesions approached through a posterior transcallosal approach in 1976 [3]. Three years later Hirsch et al. proposed coagulating the thalamostriate vein to enlarge the paraforniceal approach with a subchoroidal route [4]. In 1996, Yasargil emphasized the importance of preserving the posterior half of the corpus callosum and proposed a transprecuneus approach for trigonal lesions [5]. In 1998, Wen et al. presented an anatomical study of the choroidal fissure and of the supra- and subchoroidal surgical routes [6]. In 2001 Rosenfeld et al. reported a limited anterior forniceal splitting technique for the cure of hypothalamic hamartomas [7].