R. Noudel

Incidence of basioccipital hypoplasia in Chiari malformation type I: comparative morphometric study of the posterior cranial fossa. Clinical article.

OBJECT The chronic tonsillar herniation defining Chiari malformation Type I (CMI) is thought to result from overcrowding of a normally developing hindbrain within a congenitally small posterior cranial fossa (PCF) due to occipital hypoplasia. The goals in the present study were to authenticate the cranioencephalic disproportion in a group of patients with CMI and to discuss new developmental aspects according to which part of the occipital bone was underdeveloped. METHODS The authors retrospectively examined a group of 17 patients with CMI. Measurements of osteotentorial and neural structures of the PCF were made on MR images of the brain. The results were compared with findings in 30 healthy controls by using the Mann-Whitney U-test. RESULTS Dimensions of the neural structures did not differ between the 2 groups of patients. The mean length of the basiocciput was significantly shorter in the CMI group (19.4 mm) compared with the control group (25.7 mm; p = 0.0003). The mean diameter of the foramen magnum was larger in the CMI group, but this difference was not statistically significant. The dimensions of the supraocciput and the mean angle of the cerebellar tentorium were identical in the 2 groups. CONCLUSIONS Data in this study support the idea that occipital hypoplasia is the main cause of overcrowding within the PCF. Basioccipital shortness is a cardinal feature of the resultant shallow PCF and could proceed from a congenital disorder of the cephalic mesoderm of the parachordal plate or occur later in the infancy because of premature stenosis of the sphenooccipital synchondrosis.

FRACTIONATED STEREOTACTIC RADIOTHERAPY TREATMENT OF CAVERNOUS SINUS MENINGIOMAS: A STUDY OF 100 CASES

PURPOSE We discuss our experiences with fractionated stereotactic radiotherapy (FSR) in the treatment of cavernous sinus meningiomas. METHODS AND MATERIALS From 1995 to 2006, we monitored 100 patients diagnosed with cavernous sinus meningiomas; 84 female and 16 male patients were included. The mean patient age was 56 years. The most common symptoms were a reduction in visual acuity (57%), diplopia (50%), exophthalmy (30%), and trigeminal neuralgia (34%). Surgery was initially performed on 26 patients. All patients were treated with FSR. A total of 45 Gy was administered to the lesion, with 5 fractions of 1.8 Gy completed each week. Patient treatment was performed using a Varian Clinac linear accelerator used for cranial treatments and a micro-multileaf collimator. RESULTS No side effects were reported. Mean follow-up period was 33 months, with 20% of patients undergoing follow-up evaluation of more than 4 years later. The tumor control rate at 3 years was 94%. Three patients required microsurgical intervention because FSR proved ineffective. In terms of functional symptoms, an 81% improvement was observed in patients suffering from exophthalmy, with 46% of these patients being restored to full health. A 52% improvement was observed in diplopia, together with a 67% improvement in visual acuity and a 50% improvement in type V neuropathy. CONCLUSIONS FSR facilitates tumor control, either as an initial treatment option or in combination with microsurgery. In addition to being a safe procedure with few side effects, FSR offers the significant benefit of superior functional outcomes.

Posterior fossa volume increase after surgery for Chiari malformation Type I: a quantitative assessment using magnetic resonance imaging and correlations with the treatment response.

OBJECT The aim of this paper was to measure the posterior fossa (PF) volume increase resulting from a given-sized occipital craniectomy in Chiari malformation Type I surgery and to analyze its correlations with the PF size and the treatment response, with the perspective of tailoring the amount of bone removal to the patient-specific PF dimensions. METHODS Between January 2005 and June 2006, 11 adult patients with symptomatic Chiari malformation Type I underwent a standardized PF decompression. A prospective evaluation with clinical examination, functional grading, and MR imaging measurement protocols was performed pre- and postoperatively. A method is reported for the measurement of PF volume (PFV) after surgery. The degree of PFV increase was compared with the preoperative size of the PF and with the clinical outcome. RESULTS All 11 patients improved postoperatively, with complete and partial recovery in 4 and 7 patients, respectively. No postoperative complication occurred after a mean follow-up period of 45 months. The mean relative increase in PFV accounted for 10% (range 1.5%-19.7%) of the initial PFV; the increase was greater in cases in which the PF was small (r = -0.52, p = 0.09) and the basiocciput was short (r = -0.37, p = 0.2). A statistically significant positive correlation was found between the degree of PFV increase and the treatment response (p = 0.014); complete recovery was observed with a PFV increase of 15% and partial recovery with an increase of 7%. CONCLUSIONS The treatment response is significantly influenced by the degree of PFV increase, which is dependent on the size of the PF and the extent of the craniectomy, suggesting that the optimal patient-specific PFV increase could be predicted on the basis of preoperative MR imaging and enhancing the perspective that the craniectomy size could be tailored to the individual PFV.

Hearing preservation and facial nerve function after microsurgery for intracanalicular vestibular schwannomas: comparison of middle fossa and restrosigmoid approaches

PurposeTherapeutic options for vestibular schwannomas (VS) include microsurgery, stereotactic radiosurgery and conservative management. Early treatment of intracanalicular vestibular schwannomas (IVS) may be advisable because their spontaneous course will show hearing loss in most cases. Advanced microsurgical techniques and continuous intraoperative monitoring of cranial nerves may allow hearing preservation (HP) without facial nerve damage. However, there are still controversies about the definition of hearing preservation, and the best surgical approach that should be used.MethodsIn this study, we reviewed the main data from the recent literature on IVS surgery and compared hearing, facial function and complication rates after the retrosigmoid (RS) and middle fossa (MF) approaches, respectively.ResultsThe results showed that the average HP rate after IVS surgery ranged from 58% (RS) to 62% (MF). HP varied widely depending on the audiometric criteria that were used for definition of serviceable hearing. There was a trend to show that the MF approach offered a better quality of postoperative hearing (not statistically significant), whereas the RS approach offered a better facial nerve preservation and fewer complications (not statistically significant).ConclusionsWe believe that the timing of treatment in the course of the disease and selection between radiosurgical versus microsurgical procedure are key issues in the management of IVS. Preservation of hearing and good facial nerve function in surgery for VS is a reasonable goal for many patients with intracanalicular tumors and serviceable hearing. Once open surgery has been decided, selection of the approach mainly depends on individual anatomical considerations and experience of the surgeon.

Transcranial resection of a large sinonasal juvenile psammomatoid ossifying fibroma.

IntroductionJuvenile psammomatoid ossifying fibroma (JPOF) is a benign but potentially locally aggressive fibroosseous lesion predominantly arising in the paranasal sinuses in children and young adults. Intracranial extension is rare but occurs sometimes. In such cases, tumor resection may often require the combination of neurosurgical and facial approaches. Histological diagnosis remains a challenge because the lesion can be easily mistaken for another fibroosseous lesion or for a meningioma.Case reportWe report the case of a 12-year-old boy with a JPOF arising from the right paranasal sinuses and extension towards the anterior skull base and the orbit. Despite the tumor had eroded through nasal septum, medial orbit wall, and right maxilla, it could be entirely removed performing an extended frontobasal approach via a bifrontoorbital craniotomy, obviating the need for a transfacial approach.ConclusionRadiologically and histologically, the lesion could be mistaken either for a meningioma or another type of ossifying fibroma. Histological aspects and alternative surgical approaches to these rare entities are discussed.

Intracranial teratomas in children: the role and timing of surgical removal

OBJECT In this study, the authors report their experience with the surgical treatment of intracranial teratomas with an emphasis on the indications for delayed resection after oncological treatment. METHODS The authors retrospectively reviewed the cases of 14 children with intracranial teratomas. The mean age at diagnosis was 10.5 years (range 2 days-18 years), and 11 patients were male. The final histological analysis revealed pure mature teratoma in 5 cases, mixed teratoma with germinoma in 3 cases, and nongerminomatous malignant germ cell tumor in 6 cases. Thirteen patients underwent tumor resection, and these patients were divided into 2 subgroups according to the timing of surgery. In Group A, 10 patients underwent resection as the primary treatment because no tumor markers were detected in 4 patients, a teratomatous component was revealed on biopsy sampling in 3 patients, and a large tumor volume in 3 patients. In Group B, 3 patients underwent removal of residual pure mature teratoma after oncological treatment. RESULTS Seven of the 8 patients (87.5%) with pure mature teratomas or with mixed teratoma and germinoma are currently alive (mean follow-up of 9 years); the eighth patient died of postoperative meningitis. Two of the 6 patients (33%) with mixed nongerminomatous malignant germ cell tumors died of tumor progression regardless of the timing of surgery. CONCLUSIONS The results of this study support the belief that microsurgical removal is the only effective treatment for intracranial teratomas. Surgery may be performed as the primary therapy when there is evidence of a noninvasive teratoma, and as a secondary therapy if there is only a partial response to neoadjuvant therapy or if progression is observed in mixed malignant germ cell tumors.

Dilatation des espaces périvasculaires de Virchow-Robin (Lacunes de type III) : corrélations radio-cliniques

Resume La physiopathologie des espaces perivasculaires dits de Virchow-Robin demeure controversee. Ces espaces perivasculaires sont parfois le siege de dilatations par le biais d’accumulation de liquide. Ces dilatations sont visibles a l’IRM et au scanner X, en association avec des tableaux cliniques varies. Reconnaitre ces dilatations et aboutir a une correlation radio-clinique nous parait etre un prelude indispensable a la prise en charge des patients. Nous rapportons cinq observations cliniques et les analysons a la lumiere des donnees de la litterature. La localisation des dilatations des espaces perivasculaires est double : la substance blanche hemispherique sous corticale d’une part, la region mesencephalique et des ganglions de la base, d’autre part. Les caracteristiques de forme, de siege et de signal permettent de les differencier des lacunes ischemiques. Dans la majorite des cas, les patients sont asymptomatiques : il s’agit principalement de dilatations de petite taille de la convexite, ou « etat crible », reflet d’une variation non pathologique du normal. Les volumineuses dilatations, ou lacunes expansives, siegeant typiquement dans la region mesencephalique et les ganglions de la base, peuvent etre responsables d’une symptomatologie bruyante, notamment d’hydrocephalie bloquante necessitant un traitement adapte. En definitive, savoir reconnaitre ces dilatations permet d’une part de reperer les veritables cas symptomatiques et de les traiter, et d’autre part de rassurer la majorite des patients asymptomatiques sur la benignite de telles lesions.

Management of Radiation/Radiosurgical Complications and Failures

To describe the incidence and the course of complications after the radiosurgical treatment of vestibular schwannomas, the authors reviewed their own experience and reviewed the literature. Failure is described in less than 3% of cases, and this had to be distinguished from transient enlargement of tumor volume. In case of failure, microsurgical resection or another radiosurgical procedure should be discussed. The risk of radio-induced tumorigenesis is not clearly established with single-dose radiosurgical technique. Incidence and management of potential complications should be explained at the time of decision making in the management of vestibular schwannomas.

Postsurgical Pantoea calida meningitis: a case report

IntroductionPantoea calida, a recently described environmental Enterobacteriaceae organism, has not yet been associated with human infection.Case presentationWe report a case of postoperative meningitis caused by P. calida. After pituitary adenoma resection, a 52-year-old Caucasian woman developed febrile meningitis confirmed by cerebrospinal fluid analysis. P. calida was grown in pure culture from this fluid and was firmly identified with partial rpoB gene sequencing. She was cured by a 14-day course of meropenem.ConclusionsP. calida must be added to the list of opportunistic Enterobacteriaceae pathogens responsible for postsurgical meningitis. It is easily identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

How I do it: epidural anterior petrosectomy

BackgroundAmong the potential approaches to access the petroclival area, epidural anterior petrosectomy (EAP) appears to be the most direct and conservative transpetrous route. In this article, we aim to detail the relevant surgical steps necessary to perform EAP in a reproducible and safe manner.MethodThe temporo-pterional bone flap is tailored to access the floor of the middle fossa and expose the foramen ovale and foramen spinosum. Elevation of the dura covering the upper surface of the petrous apex is conducted medially toward the level of the petrous ridge. Identification of the landmarks of the rhomboid fossa delineates the limits of the drilling zone (necessary for removal of the petrous apex)—beneath Meckel’s cave and just anterior to the anterior margin of the internal auditory meatus. The tentorium is divided at its free edge and is followed by opening of the posterior fossa dura.ConclusionEpidural anterior petrosectomy is a conservative trans-petrous approach that offers an excellent direct surgical corridor for exposure of disease processes involving Meckel’s cave, the petroclival area and the ventrolateral pons.