William Pellet

Gamma knife radiosurgery in the management of cavernous sinus meningiomas

The purpose of this paper was to note a potential source of error in magnetic resonance (MR) imaging. Magnetic resonance images were acquired for stereotactic planning for GKS of a vestibular schwannoma in a female patient. The images were acquired using three-dimensional sequence, which has been shown to produce minimal distortion effects. The images were transferred to the planning workstation, but the coronal images were rejected. By examination of the raw data and reconstruction of sagittal images through the localizer side plate, it was clearly seen that the image of the square localizer system was grossly distorted. The patient was returned to the MR imager for further studies and a metal clasp on her brassiere was identified as the cause of the distortion.A-60-year-old man with medically intractable left-sided maxillary division trigeminal neuralgia had severe cardiac disease, was dependent on an internal defibrillator and could not undergo magnetic resonance imaging. The patient was successfully treated using computerized tomography (CT) cisternography and gamma knife radiosurgery. The patient was pain free 2 months after GKS. Contrast cisternography with CT scanning is an excellent alternative imaging modality for the treatment of patients with intractable trigeminal neuralgia who are unable to undergo MR imaging.The authors describe acute deterioration in facial and acoustic neuropathies following radiosurgery for acoustic neuromas. In May 1995, a 26-year-old man, who had no evidence of neurofibromatosis Type 2, was treated with gamma knife radiosurgery (GKS; maximum dose 20 Gy and margin dose 14 Gy) for a right-sided intracanalicular acoustic tumor. Two days after the treatment, he developed headache, vomiting, right-sided facial weakness, tinnitus, and right hearing loss. There was a deterioration of facial nerve function and hearing function from pretreatment values. The facial function worsened from House-Brackmann Grade 1 to 3. Hearing deteriorated from Grade 1 to 5. Magnetic resonance (MR) images, obtained at the same time revealed an obvious decrease in contrast enhancement of the tumor without any change in tumor size or peritumoral edema. Facial nerve function improved gradually and increased to House-Brackmann Grade 2 by 8 months post-GKS. The tumor has been unchanged in size for 5 years, and facial nerve function has also been maintained at Grade 2 with unchanged deafness. This is the first detailed report of immediate facial neuropathy after GKS for acoustic neuroma and MR imaging revealing early possibly toxic changes. Potential explanations for this phenomenon are presented.In clinical follow-up studies after radiosurgery, imaging modalities such as computerized tomography (CT) and magnetic resonance (MR) imaging are used. Accurate determination of the residual lesion volume is necessary for realistic assessment of the effects of treatment. Usually, the diameters rather than the volume of the lesion are measured. To determine the lesion volume without using stereotactically defined images, the software program VOLUMESERIES has been developed. VOLUMESERIES is a personal computer-based image analysis tool. Acquired DICOM CT scans and MR image series can be visualized. The region of interest is contoured with the help of the mouse, and then the system calculates the volume of the contoured region and the total volume is given in cubic centimeters. The defined volume is also displayed in reconstructed sagittal and coronal slices. In addition, distance measurements can be performed to measure tumor extent. The accuracy of VOLUMESERIES was checked against stereotactically defined images in the Leksell GammaPlan treatment planning program. A discrepancy in target volumes of approximately 8% was observed between the two methods. This discrepancy is of lesser interest because the method is used to determine the course of the target volume over time, rather than the absolute volume. Moreover, it could be shown that the method was more sensitive than the tumor diameter measurements currently in use. VOLUMESERIES appears to be a valuable tool for assessing residual lesion volume on follow-up images after gamma knife radiosurgery while avoiding the need for stereotactic definition.This study was conducted to evaluate the geometric distortion of angiographic images created from a commonly used digital x-ray imaging system and the performance of a commercially available distortion-correction computer program. A 12 x 12 x 12-cm wood phantom was constructed. Lead shots, 2 mm in diameter, were attached to the surfaces of the phantom. The phantom was then placed inside the angiographic localizer. Cut films (frontal and lateral analog films) of the phantom were obtained. The films were analyzed using GammaPlan target series 4.12. The same procedure was repeated with a digital x-ray imaging system equipped with a computer program to correct the geometric distortion. The distortion of the two sets of digital images was evaluated using the coordinates of the lead shots from the cut films as references. The coordinates of all lead shots obtained from digital images and corrected by the computer program coincided within 0.5 mm of those obtained from cut films. The average difference is 0.28 mm with a standard deviation of 0.01 mm. On the other hand, the coordinates obtained from digital images with and without correction can differ by as much as 3.4 mm. The average difference is 1.53 mm, with a standard deviation of 0.67 mm. The investigated computer program can reduce the geometric distortion of digital images from a commonly used x-ray imaging system to less than 0.5 mm. Therefore, they are suitable for the localization of arteriovenous malformations and other vascular targets in gamma knife radiosurgery.

Management of invasive juvenile nasopharyngeal angiofibromas: The role of a multimodality approach - Commentary

OBJECTIVEJuvenile nasopharyngeal angiofibromas involving the cranial base and intracranial compartment are challenging tumors. We reviewed our experience of these tumors and analyzed the efficacy of a multimodality management. METHODSBetween 1981 and 2000, 15 extensive juvenile nasopharyngeal angiofibromas (Fisch Grade III or IV) were treated at our institution. The mean age of the patients was 14.5 years, and the mean interval between the first symptom and diagnosis was 12.9 months. Initial management included preoperative embolization of the external carotid artery feeders, followed by tumor removal. A maxillofacial procedure was performed in eight cases, a combination of maxillofacial and neurosurgical approach was performed in four cases, and a neurosurgical cranial base approach was performed in three cases. RESULTSTotal removal after the initial procedure was obtained in eight patients. Subtotal removal justified additional surgery in one case, gamma knife radiosurgery in two cases, and fractionated irradiation in four cases. True recurrences were observed in four cases at a mean interval of 37 months (range, 24–46 mo) and required tailored multimodality management. No cases of perioperative death were observed. One patient underwent hemiparesis after embolization in the early period of our experience. Permanent facial numbness was reported in four cases, moderate cosmetic problems were reported in three cases, and hyposmia was reported in three cases. Except for one patient who was lost to follow-up at 18 months, 12 patients were free of disease and two patients were free of tumor progression. All patients had normal or near-normal daily life at the last check-up, with a median follow-up period of 108 months (mean, 117 mo; range, 91–252 mo). CONCLUSIONExtensive juvenile nasopharyngeal angiofibromas are efficiently managed with a multimodal protocol in which preoperative embolization is followed by optimal surgical removal using various transcranial or transfacial approaches. Adjunctive gamma knife radiosurgery is a valuable option for intracavernous residual tumor. Our protocol offers long-term cure with acceptable morbidity.

Endolymphatic sac tumors: report of three cases.

OBJECTIVE AND IMPORTANCE We present three cases of endolymphatic sac tumors and review the previously published cases. Despite frequent extension to the cerebellopontine angle, these rare tumors have only recently been recognized by neurosurgeons. CLINICAL PRESENTATION A 26-year-old man developed a progressive hearing loss, revealing an intrapetrous retrolabyrinthine tumor on the right side. A 28-year-old woman experienced a left cerebellopontine angle syndrome, with a lytic intrapetrous mass extending into the cerebellopontine angle. A 38-year-old woman presented with an intracranial hypertension syndrome caused by a tumor of the jugular foramen. INTERVENTION For the first and second patients, the tumors originated from the operculum of the endolymphatic sac. Total removal was achieved, via a transpetrosal approach, in these two cases. No recurrence was detected after a 20-month follow-up period. For the third patient, the tumor originated from the distal part of the sac. Recurrence was observed 8 years after subtotal removal via a retrosigmoid route. Histological analysis revealed a papillary-cystic adenocarcinomatous pattern in all cases, without features of aggressiveness. CONCLUSION Endolymphatic sac tumors are locally invasive neoplasms characterized by bipolar intrapetrous and posterior fossa involvement. The anatomic complexity of the endolymphatic sac may explain the distinct patterns of extension of these tumors. Early radical surgery is related to good outcomes.

Modern Management of Vestibular Schwannomas

Within the last 3 decades, microsurgery and stereotactic radiosurgery (SRS) have become well-established management options for vestibular schwannomas (VSs). Advancement in the management of VSs can be separated into three periods: the microsurgical pioneer period, the demonstration of SRS as a first-line therapy for small and medium-sized VSs, and currently, a period of SRS maturity based on a large worldwide patient accrual. The Marseille SRS experience includes 1,500 patients, with 1,000 patients having follow-up longer than 3 years. A long-term tumor control rate of 97%, transient facial palsy lower than 1%, and a probability of functional hearing preservation between 50 and 95% was achieved in this large series of patients treated with state-of-the-art SRS.

Hearing preservation in patients with unilateral vestibular schwannoma after gamma knife surgery

INTRODUCTION The majority of patients still lose the functionality of their hearing in spite of the technical advances in microsurgery. Our aim was to evaluate the hearing preservation potential of Gamma Knife Surgery. We have reviewed our experience and the literature in order to evaluate the probability to obtain such functional preservation and the factors influencing it. METHODS Since July 1992, 2,053 patients have been operated on by Gamma Knife Radiosurgery in Timone University Hospital. This population included 184 unilateral schwannoma patients with functional preoperative hearing (Gardner-Robertson 1 or 2) treated by first intention radiosurgery with a marginal dose lower than 13 Gy. The population included 74 patients with subnormal hearing (class 1). All have been studied with a follow-up longer than 3 years. Univariate and multivariate analyses have been carried out. RESULTS Numerous parameters greatly influence the probability of functional hearing preservation at 3 years, which is globally 60%. The main preoperative parameters of predictability are limited hearing loss that is Gardner-Robertson stage 1 (vs. 2), presence of tinnitus, young age of the patient and small size of the lesion. The functional hearing preservation at 3 years is 77.8% when the patient is initially in stage 1, 80% in patients with tinnitus as a first symptom and 95% when the patient has both. In these patients, the probability of functional preservation at 5 years is 84%. Comparison of these results with the main series of the literature confirms the reproducibility of our results. Additionally, we have demonstrated a higher chance of hearing preservation when the dose to the cochlea is lower than 4 Gy. CONCLUSION We report a large population of patients treated by radiosurgery with functional preoperative hearing. These results demonstrate the possibility to preserve functional hearing in a high percentage of selected patients. Radiosurgery offers them a higher chance of functional hearing preservation than microsurgery or simple follow-up.

Long-term outcome in intensive care unit survivors after mechanical ventilation for intracerebral hemorrhage.

ObjectiveTo evaluate long-term survival and functional outcome in intensive care unit survivors after mechanical ventilation for intracerebral hemorrhage. DesignRetrospective chart review and prospective follow-up study. SettingOutpatient follow-up. PatientsBetween 1997 and 2000, 120 patients were mechanically ventilated for an intracerebral hemorrhage at our intensive care unit. Sixty-two patients were discharged from hospital (in-hospital mortality = 48%). Sixty patients were evaluated for survival and functional outcome (two were lost to follow-up). Time between discharge and follow-up was ≥1 yr and was a mean of 27 ± 14 months (range, 12–56). InterventionsNone. Measurements and Main ResultsPatients’ physicians were first asked about survival, and patients or proxies were interviewed by phone. Barthel Index and modified Rankin Scale scores were collected, and demographic information and general data were reviewed. The estimated life-table survival curve after discharge was 64.6% at 1 yr and 57% at 3 yrs. In the 24 patients who died, the mean time between discharge and death was 5 ± 6 months. Probability of death after discharge significantly increased if age at admission was >65 yrs (p < .01; odds ratio, 3.5; 95% confidence interval, 1.4–9.1) and if Glasgow Coma Scale score at discharge was <15 (p < .01; odds ratio, 3.9; 95% confidence interval, 1.6–9.5). In the 36 long-term survivors, Barthel Index was 67.5 ± 15 (median ± median absolute dispersion) and modified Rankin Scale score was 2.6 ± 0.5. Fifteen patients (42%) had a slight or no disability (Barthel Index ≥90 and modified Rankin Scale score ≤2), whereas 21 patients (58%) had moderate or severe disability (Barthel Index ≤85 and modified Rankin Scale score >2). ConclusionsProbability of survival at 3 yrs after mechanical ventilation for an intracerebral hemorrhage was >50%. Age was an important determinant of long-term survival. Forty-two percent of long-term survivors were independent for activities of daily living. Only a few long-term survivors had a very high degree of disability.

Expression of cell adhesion molecules in normal nerves, chronic axonal neuropathies and Schwann cell tumors

Cell adhesion molecules (CAMs) play a role in the normal development and regeneration of tissues as well as in the biological behaviour of tumors. We studied the immunohistochemical expression of various CAMs, such as neural cell adhesion molecule (NCAM), its polysialylated isoform (PSA-NCAM), epithelial (E-) cadherin, and beta1 integrins (alpha2beta1, alpha5beta1, alpha6beta1) in a series of frozen specimens of 10 normal nerves, 5 axonal neuropathies, 26 benign Schwannomas and 2 malignant peripheral nerve sheath tumors (MNST). NCAM was expressed by non-myelinating Schwann cells from normal nerves and overexpressed by Schwann cells from patients with chronic axonal neuropathies and Schwannomas. The expression was lower in MNST. Expression of PSA-NCAM was heterogeneously displayed by Schwann cells from the various tissues studied. Anti E-cadherin immunoreactivity was present in myelin sheath in normal nerves and axonopathies. It was expressed in some Schwannomas especially in vestibular Schwannomas. Integrins VLA alpha2 and VLA alpha6 were widely expressed by Schwann cells from normal nerves, axonal neuropathies and Schwannomas but their expression was low in MNST. VLA alpha5 was not expressed by Schwann cells from normal nerve and Schwannomas but present in chronic axonal neuropathies and MNST. In addition VLA alpha6 was strongly expressed by perineurial cells. These data show that CAMs have a characteristic pattern of expression in normal nerve. Also, some CAMs are always expressed by Schwann cells but the expression of others differs in normal nerves versus axonopathies or tumors, suggesting a role of the microcellular environment in the regulation of CAM expression. Schwannomas have different pattern of expression than MNST.

Pneumocephalus after thoracotomy

BACKGROUND Pneumocephalus is a well-known phenomenon in which a fistula between the thoracic cavity and the subarachnoid space is one of its rare etiologies. METHODS We report a new case of pneumocephalus after thoracotomy and review eight similar cases in the literature. RESULTS In all cases, an operation was carried out for an intrathoracic neoplasm located at the apex with chest wall invasion. In the presence of symptoms, the diagnosis of pneumocephalus and identification of the subarachnoid pleural fistula were differently supplied by radiographic and isotopic exams. In the follow-up, one patient was affected by meningitis and two patients died. CONCLUSIONS The occurrence of pneumocephalus must be considered when neurologic problems emerge after thoracotomy. It appears that if conservative treatment fails, surgical closure of the fistula via thoracic or neurosurgical approach is indicated.

Cervical interbody xenograft with plate fixation : Evaluation of fusion after 7 years of use in post-traumatic discoligamentous instability

Study Design This retrospective study analyzed clinical and radiologic follow‐up evaluations of cervical arthrodesis where interbody xenograft combined with internal fixation was used for management of post‐traumatic discoligamentous instability. Objectives To report results of use of xenograft to avoid the various disadvantages linked to the use of autologous or allogenous bone graft. Summary of Background Data Ligamentous instability of the cervical spine is unlikely to heal in a high proportion of cases, and surgical arthrodesis is usually indicated. Anterior arthrodesis has proved to be a safe procedure, but many problems are associated with the use of autograft or allograft. Given the great number of xenograft procedures, there are relatively few reports in the literature. Methods A retrospective study analyzed a consecutive series of 52 patients presenting with post‐traumatic discoligamentous instability of the cervical spine in which cervical interbody xenografts with plate fixations were done. Follow‐up clinical evaluation for neck pain and radiologic evaluation for arthrodesis stability and xenograft fusion at various points in time were done. Results The long‐term results in 41 patients were satisfactory: no infectious complications, extrusion, fracture, loss of height, or resorption of the graft. Seventy‐five percent fusion was seen before 9 months after surgery, and 100% fusion was seen 3‐18 months after surgery (average, 7.4 months). Conclusions Interbody xenograft combined with a rigid plate fixation avoids the problems linked to autologous or allogenous bone graft and gives a safe and solid interbody fusion when arthrodesis is required in ligamentous instability of the cervical spine.

Recurrence of Vestibular Schwannomas after Surgery

The issue of recurrence of vestibular schwannomas is poorly studied by the surgical literature and is probably underestimated. Our own long-term retrospective analysis after translabyrinthine approach has indicated a 9.2% recurrence rate. This long-term event is mainly due to regrowth of microfragments that have been left in the operative field along the course of the facial nerve or at the surface of the pons. Management of recurrence depends on the tumor size and patients condition. Our current policy is to propose a Gamma Knife radiosurgical treatment in eligible cases. Prospective long-term follow-up studies using serial MR imaging after radical removal should bring reliable data about the incidence of vestibular schwannoma recurrence.