José Lorenzoni

Neurovascular compression anatomy and pain outcome in patients with classic trigeminal neuralgia treated by radiosurgery.

OBJECTIVE To study the influence of the anatomy of neurovascular compression (NVC) on pain outcome in patients with classic trigeminal neuralgia treated by radiosurgery. METHODS Analysis of the anatomy of the trigeminal nerve, brainstem, and vessels was performed in 89 consecutive patients treated by Leksell gamma knife (Elekta Instruments, Stockholm, Sweden) for classic trigeminal neuralgia. One-millimeter axial magnetic resonance imaging slices (T1-weighted, T1-weighted enhanced, and T2-weighted selected partial inversion recovery) with coronal, sagittal, and three-dimensional reconstructions were viewed. The end point for outcome was total pain remission and no medication. The follow-up period ranged between 6 and 42 months. RESULTS In 82 patients (92%), a vascular structure in contact with the nerve was observed. In four patients, the NVC was produced by a large vessel (basilar or vertebral artery) and in 78 by a smaller vessel. The superior cerebellar artery was the cause of the NVC in 64 patients (78%). The NVC was proximal (<3 mm to the brainstem) in 34 patients (41%) and distal in 43 patients (52%). Nerve dislocation was present in 29 patients (33%), and nerve atrophy was present in 21 (24%) patients. Visualization of NVC on magnetic resonance imaging scans was not associated with outcome. The two variables associated with poor outcome were a large vessel contacting the nerve with brainstem deformation and proximal NVC. Nerve atrophy and nerve dislocation were not associated with outcome. CONCLUSION The visualization of NVC, nerve atrophy, and nerve dislocation on magnetic resonance imaging scans was not associated with pain outcome. A large vessel compressing the nerve and deforming the brainstem and proximal NVC were associated with a lesser pain control.

Radiosurgery for trigeminal neuralgia.

Radiosurgery has recently emerged as a suitable treatment of pharmacologically resistant idiopathic trigeminal neuralgia. Results and complications of this treatment are related to parameters of the dosimetry, i.e. the dose and the target. We found that the irradiation dose delivered to the brainstem, the distance between the target and the brainstem, and the occurrence of facial numbness after radiosurgery are related to a better pain outcome.

Patterns of neurovascular compression in patients with classic trigeminal neuralgia: A high-resolution MRI-based study.

PURPOSE To describe the anatomical characteristics and patterns of neurovascular compression in patients suffering classic trigeminal neuralgia (CTN), using high-resolution magnetic resonance imaging (MRI). MATERIALS AND METHODS The analysis of the anatomy of the trigeminal nerve, brain stem and the vascular structures related to this nerve was made in 100 consecutive patients treated with a Gamma Knife radiosurgery for CTN between December 1999 and September 2004. MRI studies (T1, T1 enhanced and T2-SPIR) with axial, coronal and sagital simultaneous visualization were dynamically assessed using the software GammaPlan™. Three-dimensional reconstructions were also developed in some representative cases. RESULTS In 93 patients (93%), there were one or several vascular structures in contact, either, with the trigeminal nerve, or close to its origin in the pons. The superior cerebellar artery was involved in 71 cases (76%). Other vessels identified were the antero-inferior cerebellar artery, the basilar artery, the vertebral artery, and some venous structures. Vascular compression was found anywhere along the trigeminal nerve. The mean distance between the nerve compression and the origin of the nerve in the brainstem was 3.76±2.9mm (range 0-9.8mm). In 39 patients (42%), the vascular compression was located proximally and in 42 (45%) the compression was located distally. Nerve dislocation or distortion by the vessel was observed in 30 cases (32%). CONCLUSIONS The findings of this study are similar to those reported in surgical and autopsy series. This non-invasive MRI-based approach could be useful for diagnostic and therapeutic decisions in CTN, and it could help to understand its pathogenesis.

Morphological Observations in Brain Arteriovenous Malformations after Gamma Knife Radiosurgery

Morphological studies after Gamma Knife radiosurgery (GKRS) revealed endothelial destruction followed by spindle-shaped cell proliferation in the subendothelial region and in the connective tissue stroma of arteriovenous malformation (AVM) vessels. Histological, immunohistochemical and ultrastructural characteristics of this spindle-shaped cell population in the irradiated AVMs were reminiscent of those described as myofibroblasts in wound healing processes and pathological fibromatoses. These modified fibroblasts have contractile capacity, therefore this might contribute to the vessel occlusion, shrinking process and final volume reduction of AVMs after GKRS. Similar histopathological changes were observed in a cavernous malformation following high-dose irradiation.

Surgery for high-grade gliomas in a developing country: survival estimation using a simple stratification system

BACKGROUND In spite of great technological advances in diagnostic and therapeutic tools, survival in patients with HGG has not changed significantly in the last years. Judicious management in each case needs survival estimation after surgery. We used a simple stratification system evaluating the histology, patients age, and the KPS. METHODS We retrospectively made an analysis of survival in 103 patients with HGG operated in a 10-year period (1990--1999). Three significant prognostic variables were studied: histology, patients age, and KPS. The BS-MG was calculated, adding the partial score (0 or 1) obtained for each variable. This score ranges from 0 (worse condition) to 3 (best condition). RESULTS Overall, MS was 12 months. For glioblastoma multiforme, AA, and ODS, it was 10, 20, and 19 months, respectively (P = .0001). Patients 44 years old or younger had an MS of 28 months, higher than 10 months for patients older than 45 years (P < .0001). Median survival was 20 months for patients with KPS 80 or higher, and 9 months for those with KPS 70 or lower (P = .02). It was 3.5 months in patients with BS-MG = 0, 9 months for BS-MG = 1, 22 months for BS-MG = 2, and 55 months for BS-MG = 3 (P < .0001.). CONCLUSIONS Survival presented here is comparable with those previously reported despite lacking the most sophisticated surgical technique. The stratification score that includes the 3 most important variables for survival seems to be simple and reliable for survival estimation.

Pathological Findings following Trigeminal Neuralgia Radiosurgery

Autopsy, 3D MRI and histopathological findings are presented in a patient who had suffered from trigeminal neuralgia and was treated two times by radiosurgery. The first treatment was performed with 90 Gy at the distal part of the nerve. Because of recurrent pain, a second irradiation was carried out delivering 70 Gy at a more proximal segment of the nerve 10 months later. The patient died from a hemorrhagic stroke 26 days following the second intervention. Autopsy revealed a neurovascular conflict close to the second radiosurgery shot. Histopathology demonstrated acute and chronic stage radiation-induced lesions in the trigeminal nerve.

Diagnóstico y tratamiento de las metástasis encefálicas

Cerebral metastasis occur in 20 to 30 percent of patients with systemic cancer and are the most common type of intracranial tumor. The median survival of untreated patients is one month with a slightly longer survival in those treated with steroids. Patients treated with whole brain radiation therapy survive between 3 to 6 months. In selected cases survival can increase to 10 to 12 months with combination of surgery and radiotherapy or stereotactic radiosurgery alone or associated to radiotherapy. Most brain metastasis arise from lung, breast and melanomas. The most important criteria for selecting patients who will benefit from surgery or stereotactic radiosurgery are a Karnofsky score of 70 or more, systemic control of the cancer and absence of leptomeningeal involvement. Surgery is indicated in patients with a single lesion located in an accessible zone and stereotactic radiosurgery is indicated for lesions up to 3 cm of diameter, and in patients with up to 3 or 4 metastasis, no matter their location. The survival benefit of chemotherapy in brain metastasis has not been demonstrated.

Measurements of Extracranial Doses in Patients Treated with Leksell Gamma Knife C

Most of the patients treated with Leksell Gamma Knife® (LGK) present benign lesions, it is thus essential to evaluate extracranial doses. A study of in vivo measurements on 228 unselected patients t

MR-based follow-up of the superior cerebellar artery after radiosurgery for trigeminal neuralgia.

PURPOSE To study with a non invasive method any potential radiological change on the superior cerebellar artery (SCA) in patients treated radiosurgically for classic trigeminal neuralgia (CTN). MATERIALS AND METHODS A retrospective measure of maximal dose received by SCA was performed analyzing the treatment planning in 55 consecutive patients treated by Gamma Knife radiosurgery for an CTN, then, a prospective study was designed using high resolution MR, with T2 SPIR, T1 without and with gadolinium enhancement, Proton density, 3D TONE and MIP reconstructions. Inclusion criteria were: patients followed at our institution, follow-up of one year or more, dose received by the SCA of 15 Gy or more and voluntary patient participation in the study. Patients with repeated Gamma Knife radiosurgery for failure or recurrence were excluded. The end points were: SCA occlusion, stenosis or infarction in the territory supplied by SCA. RESULTS Sixteen patients were studied, with a mean follow-up of 25.2 months (12-42 months). The mean maximal dose received by the SCA was 57.5 Gy. (15-87 Gy). Among these 16 patients studied, neither obstruction of the SCA nor infarction was demonstrated. In one patient a suspicion of asymptomatic SCA stenosis was visualized distant to the irradiation field. CONCLUSIONS SCA can receive a high dose of irradiation during radiosurgical treatment for CTN. This study does not confirm any vascular damage to the SCA after radiosurgery for CTN.

Clinical, Anatomo-Radiological and Dosimetric Features Influencing Pain Outcome After Gamma Knife Treatment of Trigeminal Neuralgia

Gamma Knife radiosurgery has become nowadays a well validated and accepted option for the treatment of trigeminal neuralgia and numerous publications support its role in the management of this disease. The results achieved with this technique in terms of pain outcome are quite similar to other ablative treatments such as radiofrequency thermocoagulation, balloon micro-compression or glycerol gangliolysis, nevertheless, complications seem to be less frequent (Lopez 2004a).