Object. Thoracic myelopathy caused by ossification of the ligamentum flavum (OLF) is a rare entity, most evident in Japan. The authors studied the clinical manifestations, radiological aspects, surgical treatment, and pathogenesis of this disease. Methods. Eighteen patients with OLF-induced thoracic myelopathy underwent laminectomy. The severity of myelopathy varied. Complete paraplegia was seen in three cases. Compression of the upper and middle third of the thoracic spine was evident in six cases and of the lower third in 12 cases. Multilevel OLF was demonstrated in 13 cases. In most cases, the ossified ligamentum flavum appears as a V-shaped lesion on computerized tomography and magnetic resonance images. In all patients the diameter of the posterior spinal canal, already narrowed, was further exacerbated by the OLF. Laminectomy was limited to the levels of compression, and the ligamentum flavum was resected in all cases. The symptoms and signs improved in 13 cases and stabilized in four cases. In one case symptoms recurred as a result of ossified lesions forming at other sites. Histological examination showed that the mode of development of the ossified ligaments was endochondral ossification. Conclusions. Reports of OLF-induced myelopathy are rare and mainly described in Japan. The incidence also seems high in North Africa. An early laminectomy limited to the level of compression is recommended. Ossified ligamentum flavum is different from the calcification of the ligamentum flavum, which is due to crystal deposits.

Abstract

662Cerebellar liponeurocytoma (LPN) is a rare central nervous system tumour recently recognized as a distinct clinicopathological entity. It was included in the previous 2000 edition of the World Health Organization (WHO) classification as a grade I neoplasm under the heading of glioneuronal tumours 1 . With increasing recognition of this entity and longer clinical follow-up periods in its investigation, it has become clear that this tumour has a rate of recurrence that is higher than previously thought and not compatible with a grade I designation. In light of the substantial rate of tumour recurrences, the current 2007 WHO classification assigns the cerebellar liponeurocytoma to WHO grade II tumour 2 . In this paper, we report a new case of a recurrent cerebellar LPN with supratentorial extension despite persistently benign histological features. To the best of our knowledge, recurrent cerebellar LPN with supratentorial extension has never been reported before, as the nine cases of recurrent cerebellar LPN published to date were confined to the posterior fossa. CLINICAL HISTORYA 42-year-old previously healthy man, presented with a fivemonth history of headaches, vertigo, visual disturbance and progressive unsteadiness of gait. On admission, neurological examination showed signs of cerebellar dysfunction, including ataxia, wide-based gait, right dysmetria on finger-to-nose testing and a positive Romberg sign. The fundus examination revealed unilateral papilloedema. Computed tomogram scan ( Figure 1) demonstrated a hypodense lesion within the vermis and right cerebellar hemisphere compressing the 4th ventricle and enhancing after contrast injection. Magnetic resonance imaging (MRI) scan showed a heterogeneous mass measuring 5 × 4 cm, characterized by discrete hyperintensity on T1-weighted images and high signal intensity on T2-weighted images. Several central parts of the lesion were very hyperintense on both T1 and T2-weighted sequences suggesting fat content. An intra-operative frozen section was reported as being consistent with a medulloblastoma. A gross total resection of the tumour was achieved. Histological examination of the surgical specimen revealed cerebellar tissue infiltrated by a highly cellular tumour formed by sheets of isomorphic small round cells (Figure 2). A significant proportion of the tumour demonstrated lipomatous differentiation characterized by large areas of cells containing a single cytoplasmic vacuole displacing the nucleus to the periphery mimicking mature fat cells (Figure 2A). There were only occasional mitotic figures and a low rate of proliferation Figure 2B) and neuron-specific enolase. Glial fibrillary acidic protein immunopositive tumour cells confirmed the presence of an additional glial component. All of these features were considered to be consistent with the diagnosis of cerebellar liponeurocytoma. A post-operative MRI performed three days after the surgery, demonstrated no residual tumour. No adjuvant radiation therapy was administered post-operatively. At the last rout...

Introduction: Central nervous system tumours represent 20% of all childhood cancers, and are the second most common group of neoplasms after leukaemias. Objective: To describe epidemiological characteristics of central nervous system tumours in a paediatric Tunisian population. Patients and Methods: A retrospective study of 492 childhood central nervous system tumours operated between 1990 and 2004 was undertaken. We investigated the age-related location, gender distribution and the histology of all tumours, and adopted the latest WHO classification (2007) in grouping all the tumours. Results: There were 488 primary and 4 secondary tumours; 426 (86.6%) were intracranial and 66 (13.4%) were intraspinal. Of the 426 intracranial tumours, 214 (50.24%) were supratentorial and 212 (49.76%) were infratentorial. The median age at diagnosis was 8 years, with a male:female ratio of 1.14:1. Low-grade tumours (WHO I/II) constituted 67.3% of all lesions and the rest (32.7%) were high-grade tumours (WHO III/IV). The most common tumour found in our series was astrocytoma (38%), followed by medulloblastoma (16.2%), then ependymoma (6.9%), cystic tumours (6.3%) and craniopharyngioma (5.3%). The overall 5-year survival rate was 45% with a mean follow-up period of 36 months. Conclusion: In our patient population, the incidence and distribution of central nervous system tumours were similar to those reported in literature. Overall survival rates varied according to tumour location and histopathology.

No abstract