Infratentorial Compartment Research Articles

Anaplastic oligodendroglioma arising from the brain stem and featuring 1p/19q co‐deletion

With respect to localization, oligodendrogliomas are characterized by a marked preponderance of the cerebral hemispheres. Outside these typical sites, any tumor histopathologically reminiscent of oligodendroglioma a priori is likely to represent one of its morphological mimics, including clear cell ependymoma, neurocytoma, pilocytic astrocytoma or glioneuronal tumors. This is particularly relevant as several of the latter are in principle curable by surgery. Among extrahemispherical sites, bona fide oligodendroglioma - as characterized by loss of heterozygosity (LOH) of chromosome arms 1p and 19q - so far has not been documented to occur in the brain stem. Here, we report the case of a 55-year-old female patient with an anaplastic oligodendroglioma (WHO grade III) of the brain stem and cerebellum diagnosed by stereotactic biopsy and featuring combined LOH of 1p and 19q. A morphological peculiarity was a population of interspersed tumor giant cells, a phenomenon that has been referred to as polymorphous oligodendroglioma. Our findings confirm the notion that - although very infrequently - true oligodendrogliomas do occur in the infratentorial compartment.

Dermoid cysts of the posterior fossa – morbid associations of a benign lesion

Dermoid cysts of posterior fossa are uncommon benign lesions. They differ from other lesions found in the infra tentorial compartment by virtue of their associated conditions. Due to their association with dermal sinus tracts, intracranial infection is a potential threat following infection of the cyst. Due to their embryologic origin, these cysts may also be associated with other congenital anomalies. In this article we detail our eleven-year-experience with posterior fossa dermoid cysts in fifteen patients. Despite the morbid presentation with severe life-threatening complications, the overall outcome was excellent. Implications of the various associations are discussed.

Diffusivity of Cerebellar Hemispheres Enables Discrimination of Cerebellar or Parkinsonian Multiple System Atrophy from Progressive Supranuclear Palsy–Richardson Syndrome and Parkinson Disease

To explore the usefulness of histogram analysis of mean diffusivity (MD) derived from diffusion-weighted imaging of large infratentorial structures to distinguish parkinsonian syndromes. Local research ethics committee approval and informed consent were obtained. Ten patients with Parkinson disease (PD), nine with the parkinsonian variant of multiple system atrophy (MSA-P), seven with the cerebellar variant of MSA (MSA-C), 17 with progressive supranuclear palsy-Richardson syndrome (PSP-RS), and 10 healthy subjects were recruited. Histograms of MD values were generated for all pixels in the whole infratentorial compartment and separately for the whole brainstem, vermis, and cerebellar hemispheres. To assess the differences in MD values among groups, the Kruskal-Wallis test was used, followed by the Mann-Whitney U test for pairwise comparisons. All P values resulting from pairwise comparisons were corrected with the Bonferroni method. MSA-P and MSA-C groups had higher median MD values (P < .01) in the brainstem and cerebellum when compared with other groups; this finding was in line with the known consistent neurodegenerative damage in posterior cranial fossa structures in these diseases. Median MD values from cerebellar hemispheres were used to discriminate patients with MSA-C and those with MSA-P from patients with PD and those with PSP-RS (P < .01; sensitivity, specificity, and positive predictive value equaled 100%). Furthermore, patients with PSP-RS had significantly higher MD values in the vermis than did healthy subjects (P < .05) and patients with PD (P < .001). These findings support the clinical usefulness of diffusion imaging in the differential diagnosis of parkinsonism, suggesting that the minimally operator-dependent histogram analysis of the infratentorial structures and particularly of the whole cerebellar hemispheres can be used to distinguish patients with MSA-P and those with MSA-C from patients with PSP-RS and those with PD.

Neuroradiological imaging features of infratentorial cranial fossa tumors in a child

Ependymoma is a rare tumor derived from the neuroepithelia, constituting about 39% of all central nervous system (CNS) tumors. In children, approximately two-thirds of such tumors occur in the infratentorial compartment while in adults the distribution is normally supratentorial. Ependymomas can be located either intracranially or intraspinally. Intracranial ependymomas occur more commonly in children, while intraspinal ependymomas predominate in adults. Sixty percent of tumors are located in the fourth ventricle of the infratentorial cranial fossa, which develop from the floor of the ventricle and may further extend into the foramen of Luschka and Magendie. Here we reported a case of ependymoma in the infratentorial cranial fossa with a differential diagnosis of medulloblastoma on head CT scan and MRI scan.

Surgical management of double giant tuberculomas of brain involving both supratentorial and infratentorial compartments

Surgical management of double giant tuberculomas of brain involving both supratentorial and infratentorial compartments

Distinct disease-risk groups in pediatric supratentorial and posterior fossa ependymomas.

No reliable classification is in clinical use for the therapeutic stratification of children with ependymoma, such that disease risk might be identified and patients treated to ensure a combination of maximal cure rates and minimal adverse therapeutic effects. This study has examined associations between clinicopathologic and cytogenetic variables and outcome in a trial cohort of children with ependymoma, with the aim of defining a practical scheme for stratifying this heterogeneous tumor. Intracranial ependymomas (n = 146) from children treated on the RT1 trial at St. Jude Children's Research Hospital were evaluated for the status of multiple pathological features. Interphase FISH (iFISH) defined the status of loci on chromosomes 1q (EXO1), 6q (LATS1) and 9, including 9p21 (CDKN2A). Data relating to these clinicopathological and cytogenetic variables were compared with survival data in order to model disease risk groups. Extent of surgical resection was a significant determinant of outcome in both supratentorial and infratentorial compartments. Tumor cell density and mitotic count were associated with outcome among children with posterior fossa ependymomas (n = 119). Among pathologic features, only brain invasion was associated with outcome in children with supratentorial ependymomas (n = 27). For posterior fossa tumors, gain of 1q was independently associated with outcome and in combination with clinicopathological variables defined both a two-tier and three-tier system of disease risk. Among children developing posterior fossa ependymomas treated with maximal surgical resection and conformal radiotherapy, key clinicopathological variables and chromosome 1q status can be used to define tiers of disease risk. In contrast, risk factors for pediatric supratentorial tumors are limited to sub-total resection and brain invasion.

A prognostic gene expression signature in infratentorial ependymoma

Patients with ependymoma exhibit a wide range of clinical outcomes that are currently unexplained by clinical or histological factors. Little is known regarding molecular biomarkers that could predict clinical behavior. Since recent data suggest that these tumors display biological characteristics according to their location (cerebral vs. infratentorial vs. spinal cord), rather than explore a broad spectrum of ependymoma, we focused on molecular alterations in ependymomas arising in the infratentorial compartment. Unsupervised clustering of available gene expression microarray data revealed two major subgroups of infratentorial ependymoma. Group 1 tumors over expressed genes that were associated with mesenchyme, Group 2 tumors showed no distinct gene ontologies. To assess the prognostic significance of these gene expression subgroups, real-time reverse transcriptase polymerase chain reaction assays were performed on genes defining the subgroups in a training set. This resulted in a 10-gene prognostic signature. Multivariate analysis showed that the 10-gene signature was an independent predictor of recurrence-free survival after adjusting for clinical factors. Evaluation of an external dataset describing subgroups of infratentorial ependymomas showed concordance of subgroup definition, including validation of the mesenchymal subclass. Importantly, the 10-gene signature was validated as a predictor of recurrence-free survival in this dataset. Taken together, the results indicate a link between clinical outcome and biologically identified subsets of infratentorial ependymoma and offer the potential for prognostic testing to estimate clinical aggressiveness in these tumors.

089 Delayed primary CNS post-transplant lymphoproliferative disorder (PTLD)

Primary central nervous system (PCNS) PTLD is a very rare complication that occurs as a result of immunosuppression in the setting of solid organ transplantation. The median time from transplantation...

Epidemiology of pediatric primary tumors of the nervous system: A retrospective study of 633 cases from a single Moroccan institution

Background and purposeThere are several reports regarding the epidemiology of pediatric brain tumors. However, little is known about the profile of pediatric brain tumors in Africa especially in Morocco in particular. The authors report the results of epidemiological analysis of a retrospective review of childhood primary brain tumors in a single institution. MethodsA retrospective review of all cases of primary brain from 1month to 15years diagnosed at the Department of Pathology of the Hospital of Specialities of Rabat between January1991 and December 2009 was performed. ResultsSix hundred and thirty-three primary tumors of the central nervous system were reviewed with a mean of 33.31 cases per year. According to the gender, 55% of the tumors occurred in males and 45% in females. The mean age was 8.36years. Of all the tumors, 47% were situated in the supratentorial compartment, 48% in the infratentorial compartment, and 5% in spinal cord. In the infratentorial compartment, 82% of tumors are located in the cerebellum, 15% in the fourth ventricle, 2% in the brain stem and 1% in the cerebellar pontine angle. In the supratentorial compartment, two third of the tumors were located in the cerebral hemispheres and the sellar region. Thus 39% of tumors are located in the cerebral hemispheres followed by the sellar/suprasellar region (30%), lateral and third ventricles (11%), pineal region (8%), meninges (5%), choroid plexus (4%), and optic chiasma/tracts (3%). The most common types of tumors diagnosed were pilocytic astrocytoma and medulloblastoma together accounting for nearly half of the cases (46%) (23.1% and 22.9% respectively), followed by craniopharyngiomas (9%), ependymomas grade II (6.5%), glioblastomas (6%), astrocytomas grade II (4.4%), ependymomas grade III (3.9%). The other tumors represent 22.6%. ConclusionWe think that our results reflect fairly well the incidence of tumors of the nervous system in children due to the fact that this study was performed through many years in a single institution with a homogeneous neuropathological approach.

Treatment of a supratentorial primitive neuroectodermal tumor using magnetic resonance–guided laser-induced thermal therapy

Supratentorial primitive neuroectodermal tumors (PNETs) are rare tumors that carry a poorer prognosis than those arising from the infratentorial compartment (such as medulloblastoma). The overall prognosis for these patients depends on several factors including the extent of resection, age at diagnosis, CSF dissemination, and site in the supratentorial space. The authors present the first case of a patient with a newly diagnosed supratentorial PNET in which cytoreduction was achieved with MR-guided laser-induced thermal therapy. A 10-year-old girl presented with left-sided facial weakness and a large right thalamic mass extending into the right midbrain. The diagnosis of supratentorial PNET was made after stereotactic biopsy. Therapeutic options for this lesion were limited because of the risks of postoperative neurological deficits with resection. The patient underwent MR-guided laser-induced thermal ablation of her tumor. Under real-time MR thermometry, thermal energy was delivered to the tumor at a core temperature of 90°C for a total of 960 seconds. The patient underwent follow-up MR imaging at regular intervals to evaluate the tumor response to the thermal ablation procedure. Initial postoperative scans showed an increase in the size of the lesion as well as the amount of the associated edema. Both the size of the lesion and the edema stabilized by 1 week and then decreased below preablation levels at the 3-month postsurgical follow-up. There was a slight increase in the size of the lesion and associated edema at the 6-month follow-up scan, presumably due to concomitant radiation she received as part of her postoperative care. The patient tolerated the procedure well and has had resolution of her symptoms since surgery. Further study is needed to assess the role of laser-induced thermal therapy for the treatment of intracranial tumors. As such, it is a promising tool in the neurosurgical armamentarium. Postoperative imaging has shown no evidence of definitive recurrence at the 6-month follow-up period, but longer-term follow-up is required to assess for late recurrence.

Solitary Fibrous Tumor of the Central Nervous System

We reviewed the world literature on solitary fibrous tumors of the central nervous system from August 1996 to July 2011, focusing on both clinicopathological features and diagnostic findings. The anatomical distribution of the 220 cases reported so far reveals that most are intracranial and just over one-fifth are intraspinal. In decreasing frequency, intracranial tumors involve the supratentorial and infratentorial compartments, the pontocerebellar angle, the sellar and parasellar regions, and the cranial nerves. Intraspinal tumors are mainly located in the thoracic and cervical segments. Although most solitary fibrous tumors of the central nervous system are dural based, a small subset presents as subpial, intraparenchymal, intraventricular, or as tumors involving the nerve rootlets with no dural connection. Preoperative imaging and intraoperative findings suggest meningioma, schwannoma or neurofibroma, hemangiopericytoma, or pituitary tumors. Immunohistochemistry is critical to establish a definitive histopathological diagnosis. Vimentin, CD34, BCL2, and CD99 are the most consistently positive markers. The usual histologic type generally behaves in a benign manner if complete removal is achieved. Recurrence is anticipated when resection is subtotal or when the tumor exhibits atypical histology. The proliferative index as assessed by MIB1 labeling is of prognostic significance. Occasionally, tumors featuring conventional morphology may recur, perhaps because of minimal residual disease left behind during surgical extirpation. Rare extracranial metastases and tumor-related deaths are on record. Surgery is the treatment of choice. Stereotactic and external beam radiation therapy may be indicated for postsurgical tumor remnants and for unresectable recurrences. Long-term active surveillance of the patients is mandatory.

Childhood Tumors of the Brain: Demographic Pattern over a Ten-Year Period in the Kashmir Valley

Brain tumors in children represent the second most frequent tumors in this age group after hematologic malignancies. We highlight the demographic pattern after retrospective analysis of brain tumors in children from geographically and ethnically distinct Kashmir Valley managed in our center between 2000 and 2009. We had a total of 248 pediatric patients with brain tumors. The parameters analyzed were age, gender, location of tumors and histopathological subtypes as well as WHO grade of tumor. We also did a comparison between the frequencies of common varieties of tumor in the first and second 5-year periods. We found that 111 tumors (44.75%) were supratentorial, and 137 (55.25%) were infratentorial. The male-to-female ratio was 1.4:1. The proportions of low-grade and high-grade tumors were 60 and 40%, respectively. The most common tumor in our series was astrocytoma. The most common tumors in the supratentorial and infratentorial compartments were craniopharyngioma and medulloblastoma, respectively. Our experience reflects a different demographic profile of pediatric brain tumors as compared with other regions of the world.

Brain diffusion‐weighted imaging in Friedreich's ataxia

Friedreich ataxia (FRDA) is the commonest form of autosomal recessive ataxia. This study aimed to define the extent of the brain damage in FRDA patients and to identify in vivo markers of neurodegeneration, using diffusion-weighted imaging (DWI). We studied 27 FRDA patients and 21 healthy volunteers using a 1.5 T scanner. Axial DW images were obtained and mean diffusivity (MD) maps were generated. Region of interests (ROIs) included medulla, pons, inferior, middle and superior cerebellar peduncles (ICP, SCP, MCP), dentate nucleus, cerebellar white matter, thalamus, caudate, putamen, pallidus, pyramidal tracts at level of posterior limb of internal capsule (PLIC), optic radiations (OR), and corpus callosum. Histograms of MD were generated for all pixels in the whole cerebral hemispheres and infratentorial compartment. Disease severity was assessed by the International Cooperative Ataxia Rating Scale (ICARS). FRDA patients had significantly higher MD values than controls in medulla (P < 0.001), ICP (P < 0.001), MCP (P < 0.01), SCP (P < 0.001), OR (P < 0.001), and at the level of the infratentorial structures such as brainstem (P < 0.01), cerebellar hemispheres (P < 0.01), and especially in the cerebellar vermis (P < 0.001). MD values were strongly correlated with disease duration and ICARS score. Our results showed that DWI is a suitable non-invasive technique to quantify the extent of neurodegeneration in FRDA, that appears more extended than previously reported, showing a microstructural involvement of structures such as OR and MCP.

Pediatric tumors of the central nervous system: a retrospective study of 1,043 cases from a tertiary care center in South India

The objective of this study is to describe the age, sex, location, and histopathology of pediatric tumors of the central nervous system diagnosed at a tertiary care center in South India. One thousand forty-three tumors that occurred in children between 0 and 18years of age diagnosed between 1 January 1990 and 31 December 2004 were reclassified according to the WHO 2007 classification, and the clinical data were analyzed. The mean age at diagnosis was 10.9years with a male/female ratio of 1.7:1 with a male preponderance in most tumors. The five most frequent tumors were: astrocytoma (47.3%), medulloblastoma (11.4%), craniopharyngioma (9.7%), ependymal tumors (4.8%), and nerve sheath tumors (4.1%). Of these, 53.3% of the tumors were supratentorial, 40.6% were infratentorial, and 6.1% occurred in the spinal cord. Although the number of patients treated annually steadily increased over the study period, there was no relative increase in pediatric neoplasms compared to adults. The majority of tumors showed a male preponderance with astrocytoma being the most common tumor type. Although the cerebellum was the most frequent single site of occurrence, tumors involved the supraratentorial compartment more often than the infratentorial compartment.

Endoscopic Transaqueductal Placement of a Single-Catheter Cyst-Ventriculoperitoneal Shunt in a Neonate With Dandy-Walker Malformation-Associated Hydrocephalus -Case Report-

A neonate with hydrocephalus associated with Dandy-Walker malformation was successfully treated with an endoscopic placement of a transaqueductal ventricular single catheter. The modified catheter was provided with additional fenestration on its proximal side to allow simultaneous drainage from both the supra- and infratentorial compartments. This technique is well known for isolated fourth ventricles, but has not been applied to hydrocephalus associated with Dandy-Walker malformation. The cyst-ventriculoperitoneal shunt effectively drained both compartments. The patient was doing well 18 months after the surgical procedure. Endoscopic transaqueductal shunt placement can be considered, especially in patients with aqueductal patency.

Use of preoperative magnetic resonance imaging T1 and T2 sequences to determine intraoperative meningioma consistency

Background:Meningioma firmness is a critical factor that influences ease of resection and risk, notably when operating on tumors intimate with neurovascular structures such as the mesial sphenoid wing. This study develops a predictive tool using preoperative magnetic resonance imaging (MRI) characteristics to determine meningioma consistency.Methods:101 patients with intracranial meningioma (50 soft/51 firm) were included. MRI characteristics of 38 tumors (19 soft/19 firm) were retrospectively reviewed to identify preoperative imaging features that were then correlated with intraoperative description of the tumor as either “soft and/or suckable” or “firm and/or fibrous”. Criteria were developed to predict consistency and then blindly applied to the remaining 63 meningiomas (31 soft/32 firm).Results:The overall sensitivities for detecting soft and firm consistency were 90% and 56%, respectively (95% CI = 73–97% and 38–73%; P < 0.001). Compared to gray matter, meningiomas that were T2 hypointense were almost always firm. Soft meningiomas were hyperintense on T2 and hypointense on T1. Soft meningiomas were slightly larger and less likely to be associated with edema. There was a slight preponderance of firm meningiomas in the infratentorial compartment. Grade of meningioma was not predictive. Contrast enhancement, diffusion restriction, changes in overlying bone, intratumoral cysts, and angiographic features were not predictable.Conclusions:This tool using T1 and T2 series predicts meningioma consistency. Such knowledge should assist the surgeon in preoperative planning and counseling.

Cerebrospinal fluid M staging for medulloblastoma: Reappraisal of Chang's M staging based on the CSF flow

Tumor seeding is a strong negative prognostic factor for patients with medulloblastoma. Because Chang's M staging is based primarily on CT and myelographic findings and might be contradictory to the direction of normal cerebrospinal fluid (CSF) flow, seeding patterns and appropriate staging of medulloblastoma need to be revisited in patients diagnosed in the MRI era. We retrospectively reviewed the clinical and radiological data of 86 patients with a diagnosis of medulloblastoma who were treated in the MRI era. The presence of seeding in each subarachnoid space compartment and the patterns of seeding were analyzed in correlation with patient survival data. Thirty-four patients had gross seeding on perioperative MRI. Thirty-two patients had seeding in the spinal compartment. Sixteen and 12 patients had seeding in the infratentorial and supratentorial compartments, respectively. There was an apparent hierarchy of seeding (ie, from seeding in the spinal compartment up to the supratentorial compartment). Patients with seeding in the spinal compartment had longer progression-free survival (P = .038) and a tendency toward better overall survival (P = .053) compared with patients with seeding in intracranial compartments. We modified Chang's M staging based on the CSF flow and termed this approach "CSF M staging." CSF M staging for medulloblastoma, in which intracranial seeding occupies a higher rank than spinal seeding, was a better predictor of patient prognosis. This modified staging method may be applied to metastatic staging of brain tumors located in the fourth ventricle.

Coma after spinal anaesthesia in a patient with an unknown intracerebral tumour

Spinal anaesthesia is contraindicated in patients with elevated intracranial pressure or space-occupying intracranial lesions. Drainage of the lumbar cerebrospinal fluid (CSF) can increase the pressure gradient between the spinal, supratentorial and infratentorial compartments. This can result in rapid herniation of the brain stem or occluding hydrocephalus. We present a case of a female patient with an occult brain tumour who received a spinal anaesthesia for an orthopaedic procedure. The primary course of anaesthesia was uneventful. Several hours after surgery, the patient became increasingly disoriented and agitated. The next day, she was found comatose. A computed tomogram of the head revealed herniation of the brain stem, resulting in an occluding hydrocephalus due to a prior not known infratentorial mass. By acute relieving of the intracranial pressure by external CSF drainage, the mass was removed 2 days later. The further post-operative course was uneventful and the patient was discharged from the hospital without neurological deficit 3 weeks after the primary surgery.

Aetiological differences in neuroanatomy of the vegetative state: insights from diffusion tensor imaging and functional implications

BackgroundAn improved in vivo understanding of variations in neuropathology in the vegetative state (VS) may aid diagnosis, improve prognostication and help refine the selection of patients for particular treatment regimes....

Lateral extradural, supratentorial neurenteric cyst

Neurenteric cysts are rare congenital, benign, endodermal lesions of the central nervous system that occur mainly in the spinal canal. Intracranial neurenteric cysts are rare; the posterior fossa being the most common site. A laterally based supratentorial neurenteric cyst is exceptionally uncommon. The rarity of supratentorial neurenteric cysts and their variable imaging features preclude preoperative diagnosis. A search of the literature revealed no other extradural supratentorial neurenteric cyst. We present a patient with an extradural giant neurenteric cyst that occupied both the supratentorial and infratentorial compartments, further highlighting the heterogeneity of this rare intracranial lesion and emphasizing the need to consider this in the differential diagnosis of cystic intracranial brain lesions.