胼胝体发育不全的CT和MRI评价

目的：胼胝体发育不全的CT和MRI诊断评价。方法：对16例儿童和成人胼胝体发育不全患者的CT和MRI表现进行分析,并讨论其诊断作用。结果：胼胝体发育不全的CT和MRI诊断要点是：①两侧脑室前角和室间孔分离;②侧脑室体部近乎平行地分离;③侧脑室枕角扩大;④第三脑室扩张并上前移位;⑤半球间裂异常地靠近第三脑室前部。结论：根据CT和MRI的特征表现,均可正确诊断胼胝体发育不全;但MRI矢状面扫描上,还可直观地显示胼胝体的发育异常。     

The natural history of ventriculomegaly and tonsillar herniation in children with posterior fossa tumours--an MRI study

OBJECTIVE: Posterior fossa tumours in children predispose to hydrocephalus, although the natural history is unclear and the need for drainage of the ventricles is controversial. We report on the natural history of ventriculomegaly and tonsillar herniation, as seen on serial MRI scans in children with posterior fossa tumours. RESULTS: Eighty-nine children with posterior fossa tumours were reviewed retrospectively. Overall, 18 (20%) patients required permanent cerebrospinal fluid (CSF) drainage in the form of a ventriculoperitoneal shunt (n = 15) or third ventriculostomy (n = 3). On pre-operative MRI scan, the ventricular size was assessed by measurement of the ventricular index (VI) and 59 patients (66%) had a VI greater than 0.4. There was a progressive decrease in the mean VI from pre-operative to post-operative MRI scans and beyond 3-9 months after surgery, the mean VI was less than 0.4 (p = 0.0001). Patients requiring permanent CSF drainage had a greater VI pre-operatively and at 3-9 months post-operatively (p < 0.05). On pre-operative MRI scan, 75 patients (84%) had greater than 5 mm herniation of the cerebellar tonsils below the level of the foramen magnum. There was a progressive decrease in the mean tonsillar herniation from pre-operative to post-operative MRI scans, with time (p = 0.0001), although this did not relate to the need for CSF drainage. On multivariate analysis, the need for permanent CSF drainage was associated with pre- and intra-operative CSF drainage (odds ratio = 23.3; p = 0.0001) and incomplete surgical excision of tumour (odds ratio = 7.7; p = 0.006). CONCLUSIONS: Hydrocephalus and tonsillar herniation are common in children with posterior fossa tumours, although post-operatively there is a natural tendency for it to resolve and only a fifth of the patients needed permanent CSF drainage. We recommend selective drainage of CSF in children with posterior fossa tumours. Patients at risk are those with severe symptoms at presentation, needing peri-operative CSF drainage and those with subtotal resection of tumour.     

Magnetic resonance imaging and proton magnetic resonance spectroscopy of the brain in the diagnostic evaluation of developmental delay

AimTo assess the contribution of MRI and proton spectroscopy (1HMRS) in establishing an etiological diagnosis in children with developmental delay (DD) and to assess whether the chance of finding specific abnormalities correlates with the presence of neurological signs and/or abnormal head circumference (HC).MethodsPatients were derived from a cohort of 325 consecutive patients with DD receiving structured multidisciplinary evaluation in our centre. Patients had MRI/1HMRS if a diagnosis could not be made clinically and if additional neurological signs and/or abnormal HC and/or an IQ below 50 were present. The MRI protocol consisted of axial IR, T2, FLAIR, sagittal T1 and coronal T2 sequences. Multivoxel 1HMRS was located in a plane superior to the lateral ventricles with voxels in both grey matter and white matter.ResultsOne hundred and nine children were scanned, 80 of them because of neurological signs and/or abnormal HC. Although minor abnormalities were noted in the vast majority of patients, MRI and/or 1HMRS really contributed to an etiological diagnosis in only 10 (9%) patients, all of whom were scanned because of neurological signs. In these 10 patients, 1HMRS was diagnostic in one patient and of additional value to MRI findings in 3 patients.ConclusionsMRI and 1HMRS may contribute to the diagnostic evaluation of DD, especially if applied specifically to patients with neurological signs, whereas its role is very limited in children without these signs.     

Reference ranges for the linear dimensions of the intracranial ventricles in preterm neonates

AIMS: To establish normal ranges, in preterm infants < 33 weeks' gestation, for measurements of the lateral, third, and fourth ventricles and to assess intra-observer and inter-observer reliability. To assess the effect of head position during scanning on lateral ventricle size. To determine whether sex influences ventricle size. METHODS: A prospective study involving infants < 33 weeks' gestational age (GA) at birth. Cranial ultrasound scans were done during the first 3 days of life. Linear dimensions of the anterior horn width and thalamo-occipital distance of the lateral ventricles, the width of the third ventricle, and the width and length of the fourth ventricle were measured. Measurements were plotted against GA and reference ranges produced. All measurements were tested for intra-observer and inter-observer reliability. Head position and sex differences were studied. RESULTS: 120 infants with known GA (23(+1) to 32(+6) weeks) had their intracranial ventricles measured. Reference ranges obtained were-anterior horn width: 0-2.9 mm; thalamo-occipital distance: 8.7-24.7 mm; third ventricle width: 0-2.6 mm; fourth ventricle width: 3.3-7.4 mm; fourth ventricle length: 2.6-6.9 mm. Dependent and non-dependent lateral ventricles did not differ significantly in size. There was no clinically significant difference in ventricular size between sexes. CONCLUSIONS: Reference ranges for the measurement of the intracranial ventricles in preterm infants from 23 to 33 weeks' GA are provided and can be used in the diagnosis and assessment of ventricular enlargement in preterm infants. All measurements have good intra-observer and inter-observer reliability. Head position at the time of scanning does not influence the asymmetry of the lateral ventricular measurements. The infant's sex does not influence ventricular size.     

Cranial MRI of neurologically impaired children suffering from neonatal hypoglycaemia

Background. Metabolic disturbances such as anoxia and hypoglycaemia are important in causing maldevelopment of the neonatal brain. While there have been some pathology studies of the effects of neonatal hypoglycaemia on brain development, reports of MRI findings in such infants have been rare. Objectives. To describe the MRI findings in neurologically handicapped children who had suffered from neonatal hypoglycaemia and to evaluate the relationship between the neurological impairment and neonatal hypoglycaemia. Materials and methods. We retrospectively evaluated the MRI findings in eight full-term infants with neonatal symptomatic hypoglycaemia who later exhibited neurological handicap. The age at which the MRI scans were obtained ranged from 9 months to 8 years 10 months (mean 4 years 1 month, median 4 years). Results. The most striking findings were prolonged T1 weighting and T2 weighting in the parieto-occipital periventricular deep white matter in six patients, suggesting abnormal or delayed myelination. Dilatation of the lateral ventricles, especially of the trigones, was observed in five patients in whom the distance between the posterior horns of the lateral ventricles and the adjacent sulci was reduced. The volume of white matter relative to grey matter was reduced in two patients. In addition, four patients exhibited cerebral cortical atrophy, mainly in the occipital lobe. Conclusions. These findings suggest that neonatal hypoglycaemia may cause delayed or abnormal myelination, especially in the parieto-occipital, periventricular, deep white matter, and may cause cerebral cortical atrophy, especially in the occipital lobe. Received: 1 August 1997 Accepted: 15 June 1998     

Whole-body MRI of paediatric malignant tumours: comparison with conventional oncological imaging methods

Purpose: To evaluate the usefulness of whole-body (WB) MRI for detecting metastases from paediatric malignant tumours in comparison with conventional oncological imaging methods. Materials and methods: Using a 1.5-T system, a coronal short tau inversion recovery (STIR) sequence was obtained in all patients. In addition, sagittal fat-suppressed T2-weighted, sagittal STIR, or coronal fat-suppressed pre-contrast and post-contrast T1-weighted sequences were performed. Patients who underwent WB MRI and conventional oncological imaging within 15 days were enrolled in the study. In total, 58 bone scintigraphies, 26 iodine-123 (¹²³I) meta-iodo-benzylguanidine (MIBG) scintigraphies, and 48 CT scans were available for comparison in 36 patients (median age 3.5 years; 21 boys, 15 girls) who underwent 82 WB MRI examinations. Skeletal and extraskeletal metastases were evaluated for a variety of tumour types. Results: Concordance rate of WB MRI between two readers was 74%. In detecting metastases, WB MRI had higher sensitivity (99%) and PPV (94%) than bone scintigraphy (26 and 76%, respectively). In detecting skeletal metastases, WB MRI revealed higher sensitivity (100%) than ¹²³I-MIBG scintigraphy (25%) and CT (10%). In contrast, WB MRI showed lower PPV in detecting skeletal and extraskeletal metastases (8 and 57%, respectively) than ¹²³I-MIBG scintigraphy (100%), and lower sensitivity (60%) in detecting extraskeletal metastases than CT (100%). In 2 of 11 untreated patients, tumour staging was upgraded from stage 3 to 4 according to WB MRI findings. In 3 patients, WB MRI revealed early treatment responses (<1 year) of skeletal metastases. Conclusions: WB MRI can substitute for bone scintigraphy in detecting skeletal metastases of paediatric malignant tumours, and it is useful in evaluating initial tumour staging and early treatment responses. However, it still has only a complementary role in detecting extraskeletal metastases.     

EEG and MRI findings and their relation with intellectual disability in pervasive developmental disorders

Background  The diagnostic category pervasive developmental disorders (PDDs) refer to a group of five disorders: autism, Rett syndrome, childhood disintegrative disorder, Asperger syndrome, and pervasive developmental disorder not otherwise specified (PDD-NOS). EEG abnormalities and seizures are considered much frequent in autistic subjects with comorbid intellectual disability (ID). In this study, we aimed to evaluate the EEG and MRI findings and their relation with ID in pervasive developmental disorder. Methods  A retrospective, cross-sectional and non-experimental study was performed. Subjects included 81 patients diagnosed with autism or PDD-NOS according to the DSM-IV criteria. The age range of the patients was 2–15 years (mean 6.6 years, SD 3.0). Among them, 21 (25.9%) were girls and 60 boys (74.1%). Results  Patients with severe ID had a higher rate of EEG abnormalities (P=0.03) than patients without ID as well as patients with mild or moderate ID. The association remained significant after the structural MRI abnormalities were controlled (P=0.04). The severity of ID was not associated with abnormal MRI. The most frequent EEG and MRI abnormalities were active epileptic anomaly/paroxysmal abnormality and cerebral atrophy/periventricular leukomalacia, respectively. Almost a third of the EEG abnormalities were associated with temporal cortex and adjacent cortical structures. Conclusions  Consistent with previous studies, almost a fourth of the patients in this relatively large sample of patients with pervasive developmental disorders had EEG and/or MRI abnormalities. EEG results indicate that temporal cortex may play a significant role in pervasive developmental disorders.     

Physeal and epiphyseal extent of primary malignant bone tumors in childhood

Twenty-two patients with metaphyseal primary malignant bone tumors (17 osteosarcomas, 5 Ewing's tumors) occurring before closure of the growth plate were examined with plain radiographs and MRI in order to determine the physeal or epiphyseal extent of the tumor. Results were correlated with the pathologic examination. Transphyseal spread was pathologically proven in 13 cases (59%): 12 cases of osteosarcoma and 1 case of Ewing's tumor (70% and 20%, respectively). There was no significant relation between epiphyseal invasion, age of patient, length of tumor or, in the cases of osteosarcoma, response to chemotherapy. Plain radiographs showed epiphyseal involvement in 4 cases and there were 10 false negatives. MRI revealed epiphyseal involvement in all cases; there were no false positives or false negatives. T1-weighted images in coronal or sagittal planes appeared to be sufficient. These findings are very useful in planning surgical limb salvage procedures and stress the ineffectiveness of the barrier effect of the growth plate against tumor spread.     

Cerebral and occipito-atlanto-axial involvement in mucopolysaccharidosis patients: clinical,radiological, and neurosurgical features

Background

Neurosurgical features of mucopolysaccharidosis (MPS) patients mainly involve the presence of cranio-vertebral junction (CVJ) abnormalities and the development of communicating hydrocephalus. CVJ pathology is a critical aspect that severely influences the morbidity and mortality of MPS patients. Hydrocephalus is slowly progressing; it must be differentiated from cerebral atrophy, and rarely requires treatment. The aim of this paper was to review the literature concerning these conditions, highlighting their clinical, radiological, and surgical aspects to provide a practical point of view for clinicians.

Results

CVJ involvement may present with cervical pain, unsteady gait, frequent falls, and progressive impairment of autonomous ambulation, an acute tetraplegia even after minor trauma. Magnetic resonance imaging (MRI) of the cervical spine, including active dynamic flexion and extension scans, is the most powerful imaging technique for detecting spinal cord compression at the CVJ in MPS patients. The main radiological features include atlanto-axial subluxation, odontoid hypoplasia, periodontoid soft tissue masses, spinal canal narrowing, and spinal cord compression. Together with MRI, fine-cut computed tomography (CT) scans with coronal and sagittal three-dimensional reconstructions are important diagnostic tools in the preoperative workup thanks to the information gleaned about bone structure conformation and angles. Finally, angio-CT slices are equally useful in preoperative planning, defining vertebral artery position in relation to bony structures. Surgery of the CVJ is proposed both to treat cord compression with MRI signs of myelopathy or as a preventive treatment in patients at high risk of cord damage. Among different surgical options, we always suggest performing decompression and instrumented stabilization.Hydrocephalus may occasionally present clinically with intracranial hypertension symptoms such as headache, vomiting, and high sight impairment. Neurocognitive symptoms may be hidden by the constitutive cognitive impairment. MRI with a study of dynamic cerebrospinal fluid (CSF) flow is helpful to differentiate from ventriculomegaly, which does not require treatment. Ventriculo-peritoneal shunt placement is the gold standard to treat hydrocephalus, although endoscopic third ventriculostomy has recently shown good results in some patients.

Conclusion

Early recognition of CVJ pathology and hydrocephalus is critical to avoid the development of severe complications. A multidisciplinary approach involving physicians, neuroradiologists, and neurosurgeons is needed to detect such conditions and to select patients eligible for surgery.

     

Structural congenital brain disease in congenital heart disease: Results from a fetal MRI program

ObjectiveTo identify the type and incidence of fetal brain pathology in fetuses with a prenatal diagnosis of congenital heart disease (CHD).Patients and methods67 pregnant women underwent a fetal MR-examinations between 20 and 38 gestational weeks. MR was done on a 1.5 T superconducting system. The type of cardiac malformation was defined by fetal echocardiography. Fetuses with a chromosomal abnormality or an extracardiac anomaly were excluded.ResultsFetal MRI scans in the final study cohort (53 fetuses) yielded normal results in 32 fetuses and a brain abnormality in 21 fetuses. Congenital brain disease (CBD) was found in 39% of the final study cohort of fetuses with CHD. MRI findings were classified into malformations, acquired lesions and widening of the ventricles and/or outer CSF spaces (malformations: 7 fetuses, acquired lesions: 5 fetuses, changes in CSF spaces: 9 fetuses). Asymmetry of the ventricles was the most common finding in the CSF group.ConclusionsOur data suggest that fetal MRI can be used to characterize structural CBD in CHD. Advanced MRI techniques such as diffusion tensor imaging and proton spectroscopy are tools that, in the future, will certainly shed light on the spectrum of structural and functional CBDs that are associated with CHD.     

Magnetic resonance imaging in neurological disorders.

To investigate the role of magnetic resonance imaging (MRI) in neurological disorders, 115 children were studied in two groups. Group A (78 patients) was studied by paired computed tomography and MRI cranial scans. Group B (37 patients) was studied by paired computed tomography assisted myelography (CTM) and MRI spinal scans. In group A, the scans were generally equivalent for supratentorial tumours and for investigating fits, hydrocephalus, benign intracranial hypertension, and cerebral atrophies, but MRI scanning was superior for posterior fossa tumours and cysts. In group B, MRI scans were superior for intramedullary spinal tumours, spinal dysraphic problems with tethering or syrinx, and were complementary to CTM in diastematomyelia.     

High success rates of sedation-free brain MRI scanning in young children using simple subject preparation protocols with and without a commercial mock scanner–the Diabetes Research in Children Network (DirecNet) experience

Background

The ability to lie still in an MRI scanner is essential for obtaining usable image data. To reduce motion, young children are often sedated, adding significant cost and risk.

Objective

We assessed the feasibility of using a simple and affordable behavioral desensitization program to yield high-quality brain MRI scans in sedation-free children.

Materials and methods

222 children (4–9.9 years), 147 with type 1 diabetes and 75 age-matched non-diabetic controls, participated in a multi-site study focused on effects of type 1 diabetes on the developing brain. T1-weighted and diffusion-weighted imaging (DWI) MRI scans were performed. All children underwent behavioral training and practice MRI sessions using either a commercial MRI simulator or an inexpensive mock scanner consisting of a toy tunnel, vibrating mat, and video player to simulate the sounds and feel of the MRI scanner.

Results

205 children (92.3%), mean age 7?±?1.7 years had high-quality T1-W scans and 174 (78.4%) had high-quality diffusion-weighted scans after the first scan session. With a second scan session, success rates were 100% and 92.5% for T1-and diffusion-weighted scans, respectively. Success rates did not differ between children with type 1 diabetes and children without diabetes, or between centers using a commercial MRI scan simulator and those using the inexpensive mock scanner.

Conclusion

Behavioral training can lead to a high success rate for obtaining high-quality T1-and diffusion-weighted brain images from a young population without sedation.     

Importance of sagittal MR imaging in nontraumatic femoral head osteonecrosis in children

Background  In nontraumatic femoral head osteonecrosis, characterization of femoral head collapse is important in staging disease progression and planning treatment. Few prior studies have quantitatively compared the ability of sagittal and coronal MR images to detect femoral head collapse. Objective  We hypothesized that sagittal MR images show a greater degree and angular span of femoral head collapse than coronal images. Materials and methods  We reviewed 38 hip MRI scans of nontraumatic femoral head osteonecrosis from 34 pediatric patients. In both sagittal and coronal images, the maximal extent and angular location along with the angular span of the femoral head collapse were measured. Differences were evaluated using a paired t-test. The extent of bone and cartilage loss from the femoral head was evaluated. Results  Sagittal MR images showed 29% maximal femoral head radius collapse, whereas coronal images showed 16% collapse (P<0.001). Sagittal images showed a larger angular span of collapse (115°) than coronal images (55°, P<0.001). Sagittal images showed greater epiphyseal bone loss in the anterior than in the posterior portion (P<0.001), whereas coronal images did not show a significant difference in bone loss between the medial and lateral portion (P=0.32). Conclusion  Sagittal images show greater femoral head collapse than coronal images in nontraumatic femoral head osteonecrosis.     

Low Field Magnetic Resonance Imaging of the Central Nervous System in 15 Children with Autistic Disorder

ABSTRACT. Fifteen children, 10 boys and 5 girls, with autistic disorder, were studied with low field magnetic resonance imaging (MRI). The age ranged from 2.7–13.1 years, with a mean of 8.3 years. All patients but one (who refused) had a normal CT scan of the C.N.S. The MRI investigation was performed during anaesthesia with a low field magnetic resonance imager. The cerebrum, cerebellum, and brain stem were examined. No pathological changes were found in any of the patients studied.     

Cranial MRI scans are indicated in all girls with central precocious puberty

Aims: (1) To assess the value of cranial magnetic resonance imaging (MRI) scans in the investigation of girls with central precocious puberty (CPP); and (2) to determine the clinical predictors of abnormal cranial MRI scans in these patients. Methods: A retrospective study of 67 girls diagnosed with CPP who underwent cranial MRI scans at diagnosis. Patients with neurological signs or symptoms at presentation were excluded. Results: The mean age of onset of puberty was 6.2 years (range 2.0–7.9). Intracranial abnormalities were present in 10 (15%) patients (MR⁺), while 57 (85%) had no abnormalities (MR^-). There was no statistical difference between MR⁺ patients and MR^- patients at presentation with respect to age of onset of puberty, pubertal stage, bone age advance, pelvic ultrasound findings, or height or body mass index standard deviation scores (SDS). Conclusion: Girls with CPP should have a cranial MRI scan as part of their assessment since clinical features, including age, are not helpful in predicting those with underlying pathology. Implementation of such an approach may have a substantial effect on clinical practice and healthcare cost.     

Giant encephalocele: a study of 14 patients

Background: Giant encephalocele is a rare condition and few published reports are available in the English literature. It is a challenge to neurosurgeons, even today. This series consists of 14 patients with giant encephaloceles treated at our institute. Material and Observation: Over a period of 8 years, from 2002 to 2009, 110 patients with encephaloceles were managed at our institute. Amongst them, 14 were children with giant encephaloceles. All patients had CT/MRI or both prior to surgery, and all were operated upon. Four patients were neonates, under 1 month of age, and 9/14 patients (64%) were under 3 months. The youngest child was a newborn baby aged 2 days. Except for 1 with an anterior encephalocele, the rest were patients with occipital encephaloceles. A CT scan was performed on 5 and an MRI on 1 patient. Both CT and MRI scans were performed on the other 8 patients. MRI/CT showed hydrocephalus in 10/14 patients. Of these, 7 required ventriculoperitoneal (VP) shunt, and the remaining 3 with mild to moderate hydrocephalus did not. Of the 7 patients who underwent VP shunt, 5 had a shunt during the encephalocele repair and 2 had a postoperative shunt for increasing hydrocephalus. Results: Other associated anomalies recorded were acquired Chiari malformation in 3 patients, secondary craniostenosis with microcephaly in 5, and syringomyelia in 1 patient. All the patients underwent repair of encephalocele and 4 had suturectomy of coronal suture for the secondary craniostenosis. There were 2 postoperative deaths due to hypothermia. Among the 12 surviving patients, 9 had a good outcome and 3 had poor mental development. The present study shows overall good outcomes in 9/14 (66%) patients.     

How has imaging of the head,neck and spine changed over 5 years in a district general hospital?

BACKGROUND: Over recent years, MRI has become the imaging modality of choice for examination of the head, neck and spine. OBJECTIVE: The primary objective was to compare the clinical benefit of CT with MRI for children being investigated at a district general hospital. Secondary outcome measures were the change in amount of and indications for imaging. MATERIALS AND METHODS: This was a retrospective case note review of two 1-year periods. Clinical benefit was determined according to the diagnostic ability of the investigation. Statistical analysis was performed using the chi-square test. RESULTS: In 1992-1993 (period I) there were 74 CT scans, (40 boys, median age 3.4 years, range 0-18.0 years). In 1996-1997 (period II) there were 104 scans (50 CT, 54 MRI; 49 boys, median age 6.2 years, range 0.2-16.7 years). Imaging increased by 40% between the two periods. MRI gave enhanced clinical benefit over CT (P<0.02). Within period II, indications for CT differed from MRI (P<0.01). For CT there was no change in indications or rate of diagnosis between the two periods (P>0.2). CONCLUSIONS: MRI improves clinical benefit over CT. Imaging increased over 5 years with different indications for CT and MRI.     

Magnetic resonance imaging of the infant brain: anatomical characteristics and clinical significance of punctate lesions

OBJECTIVE: To describe the magnetic resonance imaging (MRI) characteristics of punctate brain lesions in neonates (number, appearance, distribution, and association with other brain abnormalities) and to relate them to neurodevelopmental outcome. METHODS: A retrospective analysis was performed of 110 MRI brain scans from 92 infants admitted in 1998 to the neonatal intensive care unit. Results of routine neurodevelopmental follow up (1998-2001) in those infants with punctate brain lesions were analysed. RESULTS: Punctate lesions were observed in 15/50 preterm and 2/42 term infants. In the preterm group, the number of lesions was < 3 in 20%, 3-10 in 27%, and > 10 in 53%. In 14/15 the lesions were linearly organised and located in the centrum semiovale. Other brain abnormalities were absent or minor--that is, "isolated" punctate lesions--in 8/15 and major in 7/15. In the term group, punctate lesions were organised in clusters and no other brain abnormalities were observed. Isolated punctate lesions were observed in 10/17 infants, and a normal neurodevelopmental outcome was seen in 9/10 (mean follow up 29.5 months). One infant showed a slight delay in language development. In the infants with associated brain lesions (7/17, mean follow up 27.5 months), outcome was normal in only two subjects. CONCLUSIONS: Punctate lesions are predominantly seen in preterm infants, are usually linearly organised, and border the lateral ventricles. Isolated punctate lesions may imply a good prognosis, because most of these subjects have a normal neurodevelopmental outcome so far.     

Imaging diagnosis of retroperitoneal ganglioneuroma in childhood

Purpose. To demonstrate the typical appearance of retroperitoneal ganglioneuromas on CT and MRI.¶Materials and methods. Retrospective analysis of diagnostic imaging (five CT scans, three MRI scans) in five children aged 3–15 years with the histological diagnosis of ganglioneuroma.¶Results. The scans showed large (maximum 11 cm diameter), round or oval tumours with sharply defined margins. Intraspinal tumour involvement occurred in two cases. Comparing CT with MRI, MRI was more accurate in defining the intraspinal involvement. The ganglioneuromas were hypodense on unenhanced CT and showed moderate enhancement with administration of contrast medium. In three patients, CT demonstrated tumour calcification with a disseminated speckled pattern. On T1-weighted MRI the tumours were homogeneous and hypointense, showing marked enhancement after gadolinium administration. On T2-weighted scans the tumours were hyperintense.¶Conclusion. At the time of diagnosis, retroperitoneal ganglioneuromas are generally large tumours that can be shown well by CT and MRI. The appearance on CT more readily suggests the diagnosis, but MRI is superior for documenting local or intraspinal tumour extension and lacks radiation load.     

Unusual case of 'trapped fourth ventricle' in a child with posthemorrhagic hydrocephalus--lessons learnt

In most of the children with posthemorrhagic hydrocephalus (PHH), multidisciplinary follow-up is performed, with the focus on consequences of prematurity, cerebral palsy (CP) and hydrocephalus. A large fourth ventricle is common in these children but imaging performed in order to document ventricles and tissue damage is not oriented to exclude coexisting rare pathologies. We report a 3-year-old child with spastic CP, secondary to prematurity and PHH. A ventriculoperitoneal shunt was inserted at the age of 2 months. On follow-up imaging the child demonstrated well-drained supratentorial ventricles with a persistent large fourth ventricle. Because of a neurological change in spasticity and new-onset torticollis, a repeat MRI was performed, suggesting a cystic, nonenhancing lesion of the fourth ventricle. The surgical exploration revealed a large dermoid of the fourth ventricle. We analyze the differential diagnosis of a clinically significant large fourth ventricle in a shunted child with PHH and CP. This includes conditions without pressure in the posterior fossa such as tissue loss due to cerebellar atrophy, or pathologies causing a true increase in pressure of the fourth ventricle (isolated fourth ventricle, cystic lesions and neoplasms of the fourth ventricle). Neurologically compromised children pose additional challenges in reaching a definitive diagnosis and hence require a careful regular assessment of their clinical status with additional well-timed imaging with appropriate protocols to allow appropriate treatment when indicated and to avoid morbidity due to delayed diagnosis. We present a rare coexistence of a dermoid tumor within the fourth ventricle in a CP child with PHH and express the dilemmas associated with its management.