Cranial CT findings in patients with meningomyelocele.

The association between meningomyelocele and various cranial abnormalities, particularly Chiari II malformation is well established. Cranial CT scans in 47 patients with meningomyelocele proved to be a safe and effective method of elucidating the type and extent of anatomic abnormalities associated with this disorder, and evaluating and following the degree of hydrocephalus seen in these patients. Of the 47 patients, 43 (92%) showed CT findings indicative of an abnormally low fourth ventricle, the hallmark finding in Chiari II malformation. In 67% the fourth ventricle was not visualized, and in 25% it was directly visualized in an abnormally caudal position. Other findings included hydrocephalus (85%), a striking and possibly unique heart-shaped psuedomass in the posterior fossa (58%), and abnormal configuration of the lateral ventricles ("vampire bat" configuration). Calvarial abnormalities, in particular lacunar skull, were also noted at CT.     

Limbic tract anomalies in pediatric myelomeningocele and Chiari II malformation: anatomic correlations with memory and learning--initial investigation

PURPOSE: To prospectively determine anomalies of limbic tracts and to describe the relationship between these anomalies, seen on diffusion-tensor magnetic resonance (MR) and fiber tract (FT) reconstruction images, and learning and memory in children with myelomeningocele (MM) and Chiari II malformation. MATERIALS AND METHODS: The investigation was HIPAA compliant and approved by institutional review boards; informed consent was obtained. In seven male and six female patients (aged 6 months to 16 years) with MM and Chiari II malformation, diffusion-tensor imaging and FT reconstruction were performed. FT reconstruction was generated with fractional anisotropy continuous tracking algorithm and manually drawn regions of interest. Limbic tract abnormalities were assessed on FT reconstruction images by an experienced pediatric neuroradiologist blinded to results of cognitive testing. Nine patients met criteria for memory and learning testing by a trained cognitive neuroscientist blinded to MR results. Exact Wilcoxon rank sum test was used to compare performance with learning and memory tasks in two groups. RESULTS: Eleven of 13 patients had defects within fornices and/or cingulum; three patients had aberrant fibers of cingulum. In nine patients, six had deficits in general memory; four, in learning; and four, in both. Atresia or hypoplasia of crura and body of fornices was noted in six patients with memory deficits and four patients with learning deficits. Five of six patients with memory deficits and three of four with learning deficits had hypoplasia or atresia of cingulum. Exact Wilcoxon rank sum test demonstrated significantly poorer performance for nonverbal immediate recall tasks in patients with anomalies of the fornix compared with those without (P = .04, exact two-tailed test). CONCLUSION: Diffusion-tensor and FT reconstruction images revealed that limbic fiber abnormalities were common in patients with MM and Chiari II malformation. Nonverbal immediate recall task performance appeared to be related to abnormalities of the fornix.     

Cloacal exstrophy: radiologic findings in 13 patients

Cloacal exstrophy is a complex, multisystem malformation that has not received much attention in the radiologic literature. The clinical histories and imaging studies of 13 cases of cloacal exstrophy proved surgically or at autopsy were reviewed. Radiologic observations were based on skeletal plain films (13), contrast-enhanced examinations of the genitourinary system (12), abdominopelvic sonograms (nine), gastrointestinal studies (seven), CT scans of the pelvis and CNS (seven), MR images of the pelvis and CNS (six), renal nuclear medicine scans (three), myelography (three), and three-dimensional scans of the pelvis (two). Genitourinary and gastrointestinal abnormalities identified in our 13 patients included bladder malformations (13), hindgut anomalies (13), undescended testes (five), malrotation (five), duplicated müllerian structures (four), and renal ectopia (four). Skeletal abnormalities included symphysis pubis diastasis (13), posterior element dysraphism (12), vertebral segmentation anomalies (12), clubfeet (six), and hip dislocations (five). CNS anomalies included meningocele (nine) and Chiari malformation (one). Immediate surgical closure of the defect with maximal bowel preservation and diverting colostomy offers optimal chances for survival. Appropriate preoperative gastrointestinal and genitourinary evaluation is essential.     

Clinically manifest or silent primary and secondary syringomyelia. The magnetic resonance findings

The MR scans were retrospectively reviewed of 40 patients who had been diagnosed as having syringomyelia. Our results demonstrate that syringomyelia can be found in asymptomatic patients as well as in many with atypical symptomatology. Our study stresses MR efficacy in investigating this pathologic condition. As a matter of fact, MR allowed us to visualize the cavity, its extension, the eventual association with Arnold Chiari type-I malformation and/or syringobulbia. In all cases cord enlargement and the presence of septations could also be demonstrated. In most cases the possible pathogenesis of syringomyelia could also be supposed.     

Sonography of the neonatal craniocervical junction

To determine the value of ultrasound scanning of the craniocervical junction in neonates via a posterior approach, we examined 50 infants with normal posterior fossae, 10 with congenital abnormalities, and eight with intracranial hemorrhage. Good evaluation of the cisterna magna, medulla, tonsils, vermis, cervical cord, and central canal was possible in most cases. In nine patients with spinal dysraphism, all displayed a Chiari II malformation; of these, a kink at the medullary cord junction was seen in six, and a cerebellar peg was noted in four. In one case, the Chiari malformation was confirmed by myelography, and all nine patients had some of the intracranial features of Chiari II malformation seen via the standard anterior fontanelle approach. The 10th patient in this group had a quadrigeminal plate cyst and gross hydrocephalus. In another four infants, diffuse subarachnoid blood in the cisterna magna was seen after recent intraventricular hemorrhage. A further two of four patients with posthemorrhagic hydrocephalus had localized clots. Direct scanning at the craniocervical junction was easily performed and allowed good evaluation of this area in normal infants and in patients with Chiari II malformation. This technique also allowed visualization of subarachnoid blood and clots obstructing the outlet of the fourth ventricle.     

MR imaging of syringohydromyelia and Chiari malformations in myelomeningocele patients with scoliosis

The brain and spinal cord were examined with MR imaging in 30 myelomeningocele patients 3-32 years old to study the prevalence of syringohydromyelia and Chiari malformations and to correlate these conditions with developmental scoliosis and spontaneously arrested hydrocephalus. Twelve patients had neurologic deficits above the level of the myelomeningocele and 10 had spontaneously arrested hydrocephalus. MR visualized syringohydromyelia in four patients with widened or focally bulging spinal cords and in eight patients with atrophic spinal cords. All patients had Chiari malformations, 28 of type II and two of type I. Syringohydromyelia was not correlated with type of scoliosis, result of ventriculoperitoneal shunting procedures, radiologic level of the myelomeningocele, or extent of the Chiari malformation. The two patients with the most rapid progression of thoracic scoliosis had the most extensive syringohydromyelia and radiologically low lumbar levels. Neurologic deterioration due to syringohydromyelia and Chiari malformations is probably more common in myelomeningocele than has been recognized previously and may cause developmental scoliosis, loss of ambulation, impaired extremity function, and progressive cranial nerve paralysis.     

The clinical significance of hindbrain herniation and deformity as shown on MR images of patients with Chiari II malformation

This study investigates whether the degree of brainstem herniation and the nature of the cervicomedullary deformity seen on sagittal plane MR images correlates with the clinical syndrome in patients with the Chiari II malformation. The amount of brainstem herniation was assessed by relating the position of the midbrain and pons to the sella turcica and the anterior lip of the foramen magnum, respectively. The cervicomedullary deformity was graded into degrees of increasing severity. We found that the neurologic status of these children was not affected by either the amount of herniation or the characteristics of the cervicomedullary deformities. Because of these findings, we believe that other factors, such as disorganization of the brainstem nuclei, may be the likely cause for the breathing and swallowing difficulties experienced by children with the Chiari II malformation.     

MR imaging of hindbrain deformity in Chiari II patients with and without symptoms of brainstem compression

We examined the MR appearance of the hindbrain deformity, including the upper cervical spinal canal and craniovertebral junction, in 33 patients with Chiari II malformation. In this disorder, there is impaction at birth of the medulla and cerebellar vermis into the upper cervical spine, resulting in obliteration of the subarachnoid space and scalloping of the dens. Spinal canal enlargement during the child's growth, combined with dorsal displacement of neural tissue, eventually causes marked widening of the precervical subarachnoid space. This enlargement may simulate an intradural mass. Our series documents the changes seen at birth and the progression of the widened precervical space through the first and second decades. Twelve (36%) of the 33 patients studied were symptomatic, with brainstem or longtract symptomatology, and 11 of these required surgery. This group was compared with the remaining 21 asymptomatic Chiari II patients to identify MR features associated with clinical deterioration. The level of descent of the hindbrain hernia was critical; eight of 12 symptomatic patients had a cervicomedullary kink at C4 or lower, while no asymptomatic patients had a fourth ventricle, medulla, or kink below C3-C4. The precervical cord subarachnoid space was slightly wider in asymptomatic patients, although there was great overlap. In five patients with follow-up scans, this space was seen to increase in width after laminectomy. A CSF flow void was present in the precervical space in about 25% of patients in both groups. In nine of 12 symptomatic patients, C1 arch indentation of the dura (causing significant compression) was confirmed surgically. However, seven (33%) of the 21 asymptomatic patients also had this appearance. Absolute measurement of the anteroposterior diameter of the canal at C1 ranged from 11 to 25 mm in both groups. Retrocollis, which persisted despite sedation for MR, was seen in two patients, both symptomatic. Recognition of the vermis, medullary kink, cervical cord, C1 arch, fourth ventricle, and precervical space in Chiari II patients is fundamental to the analysis of symptoms in     

MR evaluation of Chiari I malformations at 0.15 T

Twelve patients with known or presumed Chiari I malformations and two with clinical diagnoses of multiple sclerosis were examined by magnetic resonance (MR) imaging. MR confirmed or established the diagnosis of Chiari I malformation in all 14 cases. The spin-echo technique with a short time to echo (TE = 40 msec) and a short time to recover (TR = 1000 msec) provided optimum imaging of tonsillar position, hydromyelia cavities, and cervicomedullary "kinking." Long TE (greater than 80 msec) and TR (greater than 2000 msec) increase the signal intensity of cerebrospinal fluid and may obscure the pathology. Sagittal, transaxial, and coronal images provided complementary data; sagittal and coronal views best imaged the abnormal spinal cord and tonsils, but slitlike cavities were best seen on transaxial images. Cervicomedullary kinking was found in 10 (71%) of 14 patients and in 90% of the hydromyelic patients. This high incidence suggests that in other radiologic techniques tonsillar herniation masks the kinking. Symptoms of the Chiari I malformation overlap those of demyelinating diseases and brain tumors. Our early experience suggests MR is the preferred noninvasive procedure for identifying Chiari I malformation. Moreover, the ability to portray the variable cavity morphology of hydromyelia directly offers the potential for improved shunt placement.     

MR of postoperative syringomyelia

Twenty-seven MR scans of 20 patients surgically treated for syringomyelia were reviewed. Thirteen patients had syringomyelia associated with the Chiari I malformation, four cases were posttraumatic, and three were idiopathic. The operations performed included syringosubarachnoid and syringoperitoneal shunts, myelotomies, and foramen magnum decompressions. Three of the foramen magnum decompressions had associated posterior fossa duroplasties, two had fourth-ventricle-to-subarachnoid shunts, and two had plugging at the obex. On 20 scans of patients in whom the syrinx cavity had been shunted, the shunt catheter was seen in 15 (75%). When adequately treated by shunting, syringes are completely collapsed and show no flow void. Nine patients were treated by foramen magnum decompression; all were well seen by MR. Three of these patients had a poor clinical result; these were the only patients in whom CSF was not seen between the foramen magnum and the neural structures of the posterior fossa on any images. The proposed mechanisms of syrinx formation and extension are discussed and related to the surgical procedures used to treat syringomyelia.     

MR imaging of syringobulbia

The magnetic resonance (MR) examinations of 65 patients with syringomyelia were evaluated to determine the incidence and MR characteristics of syringobulbia. Syringobulbia was identified in 11 patients (17%), 10 of whom had communicating syringomyelia (associated with the Chiari I malformation) and one idiopathic syringomyelia. The cavities extended from 5 to 20 mm above the plane of the foramen magnum. Two types of syringobulbia were identified. The 10 patients with Chiari I malformation had thin clefts or slits extending into the medulla. These cavities were much smaller than the cervical cavities. The other patient had saccular syringobulbia in which the medullary cavity was similar to the cervical syrinx cavity. The T1-weighted images were most useful in detection of syringobulbic cavities. The theory of syringobulbia development and a brief review of the literature are included.     

Chronic seizure disorders: contribution of MR imaging when CT is normal

One hundred consecutive patients with complex partial seizures were studied by magnetic resonance (MR) imaging and computed tomography (CT). Thirty-four patients had seizures of more than 5 years' duration, yet neurologic examinations and previous pre- and postinfusion CT scans had been normal. MR imaging demonstrated surgical lesions of potentially therapeutic significance in four of these 34 patients. Two patients underwent surgery with removal of a thrombosed arteriovenous malformation and a glioma. Although CT has been found to detect structural abnormalities, its yield of therapeutically significant abnormalities has been low.     

斜坡的磁共振成像测量研究

目的　用MRI测量正常国人和Chiari畸形患者的斜坡长度和倾斜角 ,以探讨其正常值范围及其发育规律。材料与方法　在颅脑正中矢状面SET1WI上测量了 3 17例正常人、2 9例Chiari畸形和 13例可疑患者的斜坡长度和倾斜角。正常人按性别和年龄分为 16组 ,每组 2 0例 ( 70岁以上女性组仅 17例 )。MRI应用 1.0T超导MR系统 ,并以t检验作统计分析。结果　正常斜坡长度和倾斜角随性别、年龄不同而有所差异。男性斜坡长于女性 (P <0 .0 5 ) ,且于 2 0岁前随年龄而增长 ,之后基本稳定 ;其倾斜角于 2 0岁前随年龄而增大 ,于 3 0岁前后基本稳定 ,两性差异无显著性 (P >0 .0 5 )。Chiari畸形及可疑患者斜坡长度短于正常人 (P <0 .0 5 ) ,其倾斜角也小于正常人 (P <0 .0 5 )。结论　斜坡长度和倾斜角有一定的正常范围和发育规律 ;斜坡短于 41mm为发育过短 ,倾斜角小于 5 0°为斜坡发育过平。Chiari畸形以小脑扁桃体下端位置低于颅基线 3mm作为诊断标准为宜 ,其常伴斜坡短平。     

Association of persistent falcine sinus with different clinicoradiologic conditions: MR imaging and MR angiography

Nine pediatric patients are reported with persistent falcine sinuses associated with a variety of clinicoradiologic conditions and disorders. Besides MR imaging studies four patients had MR angiography examinations. Persistent falcine sinus was associated with arteriovenous malformations in three patients. In two cases persistent falcine sinus was an incidental finding. In the remaining four patients persistent falcine sinus was associated with total absence of the corpus callosum, acrocephalosyndactyly (Apert's syndrome), osteogenesis imperfecta, Chiari II malformation. The straight sinuses were either absent or rudimentary or entirely normal in these cases. It can be concluded that a mesenchymal disorder can be the primary cause for an open falcine sinus either in isolation or in association with variable changes in the straight sinus.     

胎儿胸部异常的MRI诊断

目的:分析9例胎儿胸部异常的MRI表现,探讨MRI在胎儿胸部异常诊断中的补充作用。方法:对9例产前超声检查发现的胎儿胸部异常病例,经孕母及家属同意后行胎儿多平面的MRT2WI扫描,部分病例加做T1WI扫描,对胎儿异常胸部MRI表现进行研究,进一步确定胸部异常类型。结果:9例胸部异常中,6例先天性肺囊腺瘤样畸形(CCAM),3例为右肺CCAM,3例为左肺CCAM,MRI表现为患侧肺内多囊样T2WI高信号改变,病侧肺体积增大,纵隔向对侧移位;1例为左侧先天性膈疝(CDH),MRI示左侧胸腔内正常肺组织消失,呈混杂肠腔信号,肺尖少许正常肺组织受压;2例为胸腔积液,1例表现为双侧胸水、腹水、睾丸鞘膜积液,考虑为胎儿免疫性水肿,另1例为右侧胸水、腹水、皮下软组织水肿。结论:MRI作为产科胎儿超声检查的一种重要补充方法,对病变多方位的显示,具有很高的价值,给临床诊断及治疗予以很大帮助。     

全脊柱MR成像对脊柱侧弯的术前诊断价值

目的探讨全脊柱MR成像对脊柱侧弯患者术前诊断的价值。方法使用Philips Achieva 1.5T双梯度超导磁共振成像系统和全神经系统组合线圈,对230例脊柱侧弯患者术前进行全脊柱MR扫描,分析研究MR图像。结果全脊柱MR分段图像对接良好,准确显示全脊柱解剖形态。230例脊柱侧弯患者中特发性脊柱侧弯151例,椎管内肿瘤3例,椎体及椎旁肿瘤5例,半椎体及蝴蝶椎畸形38例,Chiari畸形20例,脊髓栓系及脊髓纵裂9例。结论全脊柱MRI对脊柱侧弯患者术前的诊断具有重要的价值。     

Cervical diastematomyelia and syringohydromyelia in a myelomeningocele patient

A case of cervical diastematomyelia and syringohydromyelia in a 16-year-old female myelomeningocele patient is reported. Progressive weakness of the upper extremity led to an MR examination of the brain and spine, which revealed hydrocephalus, Chiari II malformation, cervical diastematomyelia with a syringohydromyelic cavity in each hemicord and a large dural sac in the lumbar region. Operative therapy consisted of detethering and shunting of the two syringes. Soon after surgery her symptoms improved. The need for early complete MR imaging of myelomeningocele patients presenting with new symptoms is emphasized. Received 20 March 1996; Revision received 30 May 1996; Accepted 10 July 1996     

Phase-contrast MR imaging of the cervical CSF and spinal cord: volumetric motion analysis in patients with Chiari I malformation

BACKGROUND AND PURPOSE: Most previous MR studies of the dynamics of Chiari I malformation have been confined to sagittal images and operator-dependent measurement points in the midline. To obtain a deeper insight into the pathophysiology of the Chiari I malformation, we performed a prospective study using axial slices at the level of C2 to analyze volumetric motion data of the spinal cord and CSF over the whole cross-sectional area. METHODS: Eighteen patients with Chiari I malformation and 18 healthy control subjects underwent cardiac-gated phase-contrast imaging. Cross-sectional area measurements and volumetric flow/motion data calculations were made for the following compartments: the entire intradural space, the spinal cord, and the anterior and posterior subarachnoid space. RESULTS: The most striking feature was an increased early systolic caudal and diastolic cranial motion of the spinal cord in the patients. CSF pulsations in the anterior subarachnoid space were unchanged at systole but showed an impaired diastolic upward flow. In the posterior compartment, the CSF systole was slightly shortened, with an impairment of diastolic upward flow. Fourteen of the 18 patients had associated syringeal cavities. This subgroup showed an increased systolic downward displacement of the cord as compared with patients without a syrinx. CONCLUSION: Obstruction of the foramen magnum in patients with Chiari I malformation causes an abrupt systolic downward displacement of the spinal cord and impairs the recoil of CSF during diastole.