Long-Term Imaging Follow-up from the Management of Myelomeningocele Study

BACKGROUND AND PURPOSE

Short-term results demonstrate that prenatal repair of a myelomeningocele is associated with a reduction in hydrocephalus and an increased likelihood of the reversal of Chiari II malformations compared with postnatal repair. The purpose of this study was to identify the long-term imaging findings at school age among subjects who underwent pre- versus postnatal repair of a myelomeningocele.

MATERIALS AND METHODS

A subset of subjects enrolled in the Management of Myelomeningocele Study who underwent either prenatal (n = 66) or postnatal (n = 63) repair of a lumbosacral myelomeningocele and had follow-up brain MR imaging at school age were included. The prevalence of posterior fossa features of Chiari II malformation and supratentorial abnormalities and the change in these findings from fetal to school-age MR imaging were compared between the 2 groups.

RESULTS

Prenatal repair of a myelomeningocele was associated with higher rates of normal location of fourth ventricle and lower rates of hindbrain herniation, cerebellar herniation, tectal beaking, brainstem distortion, and kinking at school age compared with postnatal repair (all P < .01). Supratentorial abnormalities, including corpus callosal abnormalities, gyral abnormalities, heterotopia, and hemorrhage, were not significantly different between the 2 groups (all P > .05). The rates of resolution of brainstem kinking, tectal beaking, cerebellar and hindbrain herniation, and normalization of fourth ventricle size from fetal to school age MR imaging were higher among the prenatal compared with postnatal surgery group (all, P < .02).

CONCLUSIONS

Prenatal repair of a myelomeningocele is associated with persistent improvement in posterior fossa imaging findings of Chiari II malformation at school age compared with postnatal repair.

Defining optic nerve tortuosity

BACKGROUND AND PURPOSE

Optic nerve tortuosity is one of several nonmalignant abnormalities documented on MR imaging in patients with neurofibromatosis type 1 and may be related to the development of optic pathway gliomas. This study seeks an operational definition for optic nerve tortuosity.

MATERIALS AND METHODS

A focus group of 3 pediatric neuroradiologists reviewed 20 MR images of the brain and orbits of patients suspected to have optic nerve tortuosity in the absence of optic pathway glioma and found 6 radiographic factors that occurred frequently. Subsequently, 28 MR images were assessed for the presence of optic nerve tortuosity, using a global assessment question that reflects a neuroradiologist's confidence in the presence of optic nerve tortuosity, and for the presence of the 6 radiographic factors, to identify a combination of these factors that best predicted a diagnosis of optic nerve tortuosity.

RESULTS

We found perfect inter-rater agreement between 3 readers on the presence/absence of tortuosity in 75% of cases. Lack of congruity of the optic nerves, in more than 1 coronal section and dilation of the subarachnoid space surrounding the optic nerves, when found together are sensitive (89%) and specific (93%) for a diagnosis of tortuosity on the global scale. The absence of these 2 factors, along with absence of deviation of the optic nerve within the axial plane, provides a reliable test to exclude tortuosity.

CONCLUSION

Lack of congruity of the optic nerves in more than 1 coronal section and dilation of the subarachnoid space surrounding the optic nerves together provide an operational radiographic definition of optic nerve tortuosity.

Natural history of Canavan disease revealed by proton magnetic resonance spectroscopy (1H-MRS) and diffusion-weighted MRI

Canavan disease is a childhood leukodystrophy caused by mutations in the gene for human aspartoacylase ( ASPA), which leads to an abnormal accumulation of the substrate molecule N-acetyl-aspartate (NAA) in the brain. This study was designed to model the natural history of Canavan disease using MRI and proton magnetic resonance spectroscopy ( (1)H-MRS). NAA and various indices of brain structure (morphology, quantitative T1, fractional anisotropy, apparent diffusion coefficient) were measured in white and gray matter regions during the progression of Canavan disease. A mixed-effects statistical model was used to fit all outcome measures. Longitudinal data from 28 Canavan patients were directly compared in each brain region with reference data obtained from normal, age-matched pediatric subjects. The resultant model can be used to non-invasively monitor the natural history of Canavan disease or related leukodystrophies in future studies involving drug, gene therapy, or stem cell treatments.

Visual loss in children with neurofibromatosis type 1 and optic pathway gliomas: relation to tumor location by magnetic resonance imaging

PURPOSE

To examine the potential for visual acuity loss, and its relation to extent and location of optic pathway gliomas in a cohort of children with neurofibromatosis type 1 studied with magnetic resonance imaging.

METHODS

We reviewed the neuro-ophthalmologic records and brain/orbital magnetic resonance imaging scans for 43 consecutive pediatric patients with neurofibromatosis type 1 and optic pathway gliomas who were followed at the Children's Hospital of Philadelphia. The presence of visual loss, defined as abnormal visual acuity for age in one or both eyes, was determined. Optic pathway gliomas were classified by tumor extent and location according to involvement of the optic nerves, chiasm, and postchiasmal structures by magnetic resonance imaging.

RESULTS

Involvement of the optic tracts and other postchiasmal structures at tumor diagnosis was associated with a significantly higher probability of visual acuity loss (P =.048, chi-square test). Visual loss was noted in 20 of 43 patients (47%) at a median age of 4 years; however, three patients developed visual acuity loss for the first time during adolescence.

CONCLUSIONS

In pediatric patients with neurofibromatosis type 1 and optic pathway gliomas, the likelihood of visual loss is dependent on the extent and location of the tumor by magnetic resonance imaging and is particularly associated with involvement of postchiasmal structures. Furthermore, older age during childhood (adolescence) does not preclude the occurrence of visual loss. Close follow-up beyond the early childhood years, particularly for those with postchiasmal tumor, is recommended.

Aspartoacylase gene transfer to the mammalian central nervous system with therapeutic implications for Canavan disease

With the ultimate goal of developing safe and effective in vivo gene therapy for the treatment of Canavan disease and other neurological disorders, we developed a non-viral lipid-entrapped, polycation-condensed delivery system (LPD) for central nervous system gene transfer, in conjunction with adeno-associated virus (AAV)-based plasmids containing recombinant aspartoacylase (ASPA). The gene delivery system was tested in healthy rodents and primates, before proceeding to preliminary studies in 2 children with Canavan disease. Toxicity and expression testing was first carried out in human 293 cells, which demonstrated effective transduction of cells and high levels of functional ASPA activity. We performed in vivo toxicity and expression testing of LPD/pAAVaspa and LPD/pAAVlac in rodents, which demonstrated widespread gene expression for more than 10 months after intraventricular delivery, and local expression in deep brain nuclei and white matter tracts for more than 6 months after intraparenchymal injections, with no significant adverse effects. We also performed intraventricular delivery of LPD/pAAVaspa to 2 cynomologous monkeys, with 2 additional monkeys receiving LPD and saline controls. None of the monkeys demonstrated significant adverse effects, and at 1 month the 2 LPD/pAAVaspa monkeys were positive for human ASPA transcript by reverse transcriptase polymerase chain reaction of brain tissue punches. Finally, we performed the first in vivo gene transfer study for a human neurodegenerative disease in 2 children with Canavan disease to assess the in vivo toxicity and efficacy of ASPA gene delivery. Our results suggest that LPD/pAAVaspa is well tolerated in human subjects and is associated with biochemical, radiological, and clinical changes.

Aspartoacylase gene transfer to the mammalian central nervous system with therapeutic implications for Canavan disease

With the ultimate goal of developing safe and effective in vivo gene therapy for the treatment of Canavan disease and other neurological disorders, we developed a non-viral lipid-entrapped, polycation-condensed delivery system (LPD) for central nervous system gene transfer, in conjunction with adeno-associated virus (AAV)-based plasmids containing recombinant aspartoacylase (ASPA). The gene delivery system was tested in healthy rodents and primates, before proceeding to preliminary studies in 2 children with Canavan disease. Toxicity and expression testing was first carried out in human 293 cells, which demonstrated effective transduction of cells and high levels of functional ASPA activity. We performed in vivo toxicity and expression testing of LPD/pAAVaspa and LPD/pAAVlac in rodents, which demonstrated widespread gene expression for more than 10 months after intraventricular delivery, and local expression in deep brain nuclei and white matter tracts for more than 6 months after intraparenchymal injections, with no significant adverse effects. We also performed intraventricular delivery of LPD/pAAVaspa to 2 cynomologous monkeys, with 2 additional monkeys receiving LPD and saline controls. None of the monkeys demonstrated significant adverse effects, and at 1 month the 2 LPD/pAAVaspa monkeys were positive for human ASPA transcript by reverse transcriptase polymerase chain reaction of brain tissue punches. Finally, we performed the first in vivo gene transfer study for a human neurodegenerative disease in 2 children with Canavan disease to assess the in vivo toxicity and efficacy of ASPA gene delivery. Our results suggest that LPD/pAAVaspa is well tolerated in human subjects and is associated with biochemical, radiological, and clinical changes.

A method for fast multislice T1 measurement: feasibility studies on phantoms, young children, and children with Canavan's disease

We have developed a multislice protocol for quantitative T1 measurements in which the processing time and the acquisition time are under 2 minutes each for a complete brain study of 15 slices. An echoplanar, inversion-recovery image sequence is designed to collect data suitable for analysis using a linear regression algorithm. The precision is approximately twice the noise to signal ratio of the images. The accuracy of the protocol is better than 1% for T1 in the range 0-2 seconds and deviates slightly for longer T1 values. The protocol is insensitive to B1 field values. If needed, the data can be postprocessed using a slow, nonlinear algorithm to give an accuracy of less than 1% and a precision of approximately the noise to signal ratio throughout a range of T1 values from 0 to 4 seconds.

Development of the paranasal sinuses in children

The development of computed tomography and functional endoscopic sinus surgery has improved diagnosis and management of sinusitis. It has also renewed interest in the developmental anatomy of the paranasal sinuses. There are significant differences between adult and pediatric sinus anatomy, and to safely perform functional endoscopic sinus surgery in children, the surgeon must be aware of these differences. To define the developmental anatomy of the paranasal sinuses, we analyzed 145 computed tomograms from patients under 18 years of age. The study emphasized landmarks at the level of the maxillary sinus ostium. In addition, distances and angles from the nasal spine to various points in the sinuses were determined. The structures were identified and traced on a digitizing tablet. Means and standard deviations were calculated for each measure as a function of age. This study can aid a better understanding of sinus development in children and provide guidance to the endoscopic sinus surgeon.

Imaging of granulomatous neck masses in children

Non-tuberculous mycobacterial (NTM) infection is the most common cause of granulomatous inflammation in pediatric neck masses. Diagnosis relies upon culture, acid-fast bacilli (AFB) staining, chest radiograph, purified protein derivative (PPD) test, and clinical features. Computed tomography (CT) and magnetic resonance (MR) imaging may provide valuable information in the work-up of children with cervical masses. We reviewed 11 CT and 5 MR studies of children with a clinical diagnosis of NTM infection. Specific findings included stranding of the subcutaneous fat, thickening and enhancement of the overlying skin, obliteration of the tissue palnes, and multichambered masses. One patient had calcifications within the mass. MR with contrast better demonstrated the soft tissues and is our recommended imaging modality, although CT is more likely to detect calcifications within the neck mass.

Recurrent meningitis and a congenital perilymph fistula

In any child with recurrent meningitis, the presence of a congenital perilymph fistula must be entertained. All of the patients must have an audiologic assessment, and if a sensorineural loss is demonstrated, CT of the temporal bones should be performed. CT is excellent in identifying malformations within the temporal bones, fistulous tracts, soft tissue densities in the middle ear, and defects in the tegmen tympani. Although MRI may provide superior discrimination of the audiovestibular and facial nerves and cerebellopontine angle, presently it does not offer any distinct advantages over CT in evaluation of the inner ear. When a fistula is suspected, an exploratory tympanotomy is recommended, and any CSF leak is sealed with muscle.

Usefulness of computed tomographic scan in the evaluation of sensorineural hearing loss in children

A retrospective chart study was conducted to determine the diagnostic yield of temporal bone imaging for children with sensorineural hearing loss of unknown cause. Seventy consecutive cases, spanning 4.5 years, were identified and individual computed tomography films reviewed. Cases were analyzed with respect to patients' age, duration of hearing loss, sudden onset vs progressive loss, unilateral vs bilateral, and other symptoms. Of the 70 computed tomographic scans, nine showed temporal bone or other intracranial abnormalities. The majority of these findings were localized to structures in the posterior and middle cranial fossae. No eight nerve tumors were identified. Congenital hearing loss and hearing loss secondary to viral infections are the most common cause of sensorineural hearing loss when discovered in early childhood and, often, have no radiographic abnormality. The decision to explore an ear for a presumed perilymph fistula is based almost exclusively on the history and physical examination, and not on the demonstration of any radiographic findings. For the children presenting with stable hearing impairment in the absence of other findings, computed tomographic scans were either negative or did not contribute to diagnosis. Since tumors of the eighth nerve are rare in children under 16 years of age (without neurofibromatosis), and radiologic studies have a low yield in identifying perilymph fistulas, the routine use of computed tomographic imaging in such children may be unjustified.

Comparison of CT, MR, and PET in Alzheimer's dementia and normal aging

We compared the findings of computed tomography (CT), magnetic resonance (MR), and positron emission tomography (PET) scans of glucose metabolism in 30 patients with clinically diagnosed Alzheimer's Disease (DAT) to those noted in 25 age-matched normal controls. Mean ratings of cortical and ventricular atrophy on CT and of metabolic abnormality on PET were significantly different (p less than 0.001 and p less than 0.0001, respectively) between two subject groups, however, there was a considerable overlap in reading of cortical atrophy. CT hypodensities were present in 17% of DAT patients and 12% of controls. MR revealed numerous additional periventricular and deep white matter signal changes. Neither hypodensities nor hyperintensities were correlated with PET abnormalities. Although, not infrequently, hypometabolic areas on PET scans corresponded to atrophic regions on anatomic images, they also occurred without such changes. Interestingly, cortical high signal intensity seen on MRI was frequently observed to be associated with areas of hypometabolism. Our results suggest that PET may be the most sensitive modality for detecting cortical involvement in DAT.

Cryptococcosis associated with sarcoidosis: CT and MR findings

Two cases of cryptococcal abscesses were identified in patients with sarcoidosis. The diagnostic imaging tests were not specific for cryptococcus prior to needle aspiration of the abscesses, but they did enable successful biopsy for diagnosis and treatment.

The value of magnetic resonance imaging in treatment planning of nasopharyngeal carcinoma

Seven patients with AJCC Stage T4 nasopharyngeal carcinoma underwent both computed tomographic (CT) and magnetic resonance (MR) examinations prior to radiation therapy treatment planning. Lateral tumor extension into the infratemporal fossa was visualized by MR as less extensive in three cases than suggested by CT, as was inferior extension into the parapharyngeal soft tissues in three cases. MR clarified uncertainties on CT regarding involvement of the pontine cistern in three patients and of the cavernous sinus in two patients. Posterior extension of tumor was underestimated by CT in four of six cases shown by MR to involve the clivus. MR appeared superior in evaluating the presence of parenchymal brain involvement in three cases. The margins of the final boost treatment fields dictated by MR findings differed measurably from those derived from CT in six of seven cases. These findings lend support for greater utilization of MR in treatment planning of nasopharyngeal carcinoma.

Chiasmatic optic glioma treated with chemotherapy. A preliminary report

Chiasmatic optic glioma is a rare tumor with an erratic natural history, usually seen in young children. A prior study from this institution demonstrated that these lesions were frequently lethal, despite initial clinical stabilization following radiation therapy, and that visual, intellectual, and late endocrinological disabilities were prevalent. A novel approach was developed in 1977, when an initial clinical response to vincristine was recorded in a child with a recurrent optic glioma. Since then, all children with recurrent optic glioma and all children aged 6 years old and under with newly diagnosed optic glioma have been offered a program of initial therapy with vincristine and actinomycin D for six cycles over 18 months. The four children with recurrent tumor who were treated with that regimen remain clinically stable 13 to 115 months after chemotherapy. Twelve children (eight under 24 months old) with newly diagnosed optic glioma have been treated with this program, and three are still on therapy. Four developed progression while on therapy, and five remain stable from 1 to 60 months posttherapy. The four children who developed progressive disease have been treated with radiation therapy and remain stable. Six of the 12 children showed shrinkage of their tumor on computerized tomography while receiving chemotherapy. This program may serve as an alternative to initial radiation therapy in young children.

Soft-tissue sarcomas of the head and neck in children

Thirty-two children aged three months to 17 years (median six years) were diagnosed with soft-tissue sarcoma of the head and neck and treated at the Children's Hospital of Philadelphia and the Hospital of the University of Pennsylvania from 1971 to 1981. Thirty-one received chemotherapy and all received radiation therapy (RT). Twenty-five patients had pre-treatment computed tomography (CT) scans, which were used for staging and treatment planning. Doses of radiation therapy ranged from 3000 to 7300 rad to the primary tumor (median 5000 rad). The overall five-year survival of the entire group of 32 patients was 75%. Ten of the 32 patients had invasive cranial parameningeal disease as demonstrated by bony erosion at the skull base, seen on CT in eight and plain radiographs in two patients. Eight of these 10 patients have developed recurrent sarcoma: four in the meninges, two locally, one regionally and one distantly. Five of these 10 children with invasive cranial parameningeal sarcoma received 3000 rad of prophylactic cranial irradiation, begun within the first 12 days of chemotherapy, and none developed meningeal disease. In contrast, only one of the 22 patients without invasive cranial parameningeal disease has relapsed (local recurrence). The data suggest that soft-tissue sarcomas of the head and neck in children without invasion into the base of the skull (invasive cranial parameningeal disease) are usually cured. CT scans are essential for staging. Patients with invasion of the base of the skull may be protected from meningeal relapse by early cranial irradiation, although they still are at high risk for relapse in other sites.

Diffuse cerebral swelling following head injuries in children: the syndrome of "malignant brain edema"

The commonest initial computerized tomography (CT) finding in head-injured children is bilateral diffuse cerebral swelling. Cerebral blood flow and CT density studies suggest that this swelling is due to cerebral hyperemia and increased blood volume, not to edema. The clinical history, course, and outcome of 63 children with this CT pattern are reviewed. Fourteen children had a Glasgow Coma Scale score of greater than 8; all made a complete recovery and follow-up CT scans were normal. Forty-nine children had Glasgow Coma Scale scores of 8 or less. Fifteen had a history of a lucid period following the initial unconsciousness. One of these children died of delayed brain swelling, the others recovered well with minimal neurological deficit. Thirty-four children were rendered immediately and continuously unconscious. There was a high incidence of second lesions on the CT scan, 50% of this group developed intracranial hypertension and five died. All of the others were in coma for periods ranging from weeks to months. Follow-up CT scans showed an extracerebral collection with a density of cerebrospinal fluid in 27% of the patients, and ventriculomegaly with large sulci in 35%, whereas this pattern was seen only once in those with a lucid period. The difference between those with and without a lucid period is related to the degree of primary diffuse impact injury to the white matter.

Characteristics of calcification in tumors of the pineal gland

Thirty-two cases of proved pineal tumor were analyzed. Calcification was seen in 75%. The size, character, and position of the calcification were useful indicators of abnormality on plain-film evaluation. Fray's cranioangle method was more sensitive than Oon's method in determining abnormal position of the calcified pineal tumor on the lateral skull film. Most calcifications were displaced postero-inferiorly or inferiorly, which can be explained by obstructive hydrocephalus or direct tumor expansion.

Priorities and indications of computed tomography in clinical practice

Because of its technical capabilities, its rapidity and its non-invasive nature, computed tomography (CT) has given a new scope to neurological diagnosis and to the understanding of various aspects of neurological science. The availability of this test is determined by the patient load. If precise clinical indications are not considered, patients requiring CT the most may be denied immediate examination because less urgent cases may be occupying valuable diagnostic time. Moreover, the test is relatively expensive for the individual patient and for the community; this presents another facet of its use that should be taken into account. The technical limitations and clinical priorities to be considered when a physician is entertaining this test for a patient have been outlined. The indications have been divided into absolute and relative, according to the degree of clinical urgency. As a result, a priority guideline for diagnostic CT has been provided.

Pneumatosis intestinalis in systemic lupus erythematosus

A benign episode of pneumatosis intestinalis developed in a 54-year old black woman with rapidly progressive systemic lupus erythematosus. This case illustrates that pneumatosis intestinalis in association with the various collagen diseases can have disparate prognostic implications.