Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy.

We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1 µT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1 pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.

Diffuse brainstem gliomas in children: should we or shouldn't we biopsy?

The decision to biopsy diffuse pontine gliomas in children remains controversial. There have been many publications over the last 30 years aiming to address this issue. The prognosis for these patients remains extremely poor regardless of treatment and many authors advocate that biopsy carries significant risk for little or no clinical benefit. However, with an increasing knowledge of tumour biology and genetics there is the potential for specific treatments tailored for individual tumours based on their biological or genetic characteristics. The progress of such science in the first instance requires histological diagnosis as part of well conducted clinical trials, then, when treatments have been developed, biopsy samples will be needed to identify the tumours that may respond to such treatments. The authors believe that there is an increasing need for performing a biopsy of these lesions.

Craniovertebral abnormalities in Type VI mucopolysaccharidosis (Maroteaux-Lamy syndrome).

INTRODUCTION: The craniovertebral abnormalities found in patients with Type VI mucopolysaccharidosis (Maroteaux-Lamy syndrome) are described, and the indications for and outcomes of surgery in this group are assessed. METHODS: The clinical histories and radiological findings in all patients with Type VI mucopolysaccharidosis treated at Royal Manchester Children's Hospital during the past 10 years were reviewed. RESULTS: The typical findings in patients with this disease are of canal stenosis at the level of the foramen magnum and upper cervical spine with or without cord compression. The stenosis is secondary to thickening of the posterior longitudinal ligament. Atlantoaxial instability is rare. Of nine patients under regular clinical review, four underwent decompressive surgery for cervical cord compression. Three of the four showed improvement in their neurological symptoms and signs postoperatively. Of the children reviewed, six had radiological evidence of cord compression, although only those with neurological signs or symptoms were treated surgically. DISCUSSION: Despite the often formidable anesthetic challenge, surgery is indicated in those patients who present with progressive neurological deficit due to cervical myelopathy. Surgery can be undertaken safely if the associated medical problems in these children are recognized and managed appropriately.

Craniosynostosis and fetal exposure to sodium valproate.

OBJECT: Fetal valproate syndrome affects one in 10 children born to mothers who ingest sodium valproate regularly during pregnancy. It has been described as producing a combination of typical dysmorphic features and major organ system anomalies. Trigonocephaly is caused by premature fusion of the metopic suture and has not previously been described as a typical feature of the syndrome. The authors reviewed the cases of 2,220 children with craniosynostosis to examine the effect of maternal sodium valproate use on the fetus. METHODS: Case files of all 2,220 children were reviewed. The type and severity of each patient's craniosynostosis was assessed. Information about maternal health and medication use was obtained, and family interviews were conducted. Children underwent mental development assessment performed using standard tests both pre- and postoperatively. Detailed maternal health information was obtained in 1,676 cases. Of these, 17 mothers were found to have undergone regular treatment with sodium valproate monotherapy at the time of their pregnancies. No other antiepileptic medical regimen was found. All 17 children exhibited trigonocephaly. These patients' intelligence quotients (JQs) at the time of the most recent follow-up examination ranged from 45 to 100, with a mean of 75; IQs were significantly higher in patients who underwent surgery before reaching 6 months of age. CONCLUSIONS: Ideally any pregnancy in a woman being treated for epilepsy should be planned, and both an obstetrician and a neurologist should be consulted. In children born with fetal valproate syndrome, it is important to be aware of the possibility of metopic suture synostosis, which we believe should be considered part of the syndrome, because early surgical intervention may improve cognitive outcome.

Can prognostic indicators be identified in a fetus with an encephalocele?

Encephaloceles, like other congenital malformations of the brain diagnosable in utero, can be either complicated (there being an associated chromosomal abnormality, abnormalities in the remainder of the central nervous system (CNS) and/or other organs), or isolated (no abnormalities in the chromosomes, the remainder of the CNS or other organs). Complicated cases invariably have a poor prognosis but amongst those with isolated lesions the outcome is variable with some affected children having poor mental and physical development but others who are only mildly or moderately disabled. To be able to make an informed decision about how to manage their pregnancy parents need to know what the prognosis is likely to be for their fetus with an encephalocele. To see if the necessary information could be reliably gathered by prenatal assessment of affected fetuses, a review was carried out of the medical records and ultrasound scans of 31 fetuses with encephaloceles referred to the Fetal Management Unit at St. Mary's Hospital in Manchester between January 1991 and December 1997. Eighteen of the cohort were classified as having a complicated encephalocele. Thirteen of the pregnancies were terminated; there were three intrauterine deaths, and one neonatal death. There is only one surviving child who is severely disabled. Thirteen fetuses were classified as having isolated encephaloceles, six had a mass of neural tissue in the encephalocele sac and were terminated, one died in utero and six had a cystic lesion or only a nubbin and have survived with few or no abnormalities. This study has shown that it is possible to identify fetuses with an encephalocele with a favourable outcome.