Development of a roof bolter canopy air curtain for respirable dust control

Testing of the roof bolter canopy air curtain (CAC) designed by the U.S. National Institute for Occupational Safety and Health (NIOSH) has gone through many iterations, demonstrating successful dust control performance under controlled laboratory conditions. J.H. Fletcher & Co., an original equipment manufacturer of mining equipment, further developed the concept by incorporating it into the design of its roof bolting machines. In the present work, laboratory testing was conducted, showing dust control efficiencies ranging from 17.2 to 24.5 percent. Subsequent computational fluid dynamics (CFD) analysis revealed limitations in the design, and a potential improvement was analyzed and recommended. As a result, a new CAC design is being developed, incorporating the results of the testing and CFD analysis.

Oceanic oxygenation events in the anoxic Ediacaran ocean

The ocean-atmosphere system is typically envisioned to have gone through a unidirectional oxygenation with significant oxygen increases in the earliest (ca. 635 Ma), middle (ca. 580 Ma), or late (ca. 560 Ma) Ediacaran Period. However, temporally discontinuous geochemical data and the patchy metazoan fossil record have been inadequate to chart the details of Ediacaran ocean oxygenation, raising fundamental debates about the timing of ocean oxygenation, its purported unidirectional rise, and its causal relationship, if any, with the evolution of early animal life. To better understand the Ediacaran ocean redox evolution, we have conducted a multi-proxy paleoredox study of a relatively continuous, deep-water section in South China that was paleogeographically connected with the open ocean. Iron speciation and pyrite morphology indicate locally euxinic (anoxic and sulfidic) environments throughout the Ediacaran in this section. In the same rocks, redox sensitive element enrichments and sulfur isotope data provide evidence for multiple oceanic oxygenation events (OOEs) in a predominantly anoxic global Ediacaran-early Cambrian ocean. This dynamic redox landscape contrasts with a recent view of a redox-static Ediacaran ocean without significant change in oxygen content. The duration of the Ediacaran OOEs may be comparable to those of the oceanic anoxic events (OAEs) in otherwise well-oxygenated Phanerozoic oceans. Anoxic events caused mass extinctions followed by fast recovery in biologically diversified Phanerozoic oceans. In contrast, oxygenation events in otherwise ecologically monotonous anoxic Ediacaran-early Cambrian oceans may have stimulated biotic innovations followed by prolonged evolutionary stasis.

Examination of a newly developed mobile dry scrubber (DS) for coal mine dust control applications

The Office of Mine Safety and Health Research of the U.S. National Institute for Occupational Safety and Health (NIOSH OMSHR) conducted laboratory testing of a self-tramming, remotely controlled mobile Dry Scrubber (DS) that J.H. Fletcher and Co. developed under a contract with NIOSH OMSHR to reduce the exposure of miners to airborne dust. The scrubber was found to average greater than 95 percent dust removal efficiency with disposable filters, and 88 and 90 percent, respectively, with optional washable filters in their prewash and post-wash test conditions. Although the washable filters can be reused, washing them generated personal and downstream respirable dust concentrations of 1.2 and 8.3 mg/m³, respectively, for a 10-min washing period. The scrubber's velocity-pressure-regulated variable-frequency-drive fan maintained relatively consistent airflow near the targeted 1.42 and 4.25 m³/s (3,000 and 9,000 ft³/min) airflow rates during most of the laboratory dust testing until reaching its maximum 60-Hz fan motor frequency or horsepower rating at 2,610 Pa (10.5 in. w.g.) of filter differential pressure and 3.97 m³/s (8,420 ft³/min) of scrubber airflow quantity. Laboratory sound level measurements of the scrubber showed that the outlet side of the scrubber was noisier, and the loaded filters increased sound levels compared with clean filters at the same airflow quantities. With loaded filters, the scrubber reached a 90 dB(A) sound level at 2.83 m³/s (6,000 ft³/min) of scrubber airflow, indicating that miners should not be overexposed in relation to MSHA's permissible exposure level - under Title 30 Code of Federal Regulations Part 62.101- of 90 dB(A) at or below this airflow quantity. The scrubber's washable filters were not used during field-testing because of their lower respirable dust removal efficiency and the airborne dust generated by filter washing. Field-testing the scrubber with disposable filters at two underground coal mine sections showed that it could clean a portion of the section return air and provide dust reduction of about 50 percent at the face area downstream of the continuous-miner operation.

Quantitative MRI detects abnormalities in relatives of patients with epilepsy and malformations of cortical development

Malformations of cortical development (MCD) are a common etiology for epilepsy. Laminar heterotopia, bilateral subependymal heterotopia, and lissencephaly have a genetic basis. No gene mutations have yet been identified in patients with focal cortical dysplasias. The aim of this study was to use quantitative morphometric tools to determine if there were gray matter abnormalities in relatives of patients with MCD. We studied 19 relatives of 13 probands with MCD and 58 healthy controls with high-resolution MRI. The relatives and controls had no neocortical abnormalities on visual inspection. MRI data were analyzed with voxel-based morphometry and autoblock analysis. Voxel-based morphometry showed significant increases of gray matter in 9 of 10 probands, 5 of 19 relatives, and 5 of 58 controls. The autoblock analysis showed significant abnormalities in 7 of 8 probands, 8 of 19 relatives, and 2 of 57 controls. This finding suggests structural abnormality in the brains of a greater number of relatives of MCD patients than would be expected, and in the context, a reasonable inference is that this reflects subtle genetically determined cerebral abnormalities, although acquired pathologies are possible and are not excluded.

Ultra-fast low-angle rapid acquisition and relaxation enhancement (UFLARE) in patients with epilepsy

MRI is an important diagnostic tool in patients with epilepsy, but patient motion during long scans may result in image artefacts. We studied the utility of an ultra-fast MR sequence in patients with epilepsy. Ultra-fast low-angle rapid acquisition and relaxation enhancement (UFLARE) images were acquired for 100 consecutive patients and nine control subjects. Scans were compared with routine T2-weighted spin echo images for signal-to-noise ratio, contrast, and conspicuity, followed by a blind review of lesion detectability. UFLARE scans were also acquired for 15 patients who moved during conventional scans. All UFLARE scans had lower signal-to-noise ratios and lower contrast than the T2-weighted images. Compared with T1- and T2-weighted, PD and FLAIR images, 86% of hippocampal sclerosis (HS), 92% of large but only 24% of small white-matter lesions were detected on the blind review of the UFLARE images. Reduced motion artefacts were seen on the UFLARE images in all 15 patients who moved during the conventional scans, and in three patients UFLARE was the only sequence we were able to obtain. Despite the lower lesion detectability for smaller lesions, the use of an ultra-fast MRI sequence such as UFLARE may be very useful in patients who are not able to co-operate during conventional MRI examinations, if a general anaesthetic is to be avoided.

Structural MRI volumetric analysis in patients with organic amnesia, 1: methods and comparative findings across diagnostic groups

BACKGROUND

If they are to be replicable, MRI volume measurements require explicit definitions of structures and of criteria for delineating these structures on MRI. Previously published volumes in healthy subjects show considerable differences in measurements across different studies, including a fourfold variation in estimates of hippocampal volume. Previous neuroimaging reports in patients with Korsakoff syndrome have generally found widespread or non-specific change, whereas in patients with herpes encephalitis the extent of pathological involvement reported beyond the temporal lobes has varied.

METHOD

In the present study, a clear set of anatomical criteria and detailed MRI segmentation procedures were applied to measure whole brain, frontal and temporal lobe, and anterolateral and medial temporal volumes, as well as thalamic areas in patients with organic amnesia (from Korsakoff's syndrome, herpes encephalitis, and focal frontal lesions) as well as healthy controls.

RESULTS

Patients with Korsakoff's syndrome showed decreased thalamic measurements but no significant changes in the medial temporal lobes, whereas patients with herpes encephalitis showed severe medial temporal but not thalamic atrophy. In the patients with known frontal lobe lesions, quantitative analysis on MRI showed reduced frontal lobe volume but no significant temporal lobe or thalamic atrophy.

CONCLUSION

Quantified MRI can be a useful technique with which to examine brain-cognitive relations, provided that detailed techniques are explicitly described. In particular, specific patterns of volume change can be found in vivo in patients with Korsakoff's syndrome and those with herpes encephalitis.

Structural MRI volumetric analysis in patients with organic amnesia, 2: correlations with anterograde memory and executive tests in 40 patients

BACKGROUND

Cognitive-MRI correlations have often been studied in disorders in which there are multiple cognitive deficits and widespread cortical atrophy, such as Alzheimer's dementia. In such circumstances, the interpretation of any single cognitive-structural correlation is equivocal. Only by measuring differing cognitive functions and a wide range of brain structures in patients with a varying distribution of lesions or atrophy can specific brain-cognitive relations be determined in neurological disorder.

METHOD

In the present study, a clear set of anatomical criteria and detailed MRI segmentation procedures were applied to measure whole brain, and left and right frontal, temporal lobe, anterolateral and medial temporal volumes, as well as thalamic cross sectional areas in 40 patients with organic amnesia (from various diseases) and 10 healthy controls.

RESULTS

Within the total patient group, anterograde memory measures correlated significantly with medial temporal, hippocampal, and thalamic measurements. A spatial memory measure correlated significantly with hippocampal volume, and temporal context memory with frontal volume. After a factor analysis of the cognitive measures, the association between anterograde memory and hippocampal volume was corroborated. Forgetting rates and subjective memory evaluations did not show any significant MR correlations and, of executive tests employed, only card sorting categories correlated significantly with frontal volume.

CONCLUSION

Loss of volume in key brain structures (for example, hippocampus, thalamus) is detectable on quantitative MRI, and this loss of volume correlates significantly with impaired performance on measures of anterograde memory function. Correlations with hippocampal volume did not indicate a specific role in either recall or verbal memory, as opposed to recognition or visual memory.

The frequency of p53, K-ras mutations, and microsatellite instability differs in uterine endometrioid and serous carcinoma: evidence of distinct molecular genetic pathways

BACKGROUND

The two most common types of uterine endometrial carcinoma, endometrioid (UEC) and serous (USC), differ in their histopathologic appearance and biologic behavior. Recent studies suggest that these differences may be associated with distinct molecular genetic alterations.

METHODS

In the current study, the authors compared the frequencies of K-ras and p53 mutations and microsatellite instability (MI) between UEC and USC by analyzing all 3 molecular genetic changes in one set of tumors. Furthermore, the distribution of these molecular genetic alterations was determined among UECs of different histopathologic grade. The authors analyzed 58 UECs with known MI status for K-ras and p53 mutations. The K-ras and p53 genes were analyzed in 45 and 6 cases of USC, respectively. These results were combined with previous data on p53 mutations (21 cases) and MI (34 cases) in USC.

RESULTS

MI was present in 16 of 57 UECs (28%) but in none of 34 USCs. p53 mutations were found in 7 of 42 UECs (17%) and 25 of 27 USCs (93%) by direct sequencing of exons 5-8. UECs and USCs with p53 mutations showed strong immunoreactivity for p53 in about 85% of the cases, whereas about 15% of the cases were immunonegative. K-ras mutations at codon 12 were found in 15 of 58 UECs (26%) and in only 1 of 45 USC (2%) by dot blot oligohybridization after polymerase chain reaction amplification of exon 1. Notably, the frequency of both K-ras and p53 mutations and MI was significantly different between UEC and USC (P < 0.001). In UECs, MI and K-ras mutations occurred in low grade as well as in high grade tumors, whereas p53 mutations were present almost exclusively in high grade tumors.

CONCLUSIONS

The results of this study suggest that different molecular genetic pathways are involved in the pathogenesis of UEC and USC and that low grade UEC may progress to high grade UEC. These findings support the hypothesis that UEC and USC are separate entities and suggest that different molecular genetic alterations may be responsible for their distinct morphology and biologic behavior.

A comparison of the effectiveness of malignancy detection in body fluid examination by the cytopathology and hematology laboratories

BACKGROUND

Body fluid specimens in many institutions are submitted for cytologic examination as well as for examination in a clinical microscopy or hematology laboratory. The cytology laboratory is generally seen as the standard for detection of malignancy, whereas the clinical microscopy laboratory is often depended on predominantly for cell counting and categorization.

METHODS

To analyze the effectiveness of the hematology laboratory at detecting malignant fluids, this study retrospectively analyzed reports on 397 body fluid specimens (cerebrospinal, pericardial, peritoneal, and pleural) that were concurrently submitted over a 12-month period to both the cytopathology laboratory and the hematology laboratory.

RESULTS

Thirty-seven (9.3%) of the cases were diagnosed as malignant by at least one of the two examinations. The cytopathology examination reported 27 (73%) of the 37 malignant cases as malignant and 30 (81.1%) as at least atypical (27 malignant and 3 inconclusive), and the hematology examination reported 34 (91.9%) as malignant and 36 (97.3%) as at least atypical. A concordant malignant diagnosis was given by both laboratories in 24 (64.9%) of the 37 cases.

CONCLUSIONS

These results show that examination of specimens by the hematology laboratory can provide a highly sensitive diagnostic evaluation in addition to its more customary role of providing timely cell counts.

Effect of octreotide on human sphincter of Oddi motility following liver transplantation

The effect of octreotide on sphincter of Oddi motility was investigated in six liver transplant patients, employing percutaneous (through the T-tube tract) manometry. Continuous and simultaneous sphincter of Oddi and duodenal motor activities were recorded before and for 60 min after the administration of octreotide (100 micrograms subcutaneously) and after the injection of cholecystokinin (0.02 microgram/kg intravenously). With octreotide, contraction frequency and basal pressure significantly increased (P < 0.05). This effect lasted more than 60 min, long after octreotide-induced duodenal migrating motor complex phase III activity had ceased. Sphincter of Oddi contraction amplitude and duration were unaffected by octreotide. Subsequent cholecystokinin administration transiently reduced sphincter of Oddi basal pressure and contraction frequency. We conclude that octreotide significantly increases sphincter of Oddi basal pressure and contraction frequency. This effect is distinct from octreotide induction of migrating motor complex phase III activity, persists for a prolonged period, and is inhibited by cholecystokinin.

The neuroradiology of Kallmann's syndrome: a genotypic and phenotypic analysis

A detailed neurological investigation of patients with Kallmann's syndrome (KS) has been performed in an attempt to relate phenotypic characterization with genotype. Twenty-seven subjects with KS were studied (including 12 males with X-linked disease and 3 females). Six male and 2 female normosmics with isolated GnRH deficiency, 1 male with KS variant, and 1 obligate female carrier were also imaged. Evidence for X-linked disease was derived both from analysis of pedigree and by mutation analysis at the KAL locus. The female carrier and all 8 normosmics had normal olfactory bulbs and sulci, as did 3 male KS. The study, therefore, confirms the value of magnetic resonance imaging in the diagnosis of KS, but suggests that the technique is not sufficiently sensitive to differentiate KS from the normosmic form of GnRH deficiency in all cases. Phenotypic characterization of KS was more effectively achieved by accurate estimation of olfactory status. Three new mutations at the KAL locus were identified, 2 single exon deletions and 1 point mutation. In 2 pedigrees with clear X-linked inheritance, no coding sequence mutations were detected; it may be that these harbor mutations of pKAL, the recently characterized 5'-promoter region. No clear relationship could be established between specific phenotypic anomalies and particular KAL mutations. Involuntary, mirror movements of the upper limbs were present in 10 of 12 cases of X-linked KS, but in none of the other subjects. Although this phenomenon has been ascribed to an abnormality of the corpus callosum, in the present study magnetic resonance imaging demonstrated no quantitative or qualitative morphological anomalies of this structure.

Reliability of visual inspection for detection of volumetric hippocampal asymmetry

Volumetric measurement of the hippocampus is of use in localisation of lesions causing focal epilepsy and in lateralisation of epilepsy due to mesial temporal sclerosis. However, it is time consuming and requires specialised equipment. Hence, we compared volumetric measurement with visual detection of hippocampal asymmetry by five trained observers. MRI studies of 19 neurologically normal subjects and of 34 consecutive patients with epilepsy and hippocampal volume ratios below the lowest normal value were employed. Agreement between visual and quantitative diagnoses was 59% for all subjects (kappa = 0.38) and 65% for those with volumetric hippocampal asymmetry. Disagreements in visual and volumetric lateralisation of hippocampal asymmetry were relatively uncommon. Visual estimates of the extent of hippocampal involvement and the observers' confidence in the diagnosis influenced the accuracy of visual inspection. However, discordance in diagnoses occurred even when confidence in the visual diagnosis was high. Reliable visual detection occurred for hippocampal volume ratios below 0.7, suggesting that visual determination of hippocampal asymmetry is of greatest clinical value in the lateralisation of seizure foci in patients already selected for the presence of intractable temporal lobe epilepsy. Volumetric measurements are particularly important if hippocampal asymmetry is used for seizure localisation in groups of patients with temporal or extratemporal epilepsy.

Neuroradiological and eye movement correlates in children with intermittent saccade failure: "ocular motor apraxia"

Ocular motor apraxia (OMA) is a clinical sign involving the intermittent inability to initiate saccades, and a failure of quick phases during optokinetic nystagmus (OKN) and vestibular nystagmus (VN). Some patients have no other associated abnormalities (idiopathic), whereas others have a variety of neurological conditions. We quantified the severity of the saccade failure and correlated it with neuro-radiological and other oculomotor findings in 62 children (aged 17 days - 14 years). Saccades, smooth pursuit, OKN and VN were recorded using electrooculography and the extent of "locking up" (absent quick phases during OKN and VN) was measured. Saccades were usually hypometric. Pursuit and OKN gains were normal in the majority of the idiopathic cases but were low in those with other neurological conditions. Twenty-four patients had essentially normal scans, whereas 38 had abnormal scans: Delayed myelination, cerebellar abnormalities (particularly involving the vermis), and agenesis of the corpus callosum were the most common findings. A significant positive correlation was present between increasing neuro-radiological deficits and severity of "locking up" during OKN. Principal component analysis showed that brainstem and cerebellar vermis abnormalities were the main factors involved. A pathophysiological basis of OMA is discussed in the light of animal and clinical studies.

Visual evoked potentials in phenylketonuria: association with brain MRI, dietary state, and IQ

At separate institutions, pattern reversal visual evoked potentials (VEPs) were recorded in children and older patients with phenylketonuria and compared with MRI of the brain. In nine patients aged less than 14 years, who were still on a diet low in phenylalanine, VEPs were clearly abnormal in only one and the abnormalities seen on MRI were mild. In 27 patients aged 14-31 years VEPs were abnormal in more than 80%, with significant reduction of amplitude and prolongation of latency despite the general absence of visual symptoms and abnormalities on routine neuro-ophthalmological examination. Among the older patients there was no significant correlation between VEP measures and plasma phenylalanine or tyrosine concentrations; neither was the incidence of VEP abnormalities dependent on whether or not the patients were still on a low phenylalanine diet. Some VEP amplitude measures were inversely correlated with the MRI lesion score, perhaps reflecting the severity of white matter abnormalities in the parieto-occipital region. In the older patients the amplitude of VEPs to stimulation of the central 8 degrees of the visual field was significantly correlated with IQ. The study confirms the high incidence of subclinical visual pathway involvement in older children and adults with phenylketonuria, and suggests the possibility of a link between the abnormal appearance of subcortical white matter on MRI and a physiological index of function of the CNS. As there was no evidence of general intellectual decline, it is suggested that the correlation between central field VEP amplitude and IQ may reflect abnormal development during infancy. Abnormalities on MRI, on the other hand, seem to be more closely related to current dietary state and phenylalanine concentration.

A prospective study of "undiagnosed" isolated myelopathy: II. Value of magnetic resonance imaging, evoked potentials and CSF analysis

We aimed to determine the sensitivity of available "diagnostic" tests in detecting subclinical abnormalities characteristic of multiple sclerosis (MS) in patients with unexplained isolated myelopathy, and any relationship between test results and level of disability. The trial investigations were carried out in 69 prospectively selected patients with acute or chronic noncompressive myelopathies. Magnetic resonance scans were the most sensitive individual tests, revealing asymptomatic brain lesions in 51 patients (74%, C.I. 64-84). An abnormal IgG/albumin ratio (IgG/A) was present in 29 (42%, C.I. 30-54), oligoclonal bands (OCB) in 27 (39%, C.I. 17-39) and abnormal evoked potentials (EP) (visual and/or auditory brain stem) in 19 cases (28%, C.I. 17-39). OCB and abnormal EP were found significantly less often than in control patients with clinically definite MS (CDMS) and significantly more often than in patients with myelopathy due to other conditions. The number of anatomical brain areas with lesions on magnetic resonance imaging (MRI) was significantly associated with CSF abnormalities; abnormal EP were correlated with abnormal MRI and elevated CSF immunoglobulins. Clinical classifications, age, symptom duration, disability levels and genetic factors did not appear to influence the prevalence of abnormal MRI or CSF. For the exclusion of compressive and structural diseases of the spinal cord, myelography has been superceded by cervical and thoracic MRI. In addition, MRI of the brain is the investigation of choice in patients with myelopathies that remain unexplained after spinal MRI. However, whether used alone or in combination with other tests, the specificity and predictive value of brain MRI abnormalities for the risk of developing MS, as well as the associated "false positive" rates, remain to be defined by long-term follow-up of prospectively ascertained and representative cases.

Magnetic resonance imaging of the brain in patients with cerebral malaria

In a prospective study of cerebral malaria, 24 adults with this disease underwent magnetic resonance imaging (MRI) of the brain. Four patients died. Two of these patients (nos. 17 and 24) had breathing abnormalities requiring ventilatory support followed by clinical signs of brain death. Four days later MRI of patient 17 showed gross swelling of the brain, and 5 hours later MRI of patient 24 showed foramen magnum herniation. Twenty-two patients had no evidence of cerebral edema, but MRI revealed that brain volume during acute cerebral malaria was slightly greater than that during the convalescent phase of the disease. This difference was attributed to an increase in the volume of intracerebral blood. The cerebral volume was lower during early convalescence than several months later. The volume of the brain in patients with cerebral malaria is increased. This increased volume probably results from sequestration of parasitized erythrocytes and compensatory vasodilatation rather than from edema. Brain stem herniation may occur, but its temporal relation to brain death in cases of cerebral malaria remains uncertain.

Cognitive functioning and magnetic resonance imaging in chronic fatigue

BACKGROUND

This study examines whether cognitive dysfunction in chronic fatigue may be accounted for by depression and anxiety or is due to brain pathology evident on magnetic resonance imaging (MRI).

METHOD

Twenty-six subjects with chronic fatigue, with and without coexisting depression, and 18 age-matched normal controls were recruited from primary care following a presumed viral illness six months previously. Comparison was made with 13 psychiatric controls with depressive illness on standardised cognitive tests. MRI determined the presence of cerebral white-matter lesions.

RESULTS

No substantial differences in performance were shown between subjects with chronic fatigue, most of whom met the criteria for chronic fatigue syndrome, and controls. Subjective cognitive dysfunction increased with psychopathology. White-matter lesions were found in a minority from all groups. Improvement in fatigue and depression coincided with improved performance on cognitive measures.

CONCLUSIONS

Subjective complaints of cognitive impairment are a prominent feature of chronic fatigue, but objective cognitive and MRI abnormalities are not. Such complaints probably reflect psychopathology rather than a post-viral process.

Cortical dysgenesis: serial EEG findings in children and adults

Cortical dysgenesis (CD) is becoming increasingly recognised as a cause of epilepsy in otherwise cryptogenic cases. We describe the serial EEG findings in 22 patients with focal/localised CD. The EEGs covered a minimum period of 5 years in each case (median = 13 years, range: 5-30 years), beginning in childhood. Median age at seizure onset was 3 years (range: 3 weeks-10 years, n = 21). The EEG was normal in the one patient, a 6 year old, who did not have epilepsy. Background rhythms appropriate for age were preserved in the majority of patients (18/22). Slow activity localised to the area of CD was seen in 11 patients; in 3 patients, this did not appear until the second decade of life. Epileptiform discharges were seen in at least one EEG in 20 patients: these were continuous or near-continuous (6 patients) or occurred recurrently in short runs (6 patients). In 6 patients, these discharges appeared only after the second decade of life and in 11 patients, they became more widespread over time. In the remaining patients, the EEG changes did not evolve. Sleep failed to produce new abnormalities (n = 15). None of the patients showed EEG features characteristic of lissencephaly or evolution to the Lennox-Gastaut syndrome. Even in this selected cohort of patients who had undergone serial clinical EEGs, the EEG abnormalities in focal/localised CD appeared relatively stable and showed only moderate changes over time. CD must be included in the differential diagnosis of any patient who presents with localised slow activity on EEG.

New autosomal dominant form of spondyloepiphyseal dysplasia presenting with atlanto-axial instability

We present a family with a radiologically distinct new form of autosomal dominant spondyloepiphyseal dysplasia, presenting with cervical instability and attendant neurological compromise and emphasise the radiological characteristics which delineate this condition. Cervical vertebral abnormalities, including malformation of the odontoid process, have been observed in some forms of spondyloepiphyseal dysplasia, but rarely lead to neurological sequelae, in contrast to the pedigree we describe.

Unusual appearances of primary central nervous system non-Hodgkin's lymphoma

There is an increasing incidence of primary central nervous system (CNS) non-Hodgkin's lymphoma (NHL) in immunocompromised and immunocompetent patients. The lymphoma commonly abuts a ventricular or meningeal surface and enhances homogeneously after injection of intravenous contrast medium. The radiological features of 39 patients with cerebral lymphoma were reviewed and five patients with less commonly observed manifestations of this disorder are presented. A differential diagnosis of lateral and third ventricular masses is given.

Parotid haemangiomas in childhood: a case for MRI

Seven infants with unilateral parotid haemangiomas seen at one centre are presented. Their case notes and special investigations are reviewed. Magnetic resonance imaging (MRI) is revealed as the investigation of choice because of picture quality, definition of soft tissues and lack of exposure to ionizing radiation. MRI allows a definite diagnosis to be made without any invasive procedure being required. A future study following up these infants may be of interest because of controversy regarding the spontaneous resolution of these lesions.

Autosomal recessive congenital intrauterine infection-like syndrome of microcephaly, intracranial calcification, and CNS disease

We present data on 10 patients from 5 families with a condition of microcephaly, intracranial calcification, and a clinical course resembling congenital TORCH infection. Repeatedly, negative TORCH investigations are a prerequisite for the identification of this disorder and the value of disturbed liver function and thrombocytopenia as aids to diagnosis is emphasised. Several similar families with recurrence of the disease in sibships are identified in the literature and the genetic implications of our observations are considered.

Dysembryoplastic neuroepithelial tumor. Features in 16 patients

Dysembryoplastic neuroepithelial tumour (DNT) is a newly recognized brain mass lesion with distinctive pathological features and a favourable prognosis. We reviewed the clinical, electroencephalographic, neuroimaging and pathological features of 16 patients with DNT who underwent surgery; only one patient did not have epilepsy. Mean age at seizure onset was 9.5 years (range: 1 week to 30 years) and surgery 17 years (range: 7 months to 37 years). The mean verbal IQ was 94.6 (range: 79-110) and performance IQ 105 (range: 79-130) (n = 10). The EEG was abnormal in all cases reviewed (n = 13): localized slow activity was seen in 12 and interictal spiking in 10 patients, being less extensive than or concordant with the lesion in three and more extensive than or distant to the lesion in seven. X-ray CT was normal in three out of 11 patients. Magnetic resonance imaging provided detailed anatomical information: the lesion was predominantly intracortical, although in six patients, there was also white matter involvement. The lesion involved the temporal lobe in all but one patient where it was in the cingulate gyrus. Of the temporal lobe cases, MRI showed that the lesion involved, or was in close proximity to, mesial temporal structures in 11 out of 14 patients. Other magnetic resonance features included: circumscribed hyperintensity on long TE/TR images (10 patients), hypointensity on short TR images (12 patients), and cyst formation (five patients). Calcification was seen on CT in four patients. Post surgical follow-up ranged from 8 to 30 months (mean 16.2 months): 12 patients are seizure free and two have a > 80% reduction in seizure frequency (n = 14). Histopathological characteristics included a heterogeneous composition in all cases, calcification (13 cases), dysplastic features (12 cases) and isolated foci of subpial spread (five cases). The presence of occasional mitoses in 12 cases and immunoreactivity to the proliferating cell nuclear antigen in six cases indicate that these lesions have cellular proliferative activity and that there may be a need to follow these patients postoperatively.

Is cranial computerized tomography useful in the diagnosis of multiple system atrophy?

Cranial computer tomographic (CT) images of 33 patients with multiple system atrophy (MSA) and of 40 age-matched controls were blindly analyzed by two neuroradiologists. All patients had autonomic dysfunction, all but one had parkinsonism, and 13 had cerebellar signs. The scans were judged entirely normal in 21%. Moderate or severe infratentorial atrophy was found in 42%. Cerebellar atrophy was present in 39%, and pontine atrophy was present in 18%. Of the 13 patients with cerebellar signs, only eight had cerebellar atrophy. Of the 20 patients without cerebellar signs, five had cerebellar atrophy. Supratentorial involvement was much less common and less severe. Thus, CT demonstrated system involvement that was not evident clinically in five of 33 cases (15%). However, in all five the clinical diagnosis was already evident from the presence of both autonomic and pyramidal signs in addition to parkinsonism. We conclude that CT imaging is of limited diagnostic use in individual patients with MSA.

Brain swelling and ischaemia in Kenyans with cerebral malaria

Computed tomography was performed on 14 unconscious Kenyan children recovering from cerebral malaria (seven of whom had another scan 12-120 days later) to elucidate the cause of intracranial hypertension and neurological sequelae. Brain swelling, defined as a loss of cerebrospinal fluid spaces, was documented in six children, while a further two had conspicuously small ventricles only. There was severe intracranial hypertension in the two children with definite brain swelling in whom intracranial pressure was monitored. There was no evidence of acute hydrocephalus or vasogenic oedema. Four children with brain swelling also had widespread low density areas suggestive of ischaemic damage. The patterns of damage were not uniform but were consistent with a critical reduction in cerebral perfusion pressure (which was documented in the two in whom this was monitored), hypoglycaemia, or status epilepticus. All four had serious neurological sequelae. These data suggest that brain injury in cerebral malaria may be due in part to secondary systemic and intracranial factors as well as to the direct effect of intravascular sequestration.

Delayed diagnosis of spinal vascular malformations presenting as intermittent myelopathy

We report our recent experience of three male patients, whose clinical diagnosis and subsequent surgery was delayed for 9.25 and 15 months respectively. Initially, they all presented with vague, either sensory or motor lower limb disturbances and intermittency of symptoms was followed by bladder dysfunction or impotence. Extensive laboratory work-up was unrevealing and the non-specific diagnosis of myelopathy further delayed the recognition of the underlying vascular lesion. Finally spinal magnetic resonance imaging (MRI), supine myelography and selective spinal arteriography indicated the presence of a tumor in the first patient and vascular malformation in the other two. Neurosurgery and histology confirmed one cavernous angioma and two arteriovenous malformations, all thoracic and dural. We believe that both the cryptic nature of these lesions and our technical limitations (spinal arteriography and MRI not readily available), accounted for the delayed diagnosis in our three patients, who nevertheless, when treated by surgery showed a satisfactory outcome in the first case, while further deterioration was prevented in the other two.

EEG features of cortical dysplasia in children

Two distinctive electroencephalographic abnormalities, very high amplitude rhythmic activity or prominent fast activity, have been described in children with extensive cortical dysplasia. Cases with cortical dysplasia identified on computerised tomography or magnetic resonance imaging, or a characteristic EEG were selected. One hundred and forty electroencephalograms from 94 cases were reviewed and related to the imaging findings. An EEG with very high amplitude rhythmic activity was found to have high specificity for severe cortical dysplasia but low sensitivity (< 50% cases). Abnormal fast activity was not specific and was seen with very diverse pathologies. The EEG features of most cases with localised cortical dysplasia were very variable. The EEG could be normal even when the cortical dysplasia was extensive.

Brain MRI changes in phenylketonuria. Associations with dietary status

Following the introduction 30 years ago of neonatal screening and early dietary treatment for phenylketonuria there has been a dramatic decrease in the severity of neurological dysfunction associated with this disorder. However, there is evidence that subtle neurological impairment remains common in early treated subjects and in the last 3 years there have been a number of reports of overt neurological impairment with white matter abnormalities on MRI. The frequency of white matter changes in phenylketonuria, and the relation of these changes to dietary management, have remained unclear. The present study examines MRI findings in 34 subjects aged 8-33 years. Twenty-five subjects had been detected by routine neonatal screening and nine had been missed in the screening programme. At the time of the investigation 16 of the early treated and two of the late treated subjects were still receiving a diet low in phenylalanine. All but two of the 34 subjects showed abnormalities on MRI. In the early diagnosed group it could be shown that the severity of MRI changes (graded 1-5) was significantly and independently associated with phenylalanine concentrations at the time of investigation and the time since dietary treatment had been withdrawn. These data are consistent with studies in animals showing that hyperphenylalaninaemia increases myelin turnover in a dose dependent manner. It is suggested that the effects of phenylalanine on myelin pose a lifelong hazard to the nervous system.

Alexander's disease: clues to diagnosis

The clinical, radiologic, neurophysiologic, and pathologic findings in 10 children with histologically proven Alexander's disease are described, and the presence of two broad clinical subgroups is confirmed. Macrocephaly, regression, and seizures are found in the infantile form, whereas bulbar signs predominate the so-called juvenile form. None of the clinical or neurophysiologic findings is pathognomonic, and radiologic features suggesting the diagnosis are not present in all cases. However, the combination of abnormalities may suggest the diagnosis and justify histologic confirmation.

Anterior pituitary function and computed tomography/magnetic resonance imaging in patients with Langerhans cell histiocytosis and diabetes insipidus

In order to document anterior pituitary dysfunction in patients with biopsy-proven Langerhans cell histiocytosis (LCH) and diabetes insipidus and to correlate this with structural changes on imaging, we performed an insulin tolerance test, enhanced computed tomography (CT), and unenhanced magnetic resonance imaging (MRI) in nine patients. Six of the nine patients had growth hormone deficiency, which in two patients was part of panhypopituitarism and in one was associated with poor cortisol response to insulin hypoglycemia. One patient had an exaggerated growth hormone response and one who had had neck irradiation as an infant, had a high resting thyroid stimulating hormone (TSH) suggesting compensated primary hypothyroidism. All enhanced CTs were abnormal, bony defects being the only abnormality in two patients and opaque mastoids in one. The remaining six patients all had structural changes in the hypothalamic/pituitary region. Unenhanced MRI confirmed the CT findings except in one child who had been treated with radiotherapy in the intervening period, but, in addition, confirmed diabetes insipidus by showing absence of the posterior pituitary bright signal and picked up white matter changes in a child with clinical neurological dysfunction. Our findings indicate that the development of diabetes insipidus in LCH is commonly associated with anterior pituitary dysfunction and is usually associated with structural changes in the hypothalamic/pituitary axis.

Magnetic resonance imaging of the central nervous system in Behçet's disease

Magnetic resonance imaging (MRI) was performed in 25 patients with Behçet's disease, of whom 15 had clinical involvement of the central nervous system (CNS). Brain MRI was abnormal in 11/15 with and in 1/10 without CNS involvement. The most common sites of MR lesions were the cerebral white matter and brainstem. Lesions were also seen in the basal ganglia, cerebellum, optic nerves and spinal cord. The cerebral white matter lesions were always asymptomatic and usually small, whereas the brainstem lesions were often symptomatic and sometimes extensive. Follow-up MRI in 2 patients presenting with brainstem syndromes and treated with immunosuppression showed resolution of a large lesion in 1 patient in whom there was clinical remission, and the development of marked brainstem atrophy in the other who became severely disabled. The pattern of MRI abnormalities may assist the diagnosis and suggests a role for MRI in monitoring the effect of treatment in patients with neurological Behçet's disease.

Magnetic resonance imaging in the assessment of craniosynostosis

Modern interest in craniosynostosis began when clinicians, regardless of their individual specialty but united in their interest in the problems raised by patients with this condition, first realised that if treatment was confined simply to opening up the fused sutures of the skull vault, success in terms of both function and the restoration of a more normal appearance was likely to be limited. Indeed, the grouping together of such specialists into formal craniofacial units was tacit recognition of this, as was the acceptance that many affected children had evidence of clinical problems that could not be explained on simple mechanical grounds alone. It is not surprising, therefore, that the advent of any new method of investigation has been welcomed by craniofacial surgeons eager to learn anything that might lead to an improvement in management, particularly of the more complex syndromes.

Serial gadolinium-enhanced MRI in relapsing/remitting multiple sclerosis of varying disease duration

In the planning of MRI protocols to monitor disease activity in multiple sclerosis (MS), the clinical subtype needs to be considered. In this serial gadolinium-enhanced MRI study, we demonstrated differences between patients with early relapsing/remitting MS and benign MS in both the production of new lesions and the occurrence of enhancement.

CT and MR imaging in lateral sinus thrombosis

Establishing a pre-operative diagnosis of lateral sinus thrombosis can be difficult, as the clinical features are non-specific and laboratory tests unhelpful. CT may demonstrate abnormal high density of the lumen of the sinus, which does not enhance after intravenous contrast medium. Enhancement of the dura surrounding the sinus may be prominent, causing the 'empty triangle' or 'delta sign' which may suggest the diagnosis. Magnetic resonance (MR) imaging may show both lack of flow and abnormal signal from the sinus, thus providing definitive evidence of thrombosis.

The clinical significance of seizures in critically ill young infants requiring intensive care

The aetiology, severity of systemic and biochemical abnormalities, seizure duration, EEGs and CT scans have been reviewed in previously normal young infants with an acute critical illness occurring after the first week of life; none of whom had birth asphyxia. Findings were related to outcome in an attempt to evaluate the significance of seizures during the acute phase of severe illness. In three years seizures occurred in 54/251 (22%) young infants requiring ventilatory support. In these patients the acute illness was most commonly infection and encephalitis/encephalopathy. Twenty-one died, 24 had good or moderate outcome and 9 poor outcome (follow-up 6-27 months). The outcome was not directly related to diagnosis, but to systemic and biochemical changes, the most important being severe hypotension (40/54). After correction of these factors, in survivors, increasing number of days over which seizures occurred during the acute phase of illness was related to worsening outcome (tau(c) = 0.66, p less than 0.0001). In many of these patients one of three abnormal low density changes (generalized, boundary zone and focal) were seen on CT scan and were not uncommonly associated with focal/multifocal clonic seizures and characteristic type, distribution and evolution of EEG discharge. In the 45 patients with EEGs from presentation, severity of encephalopathy assessed by predominant background EEG activity was most closely related to outcome, irrespective of aetiology and seizures. There was a significant relationship between graded severity of background EEG activities and outcome both in the initial and serial recordings (tauB = 0.70, p less than 0.0001 and 0.75, p less than 0.0001 respectively). Seizures are a common occurrence in the previously well young infant with an acute critical illness necessitating intensive care. Prompt recognition and treatment may influence outcome in patients with a potentially reversible encephalopathy. However, in many patients seizures reflect severe, often multifactorial cerebral insult with variable morphological changes, EEG patterns and clinical outcome.

Intracranial neurenteric cysts. Report of two cases

Two cases of intracranial neurenteric cysts are reported and the literature is reviewed. Neurenteric cysts are rare congenital lesions that tend to occur in the spinal intradural space. An intracranial location is exceptional.

Neuroradiology

Posterior fossa cysts have been reclassified, migrational defects have been matched with histology, and new abnormalities have been described in neurofibromatosis, tuberous sclerosis and ceroid lipofuscinosis. Normal myelination, progressive hydrocephalus, infantile neoplasms, cryptic angiomas and irreversible anoxic brain damage are reviewed. The distribution of grey matter changes in subacute necrotizing encephalomyelitis is discussed and the superiority of magnetic resonance imaging in partial epilepsy and neurological acquired immune deficiency syndrome is confirmed.

Pelizaeus-Merzbacher disease: classical or connatal?

The clinical features and investigation results of 7 patients with Pelizaeus-Merzbacher disease (PMD) are described; one patient had a brain biopsy and two patients had an autopsy. This paper tries to differentiate the clinical features of the connatal and classical types of PMD. Transient stridor and nystagmus were early signs in both types of PMD. Our findings support the view that the more severe connatal form shows rapid neurological deterioration from an early age leading to death usually in the first decade. In younger patients in whom the evolution is still unclear, severe feeding problems and extrapyramidal features may suggest the connatal form. By contrast, in the classical form of PMD, cerebellar signs and cognitive deterioration are more prominent with a more slowly progressive course. Nuclear magnetic resonance imaging and brainstem auditory evoked potentials were very helpful in supporting the diagnosis of PMD either in a known affected family or in sporadic cases, but were not useful in distinguishing between the two types of PMD. Genetic counseling in this condition is difficult, particularly in the connatal form in which inheritance may be either X-linked or autosomal recessive.