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Biomedical subjects

J M Stevens

Publications and source records attributed to J M Stevens.

At least 109 records · Page 6Linked to original sources
PubMed1994

Serum from continuous ambulatory peritoneal dialysis patients with acute bacterial peritonitis inhibits in vitro erythroid colony formation.

During episodes of acute infection there is a reduced response to epoetin therapy. It is well known that "endogenous pyrogens," such as interleukin-1 (IL-1) and tumor necrosis factor, inhibit erythropoiesis when administered exogenously. To determine whether there is a relationship between these observations, serum samples were obtained from nine patients with chronic renal failure maintained by continuous ambulatory peritoneal dialysis, during and after recovery from bacterial peritonitis, to study the effect of circulating factors on erythropoiesis. Normal human bone marrow-derived erythroid progenitors were cultured in vitro in 5% and 10% patient serum. Depression of the growth of late progenitors, colony-forming units-erythroid (at 10% serum, P = 0.005; 95% confidence intervals, 6.2 and 24.4, respectively), was observed but there was no effect on the earlier progenitors, burst-forming units-erythroid (at 10% serum, P = 0.7; 95% confidence intervals, -18.5 and 13, respectively). The effect was not prevented by antisera to IL-1. Similarly, when added to cultures, IL-1 inhibited the colony-forming units-erythroid and the effect was abrogated by IL-1 antisera. These findings suggest that a circulating soluble factor that is inhibitory to erythropoiesis and may contribute to loss of response to epoetin therapy, is present in cases of peritonitis in continuous ambulatory peritoneal dialysis patients.

Acute Disease↗
PubMed1994

A new appraisal of abnormalities of the odontoid process associated with atlanto-axial subluxation and neurological disability.

It is well known that abnormalities of the odontoid process may be associated with subluxation and neuraxial compression. Modern computerized imaging is demonstrating that existing classifications are in need of revision since they no longer reflect current views on development, nor do they adequately explain the patterns of abnormality commonly encountered in clinical practice. This study is a description of 62 varied clinical cases examined by high definition computerized myelography or MRI in flexion and extension, some before and after stabilization procedures. From these descriptions, and a review of the old and more recent literature concerning phylogenesis and ontogenesis of the odontoid, the following conclusions were drawn. The dens within the atlas ring is not morphologically a centrum of the first cervical vertebra, but a projection arising from it. In os odontoideum the dens forms normally, but ossifies abnormally because of abnormal motion; it is a result rather than the cause of instability. Hypoplasia of the dens is usually incorrectly diagnosed. When present it is associated with atlanto-occipital assimilation, fusion of the second and third, or more, cervical vertebrae, loss or reduction in axial rotation of the head, basilar invagination and hindbrain deformity of Chiari type. Therefore it is part of a regional anomaly involving hypoplasia of the derivatives of the occipital and upper cervical somites. Recognition of these aspects simplifies both diagnosis and the formulation of therapeutic strategies for different types of clinical presentation.

Adolescent↗
PubMed1994

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.

Adolescent↗
PubMed1994

Respiratory abnormalities due to craniovertebral junction compression in rheumatoid disease.

OBJECTIVE: To assess the extent and severity of respiratory insufficiency associated with severe rheumatoid atlantoaxial dislocation and its relation to compression of the neuraxis. METHODS: Twelve patients with severe atlantoaxial dislocation due to rheumatoid disease were studied. Detailed clinical, CT myelography and respiratory assessment including nocturnal oximetry, were performed on all patients. RESULTS: All patients were severely disabled by their underlying disease but none had symptoms of hypoventilation. All the patients with C1 compression had myelopathic features. Those with medullary deformation (moulding and/or stretch) had abnormal noctural oximetry whilst no significant desaturations were seen in the remaining patients. Post-operative studies showed resolution of noctural desaturations. CONCLUSION: This study suggests that clinically unsuspected respiratory insufficiency may be common in patients with severe medullary compression associated with rheumatoid atlantoaxial dislocation. It emphasises the importance of careful respiratory monitoring including nocturnal oxygen saturation in patients with major atlantoxial dislocation due to rheumatoid disease.

Aged↗
PubMed1994

Subependymal heterotopia: a distinct neuronal migration disorder associated with epilepsy.

Subependymal heterotopia has recently been recognised as a cause of epilepsy, but the clinical and investigational features have not been fully described. The clinical, psychometric, imaging, and electroencephalographic features of 13 adult patients with subependymal heterotopia and epilepsy have been reviewed. Age at seizure onset ranged from 18 months to 20 years (median 13 years). There were significantly more female (12) than male (1) patients (p < 0.01). Diagnosis of subependymal heterotopia was made by MRI in 11 patients and CT in two. The heterotopic grey matter was nodular in 11 patients and diffuse in two; bilateral in eight and unilateral in five. There were significantly more patients with predominant right than left cerebral hemisphere involvement (p < 0.01). The most commonly involved site was the occipital horn of the lateral ventricles (10 of 13 patients). Eleven patients presented with partial epilepsy, 10 of whom also had secondarily generalised seizures. The clinical description of the seizures often suggested either an occipital (four patients) or temporal (five patients) onset. Two patients presented with absence attacks without clear focal features. Patients demonstrated normal early milestones (12 of 13 patients), including normal motor development (all patients) and average or above average intelligence (10 of 13 patients). An EEG examination showed normal background activity in all but two patients, one of whom had large intracranial haematomas. Epileptiform activity was usually widespread (10 of 13 patients) and in three patients, there was generalised 3-Hz spike and wave activity that had previously led to an erroneous diagnosis of concomitant primary generalised epilepsy. Onset of epilepsy in the second decade of life, normal developmental milestones and intelligence, and the finding of an overwhelming female preponderance differentiates subependymal heterotopia from other cortical dysgeneses. The female preponderance supports the importance of the X chromosome and sex steroids in the maturation and development of the cerebral cortex.

Adult↗
PubMed1994

Association of hippocampal sclerosis with cortical dysgenesis in patients with epilepsy.

The possible dual occurrence of hippocampal sclerosis (HS) and other structural lesions (especially cortical dysgenesis [CD]) is well established in patients with chronic partial epilepsy. We describe the frequency of additional CD in a series of 100 patients with evidence of HS, using volumetric MRI. Additional, often subtle, CD was present in 15 patients: subependymal heterotopia (six), forme fruste of tuberous sclerosis (two), focal macrogyria (two), focal cortical dysplasia (one), laminar heterotopia (one), bilateral schizencephaly (one), and simplified gyral patterns (two). In contrast, in 46 healthy volunteers, only one had possible CD (p < 0.05). Only 2 of 15 patients had a history of childhood febrile convulsions. HS is a heterogeneous condition; patients being evaluated for temporal lobe surgery should be carefully screened for additional CD using appropriate MR techniques.

Adolescent↗
PubMed1994

Clinical diagnosis from digital displays: results and conclusions from the St Mary's evaluation project.

Preliminary results with the first commercially available digital display system to be installed in a British radiology department were published in 1989: these consisted of data from observer performance studies of digitized images displayed using a 1024-line monitor, showing a single pathological feature--subperiosteal resorption in renal osteodystrophy. Further experiments have now been conducted with the successor to this equipment, a 1280-line digital display system. Formal observer performance studies were undertaken for four pathological conditions, and the results show statistically significant differences in performance between the digitized displayed images and those on film. The display system was not considered to be good enough for the task of primary radiological diagnosis of subtle lesions; findings support the conclusion that careful, objective clinical evaluation of digital display systems is important before they are introduced into clinical use.

Bone Resorption↗
PubMed1994

Sneddon's syndrome, anti-cardiolipin antibody and glomerular thrombosis.

Sneddon's syndrome, cerebrovascular thrombosis and livedo reticularis, is often a variant of the "primary" anti-phospholipid syndrome (PAPS). We report a woman with PAPS, presenting as Sneddon's syndrome, with renal impairment and glomerular thrombosis on renal biopsy. An IgG anti-cardiolipin antibody (aCL) was identified. The aCL was purified by affinity chromatography, gel filtration chromatography and ion-exchange chromatography, assayed in a modified ELISA and found to be of the type that requires the plasma protein beta 2-GPI to bind aCL. As beta 2-GPI has anticoagulant properties it is postulated that its interaction with aCL has a pathogenic role in the thrombotic lesions associated with aCL.

Adult↗
PubMed1993

Hippocampal sclerosis in epilepsy and childhood febrile seizures.

The connection between hippocampal sclerosis and childhood febrile seizures (CFS) is a contentious issue in the study of epilepsy. We investigated 107 patients with drug-resistant epilepsy by high-resolution volumetric magnetic resonance imaging (MRI). 20 had a history of CFS, 45 had focal (26) or diffuse (19) hippocampal volume loss (HVL). The frequency of CFS was significantly (p < 0.001) higher in the patients with HVL, especially of the diffuse pattern, compared to other epileptic patients without HVL and to the general population. Furthermore, the severity of HVL was greatest in those with a history of CFS. No other clinical or demographic features were associated with either a history of CFS or HVL. The frequency of CFS in patients with other structural congenital causes of epilepsy did not differ from that in a general population. Although these findings show that hippocampal sclerosis is strongly associated with a history of CFS, they do not indicate whether this is a causal relationship. If CFS do cause some cases of hippocampal sclerosis, this can not be the only mechanism, as 64% of those with HVL gave no history of CFS. As diffuse HVL is more strongly associated with a history of CFS than focal HVL, it is also possible that CFS convert pre-existing congenital focal abnormalities into diffuse hippocampal sclerosis. Given the possibility that CFS may cause hippocampal damage and epilepsy, they require urgent medical intervention.

Adolescent↗
PubMed1993

Appearances of posterior osteophytes after sound anterior interbody fusion in the cervical spine: a high-definition computed myelographic study.

Whether posterior osteophytes in the cervical spine resorb after anterior interbody fusion is controversial. Previous studies have only used plain films. In order to study remodelling, a retrospective study of 53 patients using high-definition CT was performed. There was no evidence of remodelling or resorption of osteophytes and persistent osteophytes continued to deform the spinal cord for up to 12 years after fusion. The importance of this in relation to cervical spinal surgery is that every effort should be made to remove posterior osteophytes during anterior interbody fusion.

Bone Remodeling↗
PubMed1993

Spinal cord oedema due to venous stasis.

Venous hypertension and stagnant hypoxia in the human spinal cord are poorly understood. We report a case in which a partial Brown-Séquard syndrome resulted from obstruction of venous drainage on one side of the spinal cord. Neurological deterioration and eventual recovery paralleled the formation and clearance of oedema. The clinical and MRI findings support the contention that spinal cord injury arising as a result of obstruction to venous outflow occurs primarily in the white matter, spreading secondarily to the grey matter, and observations that obstruction of venous flow in the high cervical spinal cord results in changes in the lower cervical cord.

Adult↗
PubMed1993

Comparison of monoclonal antibody methods and a ribosomal ribonucleic acid probe test for Neisseria gonorrhoeae culture confirmation.

Recently, a chemiluminescent nucleic acid probe test that specifically detects the ribosomal ribonucleic acid of Neisseria gonorrhoeae has been released for clinical laboratory use (AccuProbe Neisseria gonorrhoeae). In this study, three coagglutination tests (GonoGen I, Meritec GC, and GC Omni), the GonoGen II immunofiltration method and the Micro Trak Neisseria gonorrhoeae fluorescent monoclonal antibody test were compared with AccuProbe for identification of gonococci. Strains tested (n = 376) included 194 Neisseria gonorrhoeae, 82 Neisseria meningitidis, 32 Neisseria lactamica, 32 Neisseria species, 32 Moraxella catarrhalis, 2 Moraxella spp. and 2 Kingella denitrificans. The GonoGen I, Meritec GC and GC Omni coagglutination tests produced clearly positive results for 93.8%, 92.3% and 95.9% of the gonococci, respectively. The GonoGen II unequivocally identified 91.8% and the MicroTrak fluorescent antibody test identified 90.7% with 2+ or greater fluorescence. AccuProbe identified 100% of the gonococci tested. GonoGen I and GonoGen II were 98% specific, Meritec GC was 99% specific and the specificity of the GC Omni, MicroTrak fluorescent antibody and AccuProbe tests was 100%. While antibody-based tests were reliable when results were clearly interpretable, the AccuProbe was the only confirmatory test that was 100% accurate. Serotyping studies indicate that an array of beta-lactamase positive and negative gonococcal serotypes fail to react with the monoclonal antibody-based tests in general and with the fluorescent antibody test in particular.

Antibodies, Monoclonal↗
PubMed1993

Chiari malformation in adults: relation of morphological aspects to clinical features and operative outcome.

To determine whether clinical features attributed to cerebellar ectopia could be related to the severity of the malformation, and if morphological features could be related to operative outcome, a retrospective study of 141 patients with the adult Chiari malformation was carried out, 81 receiving operative treatment. Morphological parameters derived from preoperative clinical imaging were compared with presenting clinical features and postoperative outcomes. Patients with the most severe cerebellar malformation, defined as descent of the cerebellar tonsils to or below the axis, had disabling ataxia and nystagmus more frequently. Those with brainstem compression had limb weakness and muscle wasting more frequently. Operative outcome was significantly less favourable in patients with severe cerebellar ectopia (12% improved, 69% deteriorated) than in those with minor ectopia (50% improved, 17% deteriorated). Patients with a distended cervical syrinx had a more favourable outcome than those without. Morphological features help predict operative risk.

Adolescent↗
PubMed1993

Volumetric analysis of epilepsy surgery resections using high resolution magnetic imaging: technical report.

A method is described for accurately measuring the volume and site of epilepsy surgery resections utilizing magnetic resonance imaging. Accuracy has been assessed using post-mortem studies, and both the intra- and interobserver variability is consistently less than 5%. The technique has so far been applied to 25 patients following a variety of operations for medically intractable epilepsy. It provides the crucially accurate baseline required for meaningful follow-up outcome studies of epilepsy surgery. Consequently, it should allow the development of more precise prognostic indices for such operations.

Brain↗
PubMed1993

Progressive myelopathy secondary to odontoid fractures: clinical, radiological, and surgical features.

Late-onset progressive myelopathy, years after odontoid fracture, is considered a rarity. Sixteen patients with diagnosis of their odontoid fractures delayed from four months to 45 years have been studied and treated. Three had forgotten about the injury and, in the rest, the significance had been minimized by their clinicians. Fifteen patients had characteristic C-2 nerve root pain and 10 had noted weak hands and walking difficulties. Fifteen patients had Type II fractures, which were mobile in 11; hypertrophic pseudoarthrosis was marked in two. In seven patients it was confirmed at surgery that all or part of the transverse ligament was interposed in the fracture. Transoral surgery, combined with a variety of posterior fusion techniques, has allowed cord decompression, an understanding of the pathomechanics, and sound posterior bone fusion with arrest of the myelopathic condition. Measurements of craniovertebral angles and cord cross-sectional area in this series revealed a rough correlation, but the most striking relationship was between length of delay in diagnosis and diminished cord area in both non-union and malunion, suggesting a progressive injury mechanism. It is proposed that late myelopathy following odontoid fracture may be more common than hitherto believed and should be considered in the evaluation of patients with cervical spondylosis. The condition may be progressive. Finally, non-union may be due to interposition of the transverse ligament.

Adolescent↗