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Biomedical subjects

D H Miller

Publications and source records attributed to D H Miller.

At least 325 records · Page 18Linked to original sources
PubMed1995

Progressive neuronal degeneration of childhood with liver disease (Alpers' disease) presenting in young adults.

Two unrelated and previously healthy girls, aged 17 and 18, presented with a subacute encephalopathy, visual and sensory symptoms and signs, and prominent seizures that were difficult to control. Brain MRI showed lesions (high signal on T2 weighted images) in the occipital lobes and thalamus; EEG showed slow wave activity with superimposed polyspikes. Inexorable downhill progression led to death in hepatic failure within eight months of onset. Histopathological findings in both patients ((a) chronic hepatitis with prominent bile duct proliferation, fatty change, and fibrosis; (b) in the brain a patchy destruction of the cerebral cortex, predominantly involving striate cortex) were characteristic of progressive neuronal degeneration of childhood with liver disease--Alpers-Huttenlocher syndrome--a rare autosomal recessive disorder usually seen in infants and young children.

Adolescent↗
PubMed1995

High resolution magnetic resonance imaging of the anterior visual pathway in patients with optic neuropathies using fast spin echo and phased array local coils.

High resolution MRI of the anterior visual pathways was evaluated using frequency selective fat suppressed fast spin echo (FSE) sequences in conjunction with phased array local coils in patients with optic neuropathies. Fifteen normal controls and 57 patients were examined. Coronal T2 weighted fat suppressed FSE images were obtained in 11 minutes with an in plane resolution of 0.39 x 0.39 mm. The optic nerve and its sheath containing CSF were clearly differentiated. Central retinal vessels were often visible. In demyelinating optic neuritis and in anterior ischaemic optic neuropathy high signal within the nerve was readily delineated. Meningiomas and gliomas involving the optic nerve were precisely visualised both in the orbit and intracranially. Extrinsic compression of the optic nerves was readily visualised in carotid artery ectasia and dysthyroid eye disease. Enlarged subarachnoid spaces around the optic nerves were demonstrated in benign intracranial hypertension. High resolution MRI of the anterior visual pathway represents an advance in the diagnosis and management of patients presenting with optic neuropathy.

Adult↗
PubMed1995

Signal intensity on MRI of basal ganglia in multiple sclerosis.

It has been reported that a relative reduction in signal intensity on T2 weighted MRI may be seen in the basal ganglia of patients with multiple sclerosis and furthermore that this is due to excessive iron deposition. The basal ganglia are, however, rarely involved clinically or pathologically in multiple sclerosis, casting some doubt on this finding. Therefore MRI was carried out in 46 patients with definite multiple sclerosis and 42 age matched controls. Contiguous, 5 mm thick axial dual echo spin-echo images of the brain were obtained on a 1.5T imager. Visual rating scales were used to measure the lesion load as well as the signal intensity of the globus pallidus, putamen, caudate nucleus, substantia nigra, red nucleus, and thalamus. There was a mild degree of low signal intensity in the patient group in the thalamus only. The signal intensity of the thalamus and putamen was never lower than that of the globus pallidus. Low signal in the basal ganglia is rarely, if ever, found in multiple sclerosis and is not a useful radiological sign.

Adolescent↗
PubMed1995

Brain kallikrein-kinin system abnormalities in spontaneously hypertensive rats.

The objective of the present study was to determine whether the brain kallikrein-kinin system differs between spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) and if so, whether any detected differences occur before the development of hypertension in SHR. We measured cerebrospinal fluid levels of various components of the system in adult and young prehypertensive SHR and WKY. Cerebrospinal fluid kinin concentration and appearance rate were higher in SHR. Cerebrospinal fluid active kallikrein level and kininogenase activity were also higher in adult SHR. In addition, cerebrospinal fluid kinin concentration and appearance rate were higher in prehypertensive, 5- to 6-week-old SHR compared with age-matched WKY. However, no differences in cerebrospinal fluid kallikrein or kininogenase activity were observed between the two strains of young rats. Cerebrospinal fluid kinin concentration was higher in young versus adult rats of the same strain. In WKY, cerebrospinal fluid kallikrein also decreased with age although cerebrospinal fluid kallikrein concentration did not decrease in young and adult SHR. Together, these data suggest that there is a hyperactive kallikrein-kinin system in the brain of SHR that may contribute to the hypertensive state in this animal model.

Aging↗
PubMed1995

Correlations between changes in disability and T2-weighted brain MRI activity in multiple sclerosis: a follow-up study.

We obtained two conventional unenhanced T2-weighted brain MRI scans, separated by an interval of 24 to 36 months, in 281 patients with multiple sclerosis (MS). At the time of each scan, clinical disability was rated using the Kurtzke Expanded Disability Status Scale (EDSS). Changes in disability between the two examinations correlated weakly but significantly with the number of new (Spearman's rank correlation coefficient = 0.13; p = 0.02) and enlarging (Spearman's rank correlation coefficient = 0.18; p = 0.002) MRI lesions. This result suggests that brain T2-weighted MRI is a useful supplementary marker of disease activity in definitive (phase III) clinical treatment trials in MS.

Adult↗
PubMed1995

Management of mitochondrial disease on an intensive care unit.

Patients with mitochondrial disease may present to the Intensive Care Unit (ICU) with a variety of neurological and general medical disorders. Eleven patients were admitted to a neurological ICU between 1970 and 1992 because of respiratory insufficiency, status epilepticus and/or metabolic encephalopathy associated with mitochondrial disease. Respiratory impairment occurred in eight patients and was associated with nocturnal hypoventilation due to respiratory muscle weakness, aspiration due to bulbar weakness and abnormalities of central control leading to a reduced CO2 drive, irregular respiratory patterns and sleep apnoea. Seven patients received continuous respiratory support during the acute illness; three were subsequently weaned to domiciliary ventilation, and four died. Five patients had stroke-like episodes, which in two were recurrent. Four patients developed tonic-clonic grand mal epilepsy associated with myoclonic fits (2 patients), absences (2), focal fits (1) and status epilepticus (2). Encephalopathy was associated with recurrent lactic acidosis (2 patients), cardiac failure (2), hyponatraemia (2), renal abnormalities (3) and complete heart block (1). Although rare, mitochondrial disease should be considered in any patient with unexplained respiratory failure, intractable epilepsy, lactic acidosis or recurrent stroke.

Acidosis, Lactic↗
PubMed1995

Management and outcome of severe Guillain-Barré syndrome.

Seventy-nine patients with Guillain-Barré syndrome admitted to a neurological intensive therapy unit (ITU) between 1985 and 1992 were studied retrospectively. The mean age was 49.8 years (range 16-86) and the time between the first neurological symptom and admission to ITU was 10.2 days (0-62). Admission was precipitated by a combination of respiratory failure requiring ventilatory support (73.4%), bulbar weakness (57.0%), autonomic features (11.4%) and general medical factors (10.1%). Specific treatments included plasma exchange (65.8%), intravenous immunoglobulin (13.9%) and methylprednisolone/placebo (12.7%). Significant complications included lower respiratory tract infections (45.6%), hyponatraemia (25.3%), dysautonomia (19.0%), urinary tract infection (12.7%) and cognitive disturbances (8.9%). Four patients (5.1%) died during the acute illness. Duration of nadir correlated with duration of ventilation, duration of ITU stay and outcomes at 3 months, 6 months and 1 year. However, time to nadir, an indicator of rapidity of deterioration, did not correlate with any outcome. The low mortality in this series of acutely ill and severely disabled patients suggests that specialized intensive therapy units continue to have an important role in the management of acutely ill patients with Guillain-Barré syndrome.

Acute Disease↗
PubMed1995

Current status of pediatric home peritoneal dialysis training in the United States.

There are little aggregate data that examine attributes of peritoneal dialysis (PD) training programs for children. We determined characteristics of pediatric home PD training programs in a sample of 54 centers in the NAPRTCS PD registry by telephone interview. Sixty-seven percent of the programs trained pediatric patients only (P-only); 33% were combined pediatric/adult (P/A) programs; 33 programs had dedicated training rooms. Most programs trained 5 to 8 patients/year; only 2 trained more than 12 patients/year. Forty-eight of 54 programs (89%) taught both automated and manual PD techniques; the preferred type of PD varied. All units preferred to train 2 people. The patient was often one of the trainees, but the minimal eligible age varied greatly. The patients were trained as inpatients (IP) in 38 units (70%) and as outpatients (OP) in 16 units (30%). P-only programs were less likely to train as OP (20%) than P/A programs (50%) (p < 0.01). There was no difference in the mean training time for P-only versus P/A programs. However, training that took more than 6 days occurred more often when done as an IP (79%) than as an OP (56%) (p = 0.057). Furthermore, only 25% of IP units that took more than 6 days to train offered training on the weekend; none of the IP units that took more than 10 days offered weekend training. In conclusion, the structure of PD training programs for children in the United States varies tremendously. OP training is usually shorter in duration and potentially more cost-effective.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1994

Correlation of magnetization transfer ratio with clinical disability in multiple sclerosis.

We performed spin echo magnetic resonance imaging with and without application of an off-resonance saturation pulse in 43 patients with multiple sclerosis (MS), 10 age-matched controls, and 4 elderly asymptomatic patients with the radiological diagnosis of small-vessel disease. Magnetization transfer (MT) ratio images were obtained from these. All MS subgroups (primary progressive, secondary progressive, benign, early relapsing-remitting) showed significantly lower average lesion MT ratios than small-vessel disease patients. Secondary progressive MS patients showed significantly lower lesion MT ratios than those with benign disease, and there was an inverse correlation of disability with average lesion MT ratio. The degree of reduction of MT ratios is an indicator of the extent of tissue destruction. Thus, reduced MT ratios in MS may provide an indication of the degree of demyelination and axonal loss, both of which are likely to cause functional deficits in MS. We conclude that MT measurement is (1) a robust quantitative method that may increase the pathological specificity of magnetic resonance imaging, (2) has the potential to differentiate demyelination in MS from less destructive pathological changes, and (3) may be useful in monitoring modifications in tissue structure brought about by treatment.

Adult↗
PubMed1994

Magnetic resonance in monitoring the treatment of multiple sclerosis.

Magnetic resonance imaging (MRI) is increasingly being used as a measure of pathological disease activity in monitoring the efficacy of potential new treatments for multiple sclerosis. A major advantage of MRI over clinical monitoring is that it detects a large amount of subclinical disease activity. The two main approaches to MRI are detecting active lesions and measuring total lesion load. In relapsing-remitting and secondary-progressive multiple sclerosis, gadolinium enhancement increases the number of detectable active lesions and also probably correlates with pathological activity. Total brain-lesion load can be measured from computerized images, either by manual outlining of lesions or by more fully automated lesion-segmentation strategies. An important limitation of MRI monitoring is that conventional brain MRI abnormalities often show little or no relationship with clinical disability. One explanation for this may be pathological heterogeneity of lesions that all look the same on a conventional image. Other MR techniques are needed that specifically identify the pathological features most likely to result in disability, namely demyelination and axonal loss. Magnetization transfer imaging and proton MR spectroscopy are two techniques that show promise in this regard.

Brain↗
PubMed1994

Dynamic gadolinium-enhanced MRI in the detection of spinal arteriovenous malformations.

Arteriovenous fistulae and malformations (AVFs and AVMs) of the spinal cord are rare, potentially treatable causes of progressive disability. Although a variety of MRI abnormalities has been described, the diagnosis rests on the findings on selective spinal angiography. Collecting T2*-weighted MR images during the passage of a gadolinium bolus gives information about perfusion and blood volume. We carried out dynamic MRI in seven patients with vascular abnormalities (5 dural AVFs, 1 intramedullary AVM, 1 cryptic angioma) and in two patients without an AVM. High resolution T1- and T2-weighted sagittal images of the whole spinal cord were first obtained using a multiarray receiver coil. Sagittal radiofrequency spoilt gradient echo images (GE34/25, flip angle 10 degrees) were then obtained during bolus injection of gadolinium-DTPA. Abnormalities were seen in all seven patients with AVFs or AVMs. In the patient with an intramedullary AVM and four of the five with dural AVFs transient signal reduction was seen within the perimedullary venous plexus during passage of the bolus. The findings correlated well with those from selective spinal angiography. We conclude that dynamic MRI offers a useful adjunct to angiography and may localise an arteriovenous shunt when conventional MRI fails to do so. In combination with high-resolution imaging of the entire spinal cord the technique may make myelography redundant; it is simple, well tolerated and can be carried out without significant time penalty.

Adult↗
PubMed1994

A comparison between fast and conventional spin-echo in the detection of multiple sclerosis lesions.

Long repetition time (TR) spin-echo (SE) with T2- or proton density weighting is the sequence of choice to detect the brain lesions of multiple sclerosis (MS). Fast spin-echo (FSE) permits the generation of T2-weighted images with similar contrast to SE but in a fraction of the time. We compared the sensitivity of FSE and SE in the detection of the brain lesions of MS. Six patients with clinically definite MS underwent brain imaging with both dual echo (long TR, long and short echo time (TE) SE and dual echo FSE. The SE and FSE images were first reviewed independently and then compared. A total of 404 lesions was detected on SE and 398 on FSE. Slightly more periventricular lesions were detected using SE than FSE (145 vs 127), whereas more posterior cranial fossa lesions were detected by FSE (77 vs 57). With both SE and FSE the short TE images revealed more lesions than the long echo. These results suggest that FSE could replace SE as the long TR sequence of choice in the investigation of MS.

Brain↗
PubMed1994

Benign and secondary progressive multiple sclerosis: a preliminary quantitative MRI study.

In a preliminary study, we compared by means of quantitative magnetic resonance imaging (MRI) methods (1) the T2 values and the decay characteristics of chronic brain lesions, (2) the T2 values of normal-appearing frontal white matter (NAWM) and (3) brain lesion volumes in patients with benign and secondary progressive multiple sclerosis (MS) in order to evaluate the mechanisms underlying the development of disability. Eleven clinically definite MS patients with either benign MS (n = 5) or secondary progressive MS (n = 6) were studied. Fifty-two chronic lesions (identified by comparison with MRI scans obtained at least 12 months previously) were identified. The mean T2 of large lesions (cross-sectional area greater than 41 mm2) and of the NAWM was similar in both clinical groups. However, small lesions had higher mean T2 values (P < 0.01) in the benign group, probably at least in part because of partial volume effects. Analysis of large lesions revealed biexponential T2 relaxation in 6 of 8 "secondary progressive" and in 2 of 16 "benign" lesions, perhaps indicating a greater degree of axonal loss in large lesions of patients with secondary progressive MS. Patients with secondary progressive MS had higher (although not significant) total and infratentorial lesion loads than those of the benign group. These preliminary findings suggest, but do not establish, that variations in the extent, site and pathological nature of lesions may all contribute to different patterns of disease evolution in MS.

Adolescent↗
PubMed1994

Magnetic resonance imaging in monitoring the treatment of multiple sclerosis patients: statistical power of parallel-groups and crossover designs.

Serial brain magnetic resonance (MR) imaging detects active lesions 5-10 times more frequently than the occurrence of clinical changes in patients with early relapsing-remitting and secondary progressive multiple sclerosis (MS). Based on monthly unenhanced and gadolinium enhanced MR findings in 23 unselected and untreated patients, the power of an MS treatment trial was calculated, using MR imaging activity as the primary measure of outcome. It was shown that a 80% reduction in the number of active lesions (i.e. an efficacy of 80%) should be detected using a placebo-controlled parallel-groups design with a power of 80%, if either 2 x 20 patients are scanned monthly for 4 months, or 2 x 30 patients monthly for 2 months. Short to medium term studies of new experimental treatments in MS, using MR imaging as the primary outcome measure, provide considerable statistical power in small patient populations studied over a short period of time.

Adult↗
PubMed1994

Short tau inversion recovery fast spin-echo (fast STIR) imaging of the spinal cord in multiple sclerosis.

The short tau inversion recovery fast spin-echo pulse sequence (fast STIR) combines the synergistic T1 and T2 contrast mechanism of conventional STIR with the reduced imaging time of fast spin-echo (FSE). We have compared fast STIR with T2-weighted FSE in evaluating the spinal cord lesions in 17 patients with multiple sclerosis and 12 healthy controls. Intrinsic lesions were seen only in patients. Twenty-five of the 58 lesions identified were more clearly demonstrated by fast STIR, 22 by FSE. Signal-to-noise and contrast-to-noise ratios were higher in all cases on FSE, suggesting other mechanisms, in particular choice of window settings and brightness of surrounding structures, must play a part in lesion conspicuousness. Fast STIR is a useful adjunct to FSE in the evaluation of multiple sclerosis in the spinal cord.

Adult↗