Temporal physiochemical changes during in vitro relaxation time measurements: the cerebrospinal fluid

Documented relaxation time measurements of body fluids such as cerebrospinal fluid (CSF) vary considerably. This may be largely due to lack of an appropriate method of maintaining the in vivo physiological and biochemical characteristics of the fluid. We have developed an in vitro technique that maintains the in vivo characteristics of body fluid samples for a sufficiently long period to establish the true relaxation times. To illustrate this we studied changes in CSF pH, pO2, and pCO2, first as it equilibrated with air and then under anaerobic conditions as found in vivo. Relaxation times of CSF were then studied under aerobic and anaerobic conditions. Under the particular aerobic conditions used the pH and pO2 of CSF increased quickly and pCO2 fell within the first 30 min. By 3-4 h equilibration with air was complete. The T1 and T2 relaxation times of CSF decreased by 14 and 16%, respectively, as a result of these physicochemical changes. It is important that such changes be considered when relaxation measurements of any body fluid are performed in vitro and efforts to maintain the in vivo milieu should not be neglected.

Is cranial CSF volume under hormonal influence? An MR study

We used magnetic resonance to investigate the hypothesis that premenstrual neurological symptoms are due to cerebral oedema and brain swelling. Total cranial and lateral ventricular CSF volumes were measured midcycle and premenstrually in 20 women with a normal menstrual cycle, and similar measurements were made 2 weeks apart in 10 postmenopausal women and 10 men. Total cranial CSF volume increased premenstrually in 19 women. The mean premenstrual increase was by 11.5 ml. There was not a significant difference between those women who were taking an oral contraceptive and those who were not. The CSF volume did not change significantly on repeat measurement in men and postmenopausal women. The CSF changes observed reflect a reduction in brain volume and do not support cerebral swelling as the cause of premenstrual neurological symptoms.

Intracranial CSF volumes: natural variations and physiological changes measured by MRI

Cranial CSF volumes, for the first time including CSF in the subarachnoid space, can be measured by Magnetic Resonance Imaging (MRI). The MRI sequence causes signal from the grey matter and white matter to cancel producing a contrast of 200: 1 between a unit of CSF and a unit of brain. We have assessed the variations between normal individuals and investigated some of the physiological factors that might influence cranial CSF volumes. Total CSF volumes were measured in 64 normal subjects, aged from 18-64 years (mean 38 years). Ventricular, cortical sulcal and posterior fossa volumes were also calculated separately. In 20 females with a normal menstrual cycle, CSF volumes were measured mid cycle and premenstrually; 10 post menopausal females and 10 males were rescanned after an interval of 2 weeks. Total cranial CSF volume were calculated before and during inhalation of 7% CO2 and before and during hyperventilation while breathing 60% O2, in 12 normal subjects. Total intracranial CSF volume ranged from 57.1-286.5 ml. Total intracranial and cortical sulcal CSF volumes increased more steeply with age than ventricular or posterior fossa CSF volumes. Males had more cranial CSF than females. Total CSF volume increased premenstrually in 19 females. Males and post-menopausal females did not have a significant change in CSF volume, on repeat examination. CO2 inhalation produced a mean increase of paCO2 of 17.2 mmHg and CSF volume decreased in all subjects (mean 9.4 ml). Cranial CSF volume increased in 11 subjects during O2 inhalation (range -0.5 to +26.7 ml mean 10.9 ml).(ABSTRACT TRUNCATED AT 250 WORDS)

MRI measurement of syrinx size before and after operation

When patients with syringomyelia fail to improve after operation, factors such as incomplete cyst decompression or type of operation are often implicated. MRI has been used to confirm adequate syrinx decompression post-operatively and to compare the degree of collapse with the type of operation. Foramen magnum decompression was at least as effective in reducing cyst size as syringo-subarachnoid shunting. MRI may also provide a better classification of syringomyelia.

Magnetic resonance imaging in the management of resistant focal epilepsy: pathological case report and experience of 12 cases

Clinical improvement in epilepsy following temporal lobectomy is more often obtained when an abnormality is found on subsequent histological examination. Pre-operative MRI demonstrated an abnormal signal in the temporal lobe of a patient with pathologically proven mesial temporal sclerosis with microvascular anomaly. MRI may therefore be helpful in the selection of patients for temporal lobectomy. MRI findings of 12 patients with resistant focal epilepsy are reviewed. A wide range of T1 and T2 weighting is suggested to maximise selection of patients.

Syringomyelia: cyst measurement by magnetic resonance imaging and comparison with symptoms, signs and disability

The severity and distribution of symptoms and signs in patients with syringomyelia is considered to be dependent on the longitudinal and transverse dimensions of the syrinx and it is thought that clinical examination can identify the extent of the cyst. Magnetic resonance imaging has made the anatomical localisation of intramedullary spinal lesions more exact and probably more specific than previous methods of investigation. Syrinx length, diameters, cyst:cord and cord:canal ratios have been studied in 12 patients with syringomyelia to assess whether the dimensions of the syrinx relate to the clinical findings. The length of syrinx appeared to be related to cyst diameter, cyst:cord and cord:canal ratios. Patients with a small syrinx tended to have a small cyst diameter, and small cyst:cord and cord:canal ratios. No significant relationship was found between muscle wasting or weakness, distribution of sensory loss, degree of disability or distress and the dimensions of the syrinx. These findings should be borne in mind when surgical management is being considered.

The neurological assault on the great toe (1893-1911)

The late 19th/early 20th century heralded a period in neurology when there was claim and counter claim about the founders of new reflex movements of the great toe. The cutaneous plantar reflex is undoubtedly one of the most important signs in clinical neurology, and there have been several methods described of eliciting this sign, each with its own eponymous name. This article reviews the background to these claims and the contribution of the various authors, to the discovery, clinical relevance and ease of eliciting reflex movements of the great toe.

MR relaxation times of cerebrospinal fluid

A review of 15 recent publications purporting to provide the relaxation times of CSF reveals a considerable disparity in the quoted results, by a factor of five in terms of T1 (range 1,000 to 5,500 ms) and by a factor of 16 for T2 (range 166 to 2,640 ms). In this article measurements are performed independently on both a spectrometer and an imager. The results indicate that for CSF T1 is greater than 3,000 ms and T2 is approximately 2,000 ms at 6 MHz. The vast differences in relaxation behaviour between CSF and other body tissues have considerable clinical implications and present profound diagnostic opportunities. The application of this knowledge to ventriculography, myelography, and image contrast methodology is discussed.

Nifedipine in the treatment of myotonia in myotonic dystrophy

Abnormal calcium transport may be implicated in the membrane defect in myotonic dystrophy. A single blind crossover trial of placebo (t.i.d.), nifedipine 10 mg (t.i.d.) and nifedipine 20 mg (t.i.d.), was performed in 10 patients with myotonic dystrophy. The severity of myotonia was assessed by measuring finger extension time after maximum voluntary finger flexion. A significant improvement in myotonia, after nifedipine, was recorded by this technique and supported by a subjective improvement in 50% of patients and clinical improvement of greater than 20% in five patients. Initial grip strength and muscle fatiguability measured by grip strength ergometry were not significantly altered.

Sexual practices and risk of infection by the human immunodeficiency virus. The San Francisco Men's Health Study

The San Francisco Men's Health Study is a prospective study of the epidemiology and natural history of the acquired immunodeficiency syndrome in a cohort of 1034 single men, 25 to 54 years of age, recruited by multistage probability sampling. At entry, June 1984 through January 1985, the seropositivity rate for human immunodeficiency virus (HIV) infection among homosexual/bisexual study participants was 48.5%. No heterosexual participants were HIV seropositive. Among homosexual/bisexual men reporting no male sexual partners in the two years before entry into the study, seropositivity was 17.6%. For those reporting more than 50 partners, seropositivity was 70.8%. Only receptive anal/genital contact had a significantly elevated risk of HIV infection. Douching was the only ancillary sexual practice that contributed significantly to risk of infection.

Human cranial CSF volumes measured by MRI: sex and age influences

Accurate measurements of CSF volumes would assist in the diagnosis of several important neurological conditions. Using Magnetic Resonance Imaging (MRI) we have devised a method to measure both total intracranial CSF volume and ventricular volume. This initial study, in normal humans, provides an answer to two longstanding questions: first, do these volumes differ between the sexes; second, do both total and ventricular CSF volumes increase with normal aging? We found that the total cranial CSF volume and skull size of males were significantly greater than those of females, but that there was not a statistically significant difference between the ventricular volumes of the sexes. Total cranial CSF volume increased steeply with age in both sexes but although there was an increase in ventricular volume with age in males, no significant increase with age could be demonstrated in females.

Evoked taste thresholds in a normal population and the application of electrogustometry to trigeminal nerve disease

No standardised method for taste threshold measurement is available and therefore comparison between clinical studies is difficult. An electrogustometer was evaluated in normal subjects. No sex difference in taste threshold was noted; however, there was a significant elevation in detection threshold with age and smoking. Electrogustometric values both in patients before and after surgery for trigeminal neuralgia and in patients with trigeminal sensory neuropathy were determined. Many patients with trigeminal nerve disorders had abnormal electrogustometric detection thresholds suggesting that there is possibly an accessory taste pathway through the trigeminal nerve, although in some individuals the site of lesion may be in the brain stem. Electrogustometry is a convenient method for clinically assessing taste.

A quantitative index of ventricular and extraventricular intracranial CSF volumes using MR imaging

A new technique is described that utilises a novel magnetic resonance pulse sequence to produce a quantitative index both for ventricular and, for the first time, extraventricular intracranial CSF volumes. The pulse sequence is a combination of a null-point inversion recovery sequence with an extended spin-echo read (echo time = 400 ms), which produces a contrast of CSF to white or grey matter of approximately 120:1. A series of experiments are performed on phantoms representing CSF filled ventricles and sulci over a wide range of volume values, and it is found that the standard deviation of differences between true and estimated values is 3.9% for ventricles, 4.6% for total cranial CSF, and 7.9% for CSF within the sulci. Normal volunteer reproducibility studies revealed corresponding standard deviations of less than 5.5%. Using the technique to produce absolute estimates of CSF volumes in normal subjects and patients produced results in good agreement with previously published necropsy studies. The technique has wide neurological and neurosurgical applicability particularly in terms of differential diagnosis and as an objective monitor of therapy or progression in conditions such as hydrocephalus, atrophy, and benign intracranial hypertension.

The consistency of thought disorder in mania and schizophrenia. II. An assessment at consecutive admissions

Manic (N = 8) and schizophrenic (N = 14) acute admissions were assessed 10 days after they arrived at the hospital. These assessments were conducted on two consecutive acute admissions for each patient. Interview-based clinical ratings were collected and examined for the stability of both positive and negative thought disorders. For schizophrenics, negative thought disorder, particularly poverty of speech, was relatively consistent across admissions. In the manic sample, much less consistency was observed. The results are evaluated in terms of the statements that they make regarding the validity of the thought disorder construct and for their implications regarding causal factors in communication disorders.

Use of magnetic resonance imaging to measure intracranial cerebrospinal fluid volume

Magnetic resonance imaging was used to measure intracranial extraventricular and ventricular cerebrospinal fluid (CSF) volume. In 10 normal subjects lateral ventricular and extraventricular intracranial CSF volumes were 25.3 +/- 4.6 ml (mean +/- SD) and 97.6 +/- 6.6 ml, respectively (total 122.8 +/- 38.7). These volumes were measured in 4 patients and the results were: 11.0 ml ventricular volume, 68.7 ml total cranial CSF in the patient with benign intracranial hypertension; 606.6 ml ventricular, 174.1 ml total in the patient with hydrocephalus due to a blocked ventriculo-peritoneal (V-P) shunt; 83.4 ml ventricular, 108.5 ml total in the patient with normal pressure hydrocephalus; and 52.7 ml ventricular, 181.0 ml total in the patient with cerebral atrophy due to Alzheimer's disease. The technique gave highly reproducible results (SD less than 5.7% of mean value). It may be useful in differential diagnosis and as an objective means of monitoring therapy or progress in conditions such as cerebral atrophy, hydrocephalus, and benign intracranial hypertension.

Sexual behaviour in a centre for epilepsy

The sexual behaviour and hormonal profiles in 97 patients with chronic epilepsy from an epilepsy centre were studied. Sexual behaviour relating to numbers of sexual contacts, orgasms, spontaneous erections, and early morning erections, whether there was difficulty in obtaining or maintaining an erection, or in ejaculation, was assessed at interview. Hormonal profiles consisted of LH, FSH, prolactin, total testosterone, free testosterone, and SHBG. Information was obtained relating to type of seizure, seizure frequency, age of onset, likely pathology, IQ, and medication. The study showed that this patient group was profoundly hyposexual and had a high level of sexual dysfunction. Serum free testosterone levels were low, and it is suggested that the high level of sexual dysfunction and lack of sexual interest may well have a hormonal basis. The reasons for this are discussed.

Comparison of HgO and CuS04 as Digestion Catalysts in Manual Kjeldahl Determination of Crude Protein in Animal Feeds: Collaborative Study

The official AOAC manual Kjeldahl method for determining crude protein in animal feeds, 7.015, uses HgO as a catalyst in the digestion step. Because of environmental considerations, there is considerable interest in alternative catalysts. A collaborative study compares the official HgO-catalyzed method and an alternative using CuS04. Fifty-four samples consisting of blind duplicates of closely matched pairs, representing a range of animal feed materials and 2 standard materials, were analyzed once by each method. Results were returned by 22 laboratories. Means and standard deviations between methods were comparable. The CuS04-catalyzed method has been adopted official first action.