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Biomedical subjects

M Besser

Publications and source records attributed to M Besser.

At least 73 records · Page 4Linked to original sources
PubMed1987

Short latency somatosensory-evoked potentials in children--Part 2. Effects of spinovertebral disorders.

Surface-recorded spinal and cortical somatosensory-evoked potentials (SEPs) following tibial or median nerve stimulation were studied in 26 children aged from 12 months to 13 years. Fifteen patients had caudal or dysraphic spinal malformations, often with a tethered cord syndrome, while the remaining patients had spinal tumors (4), syringomyelia (3), spinal canal stenosis (2), or demyelinating syndromes (2). Somatosensory-evoked potential abnormalities were found in 13 patients. Loss of a SEP at or rostral to the site of spinal pathology was the most common finding. Prolongation of central conduction times or delay in SEP peak latencies was documented in only four patients. Correlations between clinical and electrophysiological findings revealed that all patients with sensory dysfunction had abnormal SEPs, whereas patients with motor or sphincteric dysfunction, but intact sensation, usually had normal SEPs. These relationships between SEPs and clinical findings were constant irrespective of the etiology and location of the spinal pathology. The results from this study suggest that although SEP studies provide information regarding the somatosensory pathways, their clinical utility as a method of assessing spinal cord function in children with spinal disorders is limited by technical, clinical, and anatomical factors.

Adolescent↗
PubMed1987

Short latency somatosensory-evoked potentials in children--Part 3. Findings following head injury.

Fourteen children aged 3 to 11 years who suffered from coma for at least 6 hours had somatosensory-evoked potential studies performed within 24 hours of neurotrauma. The upper cervical (Cv2) and bilateral cortical somatosensory-evoked potentials were recorded for calculation of the central somatosensory conduction time. Despite the fact that the SEP recordings were performed in the intensive care unit and the patients were receiving opiate and barbiturate therapy, satisfactory somatosensory-evoked potentials were recorded in all patients. Symmetrical short latency cortical somatosensory-evoked potentials were recorded bilaterally in 10 patients. Two patients with hemorrhagic cerebral contusions and unilateral cerebral edema had ipsilateral abnormalities of the cortical somatosensory-evoked potential. These patients all had normal central somatosensory conduction times and all had satisfactory neurological recoveries, although the two patients with abnormal cortical somatosensory-evoked potentials had focal neurological deficits. Two patients whose head injuries were complicated by hypoxia and refractory intracranial hypertension had bilaterally abnormal cortical somatosensory-evoked potentials, and both had vegetative outcomes. There was no correlation between the Glasgow Coma Score and central somatosensory conduction time; however, the number of components to the cortical somatosensory-evoked potential was related to the Glasgow Coma Score. The results suggest that the recording of somatosensory-evoked potentials can provide useful information about the functional status of central and cortical somatosensory pathways in children following major head injury.

Child↗
PubMed1987

Short latency somatosensory-evoked potentials in children--Part 4. Findings with cerebral lesions.

Cortical somatosensory-evoked potential studies were performed on seven children with unilateral intracerebral lesions. Three patients had neoplasms, and four had hematomas of various etiology. All the lesions involved either directly or indirectly with the thalamocapsular or perirolandic regions of the brain. Patterns of somatosensory-evoked potential asymmetry included abnormality of the primary cortical complex (N1-P1), loss of intermediate and long latency waveform components, and attenuation of the response on the side of the lesion. The most abnormal somatosensory-evoked potentials were seen in patients with major clinical deficits, whereas patients with minimal neurologic signs had minor somatosensory-evoked potential changes. The location, etiology, and duration of the lesions all appeared to influence the somatosensory-evoked potential waveform. The value of somatosensory-evoked potential studies in the diagnosis and localization of cerebral lesions would seem to be limited because of pathophysiologic phenomena related to the primary cerebral lesion.

Brain Neoplasms↗
PubMed1987

A 16 year old boy with poor vision and nasal obstruction.

A 16 year old boy presented with visual deterioration and nasal obstruction. Investigations revealed a destructive pituitary tumour with extension into his skull base and nasopharynx. This unusual prolactin-secreting adenoma was treated by both surgery and bromocriptine.

Adenoma↗
PubMed1987

Improved survival after brain metastases in non-seminomatous germ cell tumours with combined modality treatment.

Long-term disease-free survival (78 + and 31 + months) has been achieved in two of four patients treated for brain metastases from non-seminomatous germ cell tumours between 1980 and 1984. The incidence of cerebral metastases among 101 patients seen over the 5-year period was 4%. The encouraging results from the use of combined modality treatment, incorporating cisplatin-based chemotherapy, whole brain irradiation and surgery, are reviewed.

Adult↗
PubMed1987

Dopaminergic and cholinergic influences on the growth hormone response to growth hormone-releasing hormone in man.

It is well established that compounds that modify dopaminergic and cholinergic activity in man may induce changes in circulating growth hormone (GH). We have, therefore, investigated the effect of a dopamine agonist, bromocriptine, and a dopamine antagonist, domperidone, as well as a muscarinic cholinergic antagonist, pirenzepine, on the GH response to an analogue of GH-releasing hormone (GHRH) in normal male subjects. GHRH(1-29)NH2 induced a rise in serum GH that was augmented by bromocriptine, antagonized by pirenzepine, but was unaltered by domperidone. As this dose of GHRH(1-29) NH2 has been shown to be maximally stimulatory to GH release, it is suggested that there are dopamine stimulatory and cholinergic inhibitory receptors to GH release independent of GHRH in man.

Adrenergic Fibers↗
PubMed1987

Vein of Galen malformation: diagnosis and management.

The vein of Galen malformation is a midline arteriovenous fistula with aneurysmal dilatation of the vein of Galen. The clinical details of diagnosis and treatment in 13 patients with such lesions together with a review of 232 cases collected from the literature are presented in this report. There were 132 males, 77 females, and 36 cases in which the sex was not stated. Eighty patients presented as neonates, 82 were 1 to 12 months old, 39 were 1 to 5 years old, 22 were 6 to 20 years old, and 22 were over the age of 20. The most common presenting symptoms were congestive cardiac failure (110 cases), raised intracranial pressure secondary to hydrocephalus (94 cases), cranial bruit (57 cases), focal neurological deficit (37), seizures (26 cases), and hemorrhage (25 cases). The most characteristic vascular supply to the midline fistula involved multiple bilateral vessels, although bilateral posterior cerebral and unilateral posterior cerebral supply was relatively common. The overall figures for treatment and outcome showed that 91 patients (37.1%) were treated by direct operation and 29 patients (11.3%) were treated by other forms of operation, predominantly shunting or remote vessel ligation. Forty-six patients (18.8%) were treated by medical means (digoxin, diuretics, and ventilatory support). In 79 patients (22.2%), there was no treatment or no details of treatment were available. There was an overall series mortality of 55.6% (no details were available in 33 cases) and a 37.4% mortality for surgically treated cases. After operation, there was a 46.3% incidence of significant morbidity in surviving patients. Neonatal patients fared worst, with an overall mortality of 64 of 70 cases (91.4%) where details were available. The outcome was equally bad for surgically and conservatively treated cases. Operation in the 1- to 12-month age group was more successful, but still carried a mortality of 31.7%, with a significant morbidity in approximately half of the surviving patients. Over the age of 1 year, the surgically treated patients had a 25.6% mortality and a 42.3% major morbidity in survivors. Consideration is given to some of the ways in which these figures may be improved, in particular a staged approach during the neonatal period, with the use of selective embolization or occlusion of vessels to reduce the volume of the arteriovenous shunt until the patient is older and better able to tolerate major operation.

Adolescent↗
PubMed1987

The rapid diagnosis of sensitivity or resistance to dopamine agonists with depot bromocriptine.

Some patients with hyperprolactinaemia are unable to tolerate even low doses of oral bromocriptine. In such cases, it is difficult to predict whether serum prolactin might be normalized if higher doses could be tolerated, or whether true resistance to bromocriptine is present. We have investigated 8 such patients who were subjected to a dopamine infusion (4 micrograms/kg per min for 4 h), followed by an injection of 50 mg of depot bromocriptine on a separate occasion. Serum prolactin was normalized in 4 patients during dopamine, and in 6 patients 12-48 h following depot bromocriptine. The 2 patients who failed to respond to depot bromocriptine also failed to respond to high oral doses of bromocriptine, while the remaining 6 patients were successfully transferred to oral bromocriptine without adverse reactions after the depot preparation was administered, and with a normalization of serum prolactin. It is concluded that depot bromocriptine may represent a better predictor of true unresponsiveness to dopamine agonist therapy than a dopamine infusion, and may also allow for initiation onto oral therapy of previously intolerant patients.

Administration, Oral↗
PubMed1987

Intracranial carotid artery injury in closed head trauma.

Six patients with trauma to the intracranial internal carotid artery are reported. One patient died and two are permanently disabled due to ischemic sequelae. The incidence of this complication of trauma is unknown because of the infrequent use of angiography in head-injured patients. The pathology, clinical course, and management of this condition are discussed with reference to the 25 previously reported cases in addition to the six in this series.

Adolescent↗
PubMed1987

Cerebral arteriovenous malformations, steal, and the hypertensive breakthrough threshold. An experimental study in rats.

An experiment was designed to investigate the effects of arteriovenous (AV) fistula occlusion on cerebral autoregulation. A right carotid-jugular fistula was created in 63 rats in such a way as to produce an intracranial AV fistula with a loop extension into the neck. The fistula was occluded after an 8-week interval with the rats under both normotension and metaraminol-induced hypertension, and evidence of blood-brain barrier disruption was investigated with an Evans blue dye technique. The results indicate that an intracranial AV fistula may cause cerebral steal which is responsible for a reduction in the threshold for hypertensive breakthrough following fistula occlusion.

Animals↗
PubMed1986

Treatment of intracranial aneurysms by combined proximal ligation and extracranial-intracranial bypass with vein graft.

Seven patients with internal carotid artery aneurysms, and one patient with a middle cerebral artery aneurysm, were managed by combining proximal ligation with an extracranial-intracranial bypass procedure. Five bypasses were done with an interposed vein graft between the external carotid artery and the distal middle cerebral artery (vein graft), and three were superficial temporal-middle cerebral artery bypasses (superficial temporal artery grafts). As demonstrated in postoperative angiograms, all eight patients had patent bypasses with nonfilling of the aneurysm. One patient developed transient dysphasia, but there were no permanent neurological deficits associated with carotid occlusion. Four patients had resolution of their neurological problems, and another three patients improved. The distribution of flow from vein grafts is more extensive than from superficial temporal artery grafts. This offers increased protection against ischemia, and increases the likelihood of internal carotid artery aneurysm thrombosis by reducing the turbulence in the distal internal carotid artery.

Adult↗
PubMed1986

Pseudoaneurysm complicating superficial temporal artery-superior cerebellar artery bypass.

A 60-year-old man with vertebrobasilar ischemia unrelieved by anticoagulation was found to have a midbasilar stenosis with an inadequate basilar collateral circulation. He underwent a right superficial temporal-superior cerebellar artery bypass. Following this operation he had a subarachnoid hemorrhage and right third nerve palsy that was due to formation of a pseudoaneurysm at the site of the anastomosis. This aneurysm was managed by ligation of the right superficial temporal artery. Subsequently it became necessary to perform a left superficial temporal artery-superior cerebellar artery bypass because of severe posterior circulation ischemic symptoms.

Cerebellum↗
PubMed1986

Intra-operative recording of cortical somatosensory evoked potentials as a method of spinal cord monitoring during spinal surgery.

The experience with cortical somatosensory evoked potential (SEP) recording during 13 cases of spinal neurological surgery is described. Good quality cortical SEPs were obtained in eight patients with a variety of intradural and extradural spinal disorders. The short latency components of these waveforms were stable during anaesthesia with nitrous oxide, 0.5% halothane and fentanyl. Fluctuations in signal amplitude were, however, common. In the one patient in whom the cortical SEP waveform was distorted intra-operatively, there was an increased neurological deficit. In one normal and four patients with impairment of dorsal column function, no intra-operative cortical SEP was recorded. In these five patients spinal SEPs were recorded rostral to the level of spinal disease. Monitoring spinal cord function using cortical SEPs can provide useful neurophysiological information, however, there are limitations to its utility. These relate to difficulties in signal acquisition, the low signal amplitude, attenuation of the signal during intramedullary surgery and uncertainties in signal interpretation. All these problems are exacerbated if the patient has a pre-operative clinical somatosensory deficit. Although most of these problems can be overcome using spinal SEP monitoring, intra-operative SEP recordings are not an infallible guide to spinal cord integrity since they reflect the functional status of only the dorsal column-medial lemniscus pathway.

Anesthesia↗
PubMed1986

Different opioid mechanisms are involved in the modulation of ACTH and gonadotrophin release in man.

Both the pituitary-adrenal axis and the pituitary-gonadal axis are under the tonic inhibitory control of endogenous opioid peptides in man. However, the precise opioid receptor involved in the modulation of these hormones remains unknown. The effect of a dose of intravenous naloxone on serum levels of luteinising hormone (LH), follicle-stimulating hormone (FSH) and plasma cortisol was therefore investigated in ten normal subjects. In the male subjects, naloxone at a dose of 25 micrograms/kg caused a significant increase in serum LH and FSH; no increase in response was seen at the two higher doses (100 micrograms/kg and 250 micrograms/kg). The lowest dose (6 micrograms/kg) caused no change in serum LH and FSH. In the female subjects, tested in the early follicular phase of their cycles, no dose of naloxone significantly increased circulating gonadotrophins. In both male and female subjects, naloxone only stimulated a rise in serum cortisol at the highest dose (250 micrograms/kg). A second study in six normal subjects demonstrated that the rise in cortisol with the highest dose of naloxone was secondary to a rise in plasma ACTH. It is concluded that the opioid receptor(s) controlling gonadotrophin release in man are naloxone-sensitive, and are probably epsilon-receptors; the naloxone insensitivity of the pituitary-adrenal axis suggests that these responses are modulated by kappa- or delta-receptors.

Adrenocorticotropic Hormone↗
PubMed1986

Radioimmunoassay for the carboxy-terminal cross-linking domain of type IV (basement membrane) procollagen in body fluids. Characterization and application to collagen type IV metabolism in fibrotic liver disease.

The carboxy-terminal cross-linking domain (NCl) of type IV procollagen was isolated from human placenta and used for the production of polyclonal and monoclonal antibodies. Purity of the antigen and specificity of the antibodies were verified by Western blotting and radioimmunoassays. A radioimmunoassay was developed using rabbit antiserum. Intra- and interassay coefficients of variation were 4.7% and 5.8%, respectively; recovery of NCl added to serum and bile was 95-105%. NCl concentration in sera of healthy volunteers was 6 +/- 2.9 ng/ml (mean +/- 2.5 SD) and was elevated up to 18 ng in sera of patients with autoimmune or metastatic tumor disease and up to 240 ng in sera of patients with fibrogenic liver disease. Substantial amounts of antigen were also found in bile, urine, and ascites. 67% of serum antigens eluted from an agarose A5M column with an apparent molecular weight of 60 kD and 23% with a molecular weight of 90 and 150 kD, well below the molecular weight of type IV procollagen (550 kD). Serum NCl is apparently derived from the degradation of basement membrane collagen. The time course of NCl concentrations in sera of patients with fibrogenic liver disease showed no correlation with the serum concentration of the amino-terminal procollagen type III peptide, a marker of hepatic collagen biosynthesis. A decline of serum NCl levels along with elevated serum procollagen type III peptides apparently indicates bad prognosis in fibrogenic liver disease. The radioimmunoassay for NCl is a useful tool for studying type IV collagen metabolism in conditions causing remodeling or breakdown of basement membranes.

Adult↗
PubMed1986

Recording of spinal somatosensory evoked potentials for intraoperative spinal cord monitoring.

The authors' experience with intradural and epidural recording of spinal somatosensory evoked potentials (SSEP's) during 26 cases of spinal surgery is described. The techniques of monitoring spinal cord function provided good quality SSEP waveforms in patients both with and without neurological deficits. The SSEP configuration and peak latencies remained stable for up to 5 hours during anesthesia with nitrous oxide, halothane, and fentanyl. Patterns of baseline SSEP's were characteristic of different spinal segments. Distortion and asymmetry of these baseline patterns were seen in several patients with spinal neoplasms. Loss of waveform components during surgery occurred with profound hypotension, overdistraction of the vertebral axis, dorsal midline myelotomy, and removal of intramedullary tumors. Persistent loss of waveform components was associated with an acquired neurological deficit. Fluctuations in the amplitude of the SSEP's were common but were not associated with postoperative neurological deficits. Spinal cord monitoring by means of SSEP recording would appear to be useful during extradural spinal surgery, but there are limitations associated with this technique during some types of intradural surgery.

Adolescent↗
PubMed1985

Meningoceles and the tethered cord syndrome.

This study shows that there is a relationship between simple meningocele and the tethered cord syndrome. Two groups of patients were examined: the first comprised patients presenting with neurological abnormality at some period after initial closure of a simple meningocele, and the second group (18 patients) had elective myelography after closure of a simple meningocele in the neonatal period (in 17 of the 18 cases). Of these 18 cases. 10 showed an intradural abnormality, and all underwent surgery confirming their myelographic diagnosis. The conclusion is drawn that after closure of a simple meningocele in the neonatal period, patients should have elective myelography in the first 12 months of life to determine whether or not the tethered cord syndrome is likely to develop during the period of growth.

Adolescent↗