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Biomedical subjects

A Culebras

Publications and source records attributed to A Culebras.

At least 37 records · Page 2Linked to original sources
PubMed1992

Update on disorders of sleep and the sleep--wake cycle.

Wakefulness and sleep are antagonistic states competing for the domain of brain activity. Non-REM sleep and REM sleep are different states of being, sustained by activity in brainstem nuclei, hypothalamus, basal forebrain, and thalamus. Such complex phenomenology is subject to many alterations grouped in the new International Classification of Sleep Disorders. The insomnias are the result of interacting psychosocial, psychophysiologic, neurodevelopmental, and medical factors. Proper perspective of each factor provides the clinical strategies to approach medically the symptom-complex of insomnia. The most common cause of daytime hypersomnia is chronic sleep deprivation. Obstructive sleep apnea responds to nasal CPAP, but the failure rate approaches 30%. In intolerant patients BiPAP and surgical remedies should be considered. Motor and behavioral abnormalities of sleep may be linked to REM sleep as in the REM sleep behavior disorder. Paroxysmal nocturnal dystonia and nocturnal wanderings may be associated with epilepsy. Intrusions of one state of being (wakefulness, non-REM sleep, and REM sleep) into another result in mixed, poorly defined, or only partially developed states. Dissociation of states may be responsible for confusional arousals, hallucinations, and cateplexy. Senile degeneration of the suprachiasmatic nuclei may underlie the circadian rhythm changes in old age and the "sundown" syndrome in demented patients. Misalignment of the hypothalamic pacemaker causes dysregulation of sleep-related physiologic and behavioral variables. Exposure to bright light retrains the pacemaker in night-shift workers, transmeridian travelers, and in patients with seasonal affective syndrome. Benzodiazepine compounds are very effective hypnotics, but should be used sparingly in the elderly to avoid falls, memory lapses, and aggravation of a preexisting sleep apnea syndrome. Sleep laboratory evaluations are indicated in patients with hypersomnia, suspected sleep apnea syndrome, motor-behavioral disorders of sleep, and in many individuals complaining of insomnia.

Age Factors↗
PubMed1992

Neuroanatomic and neurologic correlates of sleep disturbances.

The cyclic alternations of wakefulness and sleep competing for the domain of brain activity are controlled by neuronal systems contained in the core of the brainstem, hypothalamus, thalamus, and basal forebrain. This organization encompasses complex neuroanatomic, neurophysiologic, and neurochemical mechanisms that are subject to disruption from within, or as a result of incidental alterations of appropriate brain centers. The first section of this article reviews the wake-sleep disturbances that occur with lesions in defined neuroanatomic structures involved in sleep mechanisms, such as the brainstem, hypothalamus, thalamus, and cerebral hemispheres. The second section gives an overview of specific sleep alterations associated with neurologic disorders. These include stroke, Parkinson's disease, degenerative systemic disorders, multiple sclerosis, myotonic dystrophy, myasthenia gravis, brain tumors, head trauma, coma, epilepsy, and headache syndromes.

Brain↗
PubMed1990

The practice of neurosomnology.

Since the application of electrophysiologic methods borrowed from the EEG laboratory to the study of sleeping humans, sleep disorders medicine has acquired the scientific organization necessary for its acceptance in the modern clinic. Although still in evolution, the medical science of sleep is becoming increasingly linked to the functions of the brain, carving in the territory of neurology a parcel of its own that we call neurosomnology. Patients referred to the sleep disorders specialist receive an initial evaluation that includes general medical, neurologic and when appropriate other specialized examinations. In the sleep laboratory patients undergo nocturnal and daytime polysomnographic recordings which incorporate electrical brain activity, eye movements, muscle tone, EKG, limb movements, respirations, oximetry and in special circumstances penile tumescence. Scoring of the record is performed by a trained technologist and final interpretation is made by the clinical polysomnographer. The final diagnosis is discussed by the multidisciplinary team and recommendations are given at a follow-up visit by the sleep disorders specialist. Therapeutic management includes sleep hygiene, psychological support, pharmacologic treatment, ventilatory assistance and surgical interventions.

Electroencephalography↗
PubMed1989

Computed tomographic study of cervical carotid calcification.

Contrast-enhanced computed tomography of the neck permits low-risk evaluation of morphologic complications of carotid plaque, including (and foremost) calcification. To investigate the patterns and clinical significance of calcified deposits in the cervical carotid arteries using computed tomography we studied 40 patients with unilateral symptoms of hemispheric ischemia. Calcium deposits observed in the external, internal, and common carotid arteries were oriented in space and individually scored. We found calcified deposits in 39 patients. Stepwise multiple regression of the data provided evidence strongly suggesting a correlation between advancing age and calcium scores. Calcium was more heavily concentrated in the posterior half of arteries (p less than 0.01), in particular of the internal and common carotid arteries, and always in relation to an atheromatous plaque, suggesting a causative link to hemodynamic forces within the arteries. There was no difference in calcification scores between symptomatic and asymptomatic sides, indicating that calcium deposits do not contribute to the development of symptoms.

Adult↗
PubMed1989

Magnetic resonance findings in REM sleep behavior disorder.

Rapid eye movement (REM) sleep behavior disorder is characterized by bizarre acts during nocturnal sleep that may lead to physical injuries. Dream content suggests that motor overactivity is an attempted dream enactment and polygraphic studies reveal REM stage without atonia, an alteration of REM sleep generation that facilitates excessive motor activity. In 6 patients with REM sleep behavior disorder. MRI of the brain showed multifocal signal intensity lesions suggestive of lacunar infarcts in periventricular regions (5 patients) and in dorsal pontomesencephalic areas (3 patients). REM sleep behavior disorder may be the result of injury to the midrostral tegmentum nuclei, the tegmentoreticular tracts, or both. This condition is easily controlled with clonazepam.

Aged↗
PubMed1988

Computed tomography of the cervical carotid artery: significance of the lucent defect.

To investigate the clinical significance of lucent defects in computed tomography (CT) scans of the cervical carotid artery plaque, we studied 95 patients with recent symptoms of hemispheric ischemia. Using multiple linear regression analysis, we estimated the strength of the association of symptoms with laterality of carotid artery lucent lesions, stenoses, and ulcerations observed in CT scans. Hemispheric symptoms correlated strongly with ipsilateral carotid lucent lesions (partial p less than 0.025) and with ipsilateral severe (greater than 75%) carotid stenosis (partial p less than 0.025). Carotid artery ulcerations had a weaker association (partial p less than 0.1), and stenoses of mild and moderate degrees showed none. The overall performance of all three plaque complications was highly significant (p less than 0.005). The lucent defect indicates a morphologic change in the carotid plaque that plays an important role in the development of symptoms of hemispheric ischemia. This is in agreement with the notion that the lucent defect is the image of intraplaque hemorrhage and/or necrosis, which are complications central to the development of symptomatic carotid disease.

Carotid Artery Diseases↗
PubMed1988

The effect of epileptiform discharges on neurohormonal release in epileptic patients with complex partial seizures.

We compared the nocturnal plasma prolactin (PRL) and beta-endorphin (B-E) concentrations prior to and after sleep deprivation (SD) in eight epileptic patients with complex partial seizures. After the period of SD (1) the mean number of interictal epileptiform discharges and the mean plasma PRL levels showed a significant rise during light non-REM stages of sleep, and (2) mean nocturnal plasma PRL and B-E concentrations showed a moderate rise during the first few hours of sleep, significant only for plasma PRL. In a patient with multiple complex partial seizures during sleep, the levels of plasma PRL and B-E concentrations were closely related to ictal discharges. The data obtained in this stress-free environment suggest a centrally mediated interaction between the release of PRL and B-E, in relation to epileptic discharges.

Adult↗
PubMed1987

Nocturnal plasma prolactin and cortisol levels in epileptics with complex partial seizures and primary generalized seizures.

The nocturnal pattern of plasma prolactin (PRL) and cortisol in male epileptics with complex partial seizures and primary generalized seizures was studied by all-night polygraphic recordings with continuous video monitoring and sequential blood sampling at 30-minute intervals. Mean nocturnal plasma PRL concentrations in both groups of epileptics were significantly elevated when compared with nonepileptic control subjects studied in a similar fashion. Eight subclinical and three clinical partial seizures were recorded during sleep. Although a tenfold increase of plasma PRL level occurred following a short brief clinical complex partial seizure, there was no direct correlation between single subclinical partial seizures and nocturnal fluctuations of plasma PRL concentrations. We did not observe recognizable plasma cortisol changes following partial seizures during sleep, nor significant differences of mean nocturnal plasma cortisol levels between epileptics and controls. The data obtained in this environmentally controlled study indicate that postictal elevation of plasma PRL is a specific phenomenon related to seizure discharges; however, failure of such a rise does not exclude partial seizures.

Adult↗
PubMed1987

Computed tomographic evaluation of extracranial carotid artery disease.

Axial computed tomographic (CT) scans after intravenous contrast infusion were used to image the cervical carotid arteries of patients with cerebral ischemic symptoms. Standard transfemoral cervical carotid and cerebral angiography was the principal diagnostic modality used in all patients studied. The angiographic results were compared to the CT images and to the gross and microscopic endarterectomy pathological specimens, when available. Examples of the various types of abnormalities that can be visualized using CT scans are presented. The CT scan was useful for determining the presence of degenerative atheromatous changes including carotid artery calcification, subintimal hemorrhage, carotid occlusion, carotid segmental occlusion, and carotid pseudoocclusion, as well as carotid artery dissection. The scans were particularly useful for identification of atheromatous carotid artery disease when the carotid angiogram appeared nearly normal and for identifying the cause of postoperative carotid stenosis. CT scanning allows visualization of the carotid artery wall and lumen rather than just the lumen and, consequently, can sometimes add helpful information about the pathological processes affecting this artery.

Arterial Occlusive Diseases↗
PubMed1985

Nocturnal plasma prolactin rise in patients with complex partial seizures.

We measured plasma prolactin and cortisol concentrations in 12 epileptic men with complex partial seizures during all-night polygraphic recording, with continuous video monitoring and sequential blood sampling at 30-minute intervals. There was a significant but moderate elevation of all-night mean plasma prolactin concentration (p less than 0.001), but not of cortisol, in epileptics when compared with normal subjects studied in a similar fashion. The data obtained in this environmentally controlled study of males with complex partial seizure disorder indicate a disruption of prolactin regulatory mechanisms resulting in a modest elevation of plasma concentrations independent of ictal electrographic discharges.

Adult↗
PubMed1985

Atheromatous extracranial carotid arteries: CT evaluation correlated with arteriography and pathologic examination.

Dynamic, rapid sequence, axial computed tomography (CT) was employed to evaluate the extracranial common and internal carotid arteries in 17 patients with clinical histories suggesting recent or remote ischemia in the territory supplied by the internal carotid artery. The CT findings were correlated with arteriographic observations and with gross and histologic evaluations of endarterectomy specimens. Areas of arterial wall thickening were evaluated on CT scans with regard to both degree of thickening and radiographic density (attenuation). The degree of vessel wall thickening secondary to atheromatous plaque demonstrated on CT scans corresponded closely to the severity of luminal compromise seen on arteriograms. Isodense or mildly hypodense focal mural thickening noted on CT scans of seven endarterectomy specimens proved to be primarily fibrotic (simple) atheromatous plaque on gross and histologic examination. Areas of markedly lucent focal mural thickening on CT scans of 11 specimens all demonstrated varying amounts of subintimal hemorrhage within loosely arranged and rather acellular (complex) atheromatous plaques on pathologic examination. While arteriography provides information regarding the status of the arterial lumen, CT offers the potential of accurate characterization of pathologic changes in the wall of the extracranial carotid arteries in patients with symptoms of cerebral ischemia.

Adult↗
PubMed1985

Failure of postictal growth hormone rise in a patient with thalamic lesions.

A patient with bilateral thalamic lesions had a spontaneous generalized convulsion during nocturnal polygraphic recording. Postictal measurements of cortisol and prolactin showed the expected rise of plasma values at 30 and 60 minutes after the seizure, but growth hormone did not increase. This observation suggests that suprahypothalamic mechanisms regulating growth hormone release differ from those involved in the neural control of cortisol-ACTH and prolactin secretion. The thalamus may intervene as a regulatory center in the release of growth hormone.

Adult↗
PubMed1984

Dissociated patterns of nocturnal prolactin, cortisol, and growth hormone secretion after stroke.

The secretory activity of the hypothalamic-pituitary axis is influenced by suprahypothalamic regulatory mechanisms. To evaluate the effect of brain lesions on hormonal patterns, we investigated eight patients convalescing from hemispheric stroke and five sex- and age-matched healthy volunteers. Studies were conducted during two consecutive nights with continuous polygraphic recording and sequential blood sampling. Nocturnal plasma hormone measurements showed a normal rhythm of cortisol (a marker of ACTH), elevated prolactin concentrations (p less than 0.05) and low growth hormone values (p less than 0.05). The study suggests that major suprahypothalamic lesions influence hypothalamic function so as to facilitate prolactin secretion and inhibit growth hormone release. They have no effect on the more basic pattern of ACTH-cortisol secretion, however.

Adrenocorticotropic Hormone↗
PubMed1983

Absence of sleep-related elevation of growth hormone level in patients with stroke.

To determine the effect of defined suprahypothalamic lesions on sleep-related growth hormone (GH) secretion, eight patients with hemispheric lesions of vascular origin were studied in a sleep laboratory on two consecutive nights. Despite the normal onset and increased time spent in slow-wave sleep (SWS), the patients failed to show the nocturnal rise in plasma GH concentration that occurred in association with onset of SWS in five age-matched healthy subjects. Arginine hydrochloride infusion in the patients produced a normal GH rise, indicating integrity of the hypothalamic-pituitary axis. Dissociation between SWS and GH secretion in patients with suprahypothalamic damage suggests that cortical-subcortical structures are involved in the integration of SWS with nocturnal GH secretion. There is support for the presence of a thalamic regulatory center responsible for the control of GH release during sleep.

Aged↗
PubMed1983

The failed penile prosthetic implantation despite technical success.

Successful implantation of a penile prosthesis involves more than an operation. Psychological factors can be crucial before, during and after the operation. If these issues are not addressed the true goal of restoring the pleasure of sexual intercourse will not be achieved, regardless of the type of prosthesis used or the technical success of the procedure.

Adult↗