Detection of optic pathway misrouting in the human albino neonate.

The diagnosis of albinism is indicated by the presence of visual pathway misrouting in which temporal retinal fibers erroneously decussate at the optic chiasm disrupting the normal topographical distribution of retinal geniculate-cortical projections. Detection of misrouted fibers is effected by non-invasive electrophysiological assessment of the topographical representation of the visual evoked potential (VEP) following full field monocular stimulation. By combining appropriate state defined neonatal recording procedures with the albino VEP test paradigm, the presence of aberrant optic pathway projections was detected in a five-day-old full-term infant. The electrophysiological signature pathognomonic to albinism was observed within a long (300 ms) latency window of an otherwise normal neonatal luminance flash response. The results of this study indicate that the VEP misrouting test can be extended to reliable albino diagnosis within the neonatal period.     

Inpatient treatment of children with multiple personality/dissociative disorders and their families

A number of children who are admitted for inpatient psychiatric treatment have experienced significant trauma and abuse. It is important to evaluate them for the presence of a DD. The variety, complexity, and subtlety of the symptomatic presentation of childhood MPD makes differential diagnosis difficult, and it is probable that many cases have been missed in the past. Detailed historical information and extensive behavioral observations in a variety of settings can assist in establishing the diagnosis and in delineating areas for therapeutic intervention. Hospitalization may be necessary to conduct an adequate evaluation, develop a therapeutic alliance, safely manage behaviors that are injurious to the child or others, and/or to diffuse potentially volatile family situations. All members of a multidisciplinary inpatient team play important roles in the achievement of successful therapeutic intervention with dissociating children and their families. Skilled family therapy is often an important adjunct to therapeutic interventions focused on the child, particularly when the parent also has MPD. Knowledge of the psychodynamic issues involved in dissociation can be used to develop behavioral interventions that are successful in decreasing the child's need to dissociate, improving his or her overall functioning, and help him or her gain mastery over problematic behaviors.     

Response to treatment in panic disorder with associated depression

Thirty outpatients with panic disorder (PD) were treated at an anxiety clinic using a symptom-focused approach. Thirteen (43%) had no history of major depressive disorder (MDD), 12 (40%) had a history of secondary MDD, and 5 (17%) had history of primary MDD. The outcome was equally good in patients with no history of MDD (77% had good or excellent outcomes) and patients with a history of secondary MDD (83% had good or excellent outcomes). Patients with a history of primary MDD had the worst outcomes. These findings agree with earlier studies showing that secondary MDD does not adversely affect prognosis of patients presenting for treatment of PD.     

Pediatric intracranial pressure monitoring in hypoxic and nonhypoxic brain injury

We reviewed the results of all pediatric patients undergoing intracranial pressure (ICP) monitoring in a 2-year period at our institution. The outcome of patients suffering hypoxia or ischemic injuries (HII) is compared to those suffering non-hypoxic or non-ischemic injuries (NHII). Thirty-four patients had ICP monitors placed during the study period. Inconplete patient information led to the exclusion of 5 patients. An additional 5 patients were excluded because no measures to control ICP were taken after the monitor was placed. Twenty-four patients required treatment for raised ICP (hyperventilation, 24; mannitol, 19; barbiturate coma, 6). Admission Glasgow Coma Score in patients suffering HII (median score 5) and NHII (median score 6) were not significantly different (Mann-Whitney U Test). Only 2 of 8 patients with HII were near-drowning vietims. The remaining 6 had HII from other causes (5 survivors of various forms of asphyxia and 1 of cardiac arrest). All 8 patients had poor outcomes (1 severely disabled; 7 died). The 16 patients with NHII had a variety of diagnoses (6 trauma, 5 encephalitis, 4 bacterial meningitis, 1 diabetic ketoacidosis). Among these, 6 had good outcomes and 10 poor outcomes (2 severely disabled, 2 vegetative, and 6 died). The difference in outcome between patients with NHII and HII is significant at P=0.059 (Fischer Exact test). Patients with NHII may benefit from ICP monitoring. Patients with HII from near-drowning and other causes did not appear to benefit from ICP monitoring and interventions directed at controlling ICP.     

Extracellular serotonin levels change with behavioral state but not with pyrogen-induced hyperthermia.

Extracellular 5-HT in the anterior hypothalamus/preoptic area (AH/POA) and caudate nucleus of the freely moving cat was measured using in vivo brain microdialysis. Administration of 8-OH-DPAT, a 5-HT1A receptor agonist that decreases 5-HT neuronal activity, decreased extracellular 5-HT in both brain areas. Extracellular 5-HT levels were also examined in relationship to the sleep-wake cycle, because previous data from our laboratory have indicated that behavioral state is the primary determinant of 5-HT neuronal discharge. As with 5-HT neuronal discharge, extracellular 5-HT was increased during active behavioral states and decreased during somnolent periods. These first two sets of findings confirm the ability of the microdialysis technique to measure physiological fluctuations in extracellular 5-HT levels and support the hypothesis that neuronal discharge is a major determinant of extracellular 5-HT levels. Levels of the 5-HT metabolite 5-hydroxyindole acetic acid (5-HIAA) in the AH/POA were also responsive to changes in behavioral state and administration of 8-OH-DPAT, though fluctuations in extracellular 5-HIAA were less robust and temporally delayed. Finally, extracellular 5-HT and 5-HIAA were examined in the AH/POA during fever induced by systemic injection of the synthetic pyrogen muramyl dipeptide. Previous data from our laboratory have indicated that 5-HT neuronal activity is unaffected by this manipulation, though 5-HT has been implicated specifically in thermoregulation. Pyrogen-induced hypothermia produced no specific change in 5-HT efflux, because any changes noted could be accounted for by behavioral state changes. These data are consistent with the hypothesis that the brain serotonergic system is closely linked to the sleep-wake-arousal cycle. However, extracellular 5-HT may be involved in thermoregulatory processes as part of a global role in modulating neuronal activity in coordination with the behavioral state of the animal.     

Extracellular dopamine and neurotensin in rat prefrontal cortex in vivo: effects of median forebrain bundle stimulation frequency, stimulation pattern, and dopamine autoreceptors

In vivo microdialysis coupled with HPLC and radioimmuno-assay techniques were used to analyze dopamine (DA) and neurotensin (NT) in prefrontal cortical extracellular fluid following electrical stimulation of mesocortical axons. The release (overflow into the extracellular fluid) of both DA and NT increased with increasing number of impulses and with frequency. At the lowest frequency tested (2.5 Hz), DA release was significantly increased, while there was no significant increase in the release of NT. As the frequency of stimulation was increased from 2.5 to 20 Hz, the ratio of extracellular DA:NT decreased exponentially. Stimulation in a burst pattern produced greater release of both DA and NT than tonic stimulation when the number of impulses per second and the total number of impulses were held constant. Furthermore, blockade of DA autoreceptors with sulpiride stereoselectively increased the release of DA while decreasing the release of NT. These data suggest that the release of coexistent molecules (DA and NT) from mesocortical neurons can be influenced by physiological and pharmacological factors such that under certain conditions simultaneous or differential release may occur.     

Single-channel K+ currents recorded from the somatic and dendritic regions of cerebellar Purkinje neurons in culture

Voltage-sensitive K+ channels were studied in rat cerebellar Purkinje neurons in culture using the single-channel recording technique. Recordings in the cell-attached and outside-out configuration revealed multiple voltage-sensitive K+ channel types in patches from both the somatic and the dendritic regions. K+ channel types were present in all patches studied. The same channel types were observed in somatic and dendritic recordings. Channel types were identified by reversal potential, single-channel conductance, voltage sensitivity, and patterns of activity. In cell-attached patches recorded under physiological conditions, 3 channel types were identified. Mean single-channel conductances were 92, 57, and 12 pS. All 3 channel types were activated by membrane depolarization. Similar channel types were identified in inside-out and outside-out patches recorded under physiological conditions. Two additional channel types were identified in the outside-out patches, with mean single-channel conductances of 41 and 26 pS. In cell-attached recordings under symmetrical K+ conditions, 6 channel types were identified. Mean single-channel conductances were 222, 134, 39, 25, 14, and 15 pS. Channel types with mean conductances of 222, 134, and 39 pS required membrane depolarization for activation. A comparison of channel properties indicated that these channel types correlated with the 3 channel types observed in cell-attached patches under physiological conditions. The 3 smaller-conductance channel types (25, 14, and 15 pS) were active at potentials around rest or at hyperpolarized membrane potentials. Two K+ channel types (39 and 25 pS) were commonly associated with the late phase of extracellularly recorded spontaneous spike events, suggesting a functional role in the repolarizing phase of somatic and dendritic action potentials. These results demonstrate that voltage-sensitive K+ channels are a prominent component of both the somatic and the dendritic membrane of the cerebellar Purkinje neuron and support the view that multiple voltage-sensitive K+ channel types contribute to the membrane functions of both cellular regions in this CNS neuronal type.     

The effects of hyponatraemia and subarachnoid haemorrhage on the cerebral vasomotor responses of the rabbit

Impairment of cerebral autoregulation and development of hyponatraemia are both implicated in the pathogenesis of delayed cerebral ischaemia and infarction following subarachnoid haemorrhage (SAH) but the pathophysiology and interactions involved are not fully understood. We have studied the effects of hyponatraemia and SAH on the cerebral vasomotor responses of the rabbit. Cerebrovascular reactivity to hypercapnia and cerebral autoregulation to trimetaphan-induced hypotension were determined in normal and hyponatraemic rabbits before and 6 days after experimental SAH produced by two intracisternal injections of autologous blood. Hyponatraemia (mean plasma sodium of 119 mM) was induced gradually over 48 h by administration of Desmopressin and intraperitoneal 5% dextrose. Sham animals received normal saline. The cerebrovascular reactivity (% change +/- SD in cortical CBF/mm Hg PaCO2, measured by hydrogen clearance) of hyponatraemic (4.8 +/- 3.0%) and SAH (1.3 +/- 2.0%) animals was significantly less (p less than 0.05) than control (11.6 +/- 4.0%) and sham (8 +/- 2.0%) animals, whereas the reactivity of hyponatraemic-SAH animals was preserved (9.8 +/- 6.0%). Hyponatraemia and SAH alone each significantly impaired CBF autoregulation but their combined effects were not additive. Systemic hyponatraemia impairs normal cerebral vasomotor responses but does not augment the effects of experimental SAH in the rabbit.     

A benign tumor of the sciatic nerve: case report and review of the literature

Tumors arising from the sciatic nerve are a rare occurrence. A case is described of such a tumor developing as a large painless mass in the posterior right midthigh. The preoperative diagnosis was easily achieved by means of ultrasonography and computed tomography. Excision of the tumor, with preservation of the involved nerve, was performed. Microscopic examination showed a neurofibroma with however some features of a schwannoma. Problems of histological diagnosis and treatment are emphasized.