Hydrocephalus secondary to obstruction of the lateral apertures in two dogs.

BACKGROUND: Traditionally, hydrocephalus is divided into communicating or non-communicating (obstructive) based on the identification of a blockage of cerebrospinal fluid (CSF) flow through the ventricular system. Hydrocephalus ex vacuo refers to ventricular enlargement as a consequence of neuroparenchymal loss. Hydrocephalus related to obstruction of the lateral apertures of the fourth ventricles has rarely been described. CASE REPORT: The clinicopathologic findings in two dogs with hydrocephalus secondary to obstruction of the lateral apertures of the fourth ventricle are reported. Signs were associated with a caudal cervical spinal cord lesion in one dog and a caudal brain stem lesion in the other dog. Magnetic resonance imaging (MRI) disclosed dilation of the ventricular system, including the lateral recesses of the fourth ventricle. In one dog, postmortem ventriculography confirmed obstruction of the lateral apertures. Microscopic changes were identified in the choroid plexus in both dogs, yet a definitive cause of the obstructions was not identified. The MRI findings in both dogs are similar to membranous occlusion of the lateral and median apertures in human patients. CONCLUSION: MRI detection of dilation of the entire ventricular system in the absence of an identifiable cause should prompt consideration of an obstruction of the lateral apertures. In future cases, therapeutic interventions aimed at re-establishing CSF flow or ventriculoperitoneal catheterisation should be considered.

Hemodynamic and psychological responses to laboratory stressors in women: assessing the roles of menstrual cycle phase, premenstrual symptomatology, and sleep characteristics.

This study assessed whether premenstrual symptomatology and/or sleep characteristics explain increased luteal phase psychophysiological reactivity to laboratory stressors. We hypothesized that: (1) premenstrual symptoms and sleep characteristics would explain greater luteal versus follicular phase psychophysiological reactivity, (2) symptoms and sleep characteristics would differentially predict psychophysiological reactivity within each cycle phase, and (3) symptoms and sleep characteristics would interact to affect luteal but not follicular reactivity. Freely cycling women (N=87) completed two laboratory sessions, one follicular (cycle days 5-9) and one luteal (days 7-10 post-ovulation). We employed two stressors: one physical (cold pressor task) and the other cognitive in nature (Paced Auditory Serial Addition Task). During testing, electrocardiography monitored heart rate (HR) while a timed and auto-inflatable sphygmomanometer assessed blood pressure (BP). Participants also completed a one-time self-report measure of sleep characteristics and premenstrual symptomatology as well as a measure of state anxiety pre-post stressor. Results revealed greater luteal HR and systolic BP reactivity compared to follicular reactivity (p<0.001 for both analyses), however neither premenstrual symptoms nor sleep characteristics explained this luteal increase. Within cycle analyses revealed that symptoms and sleep characteristics interacted to affect luteal phase state anxiety reactivity (R(2)=.32, p=.002) with negative affect being associated with more reactivity when sleep hours were low (ß=.333, p=.04). Overall, significant relationships existed during the luteal phase only. Findings are discussed in terms of clinical utility and methodological challenges related to performing laboratory stress testing in women.

Cardiovascular responses to a laboratory stressor in women: Assessing the role of body awareness.

Body awareness (BA) is characterised by a general tendency towards awareness and recognition of normal, non-emotive bodily processes and physical sensations. BA considers one's sensitivity towards and belief in how well they can sense, predict, and describe their bodily functions and sensations. This study investigated the role of BA in haemodynamic and anxiety responses to a laboratory stressor. Women (n = 40) completed assessments of BA and state/trait anxiety. Women with low BA displayed higher blood pressure (BP) and heart rate (HR) reactivity in response to the stressor than women with high BA. Delayed HR recovery poststressor was observed in women with low BA. BA was a significant predictor of haemodynamic reactivity over and above trait anxiety. BA effects on state anxiety were not observed. Thus, greater BA is associated with less haemodynamic stress reactivity in women lending further support for the development of BA interventions aimed at stress reduction.