Rapid changes in cerebrovascular compliance during vasovagal syncope.

Purpose: The compensatory mechanisms supporting cerebral perfusion throughout head-up tilt (HUT) in patients with vasovagal syncope (VVS) remain unclear. We tested the hypothesis that increased cerebrovascular compliance (Ci) and decreased cerebrovascular resistance (CVR) support cerebral blood velocity (CBV) during pre-syncope in VVS.

Methods: Finger arterial blood pressure (ABP) and right middle cerebral artery blood velocity (CBV) were recorded in 15 individuals diagnosed with VVS (n = 11 female, mean age: 40 ± 16 years, mean body mass index: 24.

Canadian Cardiovascular Society Position Statement on Postural Orthostatic Tachycardia Syndrome (POTS) and Related Disorders of Chronic Orthostatic Intolerance.

The current definition of postural orthostatic tachycardia syndrome (POTS) dates back to a small case series of patients with a subacute illness who presented with excessive orthostatic tachycardia and orthostatic intolerance, in the absence of another recognized disease. Conventional POTS criteria require an excessive orthostatic tachycardia in the absence of substantial orthostatic hypotension, and predominant symptoms of orthostatic intolerance, worse with upright posture and better with recumbence. POTS is a heterogeneous syndrome with likely several underlying pathophysiological processes, and not a specific disease.

Prediction of the Time to Syncope Occurrence in Patients Diagnosed with Vasovagal Syncope.

Objective: In this study we aimed to predict the time to syncope occurrence (TSO) in patients with vasovagal syncope (VVS), solely based on measurements recorded during the supine position of the head-up tilt (HUT) testing protocol.

Methods: We extracted various time and frequency domain features related to morphological aspects of arterial blood pressure (ABP) and the electrocardiogram (ECG) raw signals as well as to dynamic interactions between beat-to-beat ABP, heart rate, and cerebral blood flow velocity. From these we identified the most predictive features related to TSO.

Impact of cancer and chemotherapy on autonomic nervous system function and cardiovascular reactivity in young adults with cancer: a case-controlled feasibility study.

Background: Preliminary evidence suggests cancer- and chemotherapy-related autonomic nervous system (ANS) dysfunction may contribute to the increased cardiovascular (CV) morbidity- and mortality-risks in cancer survivors. However, the reliability of these findings may have been jeopardized by inconsistent participant screening and assessment methods. Therefore, good laboratory practices must be established before the presence and nature of cancer-related autonomic dysfunction can be characterized.

Adult-onset painful axonal polyneuropathy caused by a dominant NAGLU mutation.

Late-onset painful sensory neuropathies are usually acquired conditions associated with common diseases. Adult presentations of known hereditary forms are often accompanied by other organ involvement. We recruited a large French-Canadian family with a dominantly inherited late-onset painful sensory neuropathy.

Rhabdomyolysis and peroneal nerve compression associated with thyroid hormone withdrawal in the setting of remnant ablation: review of the literature.

Objective: To review the putative mechanisms whereby hypothyroidism is associated with severe myopathy, neural injury, and acute compartment syndrome and report a case of nontraumatic common peroneal nerve compression associated with hypothyroidism-induced rhabdomyolysis in a patient with diabetes prepared for remnant ablation after thyroidectomy for differentiated thyroid carcinoma.

Methods: We performed a review of the English-language literature on the PubMed database using the terms hypothyroidism, muscle disease, hypothyroid myopathy, rhabdomyolysis, compression neuropathy, and acute compartment syndrome.

Results: Myopathy occurs frequently among patients with overt hypothyroidism; however, severe myoneural injury seems to be precipitated or accompanied by comorbid conditions.

Syncope: case studies.

In this series of clinical vignettes, the authors have attempted to provide a "feel" for the varied causes of syncope. The neurologist should be able to diagnose most causes of syncope using a simple algorithmic approach. Initial evaluation includes detailed clinical history, physical examination, and 12-lead ECG.

Cerebral autoregulation is preserved in postural tachycardia syndrome.

To test whether cerebral autoregulation is impaired in patients with postural tachycardia syndrome (POTS), we evaluated 17 healthy control subjects and 27 patients with POTS. Blood pressure, heart rate, and cerebral blood velocity (transcranial Doppler) were recorded at rest and during 80 degree head-up tilt (HUT). Static cerebral autoregulation, as assessed from the change in cerebrovascular resistance during HUT, was the same in POTS and in controls.

Unconscious confusion--a literature search for definitions of syncope and related disorders.

Background: Imprecise definitions of syncope and related conditions appear common in the medical literature. To investigate the scope of the problem we systematically searched for definitions in high-ranking medical journals.

Methods: Literature review of articles on 'syncope', 'neurocardiogenic syncope', 'neurally mediated syncope', 'orthostatic intolerance', and 'orthostatic hypotension' with these keywords in the title, mainly published in the ten journals with the highest impact in the fields of cardiology, internal medicine, and neurology.

Sleep quality and psychological adjustment in chronic fatigue syndrome.

Without specific etiology or effective treatment, chronic fatigue syndrome (CFS) remains a contentious diagnosis. Individuals with CFS complain of fatigue and poor sleep--symptoms that are often attributed to psychological disturbance. To assess the nature and prevalence of sleep disturbance in CFS and to investigate the widely presumed presence of psychological maladjustment we examined sleep quality, sleep disorders, physical health, daytime sleepiness, fatigue, and psychological adjustment in three samples.

Electrodermal activity in patients with neurally mediated syncope.

Electrodermal activity (EDA) increases during arousal, emotional stimuli or thermoregulatory sweating and is sometimes apparent in unfiltered ECG recordings. We hypothesized that changes in EDA precede any change in blood pressure (BP) or cerebral blood velocity (CBV) observed at syncope. Data from 70 patients referred for recurrent syncope were retrospectively analyzed.

Chronic fatigue syndrome: what role does the autonomic nervous system play in the pathophysiology of this complex illness?

Chronic fatigue syndrome (CFS) is a serious health concern affecting over 800000 Americans of all ages, races and socioeconomic groups and both genders. The etiology and pathophysiology of CFS are unknown, yet studies have suggested an involvement of the autonomic nervous system (ANS). A symposium was organized in December 2000 to explore the possibility of an association between ANS dysfunction and CFS, with special emphasis on the interactions between ANS dysfunction and other abnormalities noted in the immune and endocrine systems of individuals with CFS.