Complete remission with histamine blocker in a patient with intractable hyperadrenergic postural orthostatic tachycardia syndrome secondary to long coronavirus disease syndrome

The COVID-19 pandemic caused by the novel severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), has emerged as a global public health concern and its sequels have barely started to outcrop. A good percentage of patients who suffered from COVID-19 are prone to develop long-COVID or post-COVID condition (PCC), a multisystemic, heterogeneous, chronic disorder. Patients with PCC may experience diverse manifestations, of which cardiovascular and neurological symptoms are among the most frequently reported. Indeed, dysautonomia presented as orthostatic intolerance has gained room following recent reports linking postural orthostatic tachycardia syndrome (POTS) with PCC. Disturbances in heart rate (HR) and blood pressure (BP) during postural changes are the cornerstones of orthostatic intolerance seen in patients suffering from PCC. A subtype of POTS, hyperadrenergic POTS, has been widely studied because of its association with mast cell activation syndrome (MCAS). Although a causative relationship between PCC, hyperadrenergic POTS, and MCAS remains unrevealed, these syndromes can overlap. We want to propose here a correlation produced by a close-loop mechanism with positive feedback established after SARS-CoV-2 infection in a previously healthy young patient.

Optogenetic and Chemogenic Control of Pain Signaling: Molecular Markers

Pain is a complex experience that involves physical, emotional, and cognitive aspects. This review focuses specifically on the physiological processes underlying pain perception, with a particular emphasis on the various types of sensory neurons involved in transmitting pain signals to the central nervous system. Recent advances in techniques like optogenetics and chemogenetics have allowed researchers to selectively activate or inactivate specific neuronal circuits, offering a promising avenue for developing more effective pain management strategies. The article delves into the molecular targets of different types of sensory fibers such as channels, for example, TRPV1 in C-peptidergic fiber, TRPA1 in C-non-peptidergic receptors expressed differentially as MOR and DOR, and transcription factors, and their colocalization with the vesicular transporter of glutamate, which enable researchers to identify specific subtypes of neurons within the pain pathway and allows for selective transfection and expression of opsins to modulate their activity.

Sex Differences in the Physiological Network of Healthy Young Subjects

Within human physiology, systemic interactions couple physiological variables to maintain homeostasis. These interactions change according to health status and are modified by factors such as age and sex. For several physiological processes, sex-based distinctions in normal physiology are present and defined in isolation. However, new methodologies are indispensable to analyze system-wide properties and interactions with the objective of exploring differences between sexes. Here we propose a new method to construct complex inferential networks from a normalization using the clinical criteria for health of physiological variables, and the correlations between anthropometric and blood tests biomarkers of 198 healthy young participants (117 women, 81 men, from 18 to 27 years old). Physiological networks of men have less correlations, displayed higher modularity, higher small-world index, but were more vulnerable to directed attacks, whereas networks of women were more resilient. The networks of both men and women displayed sex-specific connections that are consistent with the literature. Additionally, we carried out a time-series study on heart rate variability (HRV) using Physionet's Fantasia database. Autocorrelation of HRV, variance, and Poincare's plots, as a measure of variability, are statistically significant higher in young men and statistically significant different from young women. These differences are attenuated in older men and women, that have similar HRV distributions. The network approach revealed differences in the association of variables related to glucose homeostasis, nitrogen balance, kidney function, and fat depots. The clusters of physiological variables and their roles within the network remained similar regardless of sex. Both methodologies show a higher number of associations between variables in the physiological system of women, implying redundant mechanisms of control and simultaneously showing that these systems display less variability in time than those of men, constituting a more resilient system.

Cardiovascular dysautonomia in Achalasia Patients: Blood pressure and heart rate variability alterations

Achalasia is a disease characterized by the inability to relax the esophageal sphincter due to a degeneration of the parasympathetic ganglion cells located in the wall of the thoracic esophagus. Achalasia has been associated with extraesophageal dysmotility, suggesting alterations of the autonomic nervous system (ANS) that extend beyond the esophagus. The purpose of the present contribution is to investigate whether achalasia may be interpreted as the esophageal manifestation of a more generalized disturbance of the ANS which includes alterations of heart rate and/or blood pressure. Therefore simultaneous non-invasive records of the heart inter-beat intervals (IBI) and beat-to-beat systolic blood pressure (SBP) of 14 patients (9 female, 5 male) with achalasia were compared with the records of 34 rigorously screened healthy control subjects (17 female, 17 male) in three different conditions: supine, standing up, and controlled breathing at 0.1 Hz, using a variety of measures in the time and spectral domains. Significant differences in heart rate variability (HRV) and blood pressure variability (BPV) were observed which seem to be due to cardiovagal damage to the heart, i.e., a failure of the ANS, as expected according to our hypothesis. This non-invasive methodology can be employed as an auxiliary clinical protocol to study etiology and evolution of achalasia, and other pathologies that damage ANS.

A physicist's view of homeostasis: how time series of continuous monitoring reflect the function of physiological variables in regulatory mechanisms

OBJECTIVE

Homeostasis is one of the key concepts of physiology and the basis to understand chronic-degenerative disease and human ageing, but is difficult to quantify in clinical practice. The variability of time series resulting from continuous and non-invasive physiological monitoring is conjectured to reflect the underlying homeostatic regulatory processes, but it is not clear why the variability of some variables such as heart rate gives a favourable health prognosis whereas the variability of other variables such as blood pressure implies an increased risk factor. The purpose of the present contribution is to quantify homeostasis using time-series analysis and to offer an explanation for the phenomenology of physiological time series.

APPROACH

Within the context of network physiology, which focusses on the interactions between various variables at multiple scales of time and space, it may be understood that different physiological variables may play distinct roles in their respective regulatory mechanisms. In the present contribution, we distinguish between regulated variables, such as blood pressure or core temperature, and physiological responses, such as heart rate and skin temperature.

MAIN RESULTS

We give evidence that in optimal conditions of youth and health the former are characterized by Gaussian statistics, low variability and represent the stability of the internal environment, whereas the latter are characterized by non-Gaussian distributions, large variability and reflect the adaptive capacity of the human body; in the adverse conditions of ageing and/or disease, adaptive capacity is lost and the variability of physiological responses is diminished, and as a consequence the stability of the internal environment is compromised and its variability increases.

SIGNIFICANCE

Time-series analysis allows one to quantify homeostasis in the optimal conditions of youth and health and the degradation of homeostasis or homeostenosis in the adverse conditions of ageing and/or disease, and may offer an alternative approach to diagnosis in clinical practice.

The charming physician (El médico encantador): neurological conditions in a short story by Silvina Ocampo

The Argentinian author Silvina Ocampo (1903-1993) left us a vast body of works which are considered outstanding in many ways. In 1960, she published a short story, entitled "El médico encantador" (The Charming Physician), in the renowned literary magazine Sur. The central character of this piece is a family doctor named Albino Morgan, who had a secret truth: in any house he visited, all variety of disease also entered. He brought with him the viruses he disseminated. The narrator of this short story-one of his patients-describes four of Morgan's diseases. These imaginary neurological conditions allowed Ocampo to explore improbable situations in everyday life.

From supine to standing: in vivo segregation of myogenic and baroreceptor vasoconstriction in humans

Myogenic vascular response is a form of systemic and regional vasoconstriction produced increasing the intra‐arterial pressure by gravity. Here, the vasoconstriction due to the myogenic response, induced by the gravitational action in a dependent limb, is separated from that caused by the baroreceptor reflex. Regional changes of skin blood flow (SBF), total blood volume of the finger (TBVF), pulse pressure (PP), heart rate (HR), systolic, and diastolic blood pressure (BP) were analyzed in 10 healthy young subjects in supine and upright positions. By lowering the arm in supine position, SBF decreased compared to its basal measurement, PR increased, and PP contracted, indicating arterial vasoconstriction that rise BP. TBVF increased, demonstrating an increment in venous volume. HR did not change, reflecting no action of the baroreceptor reflex. In upright position with lowered arm, there was an additional increase in BP variables, demonstrating vasoconstriction. Moreover, BP and HR showed oscillations at 0.1 Hz reflecting the entrance of the baroreceptor reflex. The action of gravity in a dependent limb in supine position induces a regional vasoconstriction and an increase of BP due to activation of the myogenic response, while the baroreceptor reflex or other neural factors do not appear to operate. In the upright position with the arm dependent, there is a further increase in regional vasoconstriction and BP with reciprocal changes in HR, indicating the entrance of the baroreceptor superimposed to the myogenic response. This study demonstrates that the myogenic and baroreceptor vasoconstriction can be separated in vivo.

Loss of Breathing Modulation of Heart Rate Variability in Patients with Recent and Long Standing Diabetes Mellitus Type II

Healthy subjects under rhythmic breathing have heart interbeat intervals with a respiratory band in the frequency domain that can be an index of vagal activity. Diabetes Mellitus Type II (DM) affects the autonomic nervous system of patients, thus it can be expected changes on the vagal activity. Here, the influence of DM on the breathing modulation of the heart rate is evaluated by analyzing in the frequency domain heart interbeat interval (IBI) records obtained from 30 recently diagnosed, 15 long standing DM patients, and 30 control subjects during standardized clinical tests of controlled breathing at 0.1 Hz, supine rest and standing upright. Fourier spectral analysis of IBI records quantifies heart rate variability in different regions: low-frequencies (LF, 0.04–0.15 Hz), high-frequencies (HF, 0.15–0.4 Hz), and a controlled breathing peak (RP, centered around 0.1 Hz). Two new parameters are introduced: the frequency radius r_f (square root of the sum of LF and HF squared) and β (power of RP divided by the sum of LF and HF). As diabetes evolves, the controlled breathing peak loses power and shifts to smaller frequencies, indicating that heart rate modulation is slower in diabetic patients than in controls. In contrast to the traditional parameters LF, HF and LF/HF, which do not show significant differences between the three populations in neither of the clinical tests, the new parameters r_f and β, distinguish between control and diabetic subjects in the case of controlled breathing. Sympathetic activity that is driven by the baroreceptor reflex associated with the 0.1 Hz breathing modulations is affected in DM patients. Diabetes produces not only a rigid heartbeat with less autonomic induced variability (r_f diminishes), but also alters the coupling between breathing and heart rate (reduced β), due to a progressive decline of vagal and sympathetic activity.

[On roman philonium]

The roman philonium (Philonium Romanum) is an example of pharmacological poetry. This opiate was conceived by Philo of Tarsus, who was active during the first century of the Common Era. His antidote was written in elegiac couplets. The conservation of these couplets is owed to Galen, who reproduced them in the ninth book of On the Composition of Medicines according to the Places. Most of this Galenic treatise has not been translated into Spanish. For the first time, we offer this prescription in our language from a French version of the fin de siècle. Additionally, we attempt an exegesis of Philo's poem.

Does salt addiction exist?

Abstract Background. Salt consumption activates the brain reward system, inducing cravings and the search for salted food. Its excessive intake is associated with high blood pressure and obesity. The high quantity of salt in processed food is most likely a major cause of the global pandemic of hypertension (HT). Objective. To review the current information on the topic of salt addiction and the health consequences this has. Method. A search in PubMed, ScienceDirect, and EBSCOhost databases was conducted with the keywords “salt”, “salt addiction”, and “food addiction”. Articles with information relative to the topic of interest were checked, as were references of those articles and historical and culturally complementary information. Results. We described the historical relationship between man and salt, the physiology of salty taste perception, its role in the reward system and the health consequences of a high sodium diet. Discussion and conclusion. There is physiological and behavioural evidence that some people may develop a true addiction to food. Among these people, salt addiction seems to be of great importance in the development of obesity, HT and other diseases. Sodium is present in high quantities in processed food as salt and monosodium glutamate (MSG), used as flavour enhancers and food preservatives, including in non-salty foods like bread and soft drinks.

Reward and aversion systems of the brain as a functional unit. Basic mechanisms and functions

Abstract Introduction. It is increasingly important to recognize the reward and aversion systems of the brain as a functional unit. A fundamental task of the mammalian brain is to assign an emotional/motivational valence to any stimuli by determining whether they are rewarding and should be approached or are aversive and should be avoided. Internal stimuli are also assigned an emotional/motivational valence in a similar fashion. Objective. To understand the basic mechanisms and functions of the reward and aversion system of the brain. Method. A bibliographical search was conducted in the Pubmed database using different key words. Documents on relevant aspects of the topic were selected. Results. In the ventral tegmental area, dopaminergic (VTA-DA) neurons play a role in reward-dependent behaviors. It is also known that the inhibition of the VTA-DA neurons by GABAergic neurons contributes to a reward prediction error calculation that promotes behaviors associated with aversion. The ventral dopaminergic mesolimbic system and the nucleus accumbens are activated during reward and inhibited during aversions. The amygdala is activated during aversive behavior. Discussion and conclusion. The reward/aversion system is highly relevant for survival, which is most likely its primary function. It is involved in important pathologies such as addiction, depression and autonomic and endocrine disturbances. Therefore, its knowledge has become of clinical importance. Although great advances have been made in the knowledge of the basic mechanisms of the reward/aversion system, the detailed circuits within the VTA that mediate reward and aversion and the anatomical substrates are not completely clear.

Heart rate and systolic blood pressure variability on recently diagnosed diabetics

Background

Diabetes affects approximately 250 million people in the world. Cardiovascular autonomic neuropathy is a common complication of diabetes that leads to severe postural hypotension, exercise intolerance, and increased incidence of silent myocardial infarction.

Objective

To determine the variability of heart rate (HR) and systolic blood pressure (SBP) in recently diagnosed diabetic patients.

Methods

The study included 30 patients with a diagnosis of type 2 diabetes of less than 2 years and 30 healthy controls. We used a Finapres® device to measure during five minutes beat-to-beat HR and blood pressure in three experimental conditions: supine position, standing position, and rhythmic breathing at 0.1 Hz. The results were analyzed in the time and frequency domains.

Results

In the HR analysis, statistically significant differences were found in the time domain, specifically on short-term values such as standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), and number of pairs of successive NNs that differ by more than 50 ms (pNN50). In the BP analysis, there were no significant differences, but there was a sympathetic dominance in all three conditions. The baroreflex sensitivity (BRS) decreased in patients with early diabetes compared with healthy subjects during the standing maneuver.

Conclusions

There is a decrease in HR variability in patients with early type 2 diabetes. No changes were observed in the BP analysis in the supine position, but there were changes in BRS with the standing maneuver, probably due to sympathetic hyperactivity.

Cardiovascular variability in Mexican patients with Parkinson's disease

Cardiovascular variability (CVV) has been evaluated in patients with Parkinson's disease (PD) in other countries and exhibit ethnic differences. Objective We investigated heart rate variability (HRV) and blood pressure variability (BPV) in Mexican patients with PD. Method We further compared HRV and BPV between this group and young healthy controls (YHC) in order to estimate, for the first time in our country, the magnitude of the difference. Twenty patients were examined. Time- and frequency-domain CVV parameters were studied during supine rest (SR), active standing (AS) and controlled breathing. These measurements were compared to those of 20 YHC. Results In the three conditions tested, our study showed a decrease in almost all HRV parameters in PD patients; on the contrary, decreased BPV parameters were found less frequently and only during SR and AS. Conclusion Our results indicate that HRV is impaired in PD. Some BPV parameters are also diminished.

Initial circulatory response to active standing in Parkinson's disease without typical orthostatic hypotension

While the circulatory response to orthostatic stress has been already evaluated in Parkinson's disease patients without typical orthostatic hypotension (PD-TOH), there is an initial response to the upright position which is uniquely associated with active standing (AS). We sought to assess this response and to compare it to that seen in young healthy controls (YHC).

METHOD

In 10 PD-TOH patients (8 males, 60 ± 7 years, Hoehn and Yahr ≤ 3) the changes in systolic blood pressure (SBP) and heart rate that occur in the first 30 seconds (sec) of standing were examined. Both parameters were non-invasively and continuously monitored using the volume-clamp method by Peñáz and the Physiocal criteria by Wesseling. The choice of sample points was prompted by the results of previous studies. These sample points were compared to those of 10 YHC (8 males, 32 ± 8 years).

RESULTS

The main finding of the present investigation was an increased time between the AS onset and SBP overshoot in PD-TOH group (24 ± 4 vs. 19 ± 3 sec; p<0.05).

CONCLUSION

This delay might reflect a prolonged latency in the baroreflex-mediated vascular resistance response, but more studies are needed to confirm this preliminary hypothesis.

Acido, ergo sum: Holger Hydén--the neuroscientist in Cortázar's Hopscotch

The fictional Italian author Morelli is throughout the novel "Hopscotch" (1963) Julio Cortázar's alter ego. This character proposes an unoriginal literary hypothesis in chapter 62. There is an allusion to a particular Swedish that 'is working on a chemical theory of thought.' The Swedish neuroscientist under analysis is Holger Hydén (1917-2000), by then professor and chairman of the Department of Histology at the University of Göteborg. Hydén, who was the first to work in neurobiological micromethods, is mentioned by Morelli due to his participation in a symposium held at the end of January 1961, in San Francisco. His pioneering work will never be completely forgotten, because Hydén's neuroscientific legacy lives and will live in Cortázar's "Hopscotch".

Marcel Proust: El aventurero sedentario

Si  Marcel  Proust  no  hubiera  nacido  nadie  hubiera  podido inventarlo. Su obra, insólita, desmesurada y acaso interminable ha merecido el estudio y la reflexión de muchos autores y críticos.

Korotkoff sounds -- the improbable also occurs

Very few discoveries have had such a large impact on and relevance to clinical medicine as the noninvasive measurement of the diastolic blood pressure. A number of gifted physiologists and clinicians were ineffectively in search of a noninvasive method to determine the diastolic pressure. Nonetheless, the quantification of the diastolic BP was not achieved by any of these clinical or physiological researchers, but by an unlikely and unexpected figure: Nikolai Sergeevich Korotkoff (1874-1920), a young Russian army surgeon, working under precarious conditions in the hardship of diverse wars. It is easy to dismiss the achievement of Korotkoff as a serendipitous discovery, similar to that of Alexander Fleming in the discovery of penicillin. However, Nassim N. Taleb's recent black swan theory may serve to illustrate his discovery in a new and, perhaps, surprising way.

[A brief history of the baroreceptor reflex: from Claude Bernard to Arthur C. Guyton. Illustrated with some classical experiments]

The baroreceptor reflex is poorly known by most physicians even though is fundamental in stabilizing the blood pressure on a beat to beat basis and is crucial for survival. Its fascinating history is briefly reviewed in this article. In 1852 Claude Bernard discovered that the sympathetic nerves of the neck innervate the blood vessels of the skin of the rabbit. Edgar Douglas Adrian in 1932 demonstrated that the sympathetic nerves that innervate the blood vessels discharge spontaneously at a rate of 4-6 per second and thus discovered the physiological basis of the vasomotor tone. In the XIX century Ludwig Traube and Karl Constantine Ewald Hering discovered that blood pressure fluctuates synchronously with respiratory movements and Sigmund Mayer observed that there are also slow non respiratory fluctuations of blood pressure. In 1921 Heinrich Ewald Hering found that high pressure baroreceptors are located in the carotid sinuses and demonstrated that the stimulation of the afferent nerve that innervates it induces bradycardia and hypotension. These studies were further advanced by Corneille Heymans who won the Nobel Prize for these studies in 1938. Later Cowley and Guyton produced sino-aortic denervation in dogs and thereby could demonstrate the fundamental importance of the baroreceptor reflex in the stabilization of blood pressure.

[Neural control of the peripheral circulation and blood pressure]

In the XIX century Claude Bernard discovered the action of the nervous system on the peripheral circulation. In the first half of the XX century Ewald Hering discovered the baro-receptor and the reflex control of the heart rate and blood pressure. Cowley and Guyton demonstrated that sino-aortic denervation induces persistent changes in the blood pressure in the dog. The autonomic nervous system is mainly responsible for the regulation of the circulation and blood pressure in the short term on a beat to beat basis. It controls the vasomotor tone, the heart rate and the cardiac output. With the advent of non invasive methods that measure the blood pressure on a beat to beat basis (Finapres) and with the methods of measurement of the variability of the blood pressure in the frequency domain (spectral analysis) we can currently measure many variables including heart rate, blood pressure, stroke volume, peripheral resistances and the baroreceptor sensitivity and make some inferences about their control mechanisms. These variables can be measured at rest in the supine position, standing up, during rhythmic breathing and during the Valsalva maneuver. In this article we present a review of the neural control of the blood pressure and heart rate.

A case of tactile agnosia with a lesion restricted to the post-central gyrus

Tactile agnosia has been described after lesions of the primary sensory cortex but the exact location and extension of those lesions is not clear. We report the clinical features and imaging findings in a patient with an acute ischemic stroke restricted to the primary sensory area (S1). A 73-year-old man had a sudden onset of a left alien hand, without left hemiparesis. Neurological examination showed intact primary sensory functions, but impaired recognition of shape, size (macrogeometrical) and texture (microgeometrical) of objects; damage confined to the post-central gyrus, sparing the posterior parietal cortex was demonstrated on MRI. An embolic occlusion of the anterior parietal artery was suspected as mechanism of stroke. Tactile agnosia with impaired microgeometrical and macrogeometrical features' recognition can result from a single lesion in the primary sensory cortex (S1) in the right parietal hemisphere, sparing other regions of the cerebral cortex which presumably participate in tactile object recognition.

Cerebral changes in SLE with or without antiphospholipid syndrome. a case-control MRI study

BACKGROUND

To determine and characterize the prevalence of cerebral changes on MRI in patients with antiphospholipid syndrome (APLS) within systemic lupus erythematosus (SLE).

METHODS

Seventy-one patients with SLE were prospectively studied with brain MRI: 32 with definite APLS and 39 without. Atrophy, ventricular enlargement, leukoaraiosis, interuncal distance, Evans' index, infarcts, and white matter hyperintensities (WMH) were analyzed. Demographic data, treatment, and SLE activity were analyzed.

RESULTS

Groups were similar in age (32.4 vs. 32.8 years old; P= non-significant [NS]), and gender. Duration of disease was longer in patients with APLS (87.3 vs. 55.4 months; P= .064). Cortical atrophy was common in both groups (68.7% vs. 89.7%; P= NS). Leukoaraiosis was present in only 3 patients (9.4%; P= .08), all in the APLS group. WMH were found in more than 40% of the patients from both groups. Infarcts (21.9% vs. 2.6%; P= .019) and infarcts plus WHM (12.5% vs. 0; P= .037) were more common in patients with APLS.

CONCLUSIONS

Although a higher prevalence of neurological involvement in SLE has been reported in APLS patients, we found gross brain changes to be similar between groups. Strokes and leukoaraiosis were more common in the APLS group, consistent with the idea of an APLS-induced prothrombotic state.

Respiratory and non respiratory oscillations of the skin blood flow: a window to the function of the sympathetic fibers to the skin blood vessels

OBJECTIVE OF THE STUDY

The skin blood flow (SBF) has been known to oscillate in frequency and amplitude. The nature and type of these oscillations have remained obscure. We studied the oscillations of the SBF in frequency and amplitude with non invasive techniques during normal breathing at rest and compared it to the oscillations during rhythmic paced breathing at 6 cycles per minute.

SUBJECTS AND METHODS

Thirty healthy subjects were studied under normothermic conditions. The following variables were recorded: 1) EKG signal; 2) SBF signal given by an infrared photoplethysmograph; 3) respiratory movements (RM). A correlation of the frequency of the respiration, the SBF and the EKG was made. The variability of the amplitudes of the SBF, RR intervals and pulse intervals was analyzed in the time domain and with spectral analysis using Fourier analysis.

RESULTS

We found no clear respiratory modulation of the amplitude of the SBF during natural breathing at rest. With default breathing there was a low frequency oscillations (LF 0.04 to 0.15 Hz) modulation of the amplitude of the SBF that was non respiratory in nature. During rhythmic breathing at 0.1 Hz there was a strong modulation at LF of the SBF with a typical waxing and waning appearance, decreasing in amplitude during the tachycardia period and increasing in amplitude during the bradycardia period.

CONCLUSIONS

Under normothermic conditions there is a consistent variability of the frequency and amplitude of the SBF with normal and rhythmic breathing. While breathing at rest the modulation of SBF amplitude was clearly seen at LF and non respiratory related. With rhythmic breathing there is a strong modulation of amplitude and frequency at the respiratory frequency.

Subarachnoid hemorrhage as a complication of systemic lupus erythematosus

BACKGROUND

Subarachnoid hemorrhage (SAH) is a rare complication of systemic lupus erythematosus (SLE).

METHODS

We made a retrospective search for patients with SLE and nontraumatic SAH from 1990 to 2006.

RESULTS

We found 10 patients with SLE and primary SAH of a total of 1,077 patients with SLE (0.93%); mean age of onset was 37.4 +/- 15.25 years and the mean duration of SLE at the onset of SAH was 98.3 +/- 50.32 months. SLEDAI and chronic damage scores were 3.67 +/- 5.20 (n = 9) and 2.90 +/- 1.45 (n = 10), respectively; 60% of patients had high Hunt-Hess scores and in only 50% of cases a saccular aneurysm was identified.

CONCLUSIONS

SAH presents in about 1% of SLE patients. Long duration of SLE and chronic damage scores might be associated risk factors.

[The history of myasthenia gravis. Men and ideas.]

The first description of a patient with myasthenia gravis was done by Thomas Willis (1621-1675). He was an eminent professor of natural history at Oxford University who also described the arteries of the brain and made the first precise drawings of it. At the present time myasthenia gravis is considered one of the most well described autoimmune diseases with great advances in its diagnosis, pathophysiology and treatment. In this review we summarize the most important events and ideas in the history of this disease since the original description by Willis; mention the most important clinicians, anatomists and physiologists that were concerned with its understanding and make reference of some the most recent advances in its diagnosis and treatment and finally discuss some present controversies. Neurología 2007;22(0):0-0.

[Impact factor of Latin American medical journals]

BACKGROUND

Latin American medical journals have a low impact factor. Higher quality articles originated in Latin American countries are published in North American or European journals.

AIM

To analyze the impact factor of Latin-American journals according to the language of publication.

MATERIAL AND METHODS

The data base of periodic journals of the Thomson ISI (Journal of Citation Report) in the year 2004 was used for the analysis. Four countries with more than one journal in the data base of the Thomson ISI were included (Argentina, Brazil, Chile and Mexico).

RESULTS

Few Latin-American journals are included in the Thomson ISI data base. The mean impact factor was 0.76 (0.23-3.2) for eight Mexican journals, 0.66 (0.10-2.1) for eight Chilean journals, 0.39 (0.06-0.7) for five Argentinian journals and 0.41 (0.09-1.1) for 16 Brazilian journals. The mean impact factor for 11 journals written in English was 0.74 (0.12-2.1), 0.53 (0.09-3.2) for 18 bilingual journals and 0.28 (0.06-0.56) for eight journals written in native language. The differences between countries and languages were not statistically significant.

CONCLUSIONS

The journal impact factor was similar in the four countries studied. A non-significant higher impact factor was observed in Latin-American journals published in English.

Associated conditions in myasthenia gravis: response to thymectomy

To compare the response of thymectomy in patients with associated conditions (PWAC) and without associated conditions (PWOAC). Comparative, retrospective. 198 patients with the established diagnosis of myasthenia gravis who had a thymectomy between 1987 and 2000, and who were folowed up for at least 3 years. We formed two groups, one with associated conditions and the second without associated conditions. The patients were divided into four groups: (i) patients in remission, (ii) patients with improvement, (iii) patients without changes, and (iv) patients whose condition worsened. Associated conditions (AC) were found in 49 patients (26%). The main associated conditions were hyperthyroidism in 16 patients (33%) hypothyroidism in seven (14%), rheumatoid arthritis in five (10%) and hypothyroidism and Sjogren syndrome in three (6%). Concerning the response of thymectomy, 13 patients WAC showed remission (27%), vs. 54 patients WOAC (39%). Twenty patients WAC showed improvement (41%) vs. 46 WOAC (33%). Thirteen patients WAC had no changes (27%) vs. 37 WOAC (26%). Finally, in three patients WAC their condition worsened (6%) vs. three WOAC (2%). The response to thymectomy was high (69%) in both groups. We did not identify significant differences.

[Secondary Raynaud's syndrome: skin blood flow decrease between the ischemic episodes and prolongation of the vasoconstriction during the respiratory maneuvers]

The Raynaud's syndrome is an episodic skin ischemia manifested by pallor, cyanosis and erythema of the fingers in response to cold or emotional stress. The exact pathophysiology is unknown but it has been hypothetised that may be due to an autonomic alteration in the sympathetic innervation of skin blood vessels.

OBJECTIVE

To study the changes of heart rate and skin blood flow (SBF) in healthy subjects and in patients with secondary Raynaud's syndrome during different respiratory maneuvers: 1. spontaneous respiration; 2. rhythmic respirations (RR), 3. sudden inspirations (SI), and 4. Valsalva maneuver (VM).

METHODS

We studied 22 healthy subjects and 22 patients with secondary Raynaud's syndrome. The variables measured were: 1) RR intervals; 2) amplitudes of SBF; 3) percentage of decrease of SBF; 4) latency of the maximum decrease of SBF.

RESULTS

In all patients with secondary Raynaud's syndrome the SBF was decreased basally during spontaneous rations and during all respiratory maneuvers (p < 0.001). The mean latency of recovery of the SBF was prolonged during sudden deep inspiration. The patients with Raynaud also had significant basal tachycardia at rest (p < 0.003).

CONCLUSIONS

The basal skin blood flow during spontaneous respirations and in asymptomatic periods is decreased in patients with Raynaud's syndrome; this may be related to endothelial arterioral damage. The SBF was also significantly decreased dynamically during sudden inspirations (SI), rhythmic breathing (RR) and Valsalva maneuver (VM). This dynamic change suggests sympathetic hyperactivity.

Sympathetic co-activation of skin blood vessels and sweat glands

Skin blood vessels and sweat glands are both innervated by sympathetic C fibers. We investigated whether during diverse respiratory maneuvers the vasomotor responses (VRs) and the sympathetic skin responses (SSRs) were frequently or occasionally co-activated. We simultaneously recorded the amplitude of the vasomotor responses and the sympathetic skin responses, the ECG and the respiratory movements in 30 healthy subjects during natural breathing at rest, rhythmic respirations at 6 per minute, sudden deep inspiration and Valsalva maneuver. We found: 1) The SSR habituates with all respiratory maneuvers whereas the VRs do not habituate. 2) There was slight co-activation between the SSRs and VRs during natural default breathing (56 percent). 3) During rhythmic breathing at 6 per minute the VRs and the SSRs were frequently co-activated (97 percent). The SSR appeared at the end of the inspiration coinciding with the end of the decreased blood flow. However the SSR habituated after few rhythmic respirations. 4) During sudden deep inspiration one hundred percent of co-activations were between the initial phase of the VRs and the SSR. The SSR is large in amplitude and longer in duration than during rhythmic breathing. 5) During the Valsalva maneuver there was a strong co-activation (100 percent) particularly during the phases II and III that are characterized by vaso-constriction but also during phase IV. The SSR is the longest of duration in all of the maneuvers. The sympathetic innervation to the sweat glands of the palm of the hand and to the skin blood vessels of the fingertips is differentiated. Under normothermic conditions sudden deep inspiration and Valsalva maneuver induced a large sympathetic simultaneous outflow to the skin blood vessels and sweat glands. The simultaneous recording of skin blood flow and the SSRs provides a more complete assessment of the sympathetic outflow to the skin than either one alone.

Response of thymectomy: clinical and pathological characteristics among seronegative and seropositive myasthenia gravis patients

OBJECTIVE

To identify the response to thymectomy in patients with seronegative and seropositive myasthenia gravis (SPMG). We analyzed the associated diseases, thymus histology, and the severity of symptoms between the two groups. MATERIAL AND METHODS - DESIGN: Descriptive, comparative.

STUDY UNITS

Fourteen patients with seronegative myasthenia gravis (SNMG) and 57 patients with SPMG who had a thymectomy between 1987 and 1997, with at least 3 years of follow-up. The patients were divided into four groups; (1) Remission, (2) Improvement, (3) No change and (4) Deterioration.

RESULTS

Fourteen patients (20%) were seronegative and 57 were seropositive (80%). In the group of patients with SNMG, three patients were in remission (21%), five with improvement (36%), five with no change (36%) and one with worsening (7%). In the group of patients with SPMG, 12 were in remission (21%), 17 with improvement (30%), 25 with no change (44%) and three (5%) with worsening. The patients with SNMG were older, with less associated diseases and with a lower frequency of thymomas.

CONCLUSIONS

The response to thymectomy was similar between the two groups. It has been suggested that seronegative patients have a better prognosis, but our results show no differences.

HLA class II genotypes in Mexican Mestizo patients with myasthenia gravis

Myasthenia gravis is an autoimmune, heterogeneous disorder, characterized by the presence of antibodies against acetylcholine receptors at the neuromuscular junction. There is a strong evidence that an individual's genetic composition is an important predisposing factor for the development of the disease. To correlate HLA class II genotypes with thymic pathology in Mexican Mestizo patients who had been subjected to thymectomy. HLA class II genes were analyzed in 60 patients and in 99 healthy ethnically matched controls. Thymic hyperplasia, atrophy, thymoma, and normal histology were encountered in 56, 33, 8 and 2% of patients, respectively. HLA-DR11 was significantly increased in patients with thymoma compared with healthy controls (pC = 0.001, OR = 13.35, 95% CI 3.5-51.3), compared with the subgroup of hyperplasia patients (pC = 0.005, OR = 15.5, 95% CI 2.78-95.58) and with the atrophy subgroup (pC = 0.04, OR = 10.5, 95% CI 1.75-70.95). This study provides the evidence of an association between HLA class II alleles with clinical and genetic heterogeneity in myasthenia gravis, particularly in those with thymoma (HLA-DR11).

[Effect of the graded muscle contraction on the H reflex and long latency reflexes of the thenar and hypothenar muscles to a fixed threshold stimulus]

INTRODUCTION

To determine the percentage of appearance of the H reflex and long latency reflexes (LLRs) in the thenar and hypothenar muscles of normal subjects to a fixed threshold mixed nerve electrical stimulus and variable degrees of muscle contraction.

METHODS

Fifteen subjects aged 21 to 32 years of age without any prior history of central or peripheral neurological diseases volunteered for the study. The stimulation was a constant currrent given at the wrist with the cathode positioned proximally; started at 1 mA and it was gradually increased mA by mA until the M response appeared with the subject relaxed. The intensity of the stimulation was thereafter kept constant. The contraction was an abducting movement of the thumb in the case of the thenar muscle and abduction of the digiti minimi in the case of the hypothenar muscle and was sustained throughout the study. The reflexes were elicited with a repetition rate of 3 Hz, the stimulus was a square pulse of 0.5 ms. We used a low frequency pass filter of 10 Hz and a high frequency pass filter of 10 kHz. The sweep speed was set a 10 ms per division. The responses were averaged 200 times and then smoothed.

RESULTS

The mean intensity of the stimulus that evoked the H response, for all subjects, was 7.5 2.8 mA. The mean latency of the H reflex elicited with stimulation of the median nerve was 26 ms 2.03 ms (std. error 0.28, maximum 28.2, minimum 22.0). The mean latency of the H reflex elicited with stimulation of the ulnar nerve was 25.1 ms 1.64 ms (std. error 0.230, maximum 28, minimum 22.3). The difference between the percentage of responses attained under a relaxed condition and with any kind of muscle contraction was highly significant statistically using the Chi square method (p < 0.001). When we compared the percentage of the H responses obtained with slight, moderate, strong contraction, and contraction against resistance, between them, we did no find a significant difference. The LLRs appeared only in the trials with strong contraction.

CONCLUSIONS

The H reflexes and the LLRs of the thenar and hypothenar muscle were not obtained with threshold stimulation when these muscles were relaxed. With any degree of muscle contraction the H reflex in these muscles could be obtained in 94 percent of the trials. Maximal contraction and contraction against resistance were the best conditions to elicit long latency responses.

The association of myasthenia gravis and connective tissue diseases. Effects of thymectomy in six cases with rheumatoid arthritis and one case with systemic lupus erythematosus

OBJECTIVES

To describe the effects of thymectomy in a group of patients with myasthenia gravis (MG) with associated connective tissue diseases (CTD).

PATIENTS AND METHODS

We analyzed six patients with CTD and myasthenia. They were followed-up for at least 3 years.

RESULTS

Records of a cohort of 132 patients with established diagnosis of MG undergoing thymectomy in our institution between 1987-1999 were reviewed. The percentage of patients with CTD was 5 % (6/132). Five patients had rheumatoid arthritis (RA) and one patient systemic lupus erythematosus (SLE). All patients were women, and the mean age was 38.5 years old (SD 13.7). Mean time of MG diagnosis to operation was 16 months (range from 1 to 144 months). Preoperative Osserman classification was the following: stage IIb, four patients; stage III, one patient; and stage IV, one patient. Before surgery all patients were on anticholinesterase agent (pyridostigmine), and four patients were on corticosteroids. An extended transsternal thymectomy was practiced on five patients and a transcervical thymectomy was performed in the remaining patient. Pathologic findings were as follows: thymic hyperplasia in four patients and thymic atrophy in the other two. Good response (remission or improvement) was present in three patients (50 %) and poor response (no change or worse) in the other three (50 %).

CONCLUSIONS

A low response to the thymectomy is observed in patients with MG and associated CTD (RA and an SLE).

Thymectomy in myasthenia gravis: response, complications, and associated conditions

BACKGROUND

Thymectomy is considered the most effective treatment for achieving sustained improvement as well as remission in patients with myasthenia gravis (MG), and most neurologists favor the use of this procedure. The main focus of many current studies is to determine response-predicting factors.

METHODS

Clinical records of 152 patients with an established diagnosis of MG who underwent thymectomy at our institution were reviewed. The purpose was to evaluate outcome of surgical management for MG and prognostic factors that influence that outcome.

RESULTS

The majority of patients were women (119 of 152); mean age was 32.10 +/- 14.42 years, while time elapsed from diagnosis to surgery was 20.67 +/- 19.7 months. Transsternal thymectomy was performed on 113 patients and transcervical on 39. Forty percent of patients achieved remission and 28% showed improvement; with this, a good response to thymectomy was seen in 68% of patients (n = 103). The most important variables associated with remission were <60 years of age, <2 years of preoperative symptoms, and use of pyridostigmine at low doses. Factors related with poor response were >60 years of age, preoperative Osserman stage other than II, use of high doses of pyridostigmine, use of corticosteroids, and presence of thymic atrophy or thymoma in histopathologic analyses. There was no mortality, although 20 patients (13%) presented complications.

CONCLUSIONS

Mexican patients with MG undergoing thymectomies show improvement and remission rates similar to those reported by other studies. Age, length of symptoms, thymic pathology, and medications appear to be predictors of response to thymectomy for MG.

[Response of skin blood flow to several respiratory maneuvers in healthy subjects]

INTRODUCTION

In the diagnosis of autonomic disturbances, the variability of skin blood flow (SBF) and the sympathetic skin response (SSR) in response to several respiratory maneuvers are not routinely studied.

OBJECTIVE

We sought to standardize the method of SBF variability and SSR in healthy subjects during four respiratory maneuvers: 1) spontaneous breathing (SB); 2) rhythmic breathing at a rate of 6 per minute (RB); 3) sudden deep inspiration (SDI); 4) Valsalva maneuver (VM). SUBJECTS, MATERIAL AND METHOD: We studied 30 healthy subjects with a mean age of 32 years, 60% were men and 40% women. We used a photopletysmograph in the finger pad to measure SBF and surface electrodes on the palms of the hand to register the SSR. We also recorded the ECG and the respiratory movements. The variables were: 1) amplitude of SBF; 2) latency and duration of SSR; 3) percentage of decrease of the SBF during the maneuvers compared with the basal flow.

RESULTS

During spontaneous breathing there was no respiratory modulation of the SBF and during RB the SBF was modulated with respiration. With SDI there was a 60% decrease of the SBF. VM induced a larger SBF decrease of 72 per cent. A significant statistical difference was revealed when we compared the decrease of SBF basal breathing with SDI and VM (P < 0.001). The difference was also significant between the SDI and VM (P < 0.001). The SBF decrease recovered more slowly after the SDI (beat 7) than after the VM (veat 6). The SBF decrease was more pronounced in magnitude during the VM. The latency of the SSR appears spontaneously and at random in 57% of subjects during normal breathing but it appeared consistently during RB, SDI, and VM. The latency of SSR was longer during SB (1.7 +/- 0.7 s), RB (1.6 +/- 0.7 s) than SDI (0.7 +/- 0.5 s) and VM (0.8 +/- 0.9 s) (P > 0.050). Duration of the SSR was significantly longer in the SDI (around 7.8 +/- 2.4 s) and during the VM (8 +/- 2.5 s) as compared to normal breathing (6.3 +/- 1.0 s) and RB (6.4 +/- 1.5 s) (P < 0.009).

CONCLUSIONS

SB and RB induce periodic modulation of sympathetic activity to skin blood vessels and sweat glands. SDI and VM produced a much greater activation of sympathetic skin activity than SB and RB. The increased SSR duration and the profound SBF decrease with SDI and VM as compared to SB or RB are consistent with this hypothesis. The latency of the SSR is much shorter with SDI and VM than with SB or RB. The most likely explanation is that the SSR, under these circumstances, results from a central command. The recovery to normal SBF is faster after the VM as compared to SDI. This suggests that the withdrawal of sympathetic responses is faster after the VM. The explanation for this is unknown but suggests that it might be baroreceptor mediated.