The Vagus Nerve Somatosensory-evoked Potential in Neural Disorders: Systematic Review and Illustrative Vignettes

Objective. To review the scientific publications reporting vagal nerve somatosensory-evoked potential (VSEP) findings from individuals with brain disorders, and present novel physiological explanations on the VSEP origin. Methods. We did a systematic review on the papers reporting VSEP findings from individuals with brain disorders and their controls. We evaluated papers published from 2003 to date indexed in PubMed, Web of Science, and Scielo databases. We extracted the following information: number of patients and controls, type of neural disorder, age, gender, stimulating/recording and grounding electrodes as well as stimulus side, intensity, duration, frequency, and polarity. Information about physiological parameters, neurobiological variables, and correlation studies was also reviewed. Representative vignettes were included to add support to our conclusions. Results. The VSEP was studied in 297 patients with neural disorders such as Parkinson's disease (PD), Alzheimer's disease, vascular dementia, mild cognitive impairment, subjective memory impairment, major depression, and multiple sclerosis. Scalp responses marked as the VSEP showed high variability, low validity, and poor reproducibility. VSEP latencies and amplitudes did not correlate with disease duration, unified PD rating scale score, or heart function in PD patients nor with cerebrospinal fluid β amyloid, phosphor-τ, and cognitive tests from patients with mental disorders. Vignettes demonstrated that the VSEP was volume conduction propagating from muscles surrounding the scalp recording electrodes. Conclusion. The VSEP is not a brain-evoked potential of neural origin but muscle activity induced by electrical stimulation of the tragus region of the ear. This review and illustrative vignettes argue against assessing the parasympathetic system using the so-called VSEP.

Combined Presigmoid-Subtemporal Approach in a Semi-Sitting Position for Petroclival Meningiomas: A Technical Report

The removal of petroclival meningiomas (PMs) is considered a neurosurgical challenge due to the critical mobilization of key neurovascular structures. Limited knowledge about the benefits of operating on patients with PMs using the combined presigmoid-subtemporal approach (CPSA) in a semi-sitting position has precluded its generalizability. We report on ten patients with PMs operated in a semi-sitting position using CPSA. We remark that before the surgical approach was accomplished in our group of patients, the CPSA via semi-sitting position was conducted and standardized in six adult cadaveric heads. The neuroanatomic dissections made in cadavers allowed us to confidently use CPSA in our set of patients. There were no comorbidities, perioperative complications, or deaths associated with the surgical procedure. CPSA via a semi-sitting position can be considered a safe approach to remove PMs.

Territorial and Extraterritorial Trigeminocardiac Reflex: A Review for the Neurosurgeon and a Type IV Reflex Vignette

The trigeminocardiac reflex (TCR) is a complex and, sometimes, fatal event triggered by overstimulation of the trigeminal nerve (TN) and its territorial and spinal cord branches. We reviewed and compiled for the neurosurgeon key aspects of the TCR that include a novel and straightforward classification, as well as morphophysiology, pathophysiology, neuromonitoring and neuromodulation features. Further, we present intraoperative data from a patient who developed extraterritorial, or type IV, TCR while undergoing a cervical surgery. TCR complexity, severity and unwanted outcomes indicate that this event should not be underestimated or overlooked in the surgical room. Timely TCR recognition in surgical settings is valuable for applying effective intraoperative management to prevent catastrophic outcomes.

The vagus nerve somatosensory evoked potential in the intact brain: state-of-evidence and some representative vignettes

OBJECTIVE

Scalp-recorded evoked potentials elicited by applying afferent electrical stimulation at the tragus region of the human external ear have shown inconsistent results. We aim to disentangle discrepant findings and interpretations, and put forward novel physiological explanations on the origin of the vagus nerve somatosensory evoked potentials (VSEP).

METHODS

We systematically search and critically appraise in PubMed, Web of Science, and Scielo databases the scientific reports publishing VSEP findings elicited by afferent electrical stimulation at the tragus region from individuals without brain disorders. Eligible studies published from January 2000 to April 2020 were extracted. The following information was identified from each article: number of participants; age; gender; stimulating/recording and grounding electrodes as well as stimulus side, intensity, duration, frequency, and polarity. Information about physiological parameters and neurobiological variables was also extracted. Representative vignettes with novel scalp responses induced by stimulating the tragus were also included to add support to our conclusions.

RESULTS

140 healthy participants were identified from six selected reports. Mean age ranged from 24.3 to 61.5 years. Stimulating and recording aspects were miscellaneous among studies. Scalp responses marked as the VSEP were recorded in 76% of participants, and showed high variability, low validity and poor reproducibility. Age correlated with response latencies. There were not gender differences in scalp response parameters. Cardiovascular function was unaltered by tragus stimulation. Vignettes showed that the VSEP was scalp muscle responses.

CONCLUSION

VSEP did not fulfil evoked potential guidelines. VSEP corresponded to volume conduction propagating from muscles surrounding scalp recording sites.

The Three Nociceptive Responses of the Orbicularis Oculi Reflex in Alzheimer's Disease: State of the Evidence and Meta-analysis

There is an emerging belief that electrically elicited blink reflexes (BR) may distinguish Alzheimer's disease (AD) from other disorders characterized by memory dysfunction. To qualitatively and quantitatively distinguish the effects that electrical stimulation has over the blink reflex (eBR) recorded from patients with AD and healthy controls (HCs), we did a systematic review of the literature, and conducted a meta-analysis. Following our selected criteria, 94 AD patients and 97 HCs were identified from articles published in English between 1950 and 2017. Although the 3 responses (R1, R2 and R3) of the eBR were studied in a number of patients, only the R2 response was quantified in all studies. Thresholds and stimulation intensities parameters were found to be used in a miscellaneous form, and the majority of times, such parameters deviated from validated guidelines. The stimulation frequencies used to elicit the BR responses ranged between 0.14 and 0.2 Hz. These frequencies favored HCs compared with AD patients (odds ratio = 1.08; 95% CI = 0.30-1.85), I² = 0% [P = .99]; Q = 271.89 [df = 7, P < .000]). Egger's regression test suggested publication bias (intercept = 32.38; 95% CI = -8.98 to -3.2; P = .001). Our results unveiled key shortcomings in the data reported; such shortcomings need to be corrected in future AD research looking for obtaining more reliable and reproducible eBR studies; otherwise, interventions may be misleading.

Prognostic factors for overall survival in patients with chronic myeloid leukemia treated with imatinib at the National Cancer Institute - Mexico, from 2000 to 2016

To determine potential predictors of long-term survival in a large set of Hispanic (Mexican) patients with chronic myeloid leukemia (CML) treated with imatinib. We conducted an analysis with data from 411 patients with CML treated at the National Cancer Institute - Mexico, between January 2000 and December 2016. We found a median age at diagnosis of 40 years (range: 18-84 years). The survival rate at 150 months was 82.02%, and we found that phase at diagnosis (β: 0.447, 95% Confidence Interval [95% CI]: 0.088, 0.806; P = 0.015), prognostic scales (Sokal [P = 0.021] and Hasford [β: 0.369, 95% CI: 0.049, 0.688; P = 0.024]) and hematological response at 3 months (β: 0.717, 95% CI: 0.443, 0.991; P < 0.001), but not molecular response (P = 0.834 for 6 months, P = 0.927 for 12 months, P = 0.250 for 18 months), were independently associated with overall survival. Survival analysis in subsets, according to the initial phase (chronic, accelerated and blastic phase) did not show any effect according to prognostic scales (P > 0.05). Mexican patients with CML have repeatedly been diagnosed at earlier ages. Prognostic factors in CML may differ according to the ethnic or geographical context. We found that phase at diagnosis, prognostic scale and hematological response at 3 months were independent predictors of survival.

Neurophysics Assessment of the Muscle Bioenergy Generated by Transcranial Magnetic Stimulation

The content of the rectified motor evoked potential (MEP) induced by transcranial magnetic stimulation (TMS) has ambiguously been assessed without the precision that energy calculation deserves. This fact has misled data interpretation and misguided biomedical interventions. To definitively fill the gap that exits in the neurophysics processing of these signals, we computed, in Walls ( W ^ ), the bioenergy within the rectified MEP recorded from the human first digitorum index (FDI) muscle at rest and under isometric contraction. We also gauged the biowork exerted by this muscle. Here we show that bioenergy and biowork can accurately and successfully be assessed, validated, and determined in W ^ from MEP signals induced by TMS, regardless of knowing the mathematical expression of the function of the signal. Our novel neurophysics approach represents a dramatic paradigm shift in analysis and interpretation of the content of the MEP and will give a true meaning to the content of rectified signals. Importantly, this innovative approach allowed unveiling that women exerted more bioenergy than men at the magnetic stimulations used in this study. Revisitation of conclusions drawn from studies published elsewhere assessing rectified EMG signals that have used ambiguous units is strongly recommended.

Modulation of the ultradian human nasal cycle by sleep stage and body position

Objective:

The nasal cycle, which is present in a significant number of people, is an ultradian side-to-side rhythm of nasal engorgement associated with cyclic autonomic activity. We studied the nasal cycle during REM/non-REM sleep stages and examined the potentially confounding influence of body position on lateralized nasal airflow.

Methods:

Left- and right-side nasal airflow was measured in six subjects during an eight-hour sleep period using nasal thermistors. Polysomnography was performed. Simultaneously, body positions were monitored using a video camera in conjunction with infrared lighting.

Results:

Significantly greater airflow occurred through the right nasal chamber (relative to the left) during periods of REM sleep than during periods of non-REM sleep (p<0.001). Both body position (p < 0.001) and sleep stage (p < 0.001) influenced nasal airflow lateralization.

Conclusions:

This study demonstrates that the lateralization of nasal airflow and sleep stage are related. Some types of asymmetrical somatosensory stimulation can alter this relationship.

Auditory and Lower Limb Tactile Prepulse Inhibition in Primary Restless Legs Syndrome: Clues to Its Pathophysiology

The resting sensory discomfort transiently relieved upon movement of the affected area in restless legs syndrome suggests that sensorimotor integration mechanisms, specifically gating, may be altered in the disease. The authors sought to determine the effects of prepulse auditory and tactile stimulation applied to lower limbs on the blink reflex of patients with restless legs syndrome and healthy subjects. Seventeen patients with restless legs syndrome and 17 age- and sex-matched healthy controls were investigated. Auditory stimuli and tactile lower limb stimulation were applied as prepulses. The R2 response of the blink reflex induced by electrical stimulation applied to the right supraorbital nerve was selected as the test stimulus. Time intervals between prepulses and response-eliciting stimuli were 40, 70, 90, 110, and 200 milliseconds. There were no differences in either the auditory or tactile prepulse conditions between patients and controls and no differences between these measures within subject groups. We concluded that the tactile lower limb and the auditory prepulse effects on the brainstem interneurons mediating the blink reflex share common neural pathways. Because forebrain interneurons mediate these prepulse effects, they are likely not involved in the disordered sensorimotor interaction of restless legs syndrome.

Taste dysfunction in multiple sclerosis

Empirical studies of taste function in multiple sclerosis (MS) are rare. Moreover, a detailed assessment of whether quantitative measures of taste function correlate with the punctate and patchy myelin-related lesions found throughout the CNS of MS patients has not been made. We administered a 96-trial test of sweet (sucrose), sour (citric acid), bitter (caffeine) and salty (NaCl) taste perception to the left and right anterior (CN VII) and posterior (CN IX) tongue regions of 73 MS patients and 73 matched controls. The number and volume of lesions were assessed using quantitative MRI in 52 brain regions of 63 of the MS patients. Taste identification scores were significantly lower in the MS patients for sucrose (p = 0.0002), citric acid (p = 0.0001), caffeine (p = 0.0372) and NaCl (p = 0.0004) and were present in both anterior and posterior tongue regions. The percent of MS patients with identification scores falling below the 5th percentile of controls was 15.07 % for caffeine, 21.9 % for citric acid, 24.66 % for sucrose, and 31.50 % for NaCl. Such scores were inversely correlated with lesion volumes in the temporal, medial frontal, and superior frontal lobes, and with the number of lesions in the left and right superior frontal lobes, right anterior cingulate gyrus, and left parietal operculum. Regardless of the subject group, women outperformed men on the taste measures. These findings indicate that a sizable number of MS patients exhibit taste deficits that are associated with MS-related lesions throughout the brain.

"Unclassical" Combination of Smell Dysfunction, Altered Abdominal Nociception and Human Hypertension Associated "Classical" Adrenal-Augmentation

We report a 33-year-old female patient, who arrived to the emergency ward with an abdominal pain that suddenly started 10 days before admission. Simultaneously, the patient developed sudden arterial hypertension and smell disturbances. Conventional medical treatment for pain and arterial hypertension was effortless. Laboratory tests ruled out pancreatitis. Metanephrines in her urine were also normal. A dual-phase intravenous contrast computed tomography of the abdomen showed a large mass within left adrenal gland. Adrenocortical adenoma was diagnosed. The mass was not hypervascularized but positive for synaptophysin and chromogranin A. Importantly, these proteins are heavily involved with acetylcholine metabolism. The triad of olfactory disorders, pain and arterial hypertension normalized after surgically extracting the adrenal mass. To our knowledge, this medical case is the first reported patient exhibiting immediate recovery of such unclassical triad of local and remote findings. The function and dysfunction of key nanocholinergic pathways involved with smell, blood pressure and nociception would explain the pathophysiology of this unique medical case.

Olfactory dysfunction in Parkinson's disease: Positive effect of cigarette smoking

BACKGROUND

There is compelling evidence from over 60 epidemiological studies that smoking significantly reduces the risk of Parkinson's disease (PD). In general, those who currently smoke cigarettes, as well as those with a past history of such smoking, have a reduced risk of PD compared to those who have never smoked. Recently it has been suggested that a cardinal nonmotor sensory symptom of PD, olfactory dysfunction, may be less severe in PD patients who smoke than in PD patients who do not, in contrast to the negative effect of smoking on olfaction described in the general population.

METHODS

We evaluated University of Pennsylvania Smell Identification Test (UPSIT) scores from 323 PD patients and 323 controls closely matched individually on age, sex, and smoking history (never, past, or current).

RESULTS

Patients exhibited much lower UPSIT scores than did the controls (P < 0.0001). The relative decline in dysfunction of the current PD smokers was less than that of the never- and past-PD smokers (respective Ps = 0.0005 and 0.0019). Female PD patients outperformed their male counterparts by a larger margin than did the female controls (3.66 vs. 1.07 UPSIT points; respective Ps < 0.0001 and 0.06). Age-related declines in UPSIT scores were generally present (P < 0.0001). No association between the olfactory measure and smoking dose, as indexed by pack-years, was evident.

CONCLUSIONS

PD patients who currently smoke do not exhibit the smoking-related decline in olfaction observed in non-PD control subjects who currently smoke. The physiological basis of this phenomenon is yet to be defined.

Taste function in early stage treated and untreated Parkinson's disease

Since brain stem regions associated with early Parkinson's disease (PD) pathology encroach upon those involved in taste function, the ability to taste may be compromised in PD. However, studies on this point have been contradictory. We administered well-validated whole-mouth and regional taste tests that incorporated multiple concentrations of sucrose, citric acid, caffeine, and sodium chloride to 29 early stage PD patients and 29 age-, sex-, and race-matched controls. Electrogustometry was also performed on the anterior tongue. The PD cohort was tested both on and off dopamine-related medications in counterbalanced test sessions. While whole-mouth taste identification test scores for all stimuli were, on average, nominally lower for the PD patients than for the controls, a trend in the opposite direction was noted for the intensity ratings at the lower stimulus concentrations for all stimuli except caffeine. Moreover, regional testing found that PD subjects tended to rate the stimuli, relative to the controls, as more intense on the anterior tongue and less intense on the posterior tongue. No significant associations were evident between taste test scores and UPDRS scores, L-DOPA medication equivalency values, or [(99m)Tc]TRODAT-1 SPECT imaging of dopamine transporter uptake within the striatum and associated regions. Our findings suggest that suprathreshold measures of taste function are influenced by PD and that this disease differentially influences taste function on anterior (CN VII) and posterior (CN IX) tongue regions. Conceivably PD-related damage to CN IX releases central inhibition on CN VII at the level of the brainstem, resulting in enhanced taste intensity on the anterior tongue.

Point pressure sensitivity in early stage Parkinson's disease

A number of sensory changes occur in the earliest stages of Parkinson's disease (PD), some of which precede the expression of the classic motor phenotype by years (e.g., olfactory dysfunction). Whether point pressure sensitivity (PPS), a cutaneous measure of light touch mediated by myelinated Aβ fibers, is altered in early PD is not clear. Prior studies on this point are contradictory and are based on non-forced-choice threshold tests that confound the sensitivity measure with the response criterion. While α-synuclein pathology, a defining feature of PD, is present in the skin of PD patients, it is restricted to unmyelinated nerve fibers, suggesting PPS may be spared in this disease. We determined PPS thresholds using a state-of-the-art forced-choice staircase threshold test paradigm in 29 early stage PD patients and 29 matched controls at 11 body sites: the center of the forehead and the left and right forearms, index fingers, palms, medial soles of the feet, and plantar halluces. The patients were tested, in counterbalanced sessions, both on and off dopamine-related medications (DRMs). PPS was not influenced by PD and did not correlate with DRM l-DOPA equivalents, scores on the Unified Parkinson's Disease Rating Scale, side of the major motor disturbances, or SPECT imaging of the striatal dopamine transporter, as measured by technetium-99m TRODAT. However, PPS thresholds were lower on the left than on the right side of the body (p=0.008) and on the upper extremities relative to the toes and feet (ps<0.0001). Positive correlations were evident among the thresholds obtained across all body sectors, even though disparate regions of the body differed in terms of absolute sensitivity. This study indicates that PPS is not influenced in early stage PD regardless of whether patients are on or off DRMs.

Suprathreshold odor intensity perception in early-stage Parkinson's disease

BACKGROUND

Whether Parkinson's disease (PD) influences suprathreshold changes in perceived odor intensity is unknown. In patients with Alzheimer's disease, patients with schizophrenia, and the elderly, such perception is reportedly normal. If generally true, this could reflect a core element of the olfactory system insulated to some degree from age- and disease-related pathological conditions.

METHODS

Odor intensity ratings for pentyl acetate were obtained from 29 early-stage PD patients when on and off dopamine-related medications (DRMs) and from 29 matched controls.

RESULTS

The ratings were significantly attenuated at the higher odorant concentrations, with the degree of attenuation associated with overall olfactory dysfunction. Ratings were higher on the right than on the left side of the nose of both patients and controls. No associations with DRMs, Unified Parkinson's Disease Rating Scale (UPDRS) scores, or striatal dopamine transporter imaging were found.

CONCLUSIONS

Parkinson's disease (PD) influences suprathreshold estimates of perceived odor intensity, negating the notion that such perception might be spared in this disease. No association with dopaminergic processes was apparent.

Chemosensory rehabilitation and malnutrition in the newborn: how far, how close?

Olfaction is critical to the hedonic appreciation of foods, caloric regulation of food intake, quality of life and taste preferences since birth. However, malnutrition in newborns down-regulates chemosensory function. Thus, olfactory measures might be used as early markers of chemosensory dysfunction in malnutrition, and may also be useful in assessing feeding adjustments during nutritional rehabilitation. Olfactory anomalies originated by malnutrition would be reversed by nutritional rehabilitation following flavor-enhancing odorants.

Galvanic vestibular stimulation: a novel modulatory countermeasure for vestibular-associated movement disorders

Motion sickness or kinetosis is the result of the abnormal neural output originated by visual, proprioceptive and vestibular mismatch, which reverses once the dysfunctional sensory information becomes coherent. The space adaptation syndrome or space sickness relates to motion sickness; it is considered to be due to yaw, pith, and roll coordinates mismatch. Several behavioural and pharmacological measures have been proposed to control these vestibular-associated movement disorders with no success. Galvanic vestibular stimulation has the potential of up-regulating disturbed sensory-motor mismatch originated by kinetosis and space sickness by modulating the GABA-related ion channels neural transmission in the inner ear. It improves the signal-to-noise ratio of the afferent proprioceptive volleys, which would ultimately modulate the motor output restoring the disordered gait, balance and human locomotion due to kinetosis, as well as the spatial disorientation generated by gravity transition.

Dysfunctional chemosensation in myasthenia gravis: a systematic review

OBJECTIVES

Myasthenia gravis has traditionally been viewed as a disorder that solely affects the neuromuscular junction within the peripheral nervous system. However, there is now evidence that the cholinergic dysfunction of this disorder may be more widespread than previously believed. This article provides a systematic review of the studies that examined smell and taste function in myasthenia gravis.

METHODS

We analyzed studies that reported chemosensory function alterations in patients with myasthenia gravis. PubMed, MEDLINE, Web of Science, EMBASE, and SciELO, searched to identify articles published from January 1950 through December 2012, were supplemented by relevant articles. The following information was identified from each article: the number of patients, number of controls (if any), clinical stage of patients, neurological involvement, serological state, taste or smell involvement, chemosensory test used, and country of publication.

RESULTS

Ten studies reporting smell and taste function and dysfunction in patients with myasthenia gravis were identified, most of which were case reports commenting on apparent abnormalities in the taste system. The sole empirical study that investigated taste function, however, was negative, suggesting that some reports of taste loss may reflect olfactory loss. One study clearly documented olfactory dysfunction in patients with myasthenia gravis, dysfunction most likely attributable to altered central nervous system cholinergic function.

CONCLUSIONS

Chemosensory dysfunction has been reported in a number of patients with myasthenia gravis. Given the close association between complaints of taste dysfunction and loss of flavor sensations secondary to olfactory system damage, quantitative testing should be used to accurately assess the nature and degree of the dysfunction present in this debilitating disorder.

[Present and future of the transcranial magnetic stimulation]

Magnetic stimulation has called the attention of neuroscientists and the public due to the possibility to stimulate and "control" the nervous system in a non-invasive way. It has helped to make more accurate diagnosis, and apply more effective treatments and rehabilitation protocols in several diseases that affect the nervous system. Likewise, this novel tool has increased our knowledge about complex neural behavior, its connections as well as its plastic modulation. Magnetic stimulation applied in simple or paired-pulse protocols is a useful alternative in the diagnosis of diseases such as multiple sclerosis, Parkinson disease, epilepsy, dystonia, amyotrophic lateral sclerosis, cerebrovascular disease, and sleep disorders. From the therapeutic perspective, magnetic stimulation applied repetitively has been found useful, with different degrees of efficacy, in treating resistant depression, tinnitus, psychogenic dysphonia, Alzheimer disease, autism, Parkinson disease, dystonia, stroke, epilepsy, generalized anxiety as well as post traumatic stress disorder, auditory hallucinations, chronic pain, aphasias, obsessive-compulsive disorders, L-dopa induced dyskynesia, mania and Rasmussen syndrome, among others. The potential of magnetic stimulation in neurorehabilitation is outstanding, with excellent range of safety and, in practical terms, without side effects.

Primary and Reversible Pisa Syndrome in Juvenile Normal Pressure Hydrocephalus

OBJECTIVE

To report a case of Pisa syndrome in a patient with idiopathic normal pressure hydrocephalus, who had never been exposed to psychotropic medications.

METHODS

A 26 years-old, Colombian, male patient, was referred because he had cognitive abnormalities, gait disturbances and urinary incontinence. This patient also displayed pleurothotonos. Neurofunctional evaluation of sensory and motor integration at peripheral and central nervous system levels were done.

RESULTS

Pisa syndrome disappeared after spinal tap drainage with further gait, balance and behavioral improvement. A brainstem-thalamocortical deregulation of the central sensory and motor programming, due to the chaotic enlargement of brain ventricles was thought to be the pathophysiological mechanism underlying this case.

CONCLUSION

NPH must not be longer considered as an exclusive geriatric disorder. Further, uncommon movement disorders may appear with this disorder, which should be carefully approached to avoid iatrogenic and deleterious pharmacological interventions.

Higher sensory processing sensitivity, introversion and ectomorphism: New biomarkers for human creativity in developing rural areas

The highly sensitive trait present in animals, has also been proposed as a human neurobiological trait. People having such trait can process larger amounts of sensory information than usual, making it an excellent attribute that allows to pick up subtle environmental details and cues. Furthermore, this trait correlates to some sort of giftedness such as higher perception, inventiveness, imagination and creativity. We present evidences that support the existance of key neural connectivity between the mentioned trait, higher sensory processing sensitivity, introversion, ectomorphism and creativity. The neurobiological and behavioral implications that these biomarkers have in people living in developing rural areas are discussed as well.

WITHDRAWN: Mechanisms Underlying Inhibitory and Facilitatory Transcranial Magnetic Stimulation Abnormalities in a Large Sample of Patients with Parkinson's Disease

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

[Neurorehabilitation: from a rigid past to a plastic future]

Since ancient times, several cultures including those from China, Egypt, India and Rome gave rigid solutions to improve physical problems of affected people by several neurological disorders. These measures were applied, at that time, by individuals prepared for doing such task. It evolved throughout the years supported by the discovery and comprehension of the so-called neural plasticity as well as the current evidences that the nervous system is able of remodelating itself even in adult times. It is known today that synaptic modulation is the base of neurorehabilitation improved by use and application of specific protocols to each neurological disorder. Among these, we have to consider not only all of the already known on rehabilitation measures but also on neurorobotic, neurorestauration, neuromodulation, neurostimulation as well as virtual reality, among others interventions. Neurorehabilitation has been able to put together modern science with ancient manual therapies helping to change, in a positive way, the attitude toward people with disabilities in the twenty one century; likewise, it offers new hopes for functional recovery where before was nothing. Further, it gives opportunities to get a better quality of life to affected people and its corresponding families. It is very interesting to know that the modern concepts of neurorehabilitation performed in a multidisciplinary approach are very useful for humans on the Earth and people interested in conquer Space.

[Magnetoreception: the angular stone in aerospace orientation, human balance and locomotion]

Current research is in agreement with the presence of a magnetic compass in living beings including humans. The two most accepted explanations that demonstrate the existence of magnetoreceptors in living beings are, the radical pair and the biogenic magnetite, which are discussed here with its respective experimental evidence and support. It indicates the presence of magnetite crystals in otoliths, among different inferior species of animals. Moreover, the magnetite found in several organs of human body allows predicting the existence of such element, in otoliths of vestibular system as well; further, anticipates that human magnetoreception is an additional function of the vestibular system. These geomagnetic signals would modulate balance, movement and spatial positioning of man in concordance of gravity values. This new field of otomagnetism opens new research areas for understanding the mechanisms involved in balance, equilibrium, orientation, and space positioning in normal and disease populations. Likewise, this could be the starting point for application of new human neurorehabilitation procedures, in those magnetoreception-associated neurological disorders that happen in the earth, the sea or the air.

Colombia Médica is now indexed in MEDLINE/Pubmed: A dream come true

It was said some years ago that «the shortest line in science, as well as in love, is not the straight one»1. This turned out to be true for Acta Médica del Valle, a scientific journal launched in Cali, Colombia in 1970, when Rodrigo Guerrero et al., dreamt of having a periodical to disseminate medical information - primarily in southwestern Colombia. Moreover, Jorge Lega Siccar, president of this journal's first editorial committee, envisioned that manuscripts coming from the «whole republic», as well as from overseas, would arrive at the editorial office of the newly born scientific journal. And they accomplished it. Then, Francisco Falabella et al., who took the lead from 1973 until 1998, dreamt of increasing the journal's impact and reputation throughout Colombia. Thus, in 1980, the Journal's name was changed to Colombia Médica, and hundreds of high-quality manuscripts were published in paper form only, an uninterrupted journey lasting 25 years - from 1970 to 1995, and always supported by Universidad del Valle also located in Cali. During this time, Colombia Médica disseminated important and groundbreaking research. For example, in 1981, Zaninovic et al., published on a disease prevalent in southwestern Colombia, charac­terized by spastic paraparesis, a disorder later associated with a number of environmental cofactors2. This research attracted the attention of the World Health Organization to this medical problem. Also, among the dreams of this editorial group was to set up an electronic edition of Colombia Médica, which was posted on the web page: http://colombiamedica. univalle.edu.co in 1995. And this was accomplished!

The motor evoked potential in aids and HAM/TSP State of the evidence

OBJECTIVE: We aimed to better understand the involvement of the corticospinal tract, assessed by non-invasive transcranial stimulation, in order to determine the actual involvement of the motor system in patients with HAM/TSP and AIDS. METHOD: An exhaustive MEDLINE search for the period of 1985 to 2008 for all articles cross-referenced for "HTLV-I, HTLV-II, HTLV-III and HIV, HIV1, HIV2, evoked potential, motor evoked potential, high voltage electrical stimulation, transcranial magnetic stimulation, magnetic stimulation, corticomotor physiology, motor pathways, acquired immunodeficiency syndrome, AIDS, SIDA, tropical spastic paraparesis, HTLV-I-associated myelopathy, HAM, TSP, and HAM/TSP" were selected and analysed. RESULTS: Eighteen papers published in English, Spanish, Portuguese, French and Japanese were identified. Only the central motor conduction time has been analyzed in seropositive patients to human retroviruses. The investigations done on HAM/TSP support the involvement of the pyramidal tract mainly at lower levels, following a centripetal pattern; in AIDS, such an involvement seems to be more prominent at brain levels following a centrifugal pattern. CONCLUSION: The central motor conduction time abnormalities and involvement differences of the corticospinal tract of patients with AIDS and HAM/TSP dissected here would allow to re-orient early neurorehabilitation measures in these retroviruses-associated neurodegenerative disorders. Besides this, more sophisticated and sensitive non-invasive corticospinal stimulation measures that detect early changes in thalamocortical-basal ganglia circuitry will be needed in both clinically established as well as asymptomatic patients at times when the fastest corticospinal fibers remain uninvolved.

Two Babinski signs in seropositive (HAM) and seronegative tropical spastic paraparesis

Tropical spastic paraparesis (TSP) may or may not be associated to HTLV-I antibodies and is usually characterized by clinical and pathological spinal cord abnormalities at thoracic levels. We present here five Brazilian patients who had typical chronic idiopatic spastic paraparesis; two of them were HTLV-I seropositive (HAM) and three HTLV-I seronegative (TSP) - associated-myelopathy. Three out of these five patients also displayed clinical supraspinal involvement, indeed, platysma muscle hypotrophy or atrophy (the Babinski plus sign). These findings support the view that clinical involvement in HAM and TSP is wider than the spinal cord abnormalities usually considered. Possible non-infectious co-factors (e.g., mycotoxins) may be involved in disease pathogenesis in a multistep process of viruses, toxins and environment which may account for serological differences found in this group of patients.

[Concepts, confusions and contradictions on the impact factor in Colombia]

Latin American scientists are making tremendous efforts to conduct good-quality research worthy of being published internationally. However, Colciencias, an entity created to support this research in Colombia, introduced scienciometric evaluations which had been re-evaluated elsewhere some time ago, based on measurements of aspects such as the ill-termed "impact factor". Even more serious is that the aforementioned government office is unaware that measures are based on debated mathematical principles, placing Colombian science at imminent risk of suffering from an academic yatrogeny of irreparable consequences. Therefore, an urgent restructuring of the way in which Colombia's scientific production is to be evaluated is thus mandatory before these measures have a negative impact thereon.

Abnormality of motor cortex excitability in peripherally induced dystonia

It is widely accepted that peripheral trauma such as soft tissue injuries can trigger dystonia, although little is known about the underlying mechanism. Because peripheral injury only rarely appears to elicit dystonia, a predisposing vulnerability in cortical motor areas might play a role. Using single and paired-pulse pulse transcranial magnetic stimulation, we evaluated motor cortex excitability of a hand muscle in a patient with peripherally induced foot dystonia, in her brother with craniocervical dystonia, and in her unaffected sister, and compared their results to those from a group of normal subjects. In the patient with peripherally induced dystonia, we found a paradoxical intracortical facilitation at short interstimulus intervals of 3 and 5 milliseconds, at which regular intracortical inhibition (ICI) occurred in healthy subjects. These findings suggest that the foot dystonia may have been precipitated as the result of a preexisting abnormality of motor cortex excitability. Furthermore, the abnormality of ICI in her brother and sister indicates that altered motor excitability may be a hereditary predisposition. The study demonstrates that the paired-pulse technique is a useful tool to assess individual vulnerability, which can be particularly relevant when the causal association between trauma and dystonia is less evident.

[Hemiplegia with two Babinski's sign]

Neurological signs and symptoms are very important to establish a correct neurological diagnosis. We present here a Colombian female patient, 60 years-old, who had ischaemic stroke in the left cerebral media artery. It produced right hemiplegia, motor aphasia, "central" facial palsy and atrophy of right platysma muscle. This latter finding, described originally by Joseph Babinski as "The Babinski Sign" was observed only two years and seven months after the ictus even when she had, previously, been evaluated by several neurologists. The underdiagnosis of clinical signs like the one described here may lead to erroneous diagnosis that will, ultimately, affect neurorehabilitation measures.

Visual deprivation effects on human motor cortex excitability

Single and paired-pulse transcranial magnetic stimulation (TMS) were applied to the motor cortex of 12 healthy volunteers, who were instructed to relax under eyes-open and eyes-closed conditions with room lights on and after 30 min of blindfolding. Compared to the eyes-open condition, significantly larger motor-evoked potentials and less intracortical inhibition were observed during blindfolding. Visual deafferentation changes resting human motor cortex excitability and might be a novel way to promote brain plasticity. These results raise the issue of how widespread the effects of temporary deafferentation may be and whether they are mediated by discrete or diffuse systems. These findings also illustrate an important potential confound in TMS studies of the motor cortex.

[Colciencias and disdain for Colombian scientists: from the Stone Age to the impact factor]

Writing has dramatically evolved in the world; however, qualification of scientific production in Colombia has not, including the improper use of decree 1444/93 and 1279/02. The last of these decrees authorized Colciencias, the Colombian government institute created to support scientific research in Colombia, to establish rules for its implementation. Colciencias decided to evaluate scientific papers produced in Colombia based on the non-scientific method of the "impact factor", and considered that citations in MEDLINE/PubMed and PsylNFO were second line publications thus violating Colombian law. This affects not only the progress of scientific research in Colombia but also researchers' income and puts Colombia's scientific journals and publications at great disadvantage. Scientific papers indexed in qualified databases such as MEDLINE/PubMed must be judged according to law in order to prevent further injuries to the developing Colombian scientific production.

Capsaicin effects on blinking

Blinking is a normal human phenomenom involving trigeminal and facial patways. To gain understanding on the neurobiology of blinking, five normal subjects were investigated before and after application of transdermal capsaicin at the forehead for two weeks. No effects of topical capsaicin were detected in eye blink rates. However, when capsaicin was applied to a female subject with blepharospasm, she showed a dramatic restoration of her vision subsequent to blinking modification. Deactivation of abnormal A-to-C fibers cross talks at the trigeminal-facial pathways seems to be the most likely mechanism of such improvement.