Capsaicin effects on blinking

Blinking is a normal human phenomenon involving trigeminal and facial pathways. 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.

El parpadeo es un fenómeno normal en los humanos que involucra las vías trigéminas faciales. Con el fin de conocer un poco más la neurobiología de este fenómeno estudiamos cinco individuos normales antes y después de aplicar capsaicina trasdérmica en la frente de cada uno de ellos, por dos semanas. La frecuencia de parpadeo no se alteró con la aplicación de capsaicina tópica. Sin embargo, cuando la misma sustancia se aplicó a una paciente con blefaroespasmo hubo dramática restauración de su visión, la cual fue secundaria a la modificación de la actividad muscular palpebral. La desactivación del cruce patológico de información que pasa de las fibras A a las fibras C, pertenecientes a las vías trigémino-faciales, parece ser el mecanismo de acción relacionado con la aplicación de capsaicina, el que estaría directamente relacionado con la recuperación clínica observada en la paciente con blefaroespasmo.

Cortical control of voluntary blinking: a transcranial magnetic stimulation study.

OBJECTIVE: To investigate cortical regions related to voluntary blinking. METHODS: Transcranial magnetic stimulation (TMS) was applied to the facial motor cortex (M1) and the midline frontal region (Fz) in 10 healthy subjects with eyes opened and closed. Motor-evoked potentials were recorded from the orbicularis oculi (OOC), orbicularis oris (OOR), abductor digiti minimi and tibialis anterior using surface and needle electromyography electrodes. Facial M waves and blink reflex were measured using supramaximal electrical stimulation of the facial and supraorbital nerves. RESULTS: TMS at Fz elicited 3 waves in OOC with no response in other tested muscles except for the early wave in OOR. Facial M1 stimulation produced only early and late waves. Because of their latencies, shapes, and relationship to coil position and stimulation intensity, early and late waves appeared to be analogous to the facial M wave and R1 component of the blink reflex. The intermediate wave at 6-8 ms latency was elicited in OOC by Fz stimulation with eyes closed. CONCLUSIONS: Since its latency matches the central conduction time of other cranial muscles and it has characteristic of muscle activation-related facilitation, the intermediate wave is presumably related to cortical stimulation. This result provides evidence that the cortical center for the upper facial movements, including blinking, is not principally located in the facial M1, but rather in the mesial frontal region.

[Migraine and MIDAS (MIDASELA) in Colombian hospital workers]. / Migraña y MIDAS (MIDASELA) en trabajadores hospitalarios colombianos.

AIMS: The aim of this study was to determine the prevalence of migraine and its implications in the occupational and outside employment/daily activities of the workers at a regional hospital in the Cundiboyacense Plateau in Colombia. PATIENTS AND METHODS: The available members of the house staff at this institution were interviewed by applying the neuroepidemiological protocol drawn up by the World Health Organization (WHO); general doctors performed the initial screening and the determination of neurological disease was carried out by a clinical neurologist, both in patients who were positive and negative for neurological disease. Quality of life was evaluated by means of the MIDAS (Migraine Disability Assessment) survey, MIDASELA (in Spanish for Latin America); the analysis was performed using the EPI 6.04 software application. RESULTS: A total of 238 people were studied: 188 females and 50 males; the prevalence of migraine was 22.5% (15.5% by the WHO protocol and 7% false negatives), with predominance in females (OR: 5.49; p< 0.005). In the MIDASELA questionnaire, 47.2% of the patients had a 50% alteration in their productivity, with regard to their occupational and outside employment/daily activities. A minimum number of patients (3.8%) were unable to work because of migraine, as compared to the figures for outside employment/daily activities (29.7%) or those involving leisure/family (66.4%). The average work, outside employment/daily and family time lost per patient because of migraine was 0.3, 2 and 5.2 days, respectively. CONCLUSION: A sub register in the prevalence of migraine could be reported in places where the WHO protocol is used. This pathology will have to be taken well into account in Colombian hospital workers due to its individual, occupational, family, social and economic impact. It is necessary to introduce health policies and programmes aimed at evaluating, controlling and treating this type of pathology in an appropriate manner, in order to improve the quality of life of those whose job it is to look after and improve that of the other Colombians.

[Retrovirus, mycotoxins, immunosuppression and neurodegeneration]. / Retrovirus, micotoxinas, inmunosupresión y neurodegeneración.

AIMS: To analyse the pros and cons of the etiopathogenic aspects of the different clinical entities that, over the years, have been found to be associated with the so called human retroviruses in order to propose possible etiological alternatives. METHOD: Since research on retroviruses began there has been a tendency to blame these elements for a number of clinical entities, the most important of which include Aids, tropical spastic paraparesis (TSP), fungoid mycosis, Sjogren's syndrome and T cell leukaemia. Yet many patients and scientific publications point out the existence of a large number of clinical and laboratory inconsistencies, which suggests that the so called cofactors associated with all these entities are far more likely to be the real generators of these public health problems. Among these, we pay special attention to environmental toxins, of which a prototypical example is the group of neuromycotoxins. There are several ways these can enter the organism of an individual exposed to them (through food, breathing and intravenously) or, worse still, they can be generated endogenously in immunosuppressed individuals. CONCLUSION: The possibility of some cofactors being the real causes behind a large number of entities considered to be Aids, TSP, Sjogren s syndrome, fungoid mycosis or T cell leukaemia, among others, regardless of their retroviral serological state, is becoming more and more likely and scientifically plausible. All these facts should be researched in much greater depth to determine their real dimensions, which would therefore enable us to face the future with better means of prevention, diagnosis and treatment at our disposal.

Retrovirus, micotoxinas, inmunosupresión y neurodegeneración / Retrovirus, mycotoxins, immunosuppression and neurodegeneration

Objetivo. Analizar los pros y los contra de los aspectos etiopatogénicos en las diferentes entidades clínicas que se han encontrado, a lo largo de los años, asociadas con los llamados retrovirus humanos, con el fin de proponer posibles alternativas etiológicas. Desarrollo. Desde el comienzo de las investigaciones sobre retrovirus se ha tratado de inculpar a estos elementos en múltiples entidades clínicas; sobresalen, dentro de éstas, el sida, la paraparesia espástica tropical (PET), la micosis fungoide, el síndrome de Sjögren y la leucemia de células T. Sin embargo, un número importante de pacientes y publicaciones científicas señalan una gran cantidad de inconsistencias clínicas y de laboratorio, y sugieren que los llamados cofactores asociados a todas estas entidades sean, más bien, los reales generadores de estos problemas de salud pública. Dentro de éstos, destacamos los de tipo toxicoambiental, y tomamos como prototipo a las neuromicotoxinas, que pueden ingresar en el organismo de los individuos expuestos de diversas maneras -resaltan las vías alimenticia, endovenosa y respiratoria- o, peor aún, pueden generarse de manera endógena en individuos inmunosuprimidos. Conclusión. La posibilidad de que algunos cofactores sean los verdaderos causantes de una gran cantidad de entidades, como sida, PET, Sjögren, micosis fungoides o leucemia de células T, entre otras, independientemente de su estado serológico retroviral, es cada vez mas probable y científicamente creíble. Estos hechos, per se, merecen una investigación a fondo, con el fin de establecer sus reales dimensiones, y así poder seguir adelante con más y, cada vez, mejores pautas de prevención, diagnóstico y tratamiento en estas entidades asociadas a la nueva familia de los ViH: los virus de la imaginación humana (AU)

[Neuroepidemiology in the eastern region of Colombia]. / Neuroepidemiologia en el Oriente colombiano.

OBJECTIVE: To determine the presence of eight neurological disorders (migraine, cerebrovascular disease, disorders of movement, peripheral neuropathy, mental retardation, epilepsy, dementia and the sequelas of head injuries) in the eastern region of Colombia. PATIENTS AND METHODS: Using the neuro epidemiological protocol of the World Health Organization (WHO), modified by our group, together with a questionnaire to determine the sequelas of head injuries and the abbreviated mental test (Mini mental), we interviewed people in the municipalities of Bucaramanga, Piedecuesta and Aratoca. The persons suspected of having neurological disorders, who were over 12 years old, were evaluated by neurologists and those under 12 years old by a neuropaediatrician. RESULTS: In the eastern region, 1,454 persons altogether were interviewed. Neurological conditions were suspected in 454 of these (31.2%), and confirmed in 437 (30.1%). The specific results for these neurological disorders and their respective confidence intervals (in brackets) were: migraine 198.8 (178.7 220.4); peripheral neuropathy: 26.8 (19.4 36.9); epilepsy: 22.7 (15.9 32.1); dementia: 17.9 (11.9 26.5); cerebrovascular disease: 17.2 (11.4 25.7); mental retardation and delayed nervous system development: 15.1 (9.7 23.2); extrapyramidal disorders: 8.3 (4.5 14.8); sequelas of head injuries: 6.9 (3.5 13.1). RESULTS: These results, obtained using a modified version of a WHO protocol, together with dementia and the sequelas of head injuries, will permit the development of health policies and programmes for the control and treatment of neurological disorders prevalent in this region of Colombia

Immune response, nitric oxide, autonomic dysfunction and stroke: a puzzling linkage on Trypanosoma cruzi infection.

Trypanosoma cruzi (T. cruzi) is a tissue parasite causing American trypanosomiasis or Chagas' disease (ChD) affecting, mostly, the cardiovascular and gastrointestinal systems. We have recently found that people infected by T. cruzi are also more prone to developing ischemic strokes than the general population, even without heart complications; the pathomechanism of it is not yet well understood. However, after infection occurs, immune response induces endothelial dysfunction due to an endothelial nitric oxide synthase (eNOS) inhibition and increased activity of inducible nitric oxide synthase (iNOS). These factors are active in inducing vasoconstriction and cerebral microvascular spasms, leading to ischemic stroke. In addition, patients with ChD, regardless of cardiopathy, also have autonomic dysfunction, all of which may enhance the risk of developing ischemic stroke. Moreover, the possibility that these neuroimmunomodulatory pathways are disturbed in patients with other types of stroke seems possible, and is worthy of investigation.

Three silent periods in the orbiculari oculi muscles of man: normal findings and some clinical vignettes.

PURPOSE: To investigate how many true silent periods could be found in the orbiculari oculi muscles of man. MATERIAL AND METHODS: 10 subjects, clinically healthy (5 male, 5 female), with a mean age of 34 years-old (range: 23 to 48) were evaluated by mean of the blink reflex at resting and during contraction of the orbiculari oculi reflex according to protocols validated internationally. RESULTS: Three responses called R1, R2 and R3 were obtained in the orbicular oculi muscle at resting state which had latencies and amplitudes within normal limits. What was new was to obtain three silent periods when the subjects were evaluated during muscle contraction. The duration of the first silent period was statistically longer than the second one (p < 0.004) and shorter than the third silent period (p < 0.0001). In addition, this test was found useful in detecting more specific findings in patients with hemifacial spasm and Meigge syndrome. CONCLUSION: This is by the first time that three silent periods in the orbicular oculi muscles are consistently demonstrated. The refractoriness of the alpha motoneurons and the action of gamma-collateral activity seem to be the main conditions leasing to display the first two periods of muscle suppression. The modification of gamma motoneurons firing as well as a pause of muscle spindles in facial muscles due to the action of nociceptive stimuli traveling unmyelinated C fibers of the supraorbital nerve might be the most important mechanisms involved in the production of the third silent period. These results enables further clinical application of this test.

[Orbicular eye reflex (R3) and the valsalva manoeuvre]. / El reflejo orbicular de los ojos (R3) y la maniobra de Valsalva.

INTRODUCTION: Different kinds of tests have been devised to evaluate the autonomic nervous system, including the changes in heart rate and arterial blood pressure after carrying out Valsalva s manoeuvre. However, to date, the behaviour of the three responses to the orbicular eye reflex during this manoeuvre was not known and this was the reason for carrying out our study. POPULATION AND METHODS: We evaluated 12 neurologically normal persons before and after doing a Valsalva manoeuvre by studying the orbicular eye reflex using the method of Kimura and recording the three responses: R1, R2 and R3. RESULTS: The late results (R3) of this reflex, but not those of short (R1) or medium (R2) latency were significantly modified whilst the manoeuvre was carried out (p< 0.05). CONCLUSIONS: Inhibition of the gamma motor neurones during this inspiratory manoeuvre, which are also related to activity of the facial muscles, seems to be the mechanism most likely to explain the findings during the practice of BREATH (Blink reflex autonomic testing in humans). Studies which evaluate only the first two responses to this reflex whilst the manoeuvre is carried out should not be taken too seriously since they may lead to dangerously erroneous conclusions.