Análisis bioconductual del sistema vestibular y el control postural en pacientes con mareo cervicogénico. Estudio observacional transversal / Biobehavioural analysis of the vestibular system and posture control in patients with cervicogenic dizziness. A cross-sectional study

Introducción: El mareo cervicogénico es una afección que se caracteriza por mareos y desequilibrio que se asocia a dolor de cuello. La fisiopatología no está clara, y es necesario conocer la base neurofisiológica del trastorno. El objetivo de estudio es comparar la actividad del reflejo vestíbulo-ocular y el control postural entre pacientes que presentan mareo cervicogénico y sujetos asintomáticos; además, se pretende evaluar la asociación entre la discapacidad por mareo con otras variables psicosociales. Material y métodos: Se seleccionaron un total de 20 pacientes y 22 sujetos asintomáticos, a los que se realizó una valoración del reflejo vestíbulo-ocular con el test del impulso cefálico y una valoración del control postural mediante posturografía dinámica y el test de organización sensorial, además se evaluaron mediante autoinforme la discapacidad por mareo, la discapacidad cervical, el miedo al movimiento y el estado de ansiedad y depresión. Resultados: No se encontraron diferencias en la actividad del reflejo vestíbulo-ocular (p > 0,05); a nivel del control postural se encontraron diferencias con un tamaño del efecto mediano-grande (d > 0,60) en variables relacionadas con la propiocepción e integración de la información visual, asociándose esta variable a la discapacidad por mareo. La discapacidad por mareo presentó asociaciones moderadas-fuertes con la discapacidad cervical, el miedo al movimiento y la ansiedad. Conclusión: Los resultados obtenidos descartan una alteración del sistema vestibular en el mareo cervicogénico, aunque sí se comprueba la existencia de una alteración propioceptiva. La asociación de la discapacidad por mareo con otras variables psicosociales a la vista de nuestros resultados debe tomarse en cuenta en la clínica y en futuras investigaciones (AU)

Background: Cervicogenic dizziness is a musculoskeletal disorder mainly characterised by dizziness and disequilibrium associated with neck pain. The pathophysiology is unclear and the neurophysiological basis remains to be ascertained. The aim of this study is to compare the vestibulo-ocular reflex and postural control between patients with cervicogenic dizziness and asymptomatic subjects, and to assess the association between debilitating dizziness and other psychosocial variables. Materials and methods: A total of 20 patients and 22 asymptomatic subjects were selected. Vestibulo-ocular reflex was assessed by performing the head impulse test. Computerised dynamic posturography was used to evaluate the postural control by means of the sensory organisation test. In addition, subjects self-reported their degree of disability due to dizziness, cervical disability, kinesiophobia, and state of anxiety and depression. Results: There were no differences in the vestibulo-ocular reflex (P > .05). However, we found differences with a medium-to-large effect size (d > 0.60) in variables related to proprioception and visual information integration; the former variable set was related to disability due to dizziness. Disability due to dizziness presents strong-to-moderate associations with cervical disability, kinesiophobia, and anxiety. Conclusion: Our data rule out changes in the vestibular system in cervicogenic dizziness, but they do point to proprioceptive impairment. According to our results, the association between dizziness-related disability and other psychosocial factors in cervicogenic dizziness is very relevant for clinical medicine and for future research projects (AU)

Biobehavioural analysis of the vestibular system and posture control in patients with cervicogenic dizziness. A cross-sectional study. / Análisis bioconductual del sistema vestibular y el control postural en pacientes con mareo cervicogénico. Estudio observacional transversal.

BACKGROUND: Cervicogenic dizziness is a musculoskeletal disorder mainly characterised by dizziness and disequilibrium associated with neck pain. The pathophysiology is unclear and the neurophysiological basis remains to be ascertained. The aim of this study is to compare the vestibulo-ocular reflex and postural control between patients with cervicogenic dizziness and asymptomatic subjects, and to assess the association between debilitating dizziness and other psychosocial variables. MATERIALS AND METHODS: A total of 20 patients and 22 asymptomatic subjects were selected. Vestibulo-ocular reflex was assessed by performing the head impulse test. Computerised dynamic posturography was used to evaluate the postural control by means of the sensory organisation test. In addition, subjects self-reported their degree of disability due to dizziness, cervical disability, kinesiophobia, and state of anxiety and depression. RESULTS: There were no differences in the vestibulo-ocular reflex (P>.05). However, we found differences with a medium-to-large effect size (d>0.60) in variables related to proprioception and visual information integration; the former variable set was related to disability due to dizziness. Disability due to dizziness presents strong-to-moderate associations with cervical disability, kinesiophobia, and anxiety. CONCLUSION: Our data rule out changes in the vestibular system in cervicogenic dizziness, but they do point to proprioceptive impairment. According to our results, the association between dizziness-related disability and other psychosocial factors in cervicogenic dizziness is very relevant for clinical medicine and for future research projects.

Maximum likelihood mixture estimation to determine metal background values in estuarine and coastal sediments within the European Water Framework Directive.

Some of the recently derived European Directives, such as the Water Framework and Marine Strategy, have, as ultimate aims, to achieve concentrations of hazardous substances in the marine environment near background values. Hence, the determination of natural background levels, in marine sediments, is highly relevant. The present study proposes the use of the maximum likelihood mixture estimation (MLME) to determine regional background levels and upper threshold of metal concentration, with the Basque Country as a case study (with a data set of 575 samples, from estuarine and littoral areas, including both intertidal and subtidal sediments). The heuristic procedure is applied with unimodal data distributions (Cd, Cr, Fe and Ni) and the mixture density estimations, based upon maximum likelihood, are carried out with polypopulational data distributions (As, Cu, Mn, Hg, Pb and Zn). The upper limits of the distribution are proposed, as the limits between 'High Status' and 'Good Status' (according to the Water Framework Directive terminology). The regional upper limits were 0.45 microg g(-1) for Cd, 71 microg g(-1) for Cr, 53,542 microg g(-1) for Fe, 57 microg g(-1) for Ni, 24 microg g(-1) for As, 64 microg g(-1) for Cu, 447 microg g(-1) for Mn, 0.27 microg g(-1) for Hg, 66 microg g(-1) for Pb, and 248 microg g(-1) for Zn. The results from this study can assist further in the determination of sediment reference conditions, to assess chemical status, within the above-mentioned directives; likewise, it will be studied as a useful methodology in determining regional metal backgrounds in other European countries.

Ocular fixation to nasal periosteum with a superior oblique tendon in patients with third nerve palsy.

PURPOSE: To report a new surgical approach that uses ocular fixation to the nasal periosteum with superior oblique tendon for patients with complete third nerve palsy. METHODS: Prospective study of 15 patients with complete third nerve palsy who underwent surgery using a superior oblique tenectomy and ocular fixation to the nasal periosteum with the superior oblique tendon fragment. RESULTS: Eleven (73%) patients achieved good ocular alignment, 1 (7%) patient had a cosmetically acceptable result, and 3 (20%) patients had a cosmetically unacceptable result. Five (30%) patients had preoperative diplopia; all achieved resolution of their double vision in the primary position of gaze after surgery. Two patients without preoperative diplopia did not achieve good alignment and had diplopia postoperatively. Follow-up ranged from 8-41 months (mean: 19 months). No operative complications occurred. CONCLUSION: Ocular fixation to the nasal periosteum with superior oblique tendon is a safe, effective, and technically undemanding option for the surgical management of patients with complete third nerve palsy.

Focal xanthogranulomatous pyelonephritis simulating malignancy in children.

Xantogranulomatous pyelonephritis is a severe chronic form of renal parenquimal infection that usually results in diffuse renal destruction. An unusual case of xanthogranulomatous pyelonephritis in a child is reported which presented as a focal mass without calculus in a functioning kidney and was diagnosed as a renal tumor.

Sensory nerve responses elicited by experimental ocular hypertension.

In order to clarify the neurophysiological mechanisms underlying the pain sensations that accompany certain forms of glaucoma, the responses of ocular sensory fibers to artificially induced intraocular pressure increases were studied in the cat. In lightly anesthetized animals, intraocular pressure elevations up to 120 mmHg did not evoke the sustained reflex changes in arterial pressure or heart rate that would be suggestive of strong nociceptive stimulation. Multiunit activity recorded from filaments of mixed ciliary nerves showed a sharp frequency increase (phasic response) at the onset of intraocular pressure elevations of 20 mmHg or more. In half of the nerves, the discharge stabilized at a higher firing frequency throughout the rise in pressure (tonic response). Corneal units fired phasically in response to intraocular-pressure elevations, and in one third of them this burst of impulses was followed by a low-frequency tonic discharge. Most of the fibers sensitive to light mechanical stimulation of the scleral surface discharged only phasically when intraocular pressure was raised to values of 60 mmHg or more, whereas high threshold scleral fibers were totally insensitive. Iridial fibers responded in all cases to ocular hypertension with a phasic response that became progressively tonic with higher intraocular-pressure values. It is concluded that mechanical deformation of the ocular structures resulting from intraocular-pressure elevations to pathological levels causes only transient excitation of most ocular sensory fibers. Hence, mechanical stimulation appears to be directly responsible only for the transient pain sensations during acute intraocular pressure increases experienced by glaucoma patients.

Reversal of respiratory responses to dopamine after dopamine antagonists.

The effects of dopamine (DA) antagonists upon resting ventilation and ventilatory reactions to DA, apomorphine, hyperoxia and hypoxia were studied in pentobarbitone-anesthetized cats. Intravenous administration of spiroperidol, haloperidol, perphenazine and chlorpromazine increased resting ventilation, the intensity and duration of the effect being dependent on the dose of the blocker. The enhanced ventilation was associated to increased frequency of chemosensory discharges recorded from one carotid nerve, and it was absent from section of the four buffer nerves. The drugs also provoked a dose-dependent block of the transient chemosensory inhibitions and ventilatory depressions induced by DA or apomorphine. In addition, spiroperidol and perphenazine reversed the inhibitory reactions to DA into excitatory ones, the ventilatory responses being abolished by section of carotid and aortic nerves. The ventilatory depressions caused by a few breaths of 100% O2 and the ventilatory excitations onset by a few breaths of 100% N2 persisted after applying DA blockers. Results indicate that DA antagonists enhance ventilation by increasing peripheral chemosensory drive and may invert DA-induced reflex withdrawal into transient ventilatory excitation, without reversing the reflex ventilatory depression provoked by hyperoxia.

Respiratory effects of dopamine-induced inhibition of chemosensory inflow.

In pentobarbitone-anesthetized cats, intracarotid injections of dopamin (DA) 0.05--20 micrograms produced transient ventilatory depression, enhanced by section of the contralateral carotid nerve and abolished by section of the ipsilateral one. I.v. injections of DA 0.02--2 micrograms-kg-1 also induced transient hypoventilation; this effect was abolished by bilateral section of the carotid nerves. Slow i.v. infusion of DA 10 micrograms-kg-1-min-1 elicited initially a pronounced hypoventilation followed by a steady-state of mild ventilatory depression; these changes were absent after bilateral carotid neurotomy. Recordings from carotid nerves showed that DA-induced decreases of chemosensory activity to 50% of its control did not modify ventilation, while chemosensory arrests transiently depressed ventilation to 40--75% of its control level. Interactions between the ventilatory and chemosensory depressant effects of hypertoxia and DA administration were also studied. It is proposed that the reflex decrease in ventilation caused by DA injections provides a measure of the tonic chemosensory drive exerted upon the respiratory center.

Regulatory role of carotid nerve afferences upon the frequency and pattern of spontaneous gasp complexes.

Spontaneous gasps were recorded in pentobarbitone-anesthetized adult cats. Mean interval between gasps in 11 cats with their buffer nerves intact was of 65 sec; it was significantly prolonged to 174 sec after unilateral carotid neurotomy and to 403 sec after bilateral carotid neurotomy. Additional sectioning of both aortic nerves in two cats led to a further increase of intervals between gasps. Inhibition of chemosensory activity during dopamine infusions also reduced the frequency of gasps. Recording of chemosensory impulses from one carotid nerve after unilateral carotid neurotomy, showed reduced discharge frequency or silencing immediately after the augmented inspiration. This effect probably mediated the reduced amplitude of the following series of ventilatory cycles. It is suggested that the peripheral chemosensory in flow adjusts the gain of the vagal inspiration-augmenting reflex.

Regional sympathectomy induced by intra-arterial 6-hydroxy-dopamine.

Single intra-carotid injections of 5-15 mg of 6-OH-DA HBr in adult cats reduced or abolished the responses of the ipsilateral nictitating membrane to electrical stimulation of post-ganglionic sympathetic nerves and intra-carotid injections of tyramine; the responses of the contralateral nictitating membrane to the same stimuli remained normal. One to five days after 6-OH-DA, the ipsilateral nictitating membranes, unresponsive to sympathetic stimulation, were hypersensitive to i.v. injections of adrenaline or noradrenaline. The advantages of regional over systemic chemical sympathectomy are discussed.

Effects of 6-hydroxy-dopamine on carotid body chemosensory activity.

6-OH-DA HBr 5-25 mg injected into one common carotid artery of pentobarbitone-anesthetized cats, induced a transient inhibition of chemosensory discharges recorded from the ipsilateral carotid nerve, but did not change chemosensory frequency during spontaneous ventilation, periodic deep breaths and asphyxia. Chemosensory activities recorded simultaneously from both carotid nerves showed no differences in their inhibitory responses to dopamine and their excitatory responses to NaCN, up to 48 h after the injections of 6-OH-DA. It is concluded that 6-OH-DA acts initially as a dopamine analogue, and does not impair subsequent carotid body chemoreception or dopamine-induced inhibition, as doses producing abolition of noradrenergic transmission.

Acute changes in ventilation and blood pressure induced by inhalation of tobacco smoke.

Inhalation of cigarette smoke through a tracheal cannula was induced in cats anesthetized with pentobarbital. Smoking of tobacco cigarettes produced increased ventilation and systemic hypertension, which were found to be due to their nicotine content. Respiratory stimulation and the increase in diastolic pressure were abolished by acute section of 'buffer nerves', but the mediation of carotid nerves was more important than that of the vagi for evoking reflex hyperventilation. Tobacco smoking induced a marked increase in the frequency of chemosensory impulses recorded from the carotid nerves, an effect due to its nicotine content.

Respiratory and circulatory reflexes induced by nicotine injections: role of carotid body chemoreceptors.

Intravenous and intracarotid injections of nicotine were delivered to cats anesthetized with pentobarbital. Low doses of nicotine were found to induce reflex hyperventilation and hypertension, mainly due to excitation of carotid body chemoreceptors. The frequency of discharge of carotid nerve chemosensory fibres was increased by nicotine in doses as low as 1 mug/kg when injected intravenously and 50 ng when injected into the carotid artery. Nicotine also activates vagal afferent fibres; some of them produce reflex excitation of the respiratory and vasomotor centres, but others provoke reflex inhibition. High doses of nicotine can act directly upon the medulla provoking acceleration or arrest of ventilation. Nicotine can also induce 'late' changes of b.p. (delay 5 sec or more) which are not mediated by the carotid or vagus nerves.