Name: assessment of static graviceptive perception in the roll-plane using the subjective visual vertical paradigm
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Description: Watch this Scientific Journal Video about Assessment of Static Graviceptive Perception in the Roll-Plane using the Subjective Visual Vertical Paradigm at JoVE.com

The authors have no acknowledgements.

The study was approved by the ethical committee of the Medical University of Vienna and has been performed in accordance with the ethical standards found in the Declaration of Helsinki. An informed consent was signed by all patients and controls before the study.
1. Installation of the patient in the chair
<ol>
	<li>Perform the measurement binocularly. Install the patient in a stable chair with a backrest and a head fixation unit. The latter maintains the patient&#39;s head in a stable and d...

<ol>
	<li>Dieterich, M., Brandt, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perception+of+Verticality+and+Vestibular+Disorders+of+Balance+and+Falls.">Perception of Verticality and Vestibular Disorders of Balance and Falls.</a> Frontiers in Neurology. 10, 172 (2019).</li><li>Elwischger, K., Rommer, P., Prayer, D., Mueller, C., Auff, E., Wiest, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thalamic+astasia+from+isolated+centromedian+thalamic+infarction.">Thalamic astasia from isolated centromedian thalamic infarction.</a> Neurology. 78 (2), 146-147 (2012).</li><li>Wiest, G., Zimprich, F., Prayer, D., Czech, T., Serles, W., Baumgartner, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vestibular+processing+in+human+paramedian+precuneus+as+shown+by+electrical+cortical+stimulation.">Vestibular processing in human paramedian precuneus as shown by electrical cortical stimulation.</a> Neurology. 62 (3), 473-475 (2004).</li><li>Wiest, G., Tian, J. R., Baloh, R. W., Crane, B. T., Demer, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Otolith+function+in+cerebellar+ataxia+due+to+mutations+in+the+calcium+channel+gene+CACNA1A.">Otolith function in cerebellar ataxia due to mutations in the calcium channel gene CACNA1A.</a> Brain. 124, 2407-2416 (2001).</li><li>Dakin, C. J., Rosenberg, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gravity+estimation+and+verticality+perception.">Gravity estimation and verticality perception.</a> Handbook of Clinical Neurology. 159, 43-59 (2018).</li><li>Demer, J. L., Crane, B. T., Tian, J. R., Wiest, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+tests+of+vestibular+function.">New tests of vestibular function.</a> Annals of the New Yorc Academy of Science. 942, 428-445 (2001).</li><li>Clarke, A. H., Schonfeld, U., Helling, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unilateral+examination+of+utricle+and+saccule+function.">Unilateral examination of utricle and saccule function.</a> Journal of Vestibular Research. 13 (4-6), 215-225 (2003).</li><li>Kingma, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+testing+of+the+statolith-ocular+reflex.">Clinical testing of the statolith-ocular reflex.</a> ORL Journal for Otorhinolaryngology and its Related Specialties. 59 (4), 198-208 (1997).</li><li>Bisdorff, A. R., Wolsley, C. J., Anastasopoulus, D., Bronstein, A. M., Gresty, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+perception+of+body+verticality+(subjective+postural+vertical)+in+peripheral+and+central+vestibulardisorders.">The perception of body verticality (subjective postural vertical) in peripheral and central vestibulardisorders.</a> Brain. 199 (5), 1523-1534 (1996).</li><li>Welgampola, M. S., Colebatch, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characteristics+and+clinical+applications+of+vestibular-evoked+myogenic+potentials.">Characteristics and clinical applications of vestibular-evoked myogenic potentials.</a> Neurology. 64 (10), 1682-1688 (2005).</li><li>Kingma, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Function+tests+of+the+otolith+or+statolith+system.">Function tests of the otolith or statolith system.</a> Current Opinion in Neurology. 19 (1), 21-25 (2006).</li><li>Kheradmand, A., Winnick, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perception+of+Upright:+Multisensory+Convergence+and+the+Role+of+Temporo-Parietal+Cortex.">Perception of Upright: Multisensory Convergence and the Role of Temporo-Parietal Cortex.</a> Frontiers in Neurology. 8, 552 (2017).</li><li>Zwergal, A., Rettinger, N., Frenzel, C., Dieterich, M., Brandt, T., Strupp, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+bucket+of+static+vestibular+function.">A bucket of static vestibular function.</a> Neurology. 72 (19), 1689-1692 (2009).</li><li>Bronstein, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Interaction+of+Otolith+and+Proprioceptive+Information+in+the+Perception+of+Verticality:+The+Effects+of+Labyrinthine+and+CNS+Disease.">The Interaction of Otolith and Proprioceptive Information in the Perception of Verticality: The Effects of Labyrinthine and CNS Disease.</a> Annals of the New York Academy of Science. 871, 324-333 (1999).</li><li>Saeys, W., Herssens, N., Verwulgen, S., Truijen, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensory+information+and+the+perception+of+verticality+in+post-stroke+patients.+Another+point+of+view+in+sensory+reweighting+strategies.">Sensory information and the perception of verticality in post-stroke patients. Another point of view in sensory reweighting strategies.</a> PLOS ONE. 13 (6), 0199098 (2018).</li><li>Baier, B., Th&#246;mke, F., Wilting, J., Heinze, C., Geber, C., Dieterich, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+pathway+in+the+brainstem+for+roll-tilt+of+the+subjective+visual+vertical:+evidence+from+a+lesion-behavior+mapping+study.">A pathway in the brainstem for roll-tilt of the subjective visual vertical: evidence from a lesion-behavior mapping study.</a> Journal of Neuroscience. 32 (43), 14854-14858 (2012).</li><li>Huh, Y. E., Kim, K., Chung, W., Youn, J., Kim, S., Cho, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pisa+Syndrome+in+Parkinson's+Disease:+Pathogenic+Roles+of+Verticality+Perception+Deficits.">Pisa Syndrome in Parkinson's Disease: Pathogenic Roles of Verticality Perception Deficits.</a> Science Reports. 8 (1), 1804 (2018).</li><li>Ogawa, Y., Otsuka, K., Shimizu, S., Inagaki, T., Kondo, T., Suzuki, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subjective+visual+vertical+perception+in+patients+with+vestibular+neuritis+and+sudden+sensorineural+hearing+loss.">Subjective visual vertical perception in patients with vestibular neuritis and sudden sensorineural hearing loss.</a> Journal of Vestibular Research. 22 (4), 205-211 (2012).</li><li>Toupet, M., Van Nechel, C., Bozorg, A., Grayeli, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+body+laterality+on+recovery+from+subjective+visual+vertical+tilt+after+vestibular+neuritis.">Influence of body laterality on recovery from subjective visual vertical tilt after vestibular neuritis.</a> Audiology and Neurootology. 19 (4), 248-255 (2014).</li><li>Lopez, C., Lacour, M., Ahmadi, A. E., Magnan, J., Borel, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+of+visual+vertical+perception:+a+long-term+sign+of+unilateral+and+bilateral+vestibular+loss.">Changes of visual vertical perception: a long-term sign of unilateral and bilateral vestibular loss.</a> Neuropsychologia. 45 (9), 2025-2037 (2007).</li><li>Kitahara, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Idiopathic+benign+paroxysmal+positional+vertigo+with+persistent+vertigo/dizziness+sensation+is+associated+with+latent+canal+paresis,+endolymphatic+hydrops,+and+osteoporosis.">Idiopathic benign paroxysmal positional vertigo with persistent vertigo/dizziness sensation is associated with latent canal paresis, endolymphatic hydrops, and osteoporosis.</a> Auris Nasus Larynx. 46 (1), 27-33 (2019).</li><li>Platho-Elwischger, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasticity+of+static+graviceptive+function+in+patients+with+cervical+dystonia.">Plasticity of static graviceptive function in patients with cervical dystonia.</a> Journal of the Neurological Sciences. 373, 230-235 (2017).</li><li>Aranda-Moreno, C., J&#225;uregui-Renaud, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+subjective+visual+vertical+in+vestibular+disease.">The subjective visual vertical in vestibular disease.</a> Revista de Investigaci&#243;n Cl&#237;nica. 57 (1), 22-27 (2005).</li><li>Guerraz, M., Luyat, M., Poquin, D., Ohlmann, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+neck+afferents+in+subjective+orientation+in+the+visual+and+tactile+sensory+modalities.">The role of neck afferents in subjective orientation in the visual and tactile sensory modalities.</a> Acta Otolaryngologica. 120 (6), 735-738 (2000).</li><li>Luyat, M., No&#235;l, M., Thery, V., Gentaz, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gender+and+line+size+factors+modulate+the+deviations+of+the+subjective+visual+vertical+induced+by+head+tilt.">Gender and line size factors modulate the deviations of the subjective visual vertical induced by head tilt.</a> BMC Neuroscience. 13, 28 (2012).</li><li>Fraser, L. E., Makooie, B., Harris, L. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Subjective+Visual+Vertical+and+the+Subjective+Haptic+Vertical+Access+Different+Gravity+Estimates.">The Subjective Visual Vertical and the Subjective Haptic Vertical Access Different Gravity Estimates.</a> PLOS ONE. 10 (12), 0145528 (2015).</li><li>Otero-Millan, J., Kheradmand, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Upright+Perception+and+Ocular+Torsion+Change+Independently+during+Head+Tilt.">Upright Perception and Ocular Torsion Change Independently during Head Tilt.</a> Frontiers in Human Neuroscience. 10, 573 (2016).</li><li>Kim, S. H., Kim, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Head+Position+on+Perception+of+Gravity+in+Vestibular+Neuritis+and+Lateral+Medullary+Infarction.">Effects of Head Position on Perception of Gravity in Vestibular Neuritis and Lateral Medullary Infarction.</a> Frontiers in Neurology. 9, 60 (2018).</li><li>Funk, J., Finke, K., M&#252;ller, H. J., Utz, K. S., Kerkhoff, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+lateral+head+inclination+on+multimodal+spatial+orientation+judgments+in+neglect:+Evidence+for+impaired+spatial+orientation+constancy.">Effects of lateral head inclination on multimodal spatial orientation judgments in neglect: Evidence for impaired spatial orientation constancy.</a> Neuropsychologia. 48 (6), 1616-1627 (2010).</li><li>Winnick, A., Sadeghpour, S., Otero-Millan, J., Chang, T. P., Kheradmand, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Errors+of+Upright+Perception+in+Patients+With+Vestibular+Migraine.">Errors of Upright Perception in Patients With Vestibular Migraine.</a> Frontiers in Neurololgy. 9, 892 (2018).</li><li>Deriu, F., Ginatempo, F., Manca, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancing+research+quality+of+studies+on+VEMP+in+central+neurological+disorders:+a+scoping+review.">Enhancing research quality of studies on VEMP in central neurological disorders: a scoping review.</a> Journal of Neurophysiology. 122 (3), 1186-1206 (2019).</li><li>Rosengren, S. M., Colebatch, J. G., Young, A. S., Govender, S., Welgampola, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vestibular+evoked+myogenic+potentials+in+practice:+Methods,+pitfalls+and+clinical+applications.">Vestibular evoked myogenic potentials in practice: Methods, pitfalls and clinical applications.</a> Clinical Neurophysiology Practice. 4, 47-68 (2019).</li></ol>

SVV is a method to ensure the sense of verticality. It results from the integration of several information. The vestibular system being of paramount importance in this perception, it has been shown that a lesion at any level of vestibular information pathway leads to SVV errors.
The measurement of SVV in the head upright position is now regarded as the clinical standard method for recording otolith function. However, this method is hampered by low sensitivity as SVV-deviations in darkness in h...

Impairment of otolith function can be caused by peripheral as well as by central vestibular conditions1. Peripheral vestibular causes include Meniere&#39;s disease, labyrinth infarction, as well as superior or inferior vestibular neuritis. Central otolith dysfunction can occur in lesions of central otolithic pathways from brain stem via thalamus2 to the vestibular cortex3. In addition, diminished otolith reflexes are also found in cerebellar disorders4. While a number of standardized methods, such as caloric testing or video-head impulse test, are available for the assessment of semicircular canal function, no standardized clinical measurement method exists for gravity estimation and verticality perception5.
Since the otoliths are responsible for the perception of linear acceleration, otolith function can in principle be measured by linear acceleration by recording the so-called translational vestibulo-ocular reflex (t-VOR). However, this requires the use of special and complex equipment such as a parallel swing or linear sleds4,6. For the assessment of unilateral saccular and utricular function a specific off-center centrifugation test has been developed, which could be used clinically in balance laboratories with a specific rotational chair system7. When displacing the head by 3.5&#8211;4 cm from the rotation axis, the eccentrically positioned utricle is stimulated unilaterally by a resultant centrifugal force. In this paradigm otolith function can be determined either by measuring the resulting eye torsion or the subjective visual vertical (SVV). This procedure, however, also requires sophisticated equipment and the method still shows limited sensitivities for both SVV and eye torsion assessment7. Otolith function can further be quantified through eye movement recordings. Assessment can be done in horizontal or linear acceleration, but also during head- or body tilt in the roll plane with application of 3-D videooculography. The latter allows determination of ocular torsion. The clinical application of this method is also limited due to its low sensitivity8. The perception of body verticality (i.e., the sensation that I feel my body aligned with the true vertical) can be assessed by means of the so-called subjective postural vertical. In this experimental task, patients are seated in a chair in a motorized gimbal and asked to indicate when they entered and exited the upright position, while being tilted 15 &#176; in the pitch or roll plane. The disadvantage of this technique is not only its elaborate experimental approach, but also that it measures both otolith and body proprioceptive signals9. Whether vestibular evoked myogenic potentials (VEMPs) are useful clinical screening tools for otolith function in various clinical disorders is still controversial10,11.
Visual tasks are currently the most frequently used clinical methods for measuring graviceptive function, which can be assessed through measurement of the subjective visual vertical (SVV)12. Seen from a precise physiological perspective, SVV is not a direct test of the otolith function alone, as the SVV is the result of a weighting between several sources of information (gravity, proprioceptive and also visual when they are available). However, for rapid clinical use, an easy application of this SVV task, the so-called bucket test, has been developed13 especially for the emergency setting, enabling immediate detection of acute disturbances of graviceptive perception. The more precise and standardized procedure consists of letting an observer align a light bar or rod with the estimated vertical. Tested in darkness in healthy individuals in an upright position, deviations are limited to &#177; 2&#176; from the earth vertical14. Using the SVV task, graviceptive function has so far been assessed in a variety of neurological conditions such as stroke15,16 or Parkinson&#8217;s disease17. Furthermore, impaired SVV-perception has also been reported in unilateral18,19 or bilateral vestibular lesions20, as well as in patients with benign paroxysmal positional nystagmus21.
We here present a modified SVV assessment method, which measures SVV estimates not only in head-upright position but also at &#177; 15&#176; and &#177; 30&#176; head tilts in the roll plane. This paradigm increases the information content for the detection of graviceptive deficits and for systematic tilts of the SVV.

<table>
	<tbody>
		<tr>
			<td>Adjustable plastic goniometer board 7,87&#34; x 7,87&#34;, (marked tilt angles of 0&#176;, 15&#176; and 30&#176; )</td>
			<td>self-produced</td>
			<td>6</td>
			<td>for fixation at the backrest and for adjustment of neckrest along the given tilt angles (0&#176;,15&#176;,30&#176;)</td>
		</tr>
		<tr>
			<td>Elastic head band with adjustable screw on the back</td>
			<td>Micromedical Technologies Inc</td>
			<td>4</td>
			<td>modified with attached adhesive strap</td>
		</tr>
		<tr>
			<td>HD LCD display, 1366 x 768p resolution, 19&#34;</td>
			<td>Philips</td>
			<td>5</td>
			<td>for monitoring SVV-adjustments outside the cabin (infrared camera recording)</td>
		</tr>
		<tr>
			<td>Subjective Visual Vertical Set including infrared video camera (black/white, resolution 0,25&#176;)</td>
			<td>Micromedical Technologies Inc</td>
			<td>2</td>
			<td></td>
		</tr>
		<tr>
			<td>Sytem 2000 (Rotational Vestibular Chair System with Centrifuge)</td>
			<td>Micromedical Technologies Inc., 10 Kemp Dr., Chatham, IL 62629-9769 United States</td>
			<td>1</td>
			<td></td>
		</tr>
		<tr>
			<td>Tiltable headrest&#160;</td>
			<td>Micromedical Technologies Inc</td>
			<td>3</td>
			<td>modified with attached adhesive strap</td>
		</tr>
	</tbody>
</table>

assessment of static graviceptive perception in the roll-plane using the subjective visual vertical paradigm

Vestibular disorders are among the most common syndromes in medicine. In recent years, new vestibular diagnostic systems have been introduced that allow the examination of all semicircular canals in the clinical setting. Assessment methods of the otolithic system, which is responsible for the perception of linear acceleration and perception of gravity, are far less in clinical use. There are several experimental approaches for measuring the perception of gravity. The most frequently used method is the determination of the subjective visual vertical. This is usually measured with the head in an upright position. We present here an assessment method for testing otolith function in the roll plane. The subjective visual vertical is measured in the head upright position as well as with head inclination of &#177; 15&#176; and &#177; 30&#176; in the roll plane. This extended functional paradigm is an easy-to-perform clinical test of otolith function and ensures increased information content for the detection of impaired graviceptive perception.

SVV assessment was performed using a rotational chair system (Figure 1a) comprising a tiltable headrest and an adjustable LED light bar. The SVV adjustments were recorded via an infrared camera from a goniometer display on the back of the lightbar (Figure 1b). The devices used and the test protocol correspond exactly to the test methods presented here.
SVV measurement was performed in 13 healthy individuals at a mean age of 52.8 years...

Watch this Scientific Journal Video about Assessment of Static Graviceptive Perception in the Roll-Plane using the Subjective Visual Vertical Paradigm at JoVE.com

Assessment of Static Graviceptive Perception in the Roll-Plane using the Subjective Visual Vertical Paradigm

The perception of gravity is commonly determined by the subjective visual vertical in the head upright position. The additional assessment at head tilts of &#177; 15&#176; and &#177; 30&#176; in the roll plane ensures increased information content for the detection of impaired graviceptive perception.

Vestibular disorders are among the most common syndromes in medicine. In recent years, new vestibular diagnostic systems have been introduced that allow ...

Our technique of SVV assessment at certain angles of head tilt offers a standardized protocol to detect disturbances of the graviceptive function with higher redundancy compared to non-dynamic methods representing an easy-to-perform technique in clinical practice. The main advantage of this technique is its higher information content and its simple clinical applicability. As shown in our manuscript, this technique has already been applied for the detection of treatment response to botulinum toxin in patients with cervical dystonia.Basically this method can be used for the assessment of graviceptive dysfunction in a variety of diseases. The application of this method in patients with specific cortical lesions may help to localize cortical areas involved in graviceptive processing. Fixation of the patient's head at the desired angle is crucial for the method.To further avoid bias data, we recommend a randomized protocol considering tilt angle to avoid a learning effect. Install the patient in a stable chair with a backrest and a head-fixation unit. The fixation unit maintains the patient's head in a stable and defined position.It consists of an elastic headband and a U-shaped headrest which can be fixed to each other using an adhesive strap. The headrest can be adjusted in the desired inclination angle by aligning it along the scale of a goniometer, which is attached to the chair's backrest. At the beginning of the experiment, adjust the headrest at a zero-degree inclination at sub-occipital height.Place the elastic headband on the patient's head and fix it with a screw on the back. Connect the two adhesive straps on the headband and on the headrest with each other. Mount the SVV unit with the fixation device on the chair in front of the patient.Through a connected potentiometer, adjust the position of the light bar in the roll plane exactly opposite to the patient's head and at the same level as the patient's eyes. Connect the SVV unit to the electrical connection underneath the chair. Place the potentiometer in the patient's left hand and instruct them on how to perform the SVV setting.To calibrate, tilt the light bar 30 degrees to the right or left relative to the absolute vertical and ask the patient to adjust it to the vertical position under visual control. This serves to self-calibrate the patient and to check the visual motor ability of the patient. Open the examination protocol for simultaneous entry of the SVV estimates.Close the cabin door so that the patient is in complete darkness throughout the experiment. Ask the patient via the intercom system to tilt the light bar in the starting position 30 degrees to the right or to the left. After a waiting period of 15 seconds, instruct the patient to adjust the light bar from the starting position until it reaches the subjective vertical.The patient is not under time pressure and can still correct the set position at any time. The patient confirms the setting verbally via the intercom system. Enter the tilt angle shown on the display in degrees in the protocol.In total let the patient adjust the SVV in six passes with the starting position of 30 degrees randomized. Undo the initial head fixation by disconnecting the adhesive straps. Loosen the headrest and adapt the tilt position according to the protocol, 15 degrees or 30 degrees to the right or to the left.Fix the headrest in this position firmly. Fix the patient's head with the elastic headband to the headrest. Ensure that this head tilt is tolerable for the patient and adapt the height of the headrest if needed.Instruct the patient to maintain this head position during the trial. Close the cabin door and perform the trial as in the neutral head position. Upon completion of the trial, undo the head restraint and adjust the headrest according to the randomized head tilt position given by the protocol.Close the cabin door again and perform the same procedures until all SVV settings in all head tilts have been recorded. In this study, SVV measurement was performed in 13 healthy individuals at a mean age of 52.8 years. The absolute tilt of the SVV from the adult vertical at zero-degree head position showed an SVV median of 1.33.At a head tilt of 15 degrees, an SVV median of 1.66 was achieved and the measurements of the SVV at a head tilt of 30 degrees yielded an SVV median of 5.33. The method was also used to analyze SVV tilts in 32 patients suffering from cervical dystonia. Assessment of the SVV at the patient's habitual head posture revealed major deviations from the actual vertical with a median of 2.65 degrees.In comparison to healthy individuals at their habitual head posture, approximately zero-degree head tilt, the patients'response was significantly impaired with a median difference of negative 1.34 degrees. Three weeks after injection of botulinum toxin, the patients'SVV estimates in habitual head position and at 30-degree head tilt did not differ anymore from those of the controls. Exact positioning of the patient's head is crucial for the experiment.We highly recommend using a randomized protocol for the tilt angles in order to avoid a detection bias. We ourselves use this technique to evaluate the effects of botulinum toxin injection on the verticality perception in patients with cervical dystonia.

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Medicine

An Experimental Paradigm for the Prediction of Post-Operative Pain (PPOP)

Many women undergo cesarean delivery without problems, however some experience significant pain after cesarean section. Pain is associated with negative short-term and long-term effects on the mother. Prior to women undergoing surgery, can we predict who is at risk for developing significant postoperative pain and potentially prevent or minimize its negative consequences? These are the fundamental questions that a team from the University of Washington, Stanford University, the Catholic University in Brussels, Belgium, Santa Joana Women's Hospital in S&atilde;o Paulo, Brazil, and Rambam Medical Center in Israel is currently evaluating in an international research collaboration. The ultimate goal of this project is to provide optimal pain relief during and after cesarean section by offering individualized anesthetic care to women who appear to be more 'susceptible' to pain after surgery.
A significant number of women experience moderate or severe acute post-partum pain after vaginal and cesarean deliveries. 1 Furthermore, 10-15% of women suffer chronic persistent pain after cesarean section. 2 With constant increase in cesarean rates in the US 3 and the already high rate in Brazil, this is bound to create a significant public health problem. When questioning women's fears and expectations from cesarean section, pain during and after it is their greatest concern. 4 Individual variability in severity of pain after vaginal or operative delivery is influenced by multiple factors including sensitivity to pain, psychological factors, age, and genetics. The unique birth experience leads to unpredictable requirements for analgesics, from 'none at all' to 'very high' doses of pain medication. Pain after cesarean section is an excellent model to study post-operative pain because it is performed on otherwise young and healthy women. Therefore, it is recommended to attenuate the pain during the acute phase because this may lead to chronic pain disorders. The impact of developing persistent pain is immense, since it may impair not only the ability of women to care for their child in the immediate postpartum period, but also their own well being for a long period of time.
In a series of projects, an international research network is currently investigating the effect of pregnancy on pain modulation and ways to predict who will suffer acute severe pain and potentially chronic pain, by using simple pain tests and questionnaires in combination with genetic analysis. A relatively recent approach to investigate pain modulation is via the psychophysical measure of Diffuse Noxious Inhibitory Control (DNIC). This pain-modulating process is the neurophysiological basis for the well-known phenomenon of 'pain inhibits pain' from remote areas of the body. The DNIC paradigm has evolved recently into a clinical tool and simple test and has been shown to be a predictor of post-operative pain.5 Since pregnancy is associated with decreased pain sensitivity and/or enhanced processes of pain modulation, using tests that investigate pain modulation should provide a better understanding of the pathways involved with pregnancy-induced analgesia and may help predict pain outcomes during labor and delivery. For those women delivering by cesarean section, a DNIC test performed prior to surgery along with psychosocial questionnaires and genetic tests should enable one to identify women prone to suffer severe post-cesarean pain and persistent pain. These clinical tests should allow anesthesiologists to offer not only personalized medicine to women with the promise to improve well-being and satisfaction, but also a reduction in the overall cost of perioperative and long term care due to pain and suffering. On a larger scale, these tests that explore pain modulation may become bedside screening tests to predict the development of pain disorders following surgery.

An Experimental Paradigm for the Prediction of Post-Operative Pain PPOP

Diffuse noxious inhibitory control, temporal summation and wound hyperalgesia testing are demonstrated in the obstetric patient. These tests evaluate inhibitory and excitatory mechanisms of pain processing and are here utilized to evaluate endogenous analgesia at different time-points during pregnancy and the peripartum period to help reveal individual s risk for persistent pain.

Many women undergo cesarean delivery without problems, however some experience significant pain after cesarean section. Pain is associated with negative ...

Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF. Current technologies for CMR are time consuming and difficult to implement in clinical practice. Feature tracking is a technology that can lead to more automization and robustness of quantitative analysis of medical images with less time consumption than comparable methods.
Methods: An automatic or manual input in a single phase serves as an initialization from which the system starts to track the displacement of individual patterns representing anatomical structures over time. The specialty of this method is that the images do not need to be manipulated in any way beforehand like e.g. tagging of CMR images.
Results: The method is very well suited for tracking muscular tissue and with this allowing quantitative elaboration of myocardium and also blood flow.
Conclusions: This new method offers a robust and time saving procedure to quantify myocardial tissue and blood with displacement, velocity and deformation parameters on regular sequences of CMR imaging. It therefore can be implemented in clinical practice.

An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF.

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that ...

Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects

Patients suffering from homonymous hemianopia after infarction of the posterior cerebral artery (PCA) report different degrees of constraint in daily life, despite similar visual deficits. We assume this could be due to variable development of compensatory strategies such as altered visual scanning behavior. Scanning compensatory therapy (SCT) is studied as part of the visual training after infarction next to vision restoration therapy. SCT consists of learning to make larger eye movements into the blind field enlarging the visual field of search, which has been proven to be the most useful strategy1, not only in natural search tasks but also in mastering daily life activities2. Nevertheless, in clinical routine it is difficult to identify individual levels and training effects of compensatory behavior, since it requires measurement of eye movements in a head unrestrained condition. Studies demonstrated that unrestrained head movements alter the visual exploratory behavior compared to a head-restrained laboratory condition3. Martin et al.4 and Hayhoe et al.5 showed that behavior demonstrated in a laboratory setting cannot be assigned easily to a natural condition. Hence, our goal was to develop a study set-up which uncovers different compensatory oculomotor strategies quickly in a realistic testing situation: Patients are tested in the clinical environment in a driving simulator. SILAB software (Wuerzburg Institute for Traffic Sciences GmbH (WIVW)) was used to program driving scenarios of varying complexity and recording the driver's performance. The software was combined with a head mounted infrared video pupil tracker, recording head- and eye-movements (EyeSeeCam, University of Munich Hospital, Clinical Neurosciences).
The positioning of the patient in the driving simulator and the positioning, adjustment and calibration of the camera is demonstrated. Typical performances of a patient with and without compensatory strategy and a healthy control are illustrated in this pilot study. Different oculomotor behaviors (frequency and amplitude of eye- and head-movements) are evaluated very quickly during the drive itself by dynamic overlay pictures indicating where the subjects gaze is located on the screen, and by analyzing the data. Compensatory gaze behavior in a patient leads to a driving performance comparable to a healthy control, while the performance of a patient without compensatory behavior is significantly worse. The data of eye- and head-movement-behavior as well as driving performance are discussed with respect to different oculomotor strategies and in a broader context with respect to possible training effects throughout the testing session and implications on rehabilitation potential.

Patients with visual deficits after stroke report about different constraints in daily life most likely due to variable compensatory strategies, which are difficult to differentiate in clinical routine. We present a clinical set-up which allows measurement of different compensatory head- and eye-movement-strategies and evaluating their effects on driving performance.

Patients suffering from homonymous hemianopia after infarction of the posterior cerebral artery (PCA) report different degrees of constraint in daily ...

Development of an Audio-based Virtual Gaming Environment to Assist with Navigation Skills in the Blind

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio based cues and set within the context of a video game metaphor, users gather relevant spatial information regarding a building's layout. This allows the user to develop an accurate spatial cognitive map of a large-scale three-dimensional space that can be manipulated for the purposes of a real indoor navigation task. After game play, participants are then assessed on their ability to navigate within the target physical building represented in the game. Preliminary results suggest that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building as indexed by their performance on a series of navigation tasks. These tasks included path finding through the virtual and physical building, as well as a series of drop off tasks. We find that the immersive and highly interactive nature of the AbES software appears to greatly engage the blind user to actively explore the virtual environment. Applications of this approach may extend to larger populations of visually impaired individuals.

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind.

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio ...

Echocardiographic Assessment of the Right Heart in Mice

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential therapies. Given the expense and time involved in creating animal models of disease, it is critical that researchers have tools to accurately assess phenotypic expression of disease. Right ventricular dysfunction is the major manifestation of pulmonary hypertension. Echocardiography is the mainstay of the noninvasive assessment of right ventricular function in rodent models and has the advantage of clear translation to humans in whom the same tool is used. Published echocardiography protocols in murine models of PAH are lacking.
In this article, we describe a protocol for assessing RV and pulmonary vascular function in a mouse model of PAH with a dominant negative BMPRII mutation; however, this protocol is applicable to any diseases affecting the pulmonary vasculature or right heart. We provide a detailed description of animal preparation, image acquisition and hemodynamic calculation of stroke volume, cardiac output and an estimate of pulmonary artery pressure.

This article provides a protocol for the echocardiographic assessment of right ventricular size and pulmonary hypertension in mice. Applications include phenotype determination and serial assessment in transgenic and toxin-induced mouse models of cardiomyopathy and pulmonary vascular disease.

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential ...

Dynamic Visual Tests to Identify and Quantify Visual Damage and Repair Following Demyelination in Optic Neuritis Patients

In order to follow optic neuritis patients and evaluate the effectiveness of their treatment, a handy, accurate and quantifiable tool is required to assess changes in myelination at the central nervous system (CNS). However, standard measurements, including routine visual tests and MRI scans, are not sensitive enough for this purpose. We present two visual tests addressing dynamic monocular and binocular functions which may closely associate with the extent of myelination along visual pathways. These include Object From Motion (OFM) extraction and Time-constrained stereo protocols. In the OFM test, an array of dots compose an object, by moving the dots within the image rightward while moving the dots outside the image leftward or vice versa. The dot pattern generates a camouflaged object that cannot be detected when the dots are stationary or moving as a whole. Importantly, object recognition is critically dependent on motion perception. In the Time-constrained Stereo protocol, spatially disparate images are presented for a limited length of time, challenging binocular 3-dimensional integration in time. Both tests are appropriate for clinical usage and provide a simple, yet powerful, way to identify and quantify processes of demyelination and remyelination along visual pathways. These protocols may be efficient to diagnose and follow optic neuritis and multiple sclerosis patients.
In the diagnostic process, these protocols may reveal visual deficits that cannot be identified via current standard visual measurements. Moreover, these protocols sensitively identify the basis of the currently unexplained continued visual complaints of patients following recovery of visual acuity. In the longitudinal follow up course, the protocols can be used as a sensitive marker of demyelinating and remyelinating processes along time. These protocols may therefore be used to evaluate the efficacy of current and evolving therapeutic strategies, targeting myelination of the CNS.

Object From Motion (OFM) and Time-constrained stereo protocols are sensitive tools to identify monocular and binocular dynamic visual function deficits, which are uniquely affected in optic neuritis patients. Furthermore, these tests may be used as quantitative noninvasive tools to assess the extent of myelination along visual pathways.

In order to follow optic neuritis patients and evaluate the effectiveness of their treatment, a handy, accurate and quantifiable tool is required to ...

A Standardized Obstacle Course for Assessment of Visual Function in Ultra Low Vision and Artificial Vision

We describe an indoor, portable, standardized course that can be used to evaluate obstacle avoidance in persons who have ultralow vision. Six sighted controls and 36 completely blind but otherwise healthy adult male (n=29) and female (n=13) subjects (age range 19-85 years), were enrolled in one of three studies involving testing of the BrainPort sensory substitution device. Subjects were asked to navigate the course prior to, and after, BrainPort training. They completed a total of 837 course runs in two different locations. Means and standard deviations were calculated across control types, courses, lights, and visits. We used a linear mixed effects model to compare different categories in the PPWS (percent preferred walking speed) and error percent data to show that the course iterations were properly designed. The course is relatively inexpensive, simple to administer, and has been shown to be a feasible way to test mobility function. Data analysis demonstrates that for the outcome of percent error as well as for percentage preferred walking speed, that each of the three courses is different, and that within each level, each of the three iterations are equal. This allows for randomization of the courses during administration.
Abbreviations: 
preferred walking speed (PWS) 
course speed (CS) 
percentage preferred walking speed (PPWS)

We describe an indoor, portable, standardized course that can be used to evaluate obstacle avoidance in persons who have ultralow vision. The course is relatively inexpensive, simple to administer, and has been shown to be reliable and reproducible.

We describe an indoor, portable, standardized course that can be used to evaluate obstacle avoidance in persons who have ultralow vision. Six sighted ...

Non-invasive Assessment of the Efficacy of New Therapeutics for Intestinal Pathologies Using Serial Endoscopic Imaging of Live Mice

Animal models of inflammatory bowel disease (IBD) and colorectal cancer (CRC) have provided significant insight into the cell intrinsic and extrinsic mechanisms that contribute to the onset and progression of intestinal diseases. The identification of new molecules that promote these pathologies has led to a flurry of activity focused on the development of potential new therapies to inhibit their function. As a result, various pre-clinical mouse models with an intact immune system and stromal microenvironment are now heavily used. Here we describe three experimental protocols to test the efficacy of new therapeutics in pre-clinical models of (1) acute mucosal damage, (2) chronic colitis and/or colitis-associated colon cancer, and (3) sporadic colorectal cancer. We also outline procedures for serial endoscopic examination that can be used to document the therapeutic response of an individual tumor and to monitor the health of individual mice. These protocols provide complementary experimental platforms to test the effectiveness of therapeutic compounds shown to be well tolerated by mice.

We describe methods for longitudinal monitoring of the efficacy of therapeutics for the treatment of colonic pathologies in mice using a rigid endoscope. This protocol can be readily used for the characterization of the therapeutic response of an individual tumor in live mice and also for monitoring potential disease relapse.

Animal models of inflammatory bowel disease (IBD) and colorectal cancer (CRC) have provided significant insight into the cell intrinsic and extrinsic ...

Using Retinal Imaging to Study Dementia

The retina offers a unique &#8220;window&#8221; to study pathophysiological processes of dementia in the brain, as it is an extension of the central nervous system (CNS) and shares prominent similarities with the brain in terms of embryological origin, anatomical features and physiological properties.&#160; The vascular and neuronal structure in the retina can now be visualized easily and non-invasively using retinal imaging techniques, including fundus photography and optical coherence tomography (OCT), and quantified semi-automatically using computer-assisted analysis programs. Studying the associations between vascular and neuronal changes in the retina and dementia could improve our understanding of dementia and, potentially, aid in diagnosis and risk assessment.&#160; This protocol aims to describe a method of quantifying and analyzing retinal vasculature and neuronal structure, which are potentially associated with dementia. This protocol also provides examples of retinal changes in subjects with dementia, and discusses technical issues and current limitations of retinal imaging.

The retina shares prominent similarities with the brain and thus represents a unique window to study vasculature and neuronal structure in the brain non-invasively. This protocol describes a method to study dementia using retinal imaging techniques. This method can potentially aid in diagnosis and risk assessment of dementia.

The retina offers a unique &#8220;window&#8221; to study pathophysiological processes of dementia in the brain, as it is an extension of the central ...

Assessment and Characterization of Hyaloid Vessels in Mice

In the eye, the embryonic hyaloid vessels nourish the developing lens and retina and regress when the retinal vessels develop. Persistent or failed regression of hyaloid vessels can be seen in diseases such as persistent hyperplastic primary vitreous (PHPV), leading to an obstructed light path and impaired visual function. Understanding the mechanisms underlying the hyaloid vessel regression may lead to new molecular insights into the vascular regression process and potential new ways to manage diseases with persistent hyaloid vessels. Here we describe the procedures for imaging hyaloid in live mice with optical coherence tomography (OCT) and fundus fluorescein angiography (FFA) and a detailed technical protocol of isolating and flat-mounting hyaloid ex vivo for quantitative analysis. Low-density lipoprotein receptor-related protein 5 (LRP5) knockout mice were used as an experimental model of persistent hyaloid vessels, to illustrate the techniques. Together, these techniques may facilitate a thorough assessment of hyaloid vessels as an experimental model of vascular regression and studies on the mechanism of persistent hyaloid vessels.

This protocol describes both in vivo and ex vivo methods to fully visualize and characterize hyaloid vessels, a model of vascular regression in mouse eyes, using optical coherence tomography and fundus fluorescein angiography for the live imaging and ex vivo isolation and subsequent flat mount of hyaloid for quantitative analysis.

In the eye, the embryonic hyaloid vessels nourish the developing lens and retina and regress when the retinal vessels develop. Persistent or failed ...