Restorative Neurology and Neuroscience - Volume 28, issue 1

Authors: Brandt, Thomas | Zwergal, Andreas | Jahn, Klaus | Strupp, Michael

Article Type: Research Article

Abstract: The German BMBF (German Ministry of Education and Research) has decided to establish an Integrated Center for Research and Treatment (IFB^{LMU} ) of Vertigo, Balance and Ocular Motor Disorders in Munich in 2010. With funding of \psfig{figure=eur.eps,width=1.8mm}50 million over a ten-year period, the long-term continuation of the IFB^{LMU} is envisioned.

DOI: 10.3233/RNN-2010-0531

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 1-8, 2010

Authors: Schubert, Michael C. | Zee, David S.

Article Type: Research Article

Abstract: Purpose: This paper focuses on motor learning within the saccadic and vestibulo-ocular reflex (VOR) oculomotor systems, vital for our understanding how the brain keeps these subsystems calibrated in the presence of disease, trauma, and the changes that invariably accompany normal development and aging. We will concentrate on new information related to multiple time scales of saccade motor learning, adaptation of the VOR during high-velocity impulses, and the role of saccades in VOR adaptation. The role of …the cerebellum in both systems is considered. Methods: Review of data involving saccade and VOR motor learning. Results: Data supports learning within the saccadic and VOR oculomotor systems is influenced by 1). Multiple time scales, with different rates of both learning and forgetting (seconds, minutes, hours, days, and months). In the case of forgetting, relearning on a similar task may be faster. 2). Pattern of training, learning and forgetting are not similarly achieved. Different contexts require different motor behaviors and rest periods between training sessions can be important for memory consolidation. Conclusions: The central nervous system has the difficult task of determining where blame resides when motor performance is impaired (the credit assignment problem). Saccade and VOR motor learning takes place at multiple levels within the nervous system, from alterations in ion channel and membrane properties on single neurons, to more complex changes in neural circuit behavior and higher-level cognitive processes including prediction. Show more

DOI: 10.3233/RNN-2010-0523

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 9-18, 2010

Authors: Lacour, Michel | Tighilet, Brahim

Article Type: Research Article

DOI: 10.3233/RNN-2010-0509

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 19-35, 2010

Authors: Halmagyi, G.M. | Weber, K.P. | Curthoys, I.S.

Article Type: Research Article

Abstract: Purpose: To review the extent and mechanism of the recovery of vestibular function after sudden, isolated, spontaneous, unilateral loss of most or all peripheral vestibular function – usually called acute vestibular neuritis. Methods: Critical review of published literature and personal experience. Results: The symptoms and signs of acute vestibular neuritis are vertigo, vomiting, nystagmus with ipsiversive slow-phases, ipsiversive lateropulsion and ocular tilt reaction (the static symptoms) and impairment of …vestibulo-ocular reflexes from the ipsilesional semicircular canals on impulsive testing (the dynamic symptoms). Peripheral vestibular function might not improve and while static symptoms invariably resolve, albeit often not totally, dynamic symptoms only improve slightly if at all. Conclusions: The persistent loss of balance that some patients experience after acute vestibular neuritis can be due to inadequate central compensation or to incomplete peripheral recovery and vestibular rehabilitation has a role in the treatment of both. Show more

Keywords: Vestibular, deafferentation, neuritis, compensation, rehabilitation

DOI: 10.3233/RNN-2010-0533

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 37-46, 2010

Authors: Dieterich, Marianne | Brandt, Thomas

Article Type: Research Article

Abstract: In this article we will discuss our current knowledge of multisensory vestibular structures and their functions in the human cortex. Most of it derives from brain activation studies with PET and fMRI in humans conducted over the last decade. They have confirmed the existence of several separate and distinct cortical areas that were identified earlier by tracer and electrophysiological studies in animals, especially in monkeys. The patterns of activations and deactivations during vestibular stimulations in healthy …subjects have been compared with those in patients with acute and chronic peripheral and central vestibular disorders. The following reviews what is presently known about the interconnections of vestibular structures, their activations and interactions with other sensory modalities, the correlations of perceptual and motor functions in normal humans, and the changes that result from strategic unilateral peripheral and central vestibular lesions such as vestibular neuritis and bilateral vestibular failure, on the one hand, and central vestibular nucleus lesions due to ischemic infarctions of the lateral medulla (Wallenberg's syndrome), on the other. Show more

Keywords: Functional neuroimaging, fMRI, PET, vestibular system, visual-vestibular interaction, vestibular neuritis, bilateral vestibular failure, Wallenberg's syndrome, compensation

DOI: 10.3233/RNN-2010-0505

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 47-56, 2010

Authors: Horak, Fay B.

Article Type: Research Article

Abstract: Purpose: This chapter summarizes the role of the vestibular system in postural control so that specific and effective rehabilitation can be designed that facilitates compensation for loss of vestibular function. Methods: Patients with bilateral or unilateral loss of peripheral vestibular function are exposed to surface perturbations to quantify automatic postural responses. Studies also evaluated the effects of audio- and vibrotactile-biofeedback to improve stability in stance and gait. Results: The most important role of vestibular information for …postural control is to control orientation of the head and trunk in space with respect to gravitoinertial forces, particularly when balancing on unstable surfaces. Vestibular sensory references are particularly important for postural control at high frequencies and velocities of self-motion, to reduce trunk drift and variability, to provide an external reference frame for the trunk and head in space; and to uncouple coordination of the trunk from the legs and the head-in-space from the body CoM. Conclusions: The goal of balance rehabilitation for patients with vestibular loss is to help patients 1) use remaining vestibular function, 2) depend upon surface somatosensory information as their primary postural sensory system, 3) learn to use stable visual references, and 4) identify efficient and effective postural movement strategies. Show more

Keywords: Vestibular loss, balance, posture, compensation, rehabilitation

DOI: 10.3233/RNN-2010-0515

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 57-68, 2010

Authors: Brandt, Thomas | Huppert, TDoreen | Hüfner, Katharina | Zingler, Vera C. | Dieterich, Marianne | Strupp, Michael

Article Type: Research Article

Abstract: The long-term course and the frequency of relapses for various peripheral vestibular disorders and somatoform phobic postural vertigo are discussed with respect to the clinically most important questions for thus afflicted patients. This review is mainly based on our own long-term follow-up studies and takes into consideration the most relevant literature. The following syndromes are discussed in detail. Vestibular neuritis: the recovery rate of peripheral vestibular function lies between 40–63% depending on …early-onset treatment with corticosteroids; the recurrence rate within 10 years is 2%. Menière's disease} loss of auditory and vestibular function occurs mainly in the first 5 to 10 years; frequency of vertigo attacks may decline after 5 to 10 years; bilateral involvement increases with increasing duration of the condition in up to 30–50%; vestibular drop attacks may occur early or late within the course, mostly with spontaneous remission; high-dose and long-term treatment with betahistine significantly reduces attack frequency in Menière's disease, Benign paroxysmal positioning vertigo: the recurrence rate is 50% within 10 years (in females 58%, in males 39%), most recurrences (80%) being observed within the first year after initial relief; recurrence rate in the seventh decade is half of that in the sixth decade. Vestibular paroxysmia: medical treatment with carbamazepine or oxcarbazepine leads to a continuous significant reduction in attack frequency, intensity, and duration of 10–15% of baseline. Bilateral vestibulopathy: recovery of vestibular function is limited to single cases depending on their etiology. Phobic postural vertigo: within 5 to 16 years 27% of the patients are symptom-free, 48% improve, 22% remain unchanged, and 3% worsen; a detailed explanation of the mechanisms that cause and the factors that provoke attacks is imperative, as well as instructions for self-controlled desensitization within the context of behavioral therapy. Show more

Keywords: Vestibular neuritis, Menière's disease, benign paroxysmal positioning vertigo, vestibular paroxysmia, bilateral vestibulopathy, phobic postural vertigo, long-term follow-up, relapse rate

DOI: 10.3233/RNN-2010-0504

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 69-82, 2010

Authors: Bronstein, A.M. | Lempert, Th

Article Type: Research Article

Abstract: In this review we present a pragmatic approach to the patient with chronic vestibular symptoms. Even in the chronic patient a retrospective diagnosis should be attempted, in order to establish how the patient reached the current situation. Simple questions are likely to establish if the chronic dizzy symptoms started as benign paroxysmal positional vertigo (BPPV), vestibular neuritis, vestibular migraine, Meniere's disease or as a brainstem stroke. Then it is important to establish if the original symptoms …are still present, in which case they need to be treated (e.g. repositioning maenouvres for BPPV, migraine prophylaxis) or if you are only dealing with chronic dizzy symptoms. In addition the doctor or physiotherapist needs to establish if the process of central vestibular compensation has been impeded due to additional clinical problems, e.g. visual problems (squints, cataract operation), proprioceptive deficit (neuropathy due to diabetes or alcohol), additional neurological or orthopaedic problems, lack of mobility or confidence, such as fear of falling or psychological disorders. A general neurological examination should also be conducted, amongst other reasons to make sure your patient's `chronic dizziness' is not due to a neurological gait disorder. Treatment of the syndrome of chronic dizziness is multidisciplinary but rehabilitation and simple counselling should be available to all patients. In contrast, vestibular suppressants or tranquilisers should be reduced or, if possible, stopped. Show more

DOI: 10.3233/RNN-2010-0530

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 83-90, 2010

Authors: Liao, Ke | Walker, Mark F. | Joshi, Anand C. | Reschke, Millard | Strupp, Michael | Wagner, Judith | Leigh, R. John

Article Type: Research Article

Abstract: Purpose: During locomotion, head perturbations, consisting of rotations and translations (linear movements), occur with predominant frequencies of 0.5–5.0 Hz. The vestibular reflexes act at short latency to safeguard clear vision and stable posture during locomotion. Much is known about the angular vestibulo-ocular reflex (aVOR) in response to head rotations, which depend on the semicircular canals of the vestibular labyrinth. However, the means to test reliably the linear or translational vestibulo-ocular reflex (tVOR), …which depends on the otolithic organs, has only become available more recently. Methods: We used a moving platform to translate normal human subjects vertically at frequencies similar to those occurring during locomotion, under ambient illumination. Results: Our findings suggested that, whereas aVOR is concerned with stabilizing images of visual targets on the retina to optimize visual acuity, tVOR seems best suited to minimize retinal image motion between objects lying in different depth planes, in order to optimize motion parallax information. We then asked whether the tVOR functioned abnormally in patients with two neurological disorders that often cause falls: progressive supranuclear palsy (PSP) and cerebellar ataxia. We found that patients with PSP cannot adjust tVOR responses appropriately during viewing of near objects, nor converge their eyes. Vestibular-evoked myogenic potentials (VEMPs), an otolith-spinal reflex, are also impaired in PSP patients. Patients with cerebellar ataxia also lack the ability to adjust tVOR for near viewing, even though they may be able to converge. Conclusions: Taken together, our studies suggest that abnormal otolithic vestibular reflexes contribute to postural instability in PSP and cerebellar ataxia, and deserve further investigation. Show more

Keywords: Locomotion, moving platform, motional parallax, PSP, cerebellar ataxia

DOI: 10.3233/RNN-2010-0507

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 91-103, 2010

Authors: Jahn, Klaus | Zwergal, Andreas

Article Type: Research Article

Abstract: Patients with neurological gait disorders often present to their doctor with the key symptoms of dizziness and gait unsteadiness (e.g. cerebellar ataxia, progressive supranuclear palsy). In vestibular syndromes, on the other hand, the gait disturbance is a leading sign and many aspects of the syndrome can be recognized from the analysis of posture and gait (e.g. direction of falls). For therapy in particular it is important to better understand the physiological control of posture and gait …to adapt rehabilitation programs. We recently succeeded in visualizing the hierarchic network for postural control in humans by means of functional imaging techniques. Growing evidence suggests that so-called "locomotor regions", groups of neurons able to initiate or modulate spinal stepping in the cat in response to electrical or chemical stimulation, also exist in humans. The most important locomotor regions are the mesencephalic, the subthalamic, and the cerebellar locomotor regions. Locomotor signals are transmitted from the midbrain to the spinal cord via the ponto-medullary reticular formation and integrate multisensory input at different levels. Functional imaging also demonstrated that the multisensory cortical areas are inhibited during locomotion, which is relevant for physical therapy of vestibular disorders which therefore should include exercises with different gait patterns and different speeds. The supraspinal network for locomotion is just beginning to be recognized as an important factor in the pathophysiology of common gait disorders. In Parkinson's disease, for example, low-frequency stimulation of the mesencephalic locomotor region (pedunculopontine nucleus) is already used to treat freezing and gait disturbance in selected patients. In this review we summarize different attempts to visualize human supraspinal locomotor control using functional neuroimaging techniques, both in healthy subjects and in patients suffering from balance disorders. Show more

Keywords: cerebellar locomotor region, gait disorders, mesencephalic locomotor region, motor imagery, freezing, pedunculopontine nucleus

DOI: 10.3233/RNN-2010-0506

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 1, pp. 105-114, 2010