| 1. |
- Fransson, Per-Anders, et al.
(författare)
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Deep brain stimulation in the subthalamic nuclei alters postural alignment and adaptation in Parkinson's disease
- 2021
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:12
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Tidskriftsartikel (refereegranskat)abstract
- Parkinson's disease (PD) can produce postural abnormalities of the standing body position such as kyphosis. We investigated the effects of PD, deep brain stimulation (DBS) in the subthalamic nucleus (STN), vision and adaptation on body position in a well-defined group of patients with PD in quiet standing and during balance perturbations. Ten patients with PD and 25 young and 17 old control participants were recruited. Body position was measured with 3D motion tracking of the ankle, knee, hip, shoulder and head. By taking the ankle as reference, we mapped the position of the joints during quiet standing and balance perturbations through repeated calf muscle vibration. We did this to explore the effect of PD, DBS in the STN, and vision on the motor learning process of adaptation in response to the repeated stimulus. We found that patients with PD adopt a different body position with DBS ON vs. DBS OFF, to young and old controls, and with eyes open vs. eyes closed. There was an altered body position in PD with greater flexion of the head, shoulder and knee (p≤0.042) and a posterior position of the hip with DBS OFF (p≤0.014). With DBS ON, body position was brought more in line with the position taken by control participants but there was still evidence of greater flexion at the head, shoulder and knee. The amplitude of movement during the vibration period decreased in controls at all measured sites with eyes open and closed (except at the head in old controls with eyes open) showing adaptation which contrasted the weaker adaptive responses in patients with PD. Our findings suggest that alterations of posture and greater forward leaning with repeated calf vibration, are independent from reduced movement amplitude changes. DBS in the STN can significantly improve body position in PD although the effects are not completely reversed. Patients with PD maintain adaptive capabilities by leaning further forward and reducing movement amplitude despite their kyphotic posture.
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| 2. |
- Magnusson, Måns, et al.
(författare)
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Vestibular "PREHAB"
- 2009
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923. ; 1164, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- A sudden unilateral loss or impairment of vestibular function causes vertigo, dizziness, and impaired postural function. In most occasions, everyday activities supported or not by vestibular rehabilitation programs will promote a compensation and the symptoms subside. As the compensatory process requires sensory input, matching performed motor activity, both motor learning of exercises and matching to sensory input are required. If there is a simultaneous cerebellar lesion caused by the tumor or the surgery of the posterior cranial fossa, there may be a risk of a combined vestibulocerebellar lesion, with reduced compensatory abilities and with prolonged or sometimes permanent disability. On the other hand, a slow gradual loss of unilateral function occurring as the subject continues well-learned everyday activities may go without any prominent symptoms. A pretreatment plan was therefore implemented before planned vestibular lesions, that is, "PREHAB." This was first done in subjects undergoing gentamicin treatment for morbus Meniere. Subjects would perform vestibular exercises for 14 days before the first gentamicin installation, and then continue doing so until free of symptoms. Most subjects would only experience slight dizziness while losing vestibular function. The approach-which is reported here-was then expanded to patients with pontine-angle tumors requiring surgery, but with remaining vestibular function to ease postoperative symptoms and reduce risk of combined cerebellovestibular lesions. Twelve patients were treated with PREHAB and had gentamicin installations transtympanically. In all cases there was a caloric loss, loss of VOR in head impulse tests, and impaired subjective vertical and horizontal. Spontaneous, positional nystagmus, subjective symptoms, and postural function were normalized before surgery and postoperative recovery was swift. Pretreatment training with vestibular exercises continued during the successive loss of vestibular function during gentamicin treatment, and pre-op gentamicin ablation of vestibular function offers a possibility to reduce malaise and speed up recovery.
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| 3. |
- Surano, Solmaz, et al.
(författare)
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Internet-based vestibular rehabilitation versus standard care after acute onset vertigo: a study protocol for a randomized controlled trial
- 2022
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Ingår i: Trials. - : Springer Science and Business Media LLC. - 1745-6215. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Dizziness and vertigo affect around 15% of adults annually and represent common reasons for contacting health services, accounting for around 3% of all emergency department visits worldwide. Vertigo is also associated with excessive use of diagnostic imaging and emergency care and decreased productivity, primarily because of work absenteeism. Vestibular rehabilitation is an evidence-based treatment for chronic dizziness and supervised group exercise therapy has recently been shown to be effective after vestibular neuritis, a common cause of acute onset vertigo. However, such interventions are not readily available and there is a need for more easily accessible tools. The purpose of this study is to investigate the effects on vestibular symptoms of a 6-week online vestibular rehabilitation tool after acute onset vertigo, with the aim of aiding vestibular rehabilitation by presenting a more accessible tool that can help to reduce recovery time. Methods: Three hundred twenty individuals diagnosed with acute vestibular syndrome (AVS) will be recruited from multiple hospitals in Sweden and the effects of an online vestibular rehabilitation tool, YrselTraning, on vestibular symptoms after acute onset vertigo will be compared to standard care (written instructions leaflet) in a two-armed, evaluator-blinded, multicenter randomized controlled trial. The primary outcome will be the Vertigo Symptom Scale Short Form (VSS-SF) score at 6 weeks after symptom onset. Secondary outcomes include effects of the intervention on activities of daily living, mood and anxiety, vestibular function recovery, mobility measures, health economic effects, and the reliability of the Swedish VSS-SF translation. Discussion: Participants using the online vestibular rehabilitation tool are expected to recover earlier and to a greater extent from their symptoms as compared to standard care. Since up to 50% of people with AVS without treatment develop persistent symptoms, effective treatment of AVS will likely lead to a higher quality of life and help reduce the societal costs associated with dizziness and vertigo.
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| 4. |
- Tjernström, Fredrik, et al.
(författare)
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How to Uncover the Covert Saccade During the Head Impulse Test.
- 2012
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Ingår i: Otology & Neurotology. - 1537-4505. ; 33:9, s. 1583-1585
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The appearance of "covert" saccades in the head impulse test in patients with vestibular loss may lead to diagnostic misinterpretations. Here, we demonstrate a procedure that can convert covert eye saccades to overt when performing the head impulse test. PATIENTS: Patients with known vestibular deficits that have covert saccades during head impulse test. INTERVENTION: Diagnostic: random and sudden changes of the amplitude (degree of head turn) when performing the head impulse test. MAIN OUTCOME MEASURE: Evaluation of bedside test with video recording and registration from video head impulse test (v-HIT). RESULTS: A video recording and registration from v-HIT that demonstrate the covert saccades of a subject and how the overt saccade is uncovered by changing the amplitude of the head impulse. Five cases are briefly presented. CONCLUSION: By performing the head impulse test with random amplitudes, overt saccades may become detectable and advance accuracy in bedside diagnosis of vestibular deficits.
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| 5. |
- Patel, Mitesh, et al.
(författare)
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Strategic Alterations of Posture are Delayed in Parkinson's Disease Patients during Deep Brain Stimulation
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Parkinson's disease (PD) is characterized by rigidity, akinesia, postural instability and tremor. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces tremor but the effects on postural instability are inconsistent. Another component of postural control is the postural strategy, traditionally referred to as the ankle or hip strategy, which is determined by the coupling between the joint motions of the body. We aimed to determine whether DBS STN and vision (eyes open vs. eyes closed) affect the postural strategy in PD in quiet stance or during balance perturbations. Linear motion was recorded from the knee, hip, shoulder and head in 10 patients with idiopathic PD with DBS STN (after withdrawal of other anti-PD medication), 25 younger adult controls and 17 older adult controls. Correlation analyses were performed on anterior-posterior linear motion data to determine the coupling between the four positions measured. All participants were asked to stand for a 30 s period of quiet stance and a 200 s period of calf vibration. The 200 s vibration period was subdivided into four 50 s periods to study adaptation between the first vibration period (30-80 s) and the last vibration period (180-230 s). Movement was recorded in patients with PD with DBS ON and DBS OFF, and all participants were investigated with eyes closed and eyes open. DBS settings were randomized and double-blindly programmed. Patients with PD had greater coupling of the body compared to old and young controls during balance perturbations (p ≤ 0.046). Controls adopted a strategy with greater flexibility, particularly using the knee as a point of pivot, whereas patients with PD adopted an ankle strategy, i.e., they used the ankle as the point of pivot. There was higher flexibility in patients with PD with DBS ON and eyes open compared to DBS OFF and eyes closed (p ≤ 0.011). During balance perturbations, controls quickly adopted a new strategy that they retained throughout the test, but patients with PD were slower to adapt. Patients with PD further increased the coupling between segmental movement during balance perturbations with DBS ON but retained a high level of coupling with DBS OFF throughout balance perturbations. The ankle strategy during balance perturbations in patients with PD was most evident with DBS OFF and eyes closed. The increased coupling with balance perturbations implies a mechanism to reduce complexity at a cost of exerting more energy. Strategic alterations of posture were altered by DBS in patients with PD and were delayed. Our findings therefore show that DBS does not fully compensate for disease-related effects on posture.
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| 6. |
- Fransson, Per-Anders, et al.
(författare)
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Analysis of Short- and Long-Term Effects of Adaptation in Human Postural Control
- 2002
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Ingår i: Biological Cybernetics. - : Springer Science and Business Media LLC. - 1432-0770 .- 0340-1200. ; 86:5, s. 355-365
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Tidskriftsartikel (refereegranskat)abstract
- The short-term (i.e., days) and long-term (i.e., months) effects of adaptation to posturography examinations were investigated in 12 normal subjects who were repeatedly examined for five consecutive days and again after 90 days. The examinations were conducted both with eyes open and closed, and the perturbations were evoked by a pseudorandomly applied vibration stimulation to the calf muscles. The evoked anteroposterior responses were analyzed with a method considering adaptation in the slow changes in posture and in the stimulus-response relationship. Repetition of examinations on a daily basis revealed a gradual improvement of postural-control performance. The body sway induced by the stimulation was significantly reduced and the dynamical properties changed. Most of the improvements remained after 90 days, but some parameters such as the complexity of the control system used were increased to the initial level. The results confirm previous observations that postural control contains several partially independent adaptive processes, observed in terms of alteration of posture and as a progressive reduction of body sway induced by stimulation. The method used for the adaptation analysis in this study could be applied to analyze biological systems with multiple individual adaptive processes with different time courses or characteristics, or where the adaptation processes are related to multiple internal or external factors.
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| 7. |
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| 8. |
- Sjögren, Julia, et al.
(författare)
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Functional Head Impulse Testing Might Be Useful for Assessing Vestibular Compensation After Unilateral Vestibular Loss
- 2018
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Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 9:NOV
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Tidskriftsartikel (refereegranskat)abstract
- Background: Loss of the vestibulo-ocular reflex (VOR) affects visual acuity during head movements. Previous studies have shown that compensatory eye-saccades improve visual acuity and that the timing of the saccade is important. Most of the tests involved in testing VOR are made with passive head movement, that do not necessarily reflect the activities of daily living and thus not being proportionate to symptoms and distresses of the patients. Objective: To examine differences between active (self-generated) or passive (imposed by the examiner) head rotations while trying to maintain visual focus on a target. Method: Nine subjects with unilateral total vestibular loss were recruited (4 men and 5 women, mean age 47) and tested with video Head Impulse Test (vHIT) and Head Impulse Testing Device-Functional Test (HITD-FT) during passive and active movements while looking at a target. VOR gain, latencies of covert saccades, frequency of covert saccades and visual acuity were measured and analyzed. Results: Active head-impulses toward the lesioned side resulted in better visual acuity (p = 0.002) compared to conventional passive head-impulses and generated eye-saccades with significantly shorter latencies (p = 0.004). Active movements to the lesioned side generated dynamic visual acuities that were as good as when testing the intact side. Conclusion: Actively generated head impulses resulted in normal dynamic visual acuity, even when performed toward the side of total vestibular loss. This might be attributed to the appearance of short-latency covert saccades. The results show a strong relationship between self-generated movements, latencies of covert saccades and outcome in HITD-FT, i.e., a better dynamic visual function with less retinal slip which is the main function of the VOR. The method of active HITD-FT might be valuable in assessing vestibular compensation and monitoring ongoing vestibular rehabilitation.
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| 9. |
- Sjögren, Julia, et al.
(författare)
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Short-Latency Covert Saccades - The Explanation for Good Dynamic Visual Performance After Unilateral Vestibular Loss?
- 2021
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Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Functional head impulse test (fHIT) tests the ability of the vestibulo-ocular reflex (VOR) to allow visual perception during head movements. Our previous study showed that active head movements to the side with a vestibular lesion generated a dynamic visual performance that were as good as during movements to the intact side. Objective: To examine the differences in eye position during the head impulse test when performed with active and passive head movements, in order to better understand the role of the different saccade properties in improving visual performance. Method: We recruited 8 subjects with complete unilateral vestibular loss (4 men and 4 women, mean age 47 years) and tested them with video Head Impulse Test (vHIT) and Functional Head Impulse Test (fHIT) during passive and active movements while looking at a target. We assessed the mean absolute position error of the eye during different time frames of the head movement, the peak latency and the peak velocity of the first saccade, as well as the visual performance during the head movement. Results: Active head impulses to the lesioned side generated dynamic visual performances that were as good as when testing the intact side. Active head impulses resulted in smaller position errors during the visual perception task (p = 0.006) compared to passive head-impulses and the position error during the visual perception time frame correlated with shorter latencies of the first saccade (p < 0.001). Conclusion: Actively generated head impulses toward the side with a complete vestibular loss resulted in a position error within or close to the margin necessary to obtain visual perception for a brief period of time in patients with chronic unilateral vestibular loss. This seems to be attributed to the appearance of short-latency covert saccades, which position the eyes in a more favorable position during head movements.
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| 10. |
- Sjögren, Julia, et al.
(författare)
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Steroids for Acute Vestibular Neuronitis-the Earlier the Treatment, the Better the Outcome?
- 2019
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Ingår i: Otology & Neurotology. - 1537-4505. ; 40:3, s. 372-374
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To present findings that suggest steroid treatment within 24 hours of onset of vestibular neuronitis results in better restitution of vestibular function than treatment between 25 and 72 hours. PATIENTS: Thirty-three consecutive patients (17 men, 16 women, mean age 57 yr, range 17-85 yr) with acute vestibular neuronitis and treated with steroids within 72 hours after symptom onset. Patients were divided into two groups depending on if they were treated within the first 24 hours or not. INTERVENTIONS: Oral prednisolone 50 mg/d for 5 days with tapering of doses for the next 5 days, or combined with initial intravenous betamethasone 8 mg the first 1 to 2 days if the patient was nauseous. MAIN OUTCOME MEASURES: Proportion of patients with normal caloric test result (canal paresis value < 32%) at follow-up after 3 or 12 months. RESULTS: All 9 patients (100%) treated within 24 hours from onset of vestibular neuronitis had normal caloric test results at follow-up after 3 months, as compared with 14 of 24 (58%) of the patients treated between 25 and 72 hours (p < 0,05, Fisher's exact test). CONCLUSIONS: The timing of steroid treatment of vestibular neuronitis may be of importance for subsequent vestibular restitution, and hence, for both time to recovery and late symptoms according to the literature.
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