Temporal discrimination threshold and blink reflex recovery cycle in cervical dystonia – two sides of the same coin?

Background. The somatosensory temporal discrimination threshold (STDT) is defined as the shortest interval at which an individual recognizes two stimuli as asynchronous. Some evidence suggests that STDT depends on cortical inhibitory interneurons in the basal ganglia and in primary somatosensory cortex. Several studies have reported that the STDT in patients with dystonia is abnormal. No longitudinal studies have yet investigated whether STDT values in different forms of focal dystonia change during the course of the disease.Methods. We designed a follow-up study on 25 patients with dystonia (15 with blepharospasm and 10 with cervical dystonia) who were tested twice: upon enrolment and 8 years later. STDT values from dystonic patients at the baseline were also compared with those from a group of 30 age-matched healthy subjects.Results. Our findings show that the abnormally high STDT values observed in patients with focal dystonia remained unchanged at the 8-year follow-up assessment whereas disease severity worsened.Conclusions. Our observation that STDT abnormalities in dystonia remain unmodified during the course of the disease suggests that the altered activity of inhibitory interneurons—either at cortical or at subcortical level—responsible for the increased STDT does not deteriorate as the disease progresses.

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A Headset Method for Measuring the Visual Temporal Discrimination Threshold in Cervical Dystonia

Tremor and Other Hyperkinetic Movements ◽

10.5334/tohm.196 ◽

2014 ◽

Vol 4 (0) ◽

pp. 249 ◽

Cited By ~ 1

Author(s):

Anna Molloy ◽

Okka Kimmich ◽

Laura Williams ◽

Brendan Quinlivan ◽

Adriana Dabacan ◽

...

Keyword(s):

Cervical Dystonia ◽

Temporal Discrimination ◽

Discrimination Threshold

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Faculty Opinions recommendation of Blink reflex recovery cycle in patients with essential tremor associated with resting tremor.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717959051.793462568 ◽

2012 ◽

Author(s):

Alfredo Berardelli ◽

Antonio Suppa

Keyword(s):

Essential Tremor ◽

Blink Reflex ◽

Recovery Cycle ◽

Resting Tremor

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Effects of Transcranial Ultrasound Stimulation on Trigeminal Blink Reflex Excitability

Brain Sciences ◽

10.3390/brainsci11050645 ◽

2021 ◽

Vol 11 (5) ◽

pp. 645

Author(s):

Andrea Guerra ◽

Edoardo Vicenzini ◽

Ettore Cioffi ◽

Donato Colella ◽

Antonio Cannavacciuolo ◽

...

Keyword(s):

Substantia Nigra ◽

Superior Colliculus ◽

Blink Reflex ◽

Transcranial Ultrasound ◽

Recovery Cycle ◽

Brain Areas ◽

Nucleus Raphe Magnus ◽

Ultrasound Stimulation ◽

Raphe Magnus ◽

Interstimulus Intervals

Recent evidence indicates that transcranial ultrasound stimulation (TUS) modulates sensorimotor cortex excitability. However, no study has assessed possible TUS effects on the excitability of deeper brain areas, such as the brainstem. In this study, we investigated whether TUS delivered on the substantia nigra, superior colliculus, and nucleus raphe magnus modulates the excitability of trigeminal blink reflex, a reliable neurophysiological technique to assess brainstem functions in humans. The recovery cycle of the trigeminal blink reflex (interstimulus intervals of 250 and 500 ms) was tested before (T0), and 3 (T1) and 30 min (T2) after TUS. The effects of substantia nigra-TUS, superior colliculus-TUS, nucleus raphe magnus-TUS and sham-TUS were assessed in separate and randomized sessions. In the superior colliculus-TUS session, the conditioned R2 area increased at T1 compared with T0, while T2 and T0 values did not differ. Results were independent of the interstimulus intervals tested and were not related to trigeminal blink reflex baseline (T0) excitability. Conversely, the conditioned R2 area was comparable at T0, T1, and T2 in the nucleus raphe magnus-TUS and substantia nigra-TUS sessions. Our findings demonstrate that the excitability of brainstem circuits, as evaluated by testing the recovery cycle of the trigeminal blink reflex, can be increased by TUS. This result may reflect the modulation of inhibitory interneurons within the superior colliculus.

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P23-11 The clinical utility of the blink reflex recovery cycle to distinguish between blepharospasm and atypical (presumed psychogenic) blepharospasm

Clinical Neurophysiology ◽

10.1016/s1388-2457(10)60986-8 ◽

2010 ◽

Vol 121 ◽

pp. S241

Author(s):

J.T.H. Teo ◽

P. Schwingenschuh ◽

P. Katschnig ◽

M. Edwards ◽

K. Bhatia ◽

...

Keyword(s):

Clinical Utility ◽

Blink Reflex ◽

Recovery Cycle

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Blink reflex recovery cycle distinguishes patients with idiopathic normal pressure hydrocephalus from elderly subjects

Journal of the Neurological Sciences ◽

10.1016/j.jns.2021.118511 ◽

2021 ◽

Vol 429 ◽

pp. 118511

Author(s):

Alessandro Mechelli ◽

Andrea Quattrone ◽

Rita Nisticò ◽

Marianna Crasà ◽

Domenico La Torre ◽

...

Keyword(s):

Normal Pressure Hydrocephalus ◽

Normal Pressure ◽

Blink Reflex ◽

Idiopathic Normal Pressure Hydrocephalus ◽

Elderly Subjects ◽

Recovery Cycle

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Botulinum Toxin Effects on Sensorimotor Integration in Focal Dystonias

Toxins ◽

10.3390/toxins12050277 ◽

2020 ◽

Vol 12 (5) ◽

pp. 277

Author(s):

Maria Ilenia De Bartolo ◽

Nicoletta Manzo ◽

Gina Ferrazzano ◽

Viola Baione ◽

Daniele Belvisi ◽

...

Keyword(s):

Botulinum Toxin ◽

Sensorimotor Integration ◽

Index Finger ◽

Botulinum Toxin A ◽

Temporal Discrimination ◽

Discrimination Threshold ◽

Focal Dystonia ◽

Movement Execution ◽

Proprioceptive Input ◽

Hand Dystonia

(1) Background: In dystonia, the somatosensory temporal discrimination threshold (STDT) is abnormally increased at rest and higher and longer-lasting during movement execution in comparison with healthy subjects (HS), suggesting an abnormal sensorimotor integration. These abnormalities are thought to depend on abnormal proprioceptive input coming from dystonic muscles. Since Botulinum toxin-A (BT-A) reduces proprioceptive input in the injected muscles, our study investigated the effects of BT-A on STDT tested at rest and during voluntary movement execution in patients with focal dystonia. (2) Methods: We enrolled 35 patients with focal dystonia: 14 patients with cervical dystonia (CD), 11 patients with blepharospasm (BSP), and 10 patients with focal hand dystonia (FHD); and 12 age-matched HS. STDT tested by delivering paired stimuli was measured in all subjects at rest and during index finger abductions. (3) Results: Patients with dystonia had higher STDT values at rest and during movement execution than HS. While BT-A did not modify STDT at rest, it reduced the abnormal values of STDT during movement in CD and FHD patients, but not in BSP patients. (4) Conclusions: BT-A improved abnormal sensorimotor integration in CD and FHD, most likely by decreasing the overflow of proprioceptive signaling from muscle dystonic activity to the thalamus.

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Tactile and proprioceptive dysfunction differentiates cervical dystonia with and without tremor

Neurology ◽

10.1212/wnl.0000000000008916 ◽

2020 ◽

Vol 94 (6) ◽

pp. e639-e650 ◽

Cited By ~ 8

Author(s):

Laura Avanzino ◽

Amel Cherif ◽

Oscar Crisafulli ◽

Federico Carbone ◽

Jacopo Zenzeri ◽

...

Keyword(s):

Cervical Dystonia ◽

Feedforward Control ◽

Temporal Discrimination ◽

Matching Task ◽

Proprioceptive Information ◽

Joint Position ◽

Body Segments ◽

Gating Mechanism ◽

Head Positioning ◽

Tactile Temporal Discrimination

ObjectiveTo determine whether different phenotypes of cervical dystonia (CD) express different types and levels of somatosensory impairment.MethodsWe assessed somatosensory function in patients with CD with and without tremor (n = 12 each) and in healthy age-matched controls (n = 22) by measuring tactile temporal discrimination thresholds of the nondystonic forearm and proprioceptive acuity in both the dystonic (head/neck) and nondystonic body segments (forearm/hand) using a joint position‐matching task. The head or the wrist was passively displaced along different axes to distinct joint positions by the experimenter or through a robotic exoskeleton. Participants actively reproduced the experienced joint position, and the absolute joint position‐matching error between the target and the reproduced positions served as a marker of proprioceptive acuity.ResultsTactile temporal discrimination thresholds were significantly elevated in both CD subgroups compared to controls. Proprioceptive acuity of both the dystonic and nondystonic body segments was elevated in patients with CD and tremor with respect to both healthy controls and patients with CD without tremor. That is, tactile abnormalities were a shared dysfunction of both CD phenotypes, while proprioceptive dysfunction was observed in patients with CD with tremor.ConclusionsOur findings suggest that the pathophysiology in CD can be characterized by 2 abnormal neural processes: a dysfunctional somatosensory gating mechanism involving the basal ganglia that triggers involuntary muscle spasms and abnormal processing of proprioceptive information within a defective corticocerebellar loop, likely affecting the feedback and feedforward control of head positioning. This dysfunction is expressed mainly in CD with tremor.

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