Photic Blink Reflex in People With Blepharospasm and Increased Blinking

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Brief Title

Photic Blink Reflex in People With Blepharospasm and Increased Blinking

Official Title

Study of the Photic Blink Reflex in Patients With Blepharospasm and Increased Blinking

Brief Summary

      Background:

      Some people who have increased blinking may later develop blepharospasm. Blepharospasm is a
      neurological disorder that causes involuntary closing of the eyes. Researchers want to learn
      more about how eyes close in response to different stimuli. They want to study this in
      healthy people, people with increased blinking, and people with blepharospasm.

      Objective:

      To learn how light exposure affects people with blepharospasm.

      Eligibility:

      People ages 18 and older with blepharospasm or increased blinking, and healthy volunteers

      Design:

      Participants will be screened with:

      Medical history

      Physical exam

      Neurological exam

      Participants will have up to 5 visits. The number of visits will depend on the number of
      tests they opt to have. They can opt to have up to 4 tests. Visits last 60-90 minutes. They
      cannot drink alcohol or caffeinated drinks for at least 12 hours before visits. Visits could
      include the following tests:

      Evaluation of eyelid movements. This will be video recorded.

      Electromyography: Small sticky electrodes are placed on the lower eyelid skin. These are
      attached to wires. Muscle activity is recorded during blink reflex procedures.

      Electrical stimulation: An electrode is placed close to the eyebrow. It will deliver small
      electrical shocks. The strength of the shocks will be enough to provoke a blink.

      Photic stimulation: A lamp is placed in front of the face. It will deliver single or paired
      flashes. The flashes will be at various intervals and intensities. Participants will wear a
      patch over one eye during this test.

      Combination of electrical and photic stimulation

      ...
    

Detailed Description

      Objective:

        -  The purpose of the first study of this protocol is to improve understanding of the role
           played by light sensitivity in the pathophysiology of blepharospasm (BPS).

        -  As a characteristic feature of BPS, the electrocutaneous blink reflex recovery cycle
           (EBR rc) shows an increased recovery index of R2 compared with healthy subjects.

        -  In the first study proposed under this protocol we will study the recovery cycle of the
           blink reflex evoked by a light stimulus (PBR rc) and the effect of a light stimulus on
           the EBR (MBR rc) in patient with BPS. Since photophobia and increased blinking are
           common symptoms in this group of patients, we will look for possible correlations
           between neurophysiological data and the Light Sensitivity Questionnaire (LSQ) or the
           Blink rate (Brt). The second study proposed under this protocol will explore the PBR rc
           and the MBR rc in patients with increased blinking alone, a condition indicated as a
           possible precursor of BPS.

      Study population:

      We plan to recruit 24 patients with blepharospasm, 24 healthy volunteers (HVs) and 24
      patients with increased blinking alone.

      Design:

      In two different studies, we will compare all the results from the EBR rc, PBR rc and MBR rc
      between BPS patients (first study) or increased blinking patients (second study) and HVs. We
      will also look for possible correlation between the neurophysiologic data and the clinical
      scales acquired during a clinical assessment. In the EBR rc procedure, the supraorbital nerve
      will be stimulated with paired electrical stimuli at varying ISIs and the EMG response from
      the orbicularis oculi muscles will be recorded. In the PBR rc procedure, paired light stimuli
      will be given at varying interstimulus intervals (ISIs) and the EMG responses from the
      orbicularis oculi will be recorded. In the MBR rc study a weak light stimulation will be
      given at varying ISIs before an electrical stimulation of the supraorbital nerve. Each
      experimental procedure will last about 1 hour. There will be one screening visit and up to 4
      testing visits per participant. However, participant can either undergo all the experimental
      procedures or participate in only some of them and will be allowed to participate in two
      experimental procedures per testing visit.

      Outcome measurements:

        -  EBR rc, PBR rc, MBR rc: the electromyography (EMG) responses at different interstimulus
           intervals (ISIs).

        -  Blink rate: number of eye blinks per minute.

        -  LQs: the total score of the Light Questionnaire Scale.

      These results will be compared between the two patient groups and HVs. We will look for
      possible correlations between neurophysiological and clinical data.
    


Study Type

Observational


Primary Outcome

Photic blink reflex recovery cycle

Secondary Outcome

 Electrocutaneous blink reflex recovery cycle; Blink rate; Light Questionnaire Scale

Condition

Blepharospasm


Study Arms / Comparison Groups

 Healthy
Description:  24 healthy volunteers (HVs)

Publications

* Includes publications given by the data provider as well as publications identified by National Clinical Trials Identifier (NCT ID) in Medline.

Recruitment Information



Estimated Enrollment

17

Start Date

October 30, 2017

Completion Date

April 24, 2019

Primary Completion Date

April 24, 2019

Eligibility Criteria

        -  INCLUSION CRITERIA:

          -  Must be 18 years or older

          -  For patients only: fulfill the criteria of

               -  Primary BPS (either focal or related to segmental dystonia) in accordance with
                  published criteria or

               -  Excessive involuntary eyelid closure without sustained OO spasms in accordance
                  with Conte et al + having a resting blink rate above 15 blinks per minute.

          -  Ability to give informed consent.

          -  Ability to comply with all study procedures.

          -  Agree to consume no caffeine or alcohol for 12 hours before participating in the
             testing visits.

        EXCLUSION CRITERIA:

        Any of the following will exclude PATIENTS from the study:

          -  Secondary causes of excessive involuntary eyelid closure such as ophthalmologist
             disorders involving the ocular surface, tear film, or eyelids.

          -  Any evidence suggesting a psychogenic movement disorder such as persisting unilateral
             or asymmetric symptoms, paroxysmal symptoms, and other inconsistencies such as pain,
             associated somatizations, blinking diminished by distraction, unusual sensory tricks,
             or unexpected response.

          -  Botulinum toxin treatment < 3 months prior to a testing visit.

          -  History of chronic exposure (>3 month) to dopamine receptor blocking agents before the
             onset of increased blinking alone or BPS.

        Any of the following will exclude BOTH patients and healthy controls from the study:

          -  Has any major medical problem other than increased blinking or dystonia in patient
             groups (such as decompensated chronic diseases or conditions that cause serious
             disability such as congestive heart failure/NYHA score greater than or equal to 2,
             severe COPD, advanced neoplasia, severe arthritis, HIV/AIDS, blindness).

          -  Employees, staff or fellows of HMCS in NINDS.

          -  Has used illegal drugs within the past 6 months based on history. The intent is to
             exclude those with drug use that may affect study results.

          -  Self-reported consumption of more than 7 alcoholic drinks a week in the case of a
             woman and 14 alcoholic drinks a week in the case of a man.

          -  Abnormal findings on neurologic exam (other than increased blinking or dystonia in
             patient groups).

          -  Presence of anatomical or functional eyelid abnormalities other than involuntary
             eyelid closure or OOs spasms (including apraxia of eyelid opening, and other disorders
             such as tics or tardive syndromes).

          -  Has a neurologic disorder other than increased blinking or dystonia.

          -  Has major depression or any major mental disorders (axis I disorders).

          -  Has had a head injury where there was a loss of consciousness for more than a few
             seconds.

          -  Has a deep brain stimulator, pacemaker or other implantable electronic device subject
             to malfunction by electrical stimulation.
      

Gender

All

Ages

18 Years - N/A

Accepts Healthy Volunteers

Accepts Healthy Volunteers

Contacts

Mark Hallett, M.D., , 

Location Countries

United States

Location Countries

United States

Administrative Informations


NCT ID

NCT03263000

Organization ID

170159

Secondary IDs

17-N-0159

Responsible Party

Sponsor

Study Sponsor

National Institute of Neurological Disorders and Stroke (NINDS)


Study Sponsor

Mark Hallett, M.D., Principal Investigator, National Institute of Neurological Disorders and Stroke (NINDS)


Verification Date

April 2019