Triangulating outcome assessments for blepharospasm - The dystonias overall are a rare neurologic disorder. Blepharospasm (BSP), is one of the most
common forms of dystonia. BSP is characterized by involuntary abnormal facial expressions and eye
closures. In addition to these overt motor abnormalities, the disorder is also associated with non-motor
symptoms including anxiety and depression. Treatment options for BSP are suboptimal. Many oral
medications have been tried but their efficacy is minimal and limited by dose-dependent adverse side
effects. Botulinum neurotoxin (BoNT) injections repeated every 3-4 months are the primary treatment of
choice. Although BoNT is highly efficacious for many patients, for a variety of reasons about 1/3 of
patients discontinue BoNT treatment, and of those who continue treatment about 1/3 are unsatisfied
with the response.
Because treatment options are suboptimal, there is an active effort to find better strategies for
treating BSP, as evidenced by dozens of trials listed on ClinicalTrials.gov. However, the most common
clinical outcome assessments used to measure motor abnormalities are intrinsically subjective
assessments and therefore suffer from inter-rater variability. This reduces our power to detect treatment
effects in clinical trials.
Technology-based objective measures have the potential to circumvent this variability.
Advances in computer vision technology have enabled the measurement of facial expressions and eye
closure from 2-D images of the face in conventional video recordings. One of the long-term objectives
of our group is to leverage these advances to develop software that can capture and quantify motor
abnormalities across multiple types of focal dystonia. We are calling this system the Computational
Motor Objective Rater (CMOR). In this project specifically targeting BSP, our aims are 1) to evaluate
CMOR’s convergent validity with patient reports of severity of facial spasms and excessive blinking and
2) to determine CMOR’s sensitivity to changes in severity associated with interventions. To accomplish
these aims, we will conduct CMOR analyses of motor symptoms from video recordings of 100 BSP
patients enrolled in a separate Dystonia Coalition project to evaluate the variability of efficacy of BoNT.
That project will also acquire patient reports in the form of a patient centered outcome with specific
questions about the prominent motor features of BSP and the patient’s global impression of change
(PGIC) in response to each BoNT treatment. Collectively the results will provide important information
about CMOR’s validity and a quantitative basis for sample size estimates for future clinical trials in BSP.
