Disclosures: Jessica Mulhern, DO: No financial relationships or conflicts of interest

Case Diagnosis: Determination of primary non-responder status of a cervical dystonia patient.

Case Description: 44 year old female presented with neck pain. Previous work up negative for spinal cord, orthopedic or neurologic pathologies. On physical examination, there were limitations in left rotation and right sidebending. Diagnosis of cervical dystonia was made. Diagnostic selective motor nerve blocks (DSMNB) to the motor nerves innervating the left upper trapezius and left posterior scalene were performed. Immediately following this procedure, there was improvement in discomfort and normalization of range of motion. This bode well for the use of botulinum toxin for chemodenervation. Chemodenervation with electromyographic (EMG) guidance with botulinum toxin was performed to the upper trapezius and posterior scalene. Four weeks later, the patient reported minimal improvement in symptoms. The dosage to both the upper trapezius and posterior scalene was increased the following cycle. Unfortunately, the patient had no relief. Due to failure to improve, the decision was made to inject a small dose of botulinum toxin to the abductor digiti minimi (ADM) to assess if the patient was a primary non-responder to neurotoxin.

Setting: Private PracticeAssessment/

Results: Three weeks following chemodenervation of the ADM, the patient had weakness in 5th digit abduction. This bode well for further response to dose alterations of botulinum toxin type A in the future, as well as ruled out the patient as a primary non-responder.

Discussion: Fifth digit abduction weakness is easily substituted by fifth digit extension without significant alteration in functionality. For this reason, the ADM has become a target for chemodenervation for primary non-responder assessment.

Conclusion: Use of small dose of botulinum toxin to the ADM can be used to rule out the diagnosis of a primary non-responder to botulinum toxin, avoiding the expensive immunoassay laboratory testing.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/simple-evaluation-of-primary-non-responder-to-botulinum-toxin-a-case-report/