Objective: To review the treatment characteristics of botulinum toxin in medically refractory essential tremor (ET).

Background: Treatment of medically refractory essential tremor has remained challenging but introduction of botulinum toxin as a targeted therapy has rapidly gained popularity. We conducted a retrospective survey of botulinum toxin use in ET patients with refractory upper limb tremor to better understand trends in injection strategy over time.

Method: The Movement Disorders Clinical Case Registry (MD-CCR) is an application that works within a specific US Veterans Health Administration medical center’s electronic medical record (EMR) to query and export information. The MD-CCR in Houston was queried for all patients with ICD-9/10 codes of 333.1 and/or G25.0 seen in a movement disorder specialty center’s outpatient clinics during the time period September 1, 2001 – March 31, 2018. Each patient’s EMR was reviewed to obtain information regarding botulinum toxin treatment.

Results: Of the 1051 patients identified with ET, 52 (4.9%) were treated with botulinum toxin for medically refractory tremor. Out of these 52 patients, 19.2% received first injection between 2001-2006, followed by 26.9% between 2007-2012, and 53.8% between 2013-2018. The mean age at first injection was 67.8 (SD=11.4).  The mean number of treatment visits was 5.2. Medical therapy was continued for 47 (90.4%) patients. Injections were administered in unilateral limb for 27 (51.9%) patients and in bilateral limbs for 25 (48.1%) patients. Forearm flexors were the site of injection in 49 (94.2%) patients followed by supinators in 23 (44.2%) patients, forearm extensors in 19 (36.5%) patients, and pronator teres in 10 (19.2%) patients.

Conclusion: Botulinum toxin as a treatment modality for medically refractory essential tremor is becoming more prevalent. Although treatment is individualized with various combinations of muscles selected, forearms flexors are the most common site of injection in upper limb tremor.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/use-of-botulinum-toxin-experience-in-a-cohort-of-essential-tremor-patients/