By Joseph E. Safdieh, MD
Assistant Professor of Neurology, Weill Cornell Medical College
Dr. Safdieh reports no financial relationships relevant to this field of study.
Synopsis: AbobotulinumtoxinA is effective at reducing spasticity and reducing disability in patients with upper limb spasticity due to stroke or traumatic brain injury.
Source: Gracies JM, et al. Safety and efficacy of abobotulinumtoxinA for hemiparesis in adults with upper limb spasticity after stroke or traumatic brain injury: A double-blind randomized controlled trial. Lancet Neurol 2015;14:992-1001.
Assessment of tone is an important part of the neurologic examination. Causes of increased tone include spasticity, rigidity, and paratonia. Spasticity is a common neurologic consequence of upper motor neuron damage, and can occur in the setting of stroke, traumatic brain or spinal cord injury, multiple sclerosis, and other central nervous system conditions. For many patients, spasticity can be quite disabling and may impair functional status more than weakness. Additionally, the care of the patient with spasticity may be difficult due to fixed flexion of upper limb muscles. Upper limb spasticity may impair basic daily activities such as feeding and toileting. Botulinum toxin is an approved therapy for reduction of upper limb spasticity.
These authors report the results of a randomized, controlled trial assessing the effectiveness of abobotulinumtoxinA 500 mg, abobotulinumtoxinA 100 mg, or placebo at reducing muscle tone in patients with upper limb spasticity. The primary endpoint was change in muscle tone using the Modified Ashworth Scale. Secondary endpoints included a Physician Global Assessment score and perceived function using the Disability Assessment Scale in dressing, hygiene, limb position, and pain. Injections were performed into a number of muscles including most hypertonic of the primary target muscle group (flexors of the elbow, wrist, or fingers).
Eighty-one patients were randomized to each of the three groups: 500 units, 1000 units, and placebo. Outcome measures were recorded at weeks 1, 4, 12, 16, and 20 after treatment. Reduction in Modified Ashworth Score was 0.3 in the placebo group, 1.2 in the 500 unit group, and 1.4 in the 1000 unit group at 4 weeks. Of note, benefits were seen as early as 1 week and persisted even at 16-20 weeks. The Physician Global Assessment score was also improved in the treatment group in a dose-dependent manner as compared to placebo. Disability Assessment Scale scores were better in the treatment group (no difference between low and high dose) compared to placebo. There were two deaths (one in the placebo group) that were not related to treatment effect. The most common adverse events in the treatment groups included muscle weakness and fatigue.
This study adds to the literature on the use of botulinum toxins in treating upper limb spasticity after stroke or traumatic brain injury. It demonstrates some interesting findings, including evidence of a benefit even 1 week after treatment as well as a sustained benefit from a single treatment even after 12 weeks. This is important to note because if treatment can be spaced out further than every 3 months, there would be less burden on patients and caregivers to return for frequent follow-up treatment visits. Additionally, the study demonstrated not only reduction in passive tone but also improvement in active range of motion of the affected limb. This potentially could lead to significant improvement in the quality of life of the patient and caregivers, as patients can use the affected limb in a more useful way.