Prolonged Spasticity Reduction with IncobotulinumtoxinA (Xeomin) in a Patient with Zellweger Syndrome: A Case Report

Case Diagnosis: A 40-year-old female with Zellweger Syndrome presenting for bilateral lower extremity spasticity and inability to tolerate ankle-foot orthoses (AFOs)

Case Description or Program Description: The patient has a long history of onabotulinumtoxinA (Botox) injections for spasticity management, but over time, she exhibited diminished duration of effect and functional decline between injections. Given these limitations, we transitioned to incobotulinumtoxinA (Xeomin) to evaluate its efficacy in improving muscle relaxation, functional mobility, and tolerance of AFOs.
The patient received 500 units of incobotulinumtoxinA, reconstituted with 10 mL of normal saline to a concentration of 50 units/mL. A total of 500 units was injected into the bilateral lower extremity into the muscles as follows:
• Left lower extremity: 50u medial gastrocnemius, 50u lateral gastrocnemius, 25u soleus, 75u posterior tibialis, 75u hamstring (semimembranosus/semitendinosus).
• Right lower extremity: 25u medial gastrocnemius, 25u lateral gastrocnemius, 25u soleus, 75u posterior tibialis, 75u hamstring (biceps femoris/semitendinosus).

Setting: Outpatient rehabilitation clinic

Assessment/Results: The patient tolerated the injections well, reporting minimal pain and no significant adverse effects. At two months post-injection, the patient demonstrated sustained spasticity reduction and improved tolerance of AFOs, which had previously been challenging at this stage with onabotulinumtoxinA. The patient’s mother also noted continued functional improvement beyond the typical wear-off period previously observed with onabotulinumtoxinA, suggesting a prolonged therapeutic effect of incobotulinumtoxinA.

Discussion (relevance): Zellweger Syndrome is a very rare neurodevelopmental disorder with limited literature on spasticity management. This is the first reported case, to our knowledge, evaluating the use of incobotulinumtoxinA for spasticity in Zellweger Syndrome.

Conclusions: IncobotulinumtoxinA may provide prolonged spasticity reduction in Zellweger Syndrome, suggesting it as a potential alternative for patients experiencing suboptimal duration of effect with chronic onabotulinumtoxinA use.