Objective: To evaluate the efficacy and durability of targeted incobotulinumtoxinA injections into the muscle of Riolan in patients with ALO refractory to conventional pretarsal BoNT-A therapy.
Background: Apraxia of lid opening (ALO) is a disabling focal motor phenomenon seen in atypical parkinsonism and advanced Parkinson’s disease (PD). Standard two-point pretarsal botulinum toxin type A (BoNT-A) injections often yield suboptimal outcomes. Biomechanical evidence suggests that isolated microspasm of the muscle of Riolan (pars marginalis) is a key trigger of levator palpebrae inhibition, supporting a more selective therapeutic approach.
Method: An open-label, longitudinal cohort study included 14 patients with refractory ALO. The cohort included patients with progressive supranuclear palsy (PSP-RS, PSP-P), multisystem atrophy (MSA), corticobasal degeneration (CBD), and GBA-associated PD. All patients had documented non-response to standard pretarsal BoNT-A injections. IncobotulinumtoxinA was administered strictly into the muscle of Riolan. Primary outcomes were reduction in motor severity (Jankovic Rating Scale [JRS], 0-8) and functional improvement (Blepharospasm Disability Index [BSDI], 0-4).
Results: The cohort (mean age 65.8±4.9 years; disease duration 2.3±1.3 years) showed a sustained response across multiple treatment cycles (mean 2.9 cycles/patient, range 1-9). Targeted incobotulinumtoxinA administration (mean dose 11.5±1.1 U/session) was associated with early clinical benefit. Mean JRS severity decreased significantly from 4.7±0.9 at baseline to 0.1±0.3 at peak effect (p<0.001). BSDI scores improved from 2.6±0.5 to 0.4±0.5 (p<0.001). The mean duration of benefit per cycle was 4.3±0.7 months. No diffusion-related ptosis was observed.
Conclusion: The muscle of Riolan appears to be a critical pathophysiological target in ALO. Precise chemodenervation with incobotulinumtoxinA may overcome the limitations of standard pretarsal schemes and offers an effective rescue strategy for refractory ALO in neurodegenerative disorders.
To cite this abstract in AMA style:
I. Miliukhina. Targeted IncobotulinumtoxinA Injections into the Muscle of Riolan: A Novel Rescue Strategy for Refractory Apraxia of Lid Opening in Neurodegenerative Disorders [abstract]. Mov Disord. 2026; 41 (suppl 1). https://www.mdsabstracts.org/abstract/targeted-incobotulinumtoxina-injections-into-the-muscle-of-riolan-a-novel-rescue-strategy-for-refractory-apraxia-of-lid-opening-in-neurodegenerative-disorders/. Accessed October 1, 2026.« Back to 2026 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/targeted-incobotulinumtoxina-injections-into-the-muscle-of-riolan-a-novel-rescue-strategy-for-refractory-apraxia-of-lid-opening-in-neurodegenerative-disorders/