519 - A rare case of systemic intoxication following administration of AbobotulinumtoxinA for lower extremity spasticity in a patient with hereditary spastic paraparesis

Friday, February 20, 2026

5:00 PM - 6:30 PM AST

Presenting Author(s)

VS

Vasant P. Sarthi, DO

Transitional Year Resident/PGY-1
Lehigh Valley Health Network
Newark, Delaware, United States

Co-Author(s)

MS

Michael A. Snover, II, DO

Attending Physician Physiatrist
Lehigh Valley Health Network
Easton, Pennsylvania, United States

Submitter(s)

VS

Vasant P. Sarthi, BA

Philadelphia College of Osteopathic Medicine
Newark, Delaware, United States

Case Diagnosis: Systemic toxicity following botox injection is a known but rare adverse reaction. This case discusses a prolonged illness course of botulinum toxicity and subsequent rehabilitation course.

Case Description: A 52 year old female with hereditary spastic paraparesis on baclofen presented to the emergency department with dyspnea, dysarthria, dysphagia, diplopia, blurry vision, and profound weakness. She had received AbobotulinumtoxinA (Dysport) injections three weeks prior to presentation with significant symptoms starting after three days. Neurological exam revealed mild ptosis, intact cranial nerves, no visual field deficits, significant upper and lower extremity weakness, and intact sensation and reflexes.

Discussions: Antitoxin was not administered due to plateauting symptoms without respiratory decompensation. The patient was admitted to inpatient rehabilitation, where she exhibited resolution of most of her symptoms apart from mild residual dyspnea on exertion. She was discharged on standing baclofen but later switched to tizanidine due to drowsiness and ineffectiveness with baclofen. She is currently continuing physical therapy and ambulates with a rollator walker.

Conclusions: This case reports a rare but known severe adverse reaction to Dysport and aims to add to the literature on the clinical manifestations of the documented black box warning. Although there are a limited number of reported botulinum “overdose” cases, confirmed cases of systemic botulinum toxicity are sparsely documented in the literature. Of note, the patient underwent botulinum toxin injections at a lower total dose without adverse effects. Although dosing conversions for different formulations of botulinum toxins are established, the literature is sparse that addresses whether patients injected with multiple different formulations had adverse reactions. This leaves a possibility that one molecule is more tolerated than another for specific patient populations and may warrant further research into the efficacy and safety of different chemodenervation agents.