Flu-Like Symptoms as a Complication of Botulinum Toxin Therapy

Botulinum toxin (BoNT) has become a revolutionary treatment for many neurological, autonomic, gastrointestinal, genitourinary, and cosmetic disorders. The use of this treatment requires expertise in dosage calculations and application technique to avoid potential side effects. Most adverse events (AEs) related to BoNT are local and related to its mechanism of action, i.e., paralysis of unwanted muscles. However, systemic AEs may also be observed. Flu-like symptoms (FLS) are well recognized AEs in patients treated with BoNT; however there is a paucity of information regarding the frequency, clinical impact, and associated risk factors of this particular complication. Between December 1989 and May 2003, 1,437 reports of BoNT-related AEs were registered at the Food and Drug Administration (FDA). FLS were reported in 4.6% of serious, and 3.2% of non-serious side effects. In this study, the investigators aim to assess prospectively the frequency, clinical characteristics, and risk factors for development of FLS in a group of patients affected with diverse movement disorders and treated with BoNT type A at the Parkinson's Disease Center and Movement Disorders Clinic (PDCMDC) of Baylor College of Medicine (BCM). The investigators will also assess biomarker of inflammatory response in those patients who develop FLS after treatment with BoNT.