title: The "Ram's Horns Sign": A Case Report of an Unusual Side Effect of OnabotulinumtoxinA in a Chronic Migraine Patient.
abstract: OnabotulinumtoxinA (BoNT-A) has been reported as an effective prophylactic treatment for chronic migraine to reduce disease severity improving health-related quality of life. However, BoNT-A, due to its activity on either the injected or adjacent muscles of the upper face, may induce well-known side-effects, such as the eyebrow or eyelid ptosis. However, unusual muscular side effects, related to the neurotoxic mechanism, may also arise. We describe the clinical case of a 55-year-old male patient who has been treated for chronic migraine by the injection of BoNT-A, according to the PREEMPT protocol. Two weeks later, the patient developed two symmetrical bumps on the upper part of the forehead similar to the horns of a ram. We report, for the first time, this peculiar BoNT-A side effect and suggest that the injection of additional BoNT-A doses in the upper medial frontal fibers, for each side, can normalize the forehead shape over two weeks.
authors.affiliation: Headache Center, Department of Medical, Surgical, Neurological, Metabolic and Aging Sciences, Second University of Naples, Naples, Italy.|MRI Research Center SUN-FISM, Second University of Naples, Naples, Italy.|Institute for Diagnosis and Care ''Hermitage Capodimonte,'', Naples, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Russo
authors.affiliation: Headache Center, Department of Medical, Surgical, Neurological, Metabolic and Aging Sciences, Second University of Naples, Naples, Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Silvestro
authors.affiliation: Headache Center, Department of Medical, Surgical, Neurological, Metabolic and Aging Sciences, Second University of Naples, Naples, Italy.|MRI Research Center SUN-FISM, Second University of Naples, Naples, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Tessitore
authors.affiliation: Headache Center, Department of Medical, Surgical, Neurological, Metabolic and Aging Sciences, Second University of Naples, Naples, Italy.|Institute for Diagnosis and Care ''Hermitage Capodimonte,'', Naples, Italy.
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Tedeschi
mesh_terms: D065087:Acetylcholine Release Inhibitors / Q000009:adverse effects*; D019274:Botulinum Toxins, Type A / Q000009:adverse effects*; D002908:Chronic Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000188:drug therapy*; D012871:Skin Diseases / Q000139:chemically induced*
chemical_list: D065087:Acetylcholine Release Inhibitors; D019274:Botulinum Toxins, Type A
keywords: BoNT-A; OnabotulinumtoxinA; chronic migraine; migraine; side effects