Painful Tonic Spasms with Multifocal Dystonia After Cardiac Arrest Showing Emigration-like Pattern Changes During Long-term Botulinum Toxin Type A Therapy A Case Report

Introduction. Secondary dystonia may result from various disorders, including cardiac arrest, and has been reported to be successfully treated with botulinum toxin type A (BoNT-A) injections. However, the long-term clinical course following repeated BoNT-A therapy remains largely undocumented, particularly with respect to pattern changes in dystonic contractions in non-cervical forms of dystonia. Case Presentation. A woman in her 40s developed multifocal dystonia after cardiac arrest caused by thyroid storm. She exhibited involuntary movements in her left arm and both legs. Paroxysmal painful muscle spasms occurred in the left arm more than one hundred times daily, each lasting less than one minute and accompanied by excruciating pain. Brain MRI revealed bilateral low-intensity signals in the basal ganglia consistent with hypoxic encephalopathy. She was diagnosed with painful tonic spasms (PTS) overlapping with multifocal dystonia. Oral pharmacological therapies, including tiapride, clonazepam, and levodopa, were insufficiently effective. BoNT-A injections reduced spasm frequency but provided limited pain relief. Over sixteen BoNT-A injection sessions spanning eight years, both painful and painless dystonic muscle contractions demonstrated dynamic redistribution, and the severity of involuntary movements and pain burden gradually improved. Conclusion. To our knowledge, this is the first report of PTS overlapping with multifocal dystonia following cardiac arrest. We observed an emigration-like redistribution of dystonic muscle contractions during long-term BoNT-A therapy. While pattern changes after BoNT-A injections are well documented in cervical dystonia, such changes have rarely been described in multifocal dystonia. In this case, dystonic activity shifted away from BoNT-A–injected sites to adjacent and distant muscle groups.