Contralateral weakness following botulinum toxin for poststroke spasticity.

INTRODUCTION: We describe 2 patients who received botulinum toxin A (BoNT) for poststroke spasticity and developed contralateral limb weakness. METHODS: Both patients received high doses of BoNT with large dilution volumes and injection in the proximal upper extremity muscles, and developed weakness of the contralateral upper limb. These patients then underwent electrodiagnostic testing of the affected limb. RESULTS: Repetitive nerve stimulation of the axillary and spinal accessory nerves revealed decrements of 23% and 16%, respectively. EMG revealed abnormal spontaneous activity and small polyphasic motor unit potentials with reduced recruitment. These findings indicated blockade of the neuromuscular junction. Both patients improved. CONCLUSIONS: Isolated weakness of the contralateral limb after BoNT injection for poststroke spasticity suggests diffusion of toxin through tissue planes from proximal upper extremity muscles, across the midline, to contralateral muscles. High doses of botulinum toxin, high dilution volumes, and injection of proximal upper extremity muscles appear to be risk factors for this adverse effect.

Laryngeal Electromyographic Findings in a Cohort of Recalcitrant Chronic Neurogenic Cough Patients.

OBJECTIVES: To evaluate the laryngeal electromyography findings of bilateral thyroarytenoid muscles in 10 patients with chronic, intractable coughing. METHODS: This is a retrospective cohort case series. Clinical records were reviewed for demographic information, symptoms, and findings on bilateral laryngeal EMG for 10 patients referred for chronic coughing. RESULTS: All thyroarytenoid muscles tested demonstrated electromyographic evidence of neuropathy, with signs of denervation and reinnervation. There was reduced recruitment in all 20 thyroarytenoid muscles studied. In addition, polyphasic motor units were seen in all thyroarytenoid muscles, with increased amplitude in 18 of 20 thyroarytenoid muscles and increased duration in 17 of 20 thyroarytenoid muscles. Additionally, there was electromyographic evidence of synkinesis in 19 of 20 thyroarytenoid muscles studied, a sign of aberrant reinnervation. CONCLUSION: Patients with intractable coughing, despite numerous modalities of treatment, potentially have bilateral neuropathy of the recurrent laryngeal nerves suggesting the potential peripheral as well as central neuropathic changes as the etiology.