Purpose: The purpose of this study was to report our clinical experience in treating patients with Raynaud's phenomenon and chronic digital ulcerations with botulinum toxin-A (Botox®). We also report the results of tissue bath experiments performed to determine if Botox has a direct effect on vascular tone.

Methods: Five patients with painful, chronic ischemic ulcers secondary to advanced Raynaud's disease were treated with 50-100 units of Botox injectected around the neurovascular bundles in the palm. Improvement in peripheral blood flow was documented using laser Doppler imaging pre and post injection. In vitro tissue bath experiments were conducted in the laboratory to determine if Botox had a direct effect on vascular tone.

Results: All patients had dramatic improvement in pain symptoms, improvement of vascular mottling and significant healing of ulcerations. Laser Doppler analysis revealed up to 300% increase in perfusion in some digits. Our tissue bath studies failed to show a direct effect of Botox on vascular tone. The mechanisms behind the increased peripheral perfusion seen and relief of pain symptoms are unknown but may be related to effects of Botox on the autonomic system and the blockade of nociceptive neuropeptides.