Patients will be selected for cold intolerance after finger amputation or replantation. They will be given Botox or placebo dose as treatment and assessed over 3 months.

Aim 1: To assess the efficacy of botulinum toxin type A on treating cold intolerance secondary to digital amputations, revascularizations, or replantations

Primary null hypothesis: Randomized subjects who receive botulinum toxin type A injections for pain associated with cold intolerance will experience similar changes in pain as compared to patients randomized to receive saline injections (control)

• As measured by the Cold Insensitivity and Severity Score (CISS) at one week, four weeks, and twelve weeks

Aim 2: To assess the safety of botulinum toxin type A on treating cold intolerance secondary to digital amputations and replantations

Hypothesis: Injection of botulinum toxin for cold intolerance secondary to digital amputations and replantations is not associated with any adverse reactions

III. SUBJECT SELECTION All adult, English-speaking patients who present with cold intolerance secondary to digital amputation or replantation will be approached and asked to participate in the study.

Inclusion criteria Adults (≥18 years) diagnosed with cold intolerance secondary to digital amputations, revascularizations, or replantations and a CISS score of 30 or higher (the threshold for pathological cold intolerance)11 Ability to give informed consent

Exclusion criteria Adults ≥ 75 years old Inability or unwillingness to participate in CISS or DASH survey Major medical comorbidity expected to worsen in the next 6 months Comorbid chronic pain condition Severe and untreated mental health conditions or active substance dependence Pregnant or breastfeeding Known hypersensitivity to botulinum toxin Patients with a compromised respiratory function Pre-existing neuromuscular disorders Receiving therapy with aminoglycosides, anticholinergic agents, and muscle relaxants Infection in the proposed injection site

All patients who satisfy the inclusion/exclusion criteria will be eligible for enrollment. Vulnerable populations will be excluded from this study.

IV. SUBJECT ENROLLMENT A total of twenty-eight patients will be enrolled.

Inclusion Criteria:

• Adults (≥18 years) diagnosed with cold intolerance secondary to digital amputations, revascularizations, or replantations and a CISS score of 30 or higher (the threshold for pathological cold intolerance)11 Ability to give informed consent

Exclusion Criteria:

• Adults ≥ 75 years old Inability or unwillingness to participate in CISS or DASH survey Major medical comorbidity expected to worsen in the next 6 months Comorbid chronic pain condition Severe and untreated mental health conditions or active substance dependence Pregnant or breastfeeding Known hypersensitivity to botulinum toxin Patients with a compromised respiratory function Pre-existing neuromuscular disorders Receiving therapy with aminoglycosides, anticholinergic agents, and muscle relaxants Infection in the proposed injection site