Context: Outpatient Spinal Cord Injury follow-up practice Findings: We present two cases of individuals with tetraplegia who experienced proximal arm weakness temporally related to the administration of intradetrusor onabotulinumtoxinA without other systemic effects. This arm weakness lasted approximately three months in both cases, whereas the effect of the toxin on the bladder lasted for over six months. In one of the cases, the pattern of proximal arm weakness after intravesicular botulinum toxin injection recurred after repeat injection. Conclusion: These cases represent a previously unreported phenomenon of proximal focal weakness associated with the use of intradetrusor chemodenervation. Possible mechanisms for these cases are discussed.