This study is a double blind, randomized, placebo controlled trial to explore the effect of early treatment with Onabotulinumtoxin A in patients with acute complete motor spinal cord injury (SCI) on the development of neurogenic detrusor overactivity (NDO). A total of 20 patients will be randomized to intra-detrusor injection of 300 U Onabotulinumtoxin A in 30 ml NaCl 0.9 % or placebo with 30 ml NaCl 0.9 %. Bladder biopsies will be obtained in the same procedure. The treatment will be repeated after three months. All included patients will be evaluated with urodynamic examinations. Follow-up is 12 months after the first treatment. The primary endpoint of the study is development of NDO.

Inclusion Criteria:

• Patients with documented acute, motor complete C6 to Th11 spinal cord injury
• Patients can be included in the study less than four weeks after injury
• Male or female, aged 18 to 80 years old
• Patient weight > 40 kg
• Patient is able and willing to sign informed consent
• Patient is able to complete all study requirements

Exclusion Criteria:

• Neurogenic detrusor overactivity with contractions greater than 40 cm H2O at first visit
• History or evidence of previous urological abnormalities, disease or surgery, except bladder dysfunction after spinal cord injury
• History of haematuria or ongoing haematuria, if the hematuria is determined to be a pathologic condition or is uninvestigated
• Pregnancy or females of childbearing potential unwilling to use a reliable form of contraception
• Breastfeeding
• Known allergy to Onabotulinumtoxin A
• Grave psychiatric disorder
• Use of anti-platelet or anti-coagulant other than low molecular weight heparin (LMWH) or acetylsalicylic acid
• Haemophilia or other clotting disorders that cause bleeding diathesis
• Treatment with antimuscarinic medication within 3 months of randomization
• Treatment with botulinum toxin of any serotype within 3 months of randomization
• Patient has been immunized for any botulinum toxin serotype
• Patient has any medical condition that may put the patient at increased risk with exposure to botulinum toxin including diagnosed myasthenia gravis, Eaton-Lambert syndrome or amyotrophic lateral sclerosis
• Patient has any condition or situation, which, in the investigator's opinion, puts the patient at significant risk, could confound the study results, or may interfere significantly with the patient's participation in the study