Editor-in-Chief: Kenneth D. Candido, MD
Recently, the use of botulinum toxin type A (BoNT-A) has been reported to help with neuropathic pain reduction in numerous conditions, including painful chronic scar formation. The mechanism by which BoNT-A inhibits pain is unclear, but it appears to involve a reduction of peripheral pain sensitization, which indirectly reduces central pain sensitization. Two patients who underwent surgery for brain tumor resection developed chronic painful neuropathic postcraniotomy scars. Their scar pain was not relieved with oral pain medications or trigger point injections with steroids but was helped significantly with BoNT-A injections. In the first patient, over the past 8 years, we have gradually increased her scar BoNT-A dose to 150 units diluted 2:1 with normal saline (NS) and injected the dose at 20 sites around her scar. She now reports her scar pain is 80%-90% resolved with the effect lasting 10 to 11 weeks. She denies side effects at this dose. In the second patient, over 9 years, we gradually increased the BoNT-A dose to 175 units diluted 2:1 with NS at 30 sites around her scar and in the left occipital area. She now notes her scar pain is 70%-75% improved from baseline with the effect lasting 8 to 10 weeks followed by a gradual reduction in benefit. She reports no side effects with this dose. The results of this 2-patient case study suggests BoNT-A (specifically onabotulinumtoxinA) may be helpful for patients with chronic postcraniotomy scar pain. Further studies on the dose, injection sites and timing follow-up injections are needed to determine treatment effectiveness for this patient population.
Key words: Scar pain, Botulinum toxin, chronic pain, subcutaneous, injections, post-craniotomy