Chronic eye movement induced pain and a possible role for its treatment with botulinum toxin

Oral non-steroidal anti-inflammatory agents (NSAIDs) did reduce the pain a little but only when taken in high doses (100 mg three times daily flurbiprofen). The pain relief seen in our patients may simply be the result of paralysing an inflamed muscle but there is growing evidence for a separate antinociceptive effect of botulinum toxin. 1 No direct peripheral cutaneous antinociceptive effect could be shown by Blersch et al 2 ; however inhibition of release of substance P has been demonstrated in vitro and it can be hypothesised that botulinum toxin treatment may reduce the local release of nociceptive neuropeptides from either cholinergic neurons or from C or A delta fibres in vivo. 3 The mechanisms by which botulinum toxin may relieve pain, including a possible analgesic effect of botulinum toxin metabolites, are reviewed by Guyer. 4 There is a growing literature on the use of botulinum for painful conditions, 5 particularly those in which muscle spasm plays a part.