Botulinum toxin effective, well-tolerated for periorbital pain after AACG attacks

Pain was reduced and quality of life enhanced in acute angle-closure glaucoma patients who received botulinum toxin injections in a small study.

Issue: September 10, 2011

Botulinum toxin type A injections might relieve periorbital pain for nearly 3 months after an attack in patients with acute angle-closure glaucoma, a study found.

The study, published in the Journal of Glaucoma, reported decreased pain and a higher quality of life for acute angle-closure glaucoma (AACG) patients in Taiwan who were injected with Botox (botulinum toxin type A, Allergan).

“In our experience, the intractable pain caused by AACG usually subsided by itself in 3 to 4 months. So, the purpose of injecting [botulinum toxin type A] is to relieve acute periorbital pain and to improve quality of life of the patients after an AACG attack. Hence, longer-lasting treatment may not be necessary,” Da-Wen Lu, MD, PhD, co-author of the study, said.

An effective treatment has not yet been developed to control periorbital pain following an AACG attack. Oral pain relievers have proven insufficient to address pain issues associated with AACG, the study authors noted.

Dr. Lu and colleagues said that their study was the first to assess the effects of botulinum toxin type A injection on periorbital pain after AACG.

“Based on our experience using [botulinum toxin type A] to treat migraine, we thought that patients who suffered from intractable periorbital pain despite resolving their AACG might benefit from the application of [botulinum toxin type A],” he said.

However, in the study, patients were excluded if they had a history of migraine or periorbital pain prior to AACG.

The prospective, randomized, interventional study examined 10 patients who received botulinum toxin injections and nine control patients who received a placebo injection. All 19 patients were assessed at days 1, 2 and 7 and at approximately 2 weeks, 1 month, 2 months and 3 months.

In the treatment group, the mean length of the AACG attack preceding treatment was 18.4 hours. Patients were assessed using a visual analogue scale and a quality-of-life questionnaire. The questionnaire consisted of one health descriptive system and one visual analogue rating scale. The questionnaire focused on evaluating mobility, self-care, performance of everyday activities, pain and anxiety, according to Dr. Lu.

“We thought that patients who suffered from periorbital pain after an AACG attack may be bothered not only by pain or visual field defects, but also insomnia and a poor quality of life,” Dr. Lu said. “There are many other scales for correlation between glaucoma and quality of life, but we considered that these patients may be more likely affected by their periorbital neuralgia rather than glaucoma.”

A secondary outcome to the study was the incidence and nature of adverse effects. Fourteen adverse events, none of which were considered severe, were reported by eight patients. Of the 19 patients included in the study, 21% developed local tenderness, 10.5% experienced subcutaneous hemorrhage and 10.5% had conjunctivitis.

Ptosis and an asymmetric appearance of the eyes are other possible complications, but Dr. Lu said that these issues could either resolve on their own or be corrected with additional botulinum toxin injections.

According to the questionnaire, efficacy of the injections began at day 2, persisted until day 60 and declined by day 90. The index score improved slightly in the placebo group, but the study authors said that this could be from patients’ use of oral painkillers.

The mean change in visual analogue scale was significant at day 2, peaked on days 14 and 30 and decreased gradually between day 60 and day 90.

Periorbital pain during and after AACG remains mostly unexplained, but the study authors said it could be a type of neuropathic pain that occurs after trauma, surgery or inflammation.

“We suspected that periorbital pain caused by an AACG attack may be associated with the release of substance P, calcitonin gene-related peptides and neurokinin-A, which later on induce neurogenic inflammation. This mechanism may be quite similar as the trigeminovascular theory for trigeminal neuralgia,” Dr. Lu said. – by Michelle Pagnani

Reference:

Chien KH, Lu DW, Chen YH, et al. Relief of periorbital pain after acute angle closure glaucoma attack by botulinum toxin type A. J Glaucoma. 2010;19(8):546-550.

Da-Wen Lu, MD, PhD, can be reached at the Department of Ophthalmology, Tri-Service General Hospital, No. 325, Section 2, Cheng-Gong Road, Neihu 114, Taipei, Taiwan; email: ludawen@yahoo.com.

Disclosure: Dr. Lu has no relevant financial disclosures.