Botox use may be tied to less photophobia, dry eye in migraineurs

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - Injections with botulinum toxin A (BoNT-A) appear to be associated with improved symptoms of migraine pain, dry eye and photophobia in chronic migraineurs, new research suggests.

"We found that botulinum toxin A decreased migraine pain and improved symptoms of dryness and photophobia," said Dr. Anat Galor of Bascom Palmer Eye Institute of the University of Miami, Florida.

"Dry eye, photophobia, and migraine share neural pathways that include the trigeminal cervical complex, the posterior thalamus and higher cortical centers. The improvement in these symptoms with botulinum toxin A may be due to shared neural mechanisms," Dr. Galor told Reuters Health in a phone interview.

Dr. Galor and her colleagues conducted a cross-sectional retrospective study in 117 adults (mean age, 47) who were treated with BoNT-A for chronic migraine over a three-month period at one Veterans Administration medical center. The findings were published online October 27 in Ophthalmology.

The average total number of BoNT-A treatments was 10.2, which they had received over three years. The mean time since the last injection was 64.2 days, and the mean total units injected at that time was 114.4.

The researchers reviewed the records and, in phone interviews with 91 patients, asked them to rate their photophobia severity during and between migraine episodes on a scale from 0 (no photophobia) to 10 (worst photophobia they could imagine).

All patients reported photophobia during migraine, with a mean severity of 8.59, and roughly half of them also reported inter-ictal photophobia, with a mean severity of 5.48.

When the researchers asked patients to recall symptoms before and since starting BoNT-A, 72 rated their pretreatment photophobia score as severe (7 or higher) and 36 rated their pretreatment dryness score as severe.

On paired t-test analysis, migraine pain, photophobia and dry eye symptoms all significantly improved after BoNT-A (P

Overall, 66 patients reported improvement in photophobia and 24 reported improvement in dry eye.

On univariable logistic regression, older patients were more likely to report improved photophobia with BoNT-A.

The authors acknowledge that the study is limited by recall bias, the unique patient population, varied injection protocols and reliance on chart review for medication and comorbidity information. And without a control group, they can't be sure that these findings don't represent a regression to the mean.

They also cautioned that the findings may not generalize to people without chronic migraine.

The authors would like to see a randomized placebo-controlled trial of BoNT-A to treat photophobia and recalcitrant dry eye in patients with or without chronic migraine.

In emails to Reuters Health, several experts not involved in the study also called for further related research.

"Dry-eye symptoms are very common and especially in chronic migraine and chronic photophobia are often associated with chronic migraine. The cornea is supplied by the first division of the trigeminal nerve that feeds right into the trigeminal cervical complex, where dural afferents affected in migraine also coalesce. So (the findings make) anatomic sense." said Dr. Kathleen B. Digre, a neuro-ophthalmologist at the University of Utah in Salt Lake City.

"Clearly more study is needed to understand the relationship between dry eyes, dry eye symptoms, photophobia and migraine," she noted.

Dr. Joanne F. Shen of Mayo Clinic in Phoenix, Arizona, said, "This study is important to lay the groundwork to support a future randomized placebo-controlled trial to investigate the use of BoNT-A in the treatment of photophobia and recalcitrant dry-eye symptoms in patients with and without chronic migraine."

"Based on the findings of this study, I would recommend no change in patient care except to query patients with migraine and photophobia about their dry-eye symptoms," Dr. Shen, an ophthalmologist, advised.

According to Dr. Vivian P. Shibayama of UCLA Health in Los Angeles, "This study is both interesting and promising. We see many patients with neuropathic ocular pain – dry-eye symptoms without clinical signs - which is very difficult to control and which has limited current treatment options. This intervention may greatly improve the quality of life for a subset of patients who have found no relief with current treatments."

Dr. Saba Al-Hashimi, also of UCLA Health, said, "The theory behind this effect is promising given the shared pathway of pain receptors." But he added, "Without the results of a randomized control trial, clinicians should be cautious about the results of this report."

SOURCE: https://bit.ly/2jpSH82

Ophthalmol 2017.