The injection of onabotulinumtoxinA toward the sphenopalatine ganglion in patients with trigeminal neuralgia may not reduce the number of attacks, according to results from a pilot study published in Headache.
The study included 9 participants with refractory classical trigeminal neuralgia at St. Olav’s University Hospital in Trondheim, Norway, who were injected with 25 international units of onabotulinumtoxinA toward the sphenopalatine ganglion.
The primary efficacy outcome was the number of trigeminal neuralgia attacks at weeks 5 to 8 postinjection compared with baseline, and the primary outcome was adverse events. Response to treatment was defined as a ≥50% reduction in the median number of attacks per day between baseline and weeks 5 to 8. Additional efficacy outcomes included intensity of attacks, assessed with a 0 to 10 numeric rating scale (NRS), and functional level, evaluated with a 1 to 4 scale (1, best; 4, worst) at weeks 5 to 8 compared with baseline.
Six participants reported 13 adverse events, none of which were serious. These included pain or swelling, jaw problems, nasolabial fold asymmetry, diplopia, dry eye, dysphagia, and rash.
The median number of trigeminal neuralgia attacks was 5.5 at baseline (range, 1.0-51.5) and 5 at weeks 5 through 8 (range, 0-225.0; P =.401). Four patients were classified as treatment responders.
The median intensity of attacks was 6 at baseline (range, 3.0-8.5) and 3 at weeks 5 through 8 (range, 0-9.0; P =.024). The median functional level was 2 at baseline (range, 1.0-3.3) and 1 at month 2 (range, 1.0-4.0; P =.750). Median percentage of the day with concomitant persistent pain was 75% at baseline (minimum, 37.5%; maximum, 100%) and 18.75% at week 8 (minimum, 0%; maximum, 100%; P =.023).
“Further studies examining the role of the [sphenopalatine ganglion] as a therapeutic target for [trigeminal neuralgia] are necessary,” noted the study authors.
Crespi J, Bratbak D, Dodick DW, Matharu M, Jamtoy KA, Tronvik E. Pilot study of injection of onabotulinumtoxinA toward the sphenopalatine ganglion for the treatment of classical trigeminal neuralgia [published online July 25, 2019]. Headache. doi:10.1111/head.13608