Cognitive Performance After Facial Botulinum Toxin Treatment in a Cohort of Neurologic Patients: An Exploratory Study

To investigate higher cognitive functions after mimicry changes after facial botulinum toxin (BTX) injections, we tested verbal and nonverbal reasoning in patients with blepharospasm or hemifacial spasm before and after their long-term botulinum toxin treatment.

Explorative, nonrandomized, clinical trial.

Patients receiving ambulatory care and control participants from the general community.

Volunteer sample (N=84) of patients (n=21) with blepharospasm or hemifacial spasm who received facial BTX injections. Control participants included patients (n=30) with cervical dystonia who received cervical BTX injections and individuals without neurological disorders (n=33).

The 2 groups receiving injections were tested before and 3 weeks after their treatment. The group without neurological disorders received no injections.

Verbal and nonverbal reasoning scores.

The key unexpected finding was that patients who received facial BTX injections perform significantly worse in nonverbal reasoning tasks, when compared with those who did not receive injections (P=.022). There was no significant difference in the baseline reasoning scores and at follow-up for verbal reasoning between the 3 groups. There was no correlation between toxin dose and reasoning scores (verbal: P=.132; nonverbal: P=.294).

Because of potential confounders, the results do not yet allow any conclusion on causality. Further research is needed to confirm our findings.