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Updated: Jun 22, 2026

Ultrasound-guided Botulinum Toxin-A Injections: A Method of Treating Sialorrhea
Published on: November 9, 2016
Botulinum toxin B increases mouth opening in patients with spastic trismus
U M Fietzek1, P Kossmehl, A Barthels
1Neurologisches Krankenhaus München, Center for Parkinson's disease and Movement Disorders, Parzivalplatz 4, D-80804 Munich, Germany.
Background:
Severe generalized spastic movement disorders of various aetiologies often involve the jaw muscles and lead to a spastic trismus with masseter muscle hypertonia. We report a placebo-controlled randomized study on patients with spastic trismus.
Methods:
Eleven patients with masseter hypertonia because of stroke, hypoxic encephalopathy or traumatic brain injury were allocated to either botulinum toxin serotype B (BoNT/B) injections into the masseter muscles or placebo treatment. The dental gap, the amount of saliva, salivation scales, and a clinical goal attainment were evaluated.
Results:
Three weeks after injection the BoNT/B group showed a significantly increased mouth opening compared with placebo treatment (P < 0.05). In addition to the muscle paralysing effect, a goal attainment scale demonstrated a clinical benefit for the BoNT/B group (P < 0.01).
Conclusions:
Botulinum toxin serotype B injections into the masseter muscles effectively reduce hypertonia and provide for better mouth opening, thereby contributing to a positive and desired clinical goal.
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