Low-Dose Oral Therapy of Pyridostigmine for the Treatment of Severe Side Effects from Botulinum Toxin Injection

Botulinum toxin is a potent neurotoxin that causes flaccid paralysis of muscles by blocking the release of acetylcholine at the neuromuscular junction, thus preventing muscle contraction. Injecting the toxin is a cosmetic procedure used to relax the underlying facial muscles which results in a smoothing effect on the overlying skin. The procedure is not uncommon and where available is used serially over time. The side effects of the injection typically are mild and well-tolerated. However, neck muscle injection patients may develop dysphagia, dysphonia, dystonia or even airway compromise. Treatment of these complications historically has been supportive until the effects of the injection subside. Another treatment option reported is the use of pyridostigmine, a cholinesterase inhibitor. Pyridostigmine functions through a reversible inhibition of acetylcholinesterase (AChE) which prevents acetylcholine (Ach) degradation at the neuromuscular junction, promoting muscle contraction. This treatment has not been standardized but to this point cases have mostly described using 60 mg orally as a maintanence dose until the side effect resolves. A 37-year-old healthy female with no past medical history presented with a chief complaint of a 4-day history of difficulty swallowing. The patient was unable to swallow water since the onset of symptoms and had only worsened over time. Her only notable history was a series of botulinum toxin (Botox) injections received one week prior, a total of 300 units into her bilateral forehead, masseters and anterior neck per usual protocol. The patient was found to be protecting her airway and her physical exam was unremarkable. After labs, imaging and consultations were completed the patient was diagnosed with a muscular paralysis side effect of Botox injections and started on oral pyridostigmine at 30 mg three times daily starting dose which was used until symptoms cleared. She continued the 30 mg. The patient had improved significantly following treatment with pyridostigmine at her 1-month follow-up visit. Rare sequelae of Botox injections can be life-threatening without treatment. Reversing the method of nerve conduction toxicity using a reversible acetylcholinesterase inhibitor can improve Botox’s side effects. The oral maintenance dose, however, is not standardized. This case supports the use of a much lower dose in an average-sized adult.