MS-2293

A 28-year-old plumber comes to the emergency department complaining of jaw pain that has been present for 1 day. Upon further inquiry, the patient reveals that he had stepped on a rusty nail a few days ago. He received immunizations when he was 17 years old, but he cannot recall what they were for.

During the examination, the patient experiences sustained masseter spasms and is in significant discomfort.

The patient is suspected to have tetanus, and anti-toxin immunoglobulin is administered.

What is the likely cause of the patient’s presentation, resulting in impaired neurotransmitter release?