What is the definition of spastic laryngitis?

Spasmodic dysphonia. You may be speaking about "spasmodic dysphonia" which is a disease of the communication between the brain and the nerves to the voicebox. This disorder is best diagnosed by a physician but you can find samples of how those with it sound online, i'm sure. Either way, any one with 'spastic laryngitis' sounds like they need an expert in voice.
Not a medical term. "spastic laryngitis" is not a medical term. Most likely you are referring to spasmodic dysphonia. This is a voice disorder characterized by spasm of the voice box muscles. It results in a choppy, broken sounding voice. It can be treated with voice therapy and/or botulinum toxin (botox). This disorder is best treated by an ENT with experience in this disorder. Best wishes.