the response to unilateral injection of botulinum toxin (botox) in the vocal fold has been suggested to be the definitive test of choice. botox has been used for the symptomatic treatment of hemifacial spasm because it reduces the facial contractions by weakening the affected muscles. in a similar fashion, botox in the affected muscles of the throat can reduce the severity of the choking episodes in helps. it does not have any effect on the coughing because the sensory symptoms continue. the beneficial effect typically lasts three months and needs to be repeated. botox injection in the contralateral side has no benefit (like hemifacial spasm). this unilateral beneficial effect of botox is unique to helps. patients with vocal fold dysfunction, paroxysmal vocal fold motion, or irritable larynx all obtain benefit from botox injections regardless of the side since they are symmetric conditions.