Hemi-laryngopharyngeal spasm (HeLPS) is a rare condition characterized by episodic laryngeal and/or pharyngeal spasm and cough. ^{Reference Hu, Morrison and Honey1} The spasms can be severe enough to prompt intubation and, when not recognized, may lead to tracheostomy. The cough can be severe enough to cause syncope. The underlying etiology is typically a unilateral vascular compression of the intracranial portion of the vagus nerve. We present two cases of intermittent laryngospasm and cough who had tracheostomy before they were diagnosed with HeLPS and surgically cured. The first case is also the first report of this condition due to compression of the vagus nerve by a pulsatile mass – a choroid plexus cyst. A diagnostic protocol is presented to help avoid unnecessary tracheotomy.

The first case was a 55-year-old right-handed woman who presented with a 10-year history of nonproductive cough and episodic laryngospasm. She had a history of asthma, and the symptoms started after a pneumonia that required intubation. She was experiencing 0–10 episodes/day of muscular contractions in her throat described as a circumferential squeeze, accompanied by severe coughing. Episodes could awaken her from sleep. Triggers included worsening asthma, prolonged vocalization, high humidity and strong odors. She could no longer work. Investigations ruled out: postnasal drip; gastroesophageal reflux; aspiration; lung pathology; cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS); and exposure to angiotensin-converting enzyme inhibitors (ACE) medications. Trials of carbamazepine and pregabalin improved her cough, but the spasms persisted, and a tracheostomy was placed for airway security.

An MRI demonstrated a cystic lesion distorting the right vagus nerve at the brainstem (Figure 1A). The patient underwent neurosurgical resection of the cyst without complication. The pathology was an extra-ventricular choroid plexus cyst. Postoperatively, her episodes of laryngospasm and coughing resolved, and her tracheostomy was removed after three months. She remains asymptomatic at 12 months.

Figure 1. (A) Brainstem MRI (CISS sequence) of case 1 demonstrating the right vagus nerve (arrow heads) distorted by a choroid plexus cyst (arrow) and (B) brainstem MRI of case 2 demonstrating a loop of the posterior inferior cerebellar artery (arrows) abutting the root entry zone of the left vagus nerve (arrow heads).

The second case was a 66-year-old right-handed male who presented with a five-year history of episodic, progressively severe pharyngeal and laryngeal spasms and cough. ^{Reference Honey, Morrison, Heran and Dhaliwal2} He had a history of asthma, chronic obstructive pulmonary disease (COPD) and gastroesophageal reflux. Treatment with proton pump inhibitors resolved the reflux, but the spasms continued, occasionally awakening him from sleep. He (and his wife) could feel the left side of his throat contract during the spasms. Investigations by respirology, gastroenterology, otolaryngology and psychiatry were negative. He was intubated on several occasions and eventually had a tracheostomy placed for airway protection. The spasms were reduced after botulinum toxin injection (6U) into the left vocal fold.

An MRI demonstrated a large looping vessel (posterior inferior cerebellar artery) at the root entry zone of the left vagus nerve (Figure 1B). Neurosurgical decompression of the left vagus nerve resolved his spasms and cough. Postoperatively, he experienced temporary dysphagia (two months) and hoarseness (two weeks). His tracheostomy was removed at one month, and laryngoscopy at six months showed normal vocal fold motion. He remains asymptomatic after eight years.

All previously reported cases have been due to a vascular compression of the intracranial portion of the vagus nerve at the brainstem. ^{Reference Hu, Morrison and Honey1,Reference Honey, Morrison, Heran and Dhaliwal2,Reference Katayama, Noro and Asayama3,Reference Honey, Krüger, Rheaume, Avecillas-Chasin, Morrison and Honey4} The first case of this paper is the first report of this syndrome occurring due to a mass compressing the vagus nerve. We postulate that the pulsatile motion of the choroid plexus cyst may have a similar pathological effect on the vagus nerve as a pulsatile vessel. The resultant effect on the motor portion of the vagus nerve – spasms of the laryngeal and/or pharyngeal innervated muscles – is similar to the much more common hemifacial spasm that is caused by a vascular compression of the intracranial portion of the facial nerve. The resultant effect on the sensory portion of the vagus nerve – intermittent tickling sensation in the larynx triggering an irresistible cough – is similar to the much more common trigeminal neuralgia that can also be caused by a vascular compression of the trigeminal nerve.

The symptoms of HeLPS can be severe enough to cause distressing dyspnea from the spasms and syncope from the cough. Patients presenting in extremis may be intubated, and repeated visits to the emergency department may lead to a tracheostomy. The diagnosis of HeLPS is therefore essential to prevent unnecessary tracheostomy.

Patients with chronic, episodic laryngeal and/or pharyngeal spasm and cough, who fail standard medical management, should be investigated for HeLPS. A diagnostic protocol for those patients who have lateralized findings is presented in Figure 2A. Lateralized findings include the ability to feel the contractions on one side (pharyngeal muscle involvement), laryngoscopic evidence of a pathognomonic vocal-induced unilateral vocal fold twitch ^{Reference Hu, Morrison and Honey1} or MRI evidence of an intracranial mass distorting one of the vagus nerves.

Figure 2. (A) Diagnostic protocol for hemi-laryngopharyngeal spasm (HeLPS) in patients with lateralized findings (spasms lateralized, vocal-induced unilateral vocal fold twitch, mass distorting a vagus nerve) and (B) diagnostic protocol for hemi-laryngopharyngeal spasm in patients without lateralized findings.

A diagnostic protocol for those patients who cannot lateralize their symptoms (the sensation is a circumferential squeeze due to laryngeal muscle involvement) is presented in Figure 2B. This is a more difficult protocol because asymptomatic vascular contact with the vagus nerve is common ^{Reference Avecillas-Chasin, Kozoriz, Shewchuk, Heran and Honey5} and determining the affected side is paramount. An MRI (CISS or FIESTA sequences) will document compression of the vagus nerve or not. If there is no compression, then HeLPS can be ruled out. If there is compression, it must be proven to be symptomatic. Botulinum toxin A (2–4 U) injected into the laryngeal muscles (thyroarytenoid) ipsilateral to the vagus nerve compression should dramatically reduce (>50%) the spasms (not the cough) for the duration of the toxin. Once the effects have worn off and the symptoms have returned, Botox injection into the contralateral laryngeal muscles should not be effective. This confirms a unilateral vagus nerve pathophysiology and, if it is ipsilateral to the MRI documented vascular compression of the nerve, warrants a neurosurgical consultation. The unilateral effect helps rule out bilateral conditions such as paradoxical vocal fold dysfunction, adductor respiratory dystonia, muscle tension dysphonia or irritable larynx syndrome. We do not yet have any neurophysiological tests to lateralize vagus nerve sensory/motor function.

We present a diagnostic protocol to avoid unnecessary tracheostomy. The risks of surgery for a potential cure (dysphagia and dysphonia and the general risks of microvascular decompression (MVD)) must be balanced against the risks of medical management with repeated unilateral botulinum toxin injections for the spasms (temporary dysphonia and dysphagia, cyclical effectiveness) and anti-neuralgia medications for the cough (sedation, rash, depression).