Medicine:Hemi-laryngopharyngeal spasm

Hemi-laryngopharyngeal spasm
Specialty	Neurology

Hemi-laryngopharyngeal spasm or HeLPS is a neurological condition with symptoms of episodic severe coughing and choking due to a unilateral compression of the vagus nerve. It is one of the neurovascular compression syndromes.

Compression of the trigeminal nerve can cause trigeminal neuralgia, compression of the facial nerve can cause hemifacial spasm, and compression of the glossopharyngeal nerve can cause glossopharyngeal neuralgia. Compression of the vagus nerve can cause hemi-laryngopharyngeal spasm.

Signs and Symptoms

Patients with HeLPS describe a recognizable pattern of symptoms that include episodic choking and coughing. The choking is due to a unilateral contraction of the throat. If the contraction is in the pharynx, the patient will typically be able to detect which side of the throat is affected. Even a bystander may be able to feel that the muscles on one side of the throat are in spasm. If the larynx is affected, however, the patient may not be able to feel which side is affected but will report a circumferential choking. These choking episodes tend to worsen over the years in intensity, frequency and duration. Initially, episodes last for a few seconds but can eventually progress to several minutes. The throat contraction can make breathing difficult causing stridor (not wheezing) and the patient have reported losing consciousness. Like hemifacial spasm, HeLPS is one of the very few movement disorders that can occur while sleeping. The unpredictable but inevitable choking episodes typically cause significant anxiety for the patient and may lead to a psychiatric misdiagnosis. The choking episodes can lead to intubation in the emergency room and rarely to elective tracheostomy. In between episodes, patients are normal. Repeated episodes of spontaneous severe choking followed shortly afterwards by a completely normal examination may also increase the likelihood of a psychiatric misdiagnosis. Patients have described different triggers for these choking episodes including loud or prolonged talking, and exercise but they can also occur spontaneously.

The coughing episodes are also episodic, progressively severe and eventually nocturnal. They are initiated by a “ticking sensation” deep in the throat or more typically behind the suprasternal notch. This sensation then causes the patient to cough. The cough is therefore a ‘normal’ response to this ticking sensation rather than an uncontrolled muscular contraction of the diaphragm or intercostal muscles. The coughing episodes can be severe with incontinence, vomiting, visual phosphenes (“seeing stars”), and post-tussive headache. These episodes typically progress from mild to severe over the years and eventually will awaken the patient from sleep. In between episodes, the patient is normal and respiratory examination does not reveal reactive airways disease (asthma) or allergies. The coughing episodes can be triggered by loud or prolonged talking, exercise or the choking episodes described above.

Some, but not all, patients also describe episodic changes in their voice. This may be due to unilateral contractions in the muscles controlling the vocal cords. One patient reported that this could be triggered by loud or prolonged talking and would typically last a few minutes. If the episode was mild, their voice would return to normal within a few minutes. If the episode was severe, it would progress into severe choking. Two patients also reported a sensation that their tongue was “fat” during the choking episodes. This may be due to contraction of the palatoglossus muscle. The combination of choking and a sensation of a “fat” tongue may lead to a misdiagnosis of an allergic reaction.

Patients do not report pain during an episode. This is not glossopharyngeal neuralgia although the condition can co-exist with HeLPS (see below). None of the patients have reported sudden loss of consciousness or cardiac arrythmias as is rarely seen in some cases of glossopharyngeal neuralgia (so called vago-glossopharyngeal neuralgia). None of the patients have reported gastrointestinal parasympathetic symptomatology such as abdominal pain or diarrhea. There is one case report in the literature with a patient reporting episodic diarrhea and abdominal pain that was cured following microvascular decompression of the vagus nerve.

Co-occurrence of HeLPS and Glossopharyngeal Neuralgia

The occasional co-occurrence of HeLPS and glossopharyngeal neuralgia has been recently recognized. This paper described a patient with BOTH glossopharyngeal neuralgia and hemi-laryngopharyngeal spasm (HeLPS). The paper also found 27 patients that had been previously reported in the literature with glossopharyngeal neuralgia and additional symptoms compatible with (but not recognized as) HeLPS. One such patient from the Mayo Clinic series described "inspiratory stridor". One patient from the Stockholm series in August 1947, "developed attacks of severe cramps in the throat, a feeling of suffocation and dyspnea." These are not symptoms of glossopharyngeal neuralgia; they are symptoms of HeLPS.

Cause

Neurovascular compression syndromes are due to compression of a cranial nerve. Compression of the trigeminal neural can cause trigeminal neuralgia and microvascular decompression (MVD) of the nerve can cure that condition . Trigeminal neuralgia is far more common than HeLPS and its painful sensory symptoms are often well controlled with anti-epileptic medications. Compression of the facial nerve can cause hemifacial spasm and MVD of the nerve can cure that condition. In hemifacial spasm, the motor symptoms (episodic contractions of the facial muscles) typically do not respond to anti-epileptic medications but can be symptomatically controlled with Botox injections in the affected muscles. Compression of the glossopharyngeal nerve can cause glossopharyngeal neuralgia and MVD of the nerve can cure that condition. This is a rare condition and is very similar to trigeminal neuralgia except the pain is in the distribution of the glossopharyngeal nerve. Hemi-laryngopharyngeal spasm is due to unilateral compression of the vagus nerve and can be cured with MVD of the nerve. Every reported case of HeLPS has been due to compression of the vagus nerve by a loop of the posterior inferior cerebellar artery (PICA). The compression can occur at the root entry zone of the nerve or in its cisternal portion. No nerve biopsies have been performed to investigate the pathology at the compression site but it is assumed to be similar to compressions previously reported of the trigeminal and facial nerves.

Diagnosis

The diagnosis of hemi-laryngopharyngeal spasm, like any medical condition, can be made by history, physical examination and special tests. The history of symptoms will be reported by the patient and should match the descriptions provided above. A few unique features of this condition are the eventual presence of symptoms while sleeping and (for those with pharyngeal involvement) an obviously unilateral presentation. Physical examination will be normal in between episodes. Examination during an episode is difficult because the patients are in extremis. A number of special tests have been investigated.

Magnetic resonance imaging (MRI) of the brainstem where the vagus nerve exits and crosses the cisternal space to the jugular foramen can be visualized using special sequences such as FIESTA and CISS. Similar to the other neurovascular compression syndromes, standard MRI sequences (e.g. T1- and T2-weighted) do not have the resolution require to see neurovascular compression. In a study to estimate the incidence of a vessel contacting the vagus nerve ], 50% of the normal population was found to have a vessel touching or distorting the vagus nerve. This suggests that MRI has too low a specificity to be used for the definitive diagnosis of HELPS. Instead, a ‘positive’ MRI is necessary but not sufficient for the diagnosis of HELPS. Patients without a vessel compressing their vagus nerve should prompt investigation for an alternative cause of their symptoms (see Differential Diagnosis).

Video laryngoscopy usually shows no abnormality in between episodes. Two patients, however, had a unique abnormality of their vocal cords with a unilateral twitch-like contraction following vocalization. This unilateral movement has not been previously described and may be a rare but pathognomonic phenonium. Video laryngoscopy has not been reported during a choking episode, but it may be very difficult because patients are in extremis.

Laryngeal electromyography (EMG) has not been conducted in a patient with HeLPS. It is expected the findings would be normal in between episodes and very difficult to perform during a severe bout of choking and coughing.

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.

Diagnostic Protocol

Patients with symptoms compatible with HeLPS have either obvious unilateral throat contractions when the pharynx is involved or non-lateralized throat contractions when the larynx is involved. Those with clinically obvious lateralized contractions can be managed with ipsilateral Botox injection in the affected muscles. An MRI should be ordered to confirm the presence of a vessel juxtaposed to the ipsilateral vagus nerve. Patients with clinically non-lateralized contractions should have Botox injected on one side of the throat and then, when the effect has worn off, Botox should be injected on the opposite side. A unilateral benefit should prompt an MRI to look for a vessel juxtaposed to the vagus nerve on the side that Botox was effective.

Differential Diagnosis

Coughing and choking are common symptoms. They can be caused by many conditions including irritants in the air, reactive airway disease, acid reflux, and psychological conditions. The resultant medical conditions have many different names including vocal cord dysfunction, paroxysmal vocal fold motion, irritable larynx. Patients are often treated by laryngologists. Treatments can include avoidance of irritants, proton pump inhibitors, speech therapy and psychological therapy. Patients with similar symptoms may have been described before in the surgical literature.

Treatment

Medical

The choking episodes can be eased with Botox injections in the appropriate muscles. The sensory symptoms may respond to anti-epileptic medications. Confirmation of the diagnosis may ease the associated psychological stress commonly found in patients with HeLPS.

Surgical

Like other neurovascular compression syndromes, HeLPS can be ameliorated or cured with decompression of the affected nerve. The surgery to accomplish this is called microvascular decompression (MVD) of the vagus nerve.

Epidemiology

The prevalence and incidence of HeLPS is unknown. It may be similar to glossopharyngeal neuralgia at approximately 1 per 1,000,000 per year.

History

The first patient with HELPS was reported in 2017. That single case report focused on the similarity of the motor symptoms between hemifacial spasm and hemi-laryngopharyngeal spasm. Both conditions have unilateral involuntary motor contractions that are episodic, progressive, can occur while sleeping, can be ameliorated with Botox, and cured by MVD. The patient also had episodic coughing which was not described in detail because it was not realized to be a fundamental part of the syndrome until more patients were studied. The original microscope images and video of the case were lost when the Pentero microscope was upgraded before the data was transferred. Ms. Vicky Earle provided profession illustrations of the anatomy for the publication.

The name of this condition was originally going to be called episodic hemi-laryngopharyngeal spasm. This was adjusted to hemi episodic laryngopharyngeal spasm to provide the more memorable acronym HELPS. There was some resultant confusion was to what ‘hemi episodic’ meant. The similar condition of hemifacial spasm is also episodic but does not use the adjective ‘episodic’. The name was therefore altered slightly to just hemi-laryngopharyngeal spasm omitting the word ‘episodic’. The acronym was then also adjusted to HeLPS with the ‘He’ referring to ‘hemi’.

The first case series was reported in 2018. With the addition of several patients, the core symptoms became clearer. All patients had severe, episodic choking and coughing. Some patients also had episodic vocal changes presumably due to contraction of the laryngeal musculature. Some patients had sensations of a ‘fat’ tongue (e.g. patient 1) presumably on the basis of contraction of the palatoglossus muscle. Some patients could feel what side of their throat was contracting (presumably due to pharyngeal muscle contractions) and some patients could not lateralize the circumferential choking (presumably due to laryngeal muscle contraction).

The etiology of unconsciousness in some patients was raised in an editorial that was published with the case series. The universal association of unconsciousness with severe coughing and the time course of unconsciousness – a slow fading out rather than a sudden loss - suggests that the etiology of unconsciousness may be ‘cough syncope’ not cardiac arrythmia or hypoxia.