VANCOUVER syndrome
| VANCOUVER syndrome | |
|---|---|
| Classification and external resources | |
| Specialty | neurology |
| Patient UK | [1] |
VANCOUVER syndrome is a neurological condition with symptoms of episodic severe coughing due to a unilateral compression of the vagus nerve.[1] It is a newly described neurovascular compression syndrome.
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 (coughing and choking) if both the motor and sensory components of the nerve are affected. Compression of the vagus nerve can cause VANCOUVER syndrome (just coughing) if only the sensory component of the nerve is affected.
Signs and symptoms[edit]
Patients with VANCOUVER syndrome have a chronic neurogenic cough due to compression of their vagus nerve by a blood vessel near their brainstem. The acronym, VANCOUVER syndrome, comes from 'Vagus Associated Neurogenic Cough Occurring due to Unilateral Vascular Encroachment of its Root'. The vessel causing the vascular encroachment of the nerve is typically the posterior inferior cerebellar artery. The vagus nerve is formed from several (usually five or six) small rootlets which enter/leave the brainstem at the side of the medulla. The ‘root’ of the nerve is its most proximal portion where it enters the brainstem. The nerve is tethered at its root where it enters the brainstem and is therefore more susceptible to any compression in this area compared to its more distal course where the nerve is freer to move out of the way of any potential compression.
The compression of the vagus irritates the nerve and produces a “tickling” sensation felt by the patient deep in their throat or more typically behind their suprasternal notch. This intermittent tickling sensation causes the patient to cough. The vagus nerve does not transmit pain sensation from the trachea or lungs and thus VANCOUVER syndrome is not painful like trigeminal neuralgia or glossopharyngeal neuralgia.
Over the years, the cough slowly progresses in severity, frequency and duration. The cough can be severe enough to cause incontinence, visual phosphenes (seeing stars), post-tussive headaches, and coughing syncope (unconsciousness). Eventually, the cough can occur even while asleep. The coughing episodes can be triggered by loud or prolonged talking.
Patients typically do not complain of throat contractions (hemi-laryngopharyngeal spasm) or throat pain (glossopharyngeal neuralgia). If the vascular encroachment of the vagus nerve is severe enough, it can also trigger unilateral throat contractions – hemi-laryngopharyngeal spasm. If the vascular encroachment also impinges on the glossopharyngeal nerve, it will cause simultaneous glossopharyngeal neuralgia.
In between episodes of coughing, the patient is completely normal. This dramatic contrast between moments when the coughing is so severe it can cause unconsciousness and then a completely asymptomatic individual with a normal examination can lead to a psychiatric misdiagnosis.
Cause[edit]
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. The trigeminal neuralgia carries pain sensations from one side of the face and when it is irritated, the patient feels painful sensations on one side of their face.
VANCOUVER syndrome is similar to trigeminal neuralgia in that it is also caused by the compression of a nerve – only in this case, it is the vagus nerve. The vagus nerve carries a variety of sensations from the body to the brain including “tickling” sensations from the trachea, bronchi and lungs. When it is irritated, the patient feels this “tickling” sensation deep in their chest and it triggers an uncontrollable cough.
No vagus nerve has been biopsied to determine its pathology during VANCOUVER syndrome. Patients with trigeminal neuralgia have had their trigeminal nerve biopsied and this has shown demyelination of the nerve. This has led to the theory that compression of the nerve causes demyelination with ectopic generation and ephaptic transmission of impulses along the compressed nerve.[2]
Diagnosis[edit]
The diagnosis of VANCOUVER syndrome, 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. Essential they report a chronic, intermittent, dry cough that does not respond to the usual treatments for cough. Physical examination will be normal in between episodes. A number of special tests are being 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[3], 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 VANCOUVER syndrome. Instead, a ‘positive’ MRI is necessary but not sufficient for the diagnosis of VANCOUVER syndrome. Patients without a vessel compressing their vagus nerve should prompt investigation for an alternative cause of their symptoms (see Differential Diagnosis).
Video laryngoscopy would not be expected to show any abnormality in between episodes.
Laryngeal electromyography (EMG) has not been conducted in a patient with VANCOUVER syndrome. It is expected the findings would be normal in between episodes and be very difficult to perform during a severe bout of coughing.
Researchers are investigating if the definitive diagnostic test for VANCOUVER syndrome is a unilateral vagal nerve block. A unilateral vagal nerve block on the side of the nerve encroachment should block the “tickling” sensation and temporarily reduce the urge to cough (for the duration of the anesthetic block). A contralateral vagal nerve block should have no beneficial effect on coughing.
Diagnostic Protocol[edit]
Patients with VANCOUVER syndrome have a chronic dry cough that remains refractory to all the usual therapies for chronic cough. Anti-neuralgia medications such as amitriptyline, gabapentin and carbamazepine can be beneficial. This is similar to trigeminal neuralgia. Patients who cannot tolerate the side-effects of these medications (e.g. sedation) or only obtain a partial benefit should be investigated for VANCOUVER syndrome.
Inhaled lidocaine should block the cough for the duration of the anesthetic. This confirms that the patient’s cough is due to a sensory neuropathy of the vagus nerve. This phenomenon is similar to trigeminal neuralgia which can be temporarily blocked by a local anesthetic in the correct dermatome.
If the lidocaine test suppresses the cough, an MRI should be ordered to confirm the presence of a vessel encroaching the ipsilateral vagus nerve. Special MRI sequences (e.g. CISS or FIESTA) are needed to visualize the vascular compression.[2] If there is no vessel encroaching the vagus nerve, the diagnosis of VANCOUVER syndrome can be excluded. If there is a vessel encroaching the nerve, further tests are required to confirm the diagnosis.
A unilateral vagus nerve block should reduce the “tickling” sensation that triggers the cough and dramatically improve the cough for the duration of the anesthetic. Once the effect has completely worn off, the test can be repeated on the contralateral side. Simultaneous bilateral vagus nerve block is dangerous because the resultant bilateral vocal cord palsy can cause suffocation.
Cough reduction following a vagus nerve block ipsilateral but not contralateral to the vascular encroachment of the vagus nerve documented on the MRI is proposed as the definitive diagnostic test for VANCOUVER syndrome.[1]
Differential Diagnosis[edit]
Chronic cough can be caused by many conditions including irritants in the air, reactive airway disease, acid reflux, and psychological conditions.[4][5] Treatments can include avoidance of irritants, proton pump inhibitors, speech therapy and psychological therapy.[5]
Neurogenic cough is typically diagnosed when the common causes of cough have been excluded. It is defined as ‘a chronic cough (more than 8 weeks duration) in the absence of typical external stimuli to the cough mechanism, and thus is by definition a diagnosis of exclusion, possible only after the extensive investigations to eliminate the possibility of other causes.’[4] The American College of Chest Physicians (ACCP) recommends that these investigations include those for sinonasal disease, asthma, nonasthmatic eosinophilic bronchitis, and gastroesophageal reflux disease.[5]
Neurogenic cough has been reported to respond to gabapentin[6], amitriptyline[7], pregabalin[8], tramadol[9], and nonpharmacologic intervention, like speech therapy.[8] A subset of these patients may have VANCOUVER syndrome (Vagus Associated Neurogenic Cough due to Unilateral Vascular Encroachment of its Root) and, if refractory to medical treatment, could potentially benefit from microvascular decompression.
VANCOUVER syndrome requires confirmation by a larger case series.
Treatment[edit]
Medical[edit]
Neurogenic cough from any cause may respond to anti-neuralgia medications such as gabapentin[6], amitriptyline[7], pregabalin[8], as well as tramadol[9] and speech therapy[8]. The common side-effects of anti-neuralgia medications include sedation and cognitive blunting. Rare side effects include Stephens-Johnson syndrome, suicidal ideation, electrolyte abnormalities and liver enzyme induction.
Consideration for surgery should be reserved for patients either who do not respond sufficiently to medications or can not tolerate the associated side-effects of the medications required to control their cough.
Surgical[edit]
Like other neurovascular compression syndromes, VANCOUVER syndrome 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.
MVD is a common neurosurgical operation used for the treatment of trigeminal neuralgia[10], hemifacial spasm[11] and glossopharyngeal neuralgia[12]. These are neurovascular compression syndromes of the Vth, VIIth, and IXth cranial nerves respectively. It has recently been demonstrated that MVD can cure the two syndromes associated with compression of the Xth cranial nerve – hemi-laryngopharyngeal spasm[13] and VANCOUVER syndrome.[1]
MVD is performed under general anesthesia through a small incision behind the ear.
A small window of bone is removed, and the dura opened to expose the cerebellum.
Under the operating microscope, the lower cranial nerves can be seen once the cerebellum has fallen away from the skull (by gravity). The multiple small rootlets of the vagus nerve can be seen entering the brainstem. Typically, one or more of these roots are compressed by the posterior inferior cerebellar artery.
The vessel can be moved away from the vagus nerve and held in place with a small roll of Teflon felt. At the conclusion of the operation, the vagus nerve has been decompressed.
Epidemiology[edit]
The prevalence and incidence of VANCOUVER syndrome is unknown.
History[edit]
The first patient with VANCOUVER syndrome was reported in 2019.[1] That single case report focused on the similarity between trigeminal neuralgia and VANCOUVER syndrome. Both can be caused by compression of their respective cranial nerves, improved with anti-neuralgia medications, and cured by decompression of those nerves.
References[edit]
- ↑ 1.0 1.1 1.2 1.3 Honey, Christopher R.; Krüger, Marie T.; Morrison, Murray D.; Dhaliwal, Baljinder S.; Hu, Amanda (2019-12-01). "Vagus Associated Neurogenic Cough Occurring Due to Unilateral Vascular Encroachment of Its Root: A Case Report and Proof of Concept of VANCOUVER Syndrome". Annals of Otology, Rhinology & Laryngology: 000348941989228. doi:10.1177/0003489419892287. ISSN 0003-4894.
- ↑ 2.0 2.1 Nielsen, Viggo Kamp (1985). "Electrophysiology of the facial nerve in hemifacial spasm: Ectopic/ephaptic excitation". Muscle Nerve. 8 (7): 545–555. doi:10.1002/mus.880080702. ISSN 0148-639X.
- ↑ Avecillas-Chasin, J.; Kozoriz, M.G.; Shewchuk, J.R.; Heran, M.K.S.; Honey, C.R. (2018). "Imaging and Surgical Findings in Patients with Hemi-Laryngopharyngeal Spasm and the Potential Role of MRI in the Diagnostic Work-Up". American Journal of Neuroradiology. 39 (12): 2366–2370. doi:10.3174/ajnr.A5851. ISSN 0195-6108.
- ↑ 4.0 4.1 Altman, Kenneth W.; Noordzij, J. Pieter; Rosen, Clark A.; Cohen, Seth; Sulica, Lucian (2015). "Neurogenic cough: Neurogenic Cough". Laryngoscope. 125 (7): 1675–1681. doi:10.1002/lary.25186.
- ↑ 5.0 5.1 5.2 Gibson, Peter; Wang, Gang; McGarvey, Lorcan; Vertigan, Anne E.; Altman, Kenneth W.; Birring, Surinder S.; Adams, Todd M.; Altman, Kenneth W.; Barker, Alan F.; Birring, Surinder S.; Blackhall, Fiona (2016). "Treatment of Unexplained Chronic Cough". Chest. 149 (1): 27–44. doi:10.1378/chest.15-1496. PMID 26426314.
- ↑ 6.0 6.1 Ryan, Nicole M; Birring, Surinder S; Gibson, Peter G (2012). "Gabapentin for refractory chronic cough: a randomised, double-blind, placebo-controlled trial". Lancet. 380 (9853): 1583–1589. doi:10.1016/S0140-6736(12)60776-4.
- ↑ 7.0 7.1 Jeyakumar, Anita; Brickman, Todd M.; Haben, Michael (2006). "Effectiveness of Amitriptyline Versus Cough Suppressants in the Treatment of Chronic Cough Resulting From Postviral Vagal Neuropathy". Laryngoscope. 116 (12): 2108–2112. doi:10.1097/01.mlg.0000244377.60334.e3. ISSN 0023-852X.
- ↑ 8.0 8.1 8.2 8.3 Vertigan, Anne E.; Kapela, Sarah L.; Ryan, Nicole M.; Birring, Surinder S.; McElduff, Patrick; Gibson, Peter G. (2016). "Pregabalin and Speech Pathology Combination Therapy for Refractory Chronic Cough". Chest. 149 (3): 639–648. doi:10.1378/chest.15-1271.
- ↑ 9.0 9.1 Dion, Gregory R.; Teng, Stephanie E.; Achlatis, Efstratios; Fang, Yixin; Amin, Milan R. (2017). "Treatment of Neurogenic Cough with Tramadol: A Pilot Study". Otolaryngol. Head Neck Surg. 157 (1): 77–79. doi:10.1177/0194599817703949. ISSN 0194-5998.
- ↑ Jannetta, Peter J. (1967). "Arterial Compression of the Trigeminal Nerve at the Pons in Patients with Trigeminal Neuralgia". Journal of Neurosurgery. 26 (1part2): 159–162. doi:10.3171/jns.1967.26.1part2.0159. ISSN 0022-3085.
- ↑ Jannetta, Peter J.; Abbasy, Munir; Maroon, Joseph C.; Ramos, Francisco M.; Albin, Maurice S. (1977). "Etiology and definitive microsurgical treatment of hemifacial spasm". Journal of Neurosurgery. 47 (3): 321–328. doi:10.3171/jns.1977.47.3.0321. ISSN 0022-3085.
- ↑ Sampson, John H.; Grossi, Peter M.; Asaoka, Katsuyuki; Fukushima, Takanori (2004-04-01). "Microvascular Decompression for Glossopharyngeal Neuralgia: Long-term Effectiveness and Complication Avoidance". Neurosurgery. 54 (4): 884–890. doi:10.1227/01.NEU.0000114142.98655.CC. ISSN 0148-396X.
- ↑ Honey, Christopher R.; Morrison, Murray D.; Heran, Manraj K. S.; Dhaliwal, Baljinder S. (2019). "Hemi-laryngopharyngeal spasm as a novel cause of inducible laryngeal obstruction with a surgical cure: report of 3 cases". Journal of Neurosurgery. 130 (6): 1865–1869. doi:10.3171/2018.2.JNS172952. ISSN 0022-3085.
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