Fleet et al. BMC Neurology
(2020) 20:222
https://doi.org/10.1186/s12883-020-01800-6

CASE REPORT

Open Access

Palato-pharyngo-laryngeal myoclonus with
recurrent retrograde feeding tube
migration after cerebellar hemorrhagic
stroke: a case report and review of
hypertrophic olivary degeneration
Jamie L. Fleet, Ronelle Calver, Gihan C. Perera and Zhihui Deng*

Abstract
Background: Palato-pharyngo-laryngeal myoclonus, a variant of palatal myoclonus, is characterized by involuntary
rhythmic movements of palatal, pharyngeal, and laryngeal muscles. Symptomatic palatal myoclonus is classically
associated with hypertrophic olivary degeneration on MRI imaging due to a lesion in the triangle of Guillain-Mollaret.
Case presentation: We report a case of palato-pharyngo-laryngeal myoclonus in a patient post-cerebellar
hemorrhagic stroke who presented with recurrent retrograde migration of his gastrojejunostomy feeding tubes.
Treatment with either divalproex sodium or gabapentin resulted in a significant decrease in his gastrointestinal
symptoms and no further episodes of gastrojejunostomy tube migration.
Conclusions: This case study indicates that the movement disorder associated with hypertrophic olivary degeneration
may involve the gastrointestinal system. Anticonvulsants, such as gabapentin and divalproex sodium, may reduce the
severity of gastrointestinal symptoms in cases associated with hypertrophic olivary degeneration. The anatomy of the
Guillain-Mollaret triangle and the pathophysiology of hypertrophic olivary degeneration are reviewed.
Keywords: Symptomatic palatal myoclonus, Hypertrophic olivary degeneration, Guillain-Mollaret triangle

Background
Palatal myoclonus, also known as palatal tremor, is a rare
condition first described by Politzer in the 1860’s characterized by involuntary persistent rhythmic muscle contraction involving the soft palate [1]. Two types of palatal
myoclonus have been described: a symptomatic form attributable to a pathologic lesion involving the brainstem
or cerebellum often identified on MRI imaging, and an essential form without an identifiable structural cause [2].
Palato-pharyngo-laryngeal myoclonus is a rare variant of
* Correspondence: dengz22@mcmaster.ca
Division of Physical Medicine and Rehabilitation, Department of Medicine,
McMaster University, Hamilton, Canada

palatal myoclonus affecting not only the palate but the
pharynx and larynx as well, which may result in dysphagia,
dysphonia, and dysarthria [3–5]. Upon review of the
current literature, there are minimal, if any, gastrointestinal (GI) symptoms reported by patients with this condition. We report a novel case of recurrent retrograde
migration of enteral feeding tubes associated with palatopharyngo-laryngeal myoclonus following a cerebellar
hemorrhagic stroke.

Case presentation
A 57-year-old man was admitted to our acquired brain
injury (ABI) rehabilitation unit 8 months after he

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Fleet et al. BMC Neurology

(2020) 20:222

suffered a large right cerebellar hemorrhage with significant mass effect requiring an emergent posterior fossa
decompressive craniectomy. His past medical history included hypertension, vertigo, a remote concussion, and
history of a fractured jaw. He developed significant dysphagia early following his stroke, including difficulty
with secretion management. The dysphagia was likely
multifactorial, related to the cerebellar bleed with initial
mass effect and possible subsequent structural injury to
the brain stem (central) and cranial nerves (peripheral)
as well as an early altered level of consciousness (drowsiness, somnolence) following his stroke. A percutaneous
endoscopic gastrostomy (PEG) tube was placed 11 days
after his stroke, but refractory vomiting and aspiration
pneumonia eventually necessitated gastrojejunostomy
(GJ) tube placement. He continued to have ongoing issues with vomiting despite a trial of metoclopramide.
Imaging performed 1 month after placement of the GJ
tube revealed retrograde migration with the tip of the
catheter visualized within the oropharynx, which was approximately 14 weeks after his stroke. The GJ tube was
then replaced under fluoroscopic guidance. Within 2
weeks the tube had again migrated and was visualized
within the esophagus on imaging. He underwent endoscopic placement of a gastrostomy tube with addition of
a jejunal extension. Ten weeks after placement, the GJ
tube had migrated with the tip now located in the duodenum. At this point, his chronic vomiting appeared to
be improving with a trial of erythromycin so no further
adjustments to the tube were made.
Upon admission to our ABI unit he had ongoing dysphagia, significant hypophonia, and intermittent episodes
of regurgitation and vomiting, though often only small
amounts of bile or fluids. The vomiting was not stereotyped, nor did he have long episodes where he was completely symptom free, as seen in cyclic vomiting
syndrome [6]. He had two further episodes of retrograde
tube migration requiring replacement by interventional
radiology. A video fluoroscopy study was performed 10
months after his stroke that revealed rhythmic pulsations of the palate, pharynx, and larynx involving the
vocal cords, in keeping with palato-pharyngo-laryngeal
myoclonus (see video). Subsequently, a brain MRI was
completed showing apparent unilateral hypertrophy and
increased FLAIR signal in the left inferior olive suggestive of hypertrophic olivary degeneration.
Several medication trials including clonazepam, divalproex sodium, and gabapentin, were undertaken to help
control his palato-pharyngo-laryngeal myoclonus. Medications were administered independently with no combination therapies trialed. Clonazepam was poorly
tolerated due to drowsiness and thus discontinued.
Divalproex sodium titrated up to 1000 mg per day and
gabapentin titrated up to 600 mg per day did not lead to

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significant changes in the frequency or intensity of his
myoclonus on repeat video fluoroscopic studies. However, his GI symptoms improved significantly with these
medication trials such that he no longer vomited and
there were no further incidents of retrograde migration
of the feeding tube. Imaging performed 3 months after
the initiation of the medication trials and 2 months after
the most recent GJ tube replacement demonstrated the
tip of the tube appropriately located within the jejunum.

Discussion and conclusions
Symptomatic palatal myoclonus is attributable to hypertrophic olivary degeneration (HOD), a transsynaptic degeneration caused by a lesion in the anatomic triangle of
Guillain-Mollaret [7, 8]. The Guillain-Mollaret triangle,
also known as the dentato-rubro-olivary pathway, is a
neural circuit involved in motor modulation. The triangle comprises the ipsilateral red nucleus in the midbrain, inferior olivary nucleus (ION) in the medulla, and
the contralateral dentate nucleus in the cerebellum
(Fig. 1). The efferent fibres from the dentate nucleus ascend through the superior cerebellar peduncle, decussate
at the midline, and then connect with the contralateral
red nucleus in the rostral midbrain. The efferent fibers
of the red nucleus then descend via the central tegmental tract and reach the ipsilateral inferior olivary nucleus.
The inferior olivary nucleus completes the triangle by
sending decussating efferent fibers via the inferior cerebellar peduncle to the original dentate nucleus within
the cerebellum [7, 9].
The exact mechanism underlying palatal myoclonus is
not completely understood. The inferior olivary neurons
are electronically coupled via gap junctions and show
spontaneous rhythmic electric discharges in animal
models [10]. The dentate nucleus primarily inhibits the
inferior olivary nucleus via GABA-mediated modulation.
When a pathologic lesion interrupts this inhibitory
modulation, inferior olivary neurons enlarge and develop
abnormal soma-somatic gap junctions within weeks to
months [11]. It has been established that HOD occurs
with lesions involving the dentato-rubral pathway in the
superior cerebellar peduncle or the rubro-olivary pathway in the central tegmental tract, but not in nearby
areas [9]. This supports the theory that it is the loss of
inhibitory input from the dentate nucleus to the ION
that causes overactivity in the latter [11]. As a result, the
ION may become an autonomous oscillator due to its
intrinsic rhythmic capabilities leading to hyperkinetic
movement disorders [11]. Symptoms can present anywhere from 1 month to 8 years after lesion to the
Guillain-Mollaret triangle, though most commonly onset
is within the first year [9, 12–15].
In addition to the hypothesis of the ION as an oscillator in the pathophysiology of palatal myoclonus, a

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Fig. 1 Guillain-Mollaret Triangle. Graphical representation of The Guillain-Mollaret triangle (dentate-rubro-olivary pathway) with connections
between the dentate nucleus, contralateral red nucleus, and inferior olivary nucleus highlighted

second mechanism has been proposed that maladaptive
cerebellar plasticity may facilitate and amplify the rhythmic output from the hypertrophic ION [11]. Moreover, a
recent case report of oculopalatal myoclonus following
medullary infarcts without development of HOD suggests
a possible source of oscillation outside the ION [16].
The nucleus ambiguus (found in close proximity to
the ION) innervates the pharyngeal, laryngeal, and palatal musculature as well as upper esophagus via cranial
nerves 9,10, and 11 [11, 17]. Interestingly, HOD commonly results in palatal myoclonus caused by the rhythmic contraction of the levator veli palatini muscle [18].
It is unclear why this specific muscle is most often affected. Sometimes other muscles innervated by the nucleus ambiguus may be involved leading to palatopharyngo-laryngeal myoclonus. Connections from the
central tegmental tract to the nucleus ambiguus have
been implicated as part of the pathway leading to palatal
myoclonus [9, 19]. Possibly the close proximity of the
two structures in the medulla (ION and nucleus ambiguus) may also play a role in this relationship.
Other areas of body, such as the extraocular muscles,
head, diaphragm, and even extremities, can also be affected in HOD [18]. The remote effects of HOD have
been demonstrated with EMG studies that revealed
rhythmic electrical discharges in leg musculature,
though patients did not necessarily present with overt
myoclonus in their extremities [20]. Whether HOD can

have an effect on autonomic function, such as in the GI
tract, is unknown.
Consistent with previously documented findings in
HOD, our patient presented with myoclonus involving
the palate, pharynx, and larynx causing hypophonia and
contributing to his multifactorial dysphagia. He also presented with disrupted upper GI motility, likely retrograde peristalsis, causing recurrent GJ tube migration –
an extremely rare clinical phenomenon. Retrograde GJ
tube migration into the upper GI tract has been described secondary to persistent and forceful vomiting
[21]. The patient in this case did not have forceful
vomiting, and his emesis was generally small amounts of
bile and rarely his enteral feeds. We hypothesized that his
GI symptoms may be related to his HOD given the delayed onset post-stroke; his nausea and vomiting were first
documented 3 weeks after his cerebellar hemorrhage and
the first occurrence of enteral feeding tube migration was
at 14 weeks.
The GI tract has both intrinsic enteric neural plexuses
and extrinsic innervation from parasympathetic and
sympathetic pathways. While the sympathetic system inhibits motor activity, the parasympathetic system modulates the tone and motility of GI musculature via the
vagal nerve. Vagal innervation of the GI tract arises from
the dorsal vagal nucleus in the medulla. As discussed
above, the nucleus ambiguus is often affected in HOD
leading to palatal myoclonus. Given the remote effects

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of HOD detailed in previous literature, other motor nuclei
in the brainstem (for example, innervating eye movements) and motoneurons in the spinal cord (for example,
innervating the diaphragm and extremities) may also be
affected. In this case, we postulate that the dorsal vagal
nucleus may have been affected by HOD resulting in this
patient’s atypical GI symptoms (retrograde peristalsis) in
addition to his palatal myoclonus (Fig. 2). Alternatively,
but less likely, this may be related to the close proximity
of the efferent fibres of the dorsal vagal nucleus and the
nucleus ambiguus via the vagal nerve. Another possibility
is that the nucleus ambiguus itself may play a role in our
patient’s GI dysfunction, as the gastric innervation by the
nucleus ambiguus has been demonstrated in animal
models [22]. Further research in this area is warranted.
There is no widely accepted pharmacologic treatment
for symptomatic palatal myoclonus, though there have
been case reports of successful treatment with valproic
acid or other anticonvulsants [23, 24], trihexyphenidyl
[25], and piracetam [26]. Gabapentin and memantine
were observed to be effective in treating some patients
with pendular nystagmus secondary to HOD [12]. Based
on our theory that his GI symptoms were related to his
HOD and palatal myoclonus, several medication trials
were initiated in our patient. While his palato-pharyngolaryngeal myoclonus did not show significant response
to treatment with divalproex sodium or gabapentin, his

Page 4 of 5

GI symptoms dramatically improved, even with each
medication used singly. This may suggest that the retrograde tube migration was more related to the HOD effect on the dorsal vagal nucleus rather than the palatopharyngo-laryngeal myoclonus itself. Divalproex sodium
was effective in improving his GI symptoms, however
the patient’s family was concerned about the side effect
profile, therefore it was weaned down and switched to
gabapentin. Prior to initiation of these medication trials,
his GJ tube required replacement on four occasions within
7 months. Additionally, while his vomiting was unresponsive to more traditional anti-emetics, such as metoclopramide, it did improve with addition of anticonvulsants. At
discharge, he was on gabapentin 600 mg PO QHS with no
significant vomiting or migration of his GJ tube within the
previous 2 months, lending support to his GI symptoms
being related to underlying HOD.

Conclusion
This is the first case report of significant GI symptoms associated with HOD following a lesion in the Guillain-Mollaret
triangle. If patients with HOD present with atypical GI symptoms unresponsive to standard treatments, anticonvulsants,
such as divalproex sodium and gabapentin, may be effective.
Further studies are needed to determine the underlying
pathophysiology of HOD and associated movement disorders in order to better target clinical treatment.

Fig. 2 Hypertrophic Olivary Degeneration Pathway. Proposed mechanism for pathologic signs developed in the setting of hypertrophic olivary
degeneration. With loss of inhibitory input to the inferior olivary nucleus, hypertrophic olivary degeneration occurs. Anatomic structures affected
by hypertrophic olivary degeneration are identified by text with arrows leading to resultant movement disorders

Fleet et al. BMC Neurology

(2020) 20:222

Supplementary information
Supplementary information accompanies this paper at https://doi.org/10.
1186/s12883-020-01800-6.
Additional file 1. Top down view of pharynx and larynx demonstrating
rhythmic pulsations, most prominent on the left vocal cord.
Abbreviations
ABI: Acquired brain injury; GI: Gastrointestinal; GJ: Gastrojejunostomy;
HOD: Hypertrophic olivary degeneration; ION: Inferior olivary nucleus
Acknowledgements
We thank the patient in the study and all the team members who provided
care for him on the Acquired Brain Injury Rehabilitation Unit. We are grateful
to Banu Sivaram SLP, Elizabeth Timleck SLP, and Sandra Sanmartin SLP.
Authors’ contributions
Conception and design of the work - JF, RC, GP, ZD. Drafting the work or
substantively revising it - JF, RC, GP, ZD. All authors have read and approved
the final manuscript.
Funding
No funding was received for this work.
Availability of data and materials
Not applicable.
Ethics approval and consent to participate
Not applicable.
Consent for publication
Written informed consent for publication was obtained and is available upon
request.
Competing interests
The authors declare that they have no competing interests.

Page 5 of 5

13. Samuel M, Torun N, Tuite PJ, Sharpe JA, Lang AE. Progressive ataxia and
palatal tremor (PAPT): clinical and MRI assessment with review of palatal
tremors. Brain. 2004;127(6):1252–68.
14. Matsuo F, Ajax ET. Palatal myoclonus and denervation supersensitivity in the
central nervous system. Ann Neurol. 1979;5(1):72–8.
15. Turazzi S, Alexandre A, Bricolo A, Rizzuto N. Opsoclonus and palatal
myoclonus during prolonged post-traumatic coma: a clinico-pathologic
study. Eur Neurol. 1977;15(5):257–63.
16. Kattah JC, Elble RJ, De Santo J, Shaikh AG. Oculopalatal tremor following
sequential medullary infarcts that did not cause hypertrophic olivary
degeneration. Cerebellum Ataxias. 2020;7(1):3.
17. Walker HK. Cranial nerves IX and X: the glossopharyngeal and Vagus nerves.
In: Walker HK, Hall WD, Hurst JW, editors. Clinical methods: the history,
physical, and laboratory examinations. 3rd ed. Boston: Butterworths; 1990.
18. Deuschl G, Wilms H. Clinical spectrum and physiology of palatal tremor.
Mov Disord. 2002;17(Suppl 2):S63–6.
19. Ash L, Srinivasan A. Case of the season: hypertrophic olivary degeneration.
Semin Roentgenol. 2008;43(3):171–2.
20. Nagaoka M, Narabayashi H. Palatal myoclonus--its remote influence. J
Neurol Neurosurg Psychiatry. 1984;47(9):921–6.
21. Adesina A, Rammohan G, Jeanmonod R. Retrograde gastrojejunostomy
tube migration. Case Rep Emerg Med. 2014;2014:738506.
22. Zhang X-Y, Ai H-B, Cui X-Y. Effects of nucleus ambiguus and dorsal motor
nuclei of vagus on gastric H(+) and HCO (3)(−) secretion in rats. World J
Gastroenterol. 2006;12(20):3271–4.
23. Kim B-R, Lee Y, Kim SJ, Kim H, Lee JW, Lee S, et al. Effectiveness of
combining behavioral treatment with Valproic acid for dysphagia caused by
palatal myoclonus in patients with stroke: two case reports. Ann Rehabil
Med. 2018;42(1):180–3.
24. Lang AE. Treatment of palatal tremor. In: Reich S, Factor S, editors. Therapy
of movement disorders. Cham: Humana; 2019. p. 179–83.
25. Jabbari B, Rosenberg M, Scherokman B, Gunderson CH, McBurney JW,
McClintock W. Effectiveness of trihexyphenidyl against pendular nystagmus
and palatal myoclonus: evidence of cholinergic dysfunction. Mov Disord.
1987;2(2):93–8.
26. Karacostas D, Doskas T, Artemis N, Vadicolias K, Milonas I. Beneficial effect of
piracetam monotherapy on post-ischaemic palatal myoclonus. J Int Med
Res. 1999;27(4):201–5.

Received: 4 February 2020 Accepted: 20 May 2020

Publisher’s Note
References
1. Stern MM. Rhythmic palatopharyngeal myoclonus, review, case report and
significance. J Nerv Ment Dis. 1949;109(1):48–53.
2. Deuschl G, Toro C, Valls-Solé J, Zeffiro T, Zee DS, Hallett M. Symptomatic
and essential palatal tremor. Brain. 1994;117(4):775–88.
3. Drysdale AJ, Ansell J, Adeley J. Palato-pharyngo-laryngeal myoclonus: an
unusual cause of dysphagia and dysarthria. J Laryngol Otol. 1993;107(8):
746–7.
4. Juby AG, Shandro P, Emery D. Palato-pharyngo-laryngeal myoclonus ... an
unusual cause of dysphagia. Age Ageing. 2014;43(6):877–9.
5. Barkmeier-Kraemer JM, Clark HM. Speech-Language Pathology Evaluation
and Management of Hyperkinetic Disorders Affecting Speech and
Swallowing Function. Tremor Other Hyperkinet Mov (N Y). 2017;7:489.
6. Lee KL, Shin JI. Cyclic vomiting syndrome developed after stroke. Ann
Rehabil Med. 2012;36(1):141–3.
7. Wang H, Wang Y, Wang R, Li Y, Wang P, Li J, et al. Hypertrophic olivary
degeneration: a comprehensive review focusing on etiology. Brain Res.
2019;1718:53–63.
8. Pearce JMS. Palatal Myoclonus (syn. Palatal Tremor). Eur Neurol. 2008;60(6):
312–5.
9. Van Eetvelde R, Lemmerling M, Backaert T, Favoreel N, Geerts B, Sommeling
C, et al. Imaging features of hypertrophic Olivary degeneration. J Belgian
Soc Radiol. 2016;100(1):71.
10. Armstrong DM. Functional significance of connections of the inferior olive.
Physiol Rev. 1974;54(2):358–417.
11. Shaikh AG, Hong S, Liao K, Tian J, Solomon D, Zee DS, et al. Oculopalatal
tremor explained by a model of inferior olivary hypertrophy and cerebellar
plasticity. Brain. 2010;133(3):923–40.
12. Tilikete C, Desestret V. Hypertrophic Olivary degeneration and palatal or
Oculopalatal tremor. Front Neurol. 2017;8:302.

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