Neurogenic irritable bowel syndrome? Long-term resolution of chronic gastrointestinal stress following vagus nerve microvascular decompression: illustrative case

Abstract

BACKGROUND

Microvascular decompression (MVD) is a well-established treatment for compressive cranial neuralgias such as trigeminal neuralgia and hemifacial spasm. The vagus nerve (cranial nerve [CN] X), with its extensive parasympathetic innervation to the gastrointestinal (GI) system, has less clearly defined neuropathic symptomatology, and MVD of CN X has only been reported once. The authors report a unique case of treatment-refractory GI distress that resolved completely following CN X MVD.

OBSERVATIONS

A 32-year-old male with a 13-year history of hemifacial spasm also experienced chronic, debilitating GI distress characterized by sudden, painful abdominal cramping and diarrhea. Despite extensive workup, including three colonoscopies, no clear etiology was found. During MVD for his facial nerve, a large vertebral artery loop was incidentally found significantly displacing CN X. Both nerves were decompressed. Both the patient’s hemifacial spasms and GI symptoms resolved immediately, and this has persisted for more than 5 years of follow-up.

LESSONS

While vagal injury (including intentionally via vagotomy) results in gastroparesis, the authors propose that chronic CN X compression may induce a “hyperactive rhizopathy” resulting in symptoms of overactive peristalsis. CN X compression may be an underrecognized, reversible etiology of chronic GI distress, and clinicians should consider the possibility of neurovascular conflict in this patient population.

https://thejns.org/doi/10.3171/CASE2688

Vascular compression of cranial nerves (CNs) is a well-described cause of neuralgias. The most common of these is trigeminal neuralgia, characterized by lancinating facial pain from trigeminal nerve compression—most commonly from the superior cerebellar artery.¹ Secondary among these cranial neuralgias is hemifacial spasm, characterized by involuntary facial twitching secondary to compression of the facial nerve.^2,3 Glossopharyngeal neuralgia is a rarer but well-characterized pathology commonly causing lancinating throat pain secondary to compression of the glossopharyngeal (CN IX) or vagus (CN X) nerve.^4,5

Beyond uvulopalatal pain, glossopharyngeal neuralgia has occasionally been associated with symptoms stemming from sudden vagal parasympathetic output, most notably cardiac syncope and essential hypertension.⁶ One case report also described chronic gastrointestinal (GI) distress secondary to right vagus nerve compression.⁷

Microvascular decompression (MVD) is a safe and effective treatment for these conditions.^8–10 Herein, we report a patient who presented for MVD for hemifacial spasm and had a history of chronic, severe GI distress. Intraoperatively, he was found to have concurrent CN X compression. After decompression, he had complete resolution of his facial symptoms and total relief of his GI distress, sustained for more than 5 years of follow-up.

Illustrative Case

Patient History

A 32-year-old male with right-sided hemifacial spasm, chronic GI distress, generalized anxiety disorder (GAD), and major depressive disorder (MDD) experienced a severe neck sprain at age 18 while wrestling and was treated with 6 months of chiropractic therapy. One year later he developed intermittent, self-resolving right hemifacial spasm and progressive GI symptoms—episodic sudden-onset diarrhea with painful abdominal cramps and a “fluttering” stomach sensation, meeting criteria for irritable bowel syndrome with diarrhea. These symptoms led to GAD and MDD and significant social and educational impairment, including dropping out of college. Over 4 years, he received counseling and tried loperamide and probiotics for his GI symptoms with little benefit. He had regular botulinum toxin injections with spasm improvement. He sought evaluation from multiple providers for his GI complaints; testing for fecal parasites and celiac disease was negative. He denied weight loss and a family history of colorectal cancer or inflammatory bowel disease but reported nocturnal diarrhea and had a positive fecal occult blood test. This prompted a colonoscopy, which was negative; he ultimately underwent three colonoscopies, all without diagnostic findings. Upper endoscopy was not performed given the absence of red flag symptoms such as significant dyspepsia or hematemesis. At presentation, he was taking sertraline and had just completed a 60-day mental health retreat. He denied syncope, palpitations, uvular/palatal pain or spasm, hoarseness, or changes in taste.

Examination and Diagnostic Imaging

Examination showed right hemifacial spasm without other focal deficits. Brain MR angiography demonstrated a right superior cerebellar artery near the trigeminal nerve without compression and a right posterior inferior cerebellar artery (PICA) abutting but not displacing the facial (CN VII) and vestibulocochlear (CN VIII) nerve complex (Fig. 1A). Incidentally, lower axial images at the level of the hypoglossal canal showed the ipsilateral vertebral artery (VA) indenting the medulla at the CN IX/X root (Fig. 1B). He was offered MVD to address right facial nerve compression resulting in hemifacial spasm.

FIG. 1.

Preoperative axial MR angiograms. A: MR angiogram at the level of the internal auditory canal (IAC). The right PICA courses superiorly and has a loop between the anterior branches in the IAC (facial and cochlear nerve) and the posterior branches (superior and inferior vestibular nerve) splaying them apart (arrow). B: MR angiogram at the level of the hypoglossal canal. The right VA indents the brainstem as CNs XI and X exit (arrow).

Surgery

The patient was placed in the left lateral position, and a lumbar drain was placed for CSF drainage and brain relaxation. Neuronavigation was used for a right retrosigmoid craniotomy. After dural opening, arachnoidal dissection was performed under the microscope, and CN V, the CN VII/VIII complex, and the CN IX/X/XI complex were identified. A large-vessel loop was found abutting and displacing the CN VII/VIII complex. It was gently retracted inferiorly and separated from the nerves with small felt bolsters/padding. Exploration of the CN IX/X/XI complex revealed another vascular loop abutting and displacing CN IX and CN X posteriorly (Fig. 2A), which was similarly decompressed with appropriately sized bolsters/padding(Fig. 2B). Surgical closure was performed in the usual fashion (Video 1).

FIG. 2.

Intraoperative images A:The VA can be seen ventromedial to and splitting CNs IX and X (arrow). It is compressing and displacing them dorsolaterally. B: Felt patties (arrows) are placed for decompression of CNs IX and X.

VIDEO 1. Operative video demonstrating a right-sided retrosigmoid approach for MVD, with an indication of hemifacial spasm. While exploring the CN VII/VIII complex, significant compression by the VA was discovered on CNs IX and X. The offending vessel was mobilized and felt bolsters were used to achieve adequate decompression. Postoperatively, the patient experienced immediate and sustained resolution of a 13-year history of treatment-refractory GI distress. Click here to view.

Postoperative Course

The patient had immediate improvement of hemifacial spasm on awakening, with only minimal residual right orbicularis oculi spasm and markedly reduced involvement of other facial muscles. On postoperative day (POD) 2, he reported complete absence of GI distress—his first symptom-free interval in > 10 years—and improved mood, which he attributed to the near-total symptom resolution.

At POD 47, he continued to have minimal residual orbicularis oculi spasm, sustained GI improvement, and no longer required GI medication.

At telephone follow-up 5.5 years later, he reported complete resolution of his hemifacial spasm (last episode 6 months postoperatively), and a sustained approximately 90% reduction in GI symptoms and use of prophylactic loperamide (previously three times per day with minimal effect).

Informed Consent

The necessary informed consent was obtained in this study.

Discussion

Observations

The vagus nerve (CN X) has broad functions including taste, swallowing and soft palate elevation, speech through the recurrent laryngeal nerve, cough reflex, aortic arch chemo- and baroreceptors, and parasympathetic innervation of the heart, lungs, and GI viscera. It is mainly composed of four nuclei, arises from the medulla, exits between the olivary body and inferior cerebellar peduncle, and courses near the VA and PICA, before exiting the skull base via the jugular foramen. Although the offending vessels in CN X compression are less established than in trigeminal/facial neuralgias, reports implicate the VA and PICA.^7,11,12

Vagal irritation is uncommon and often presents with glossopharyngeal neuralgia symptoms, likely from concurrent CN IX involvement. This syndrome has been described since 1910 and responds favorably to MVD.^13–18 Glossopharyngeal neuralgia has rarely been associated with cardioinhibitory syncope.^19–21 The proposed mechanism is that aberrant glossopharyngeal afferent activity—potentially mimicking baroreceptor input from the carotid sinus—elicits a reflex increase in vagal efferent outflow, resulting in bradycardia and hypotension. Supporting evidence includes a study in which stimulation confined to the most caudal CN X rootlet induced bradycardia, suggesting that preganglionic parasympathetic (general visceral efferent) fibers may be somatotopically concentrated within the inferior rootlets. Additionally, resolution of syncope after transection of the glossopharyngeal nerve without CN X decompression implicates CN IX as the afferent limb of the reflex arc.²² In our case, we could not determine whether the VA produced preferential compression of specific vagal rootlets.

The vagus nerve exhibits anatomical and functional laterality. As the esophageal plexus coalesces near the esophageal hiatus, the left vagus becomes the anterior vagal trunk, whereas the right vagus becomes the posterior vagal trunk. Functionally, the right vagus more strongly influences the sinoatrial nodal rate, while the left vagus more strongly influences atrioventricular nodal conduction.²³ In the abdomen, however, laterality is less discrete, with substantial overlap of left-right vagal contributions to the enteric nervous system; some evidence suggests slightly greater contribution to the celiac plexus from the posterior vagal trunk.^24,25

There is a reasonable mechanism by which vagal irritation could lead to GI complaints. CN X provides parasympathetic efferents to the alimentary canal up to the left colic flexure regulating secretions and peristalsis. A recent systematic review on the emerging use of noninvasive vagus nerve stimulation for treating organic and functional GI disorders reinforces the mechanistic link between vagal modulation and intestinal motility.²⁶ Furthermore, vagal injury has been strongly associated with GI dysfunction—most notably gastroparesis.²⁷ Surgical vagotomy, historically used to treat refractory peptic ulcer disease, bore with it gastroparesis as a side effect.²⁸ It stands to reason, then, that intermittent overactivity of the vagus nerve (vagus rhizopathy) could result in the opposite effect, namely hyperperistalsis with abdominal pain.

Only one prior case report attributed GI symptoms to vagus nerve compression.⁷ A 58-year-old female had episodes of nausea, vomiting, and diarrhea three to four times per day and later developed lancinating throat/cheek pain. After no response to standard neuropathic pain agents, MRI revealed the right PICA compressing the CN IX/X complex. She was symptom free at 1year of follow-up after MVD. Notably, the laterality of vagus nerve compression in that report was the same as in our case.

Similarly, our patient had long-standing idiopathic GI distress unresponsive to medical therapy. He underwent surgery for hemifacial spasm and was incidentally found to have CN X compression intraoperatively. MVD produced immediate relief of a 13-year GI symptom history that has been sustained after multiple years of follow-up. This suggests a permanent physiological correction rather than transient placebo.

It must be noted that the patient’s comorbid anxiety and depression could be considered confounders of his symptoms; that is, his GI distress was possibly a somatic disorder due to psychological disturbance. However, the immediate resolution of his GI symptoms after surgical intervention seems to suggest a primary mechanical/neurogenic etiology rather than a secondary psychosomatic response.

While vagal neuropathy accounts for only a small fraction of GI distress, there are countless people living worldwide with these debilitating symptoms. A meta-analysis of eight international studies estimated irritable bowel syndrome prevalence at approximately 11% worldwide, which is, in essence, a diagnosis of exclusion.²⁹ It may be the case that a small subset of these patients have an underlying vagus nerve compression.

Lessons

Vagus nerve compression has been associated with glossopharyngeal neuralgia and cardiac syncope. As the vagus nerve also supplies significant input to the GI system, compression of this nerve may be an underrecognized cause of GI distress. In this case, vagus nerve MVD produced immediate relief of GI distress. When evaluating patients with idiopathic GI symptoms recalcitrant to medical therapy, clinicians should consider the possibility of this rare etiology.

Acknowledgments

We used ChatGPT version 5.2 to improve grammar and sentence structure.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: McMahon, Weinberg, Boulis. Acquisition of data: Raheb Khelo, McMahon, Boulis. Analysis and interpretation of data: Raheb Khelo, McMahon, Boulis. Drafting the article: all authors. Critically revising the article: Raheb Khelo, McMahon, Weinberg. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Raheb Khelo.

Supplemental Information

Videos

  Video 1. https://vimeo.com/1172954141.

Correspondence

Roy Raheb Khelo: Emory University School of Medicine, Atlanta, GA. royraheb@gmail.com.