Anterolateral intervertebral disc herniation presenting as visceral pain in a patient with renal keratinising desquamative squamous metaplasia
- 1 Department of Anesthesiology, University of Florida, Gainesville, Florida, USA
- 2 Department of Medicine/Nephrology, University of Florida, Gainesville, Florida, USA
- Correspondence to Dr Sanjeev Kumar; SKumar@anest.ufl.edu
Abstract
We report the case of a 70-year-old man who presented to the clinic with back pain and presumed chronic kidney pain from renal keratinising desquamative squamous metaplasia, in which he would intermittently pass keratin plugs in urine. The pain had a visceral-sounding component that was inconsistent with renal colic. MRI of the spine revealed anterolateral disc bulges, which were likely irritating the anterolateral sympathetic nerves of the intervertebral disc, mimicking visceral pain. Transforaminal epidural steroid injection (TFESI) was performed at the levels of the disc bulges. He had no pain during passage of keratin plugs for 6.5 months after the TFESI which could be attributed to the expected duration of symptoms relief after a properly done TFESI.
Background
Chronic pain is not only one of the most common reasons why adults seek medical care, but is also associated with mental health issues, activity limitations and disruption to daily life.1 Diagnosing the aetiology and determining appropriate treatment of chronic pain can be very challenging.
We report a case of lumbar anterolateral disc bulges causing visceral-type pain in a patient with renal keratinising desquamative squamous metaplasia (RKDSM), who had been attributing his worsening chronic pain to his kidney disease. RKDSM is a rare disease in which the urothelium is replaced with keratinised cells, which slough off into the urine, with the potential to cause renal colic-like symptoms.2 The concurrent existence of intermittent passage of keratin plugs, the episodic nature of discogenic back pain and the little-discussed possibility of anterolateral disc pathology causing visceral pain, presented a diagnostic challenge.
Case presentation
A 70-year-old man with a rare diagnosis of RKDSM presented to the chronic pain clinic with multiple years of severe pain, which he attributed to the passing of keratin plugs (figure 1). He had attempted physical therapy and daily stretching exercises, as well as multimodal pain management including acetaminophen, nonsteroidal anti-inflammatory drugs, opioids and pregabalin, with limited success. However, the frequency and duration of his painful episodes was increasing, and he had required multiple emergency department visits and one hospital admission for pain management.
The patient reported a baseline 3/10 right flank pain with episodes leading to excruciating 10/10 diffuse visceral and back pain. Upon detailed questioning, the painful episodes and passage of plugs did not exactly align; while at times he had intense pain during plug passage, other times he did not. The pain was also not correlated with plug size and often did not resolve with the passing of the plug. Despite this, the patient was in so much distress he was considering nephrectomy as a permanent option to alleviate his pain.
(A) Material obtained from the patient’s right renal pelvis during ureteroscopy. 100% mucin. (B, C) Debris from the patient’s urine.
Investigations
Though the patient certainly had a potential renal source for his pain, the episodic nature of his discomfort and its lack of correlation to plug size and passage did not fit the picture of renal colic. Upon further discussion, the patient also stated he had one episode of this flank/back pain following a total knee replacement, with no associated plug passage. He also had underlying chronic back pain; this led us to consider a spinal pathology as the aetiology of the patient’s pain. MRI revealed anterolateral disc bulges at L3–4 (figure 2) and L4–5 as well as right lumbar neuroforaminal stenosis at L4–5 (figure 3).
Axial and sagittal images at L3–4 level revealing right anterolateral disc bulge (arrow).
Axial and sagittal images at L4–5 level revealing right anterolateral disc bulge (arrow) and lateral recess stenosis.
Differential diagnosis
Both renal and spinal causes for this patient’s pain were considered.
Kidney pain
Renal keratinising desquamative squamous metaplasia is a rare condition which has been reported to mimic renal colic.3 Characteristically, the transitional epithelium of the urinary tract is replaced by keratinising squamous epithelial cells. Subsequent desquamation and urinary passage of the superficial epithelial layers and keratin results in renal colic.4 The symptoms may mimic nephrolithiasis and/or malignancy. Risk factors include chronic infection, smoking or stones. Our patient was a smoker and his diagnosis of RKDSM had been confirmed by findings of acellular keratin debris obtained from upper ureter during ureteroscopy.
Our discussion with the patient initially included celiac plexus block and splanchnic block, as both are used for abdominal visceral pain.5 However, upon more detailed questioning it became apparent that the intensity of the patient’s pain was not related to keratin plug size, and was not consistently temporally related to plug passage. This led us to explore other aetiologies for his pain.
Neuroforaminal stenosis
The patient did have L4–5 neuroforaminal stenosis on MRI. However, the pain associated with neuroforaminal stenosis is in the anatomical distribution of the nerve, and can involve altered sensation and weakness. This diagnosis did not fit with our patient’s constellation of symptoms.
Spinal cause of visceral pain
The nerves innervating the anterior intervertebral disc have been linked to nerves supplying enteric structures and hypothesised to contain sympathetic afferents conveying visceral-type pain.6 Our patient had anterolateral disc bulges, which would lead to irritation of these anterior and anterolateral sympathetic nerves of the intervertebral disc, potentially leading to the episodic visceral-type pain he was experiencing.
Treatment
The most likely explanation for the patient’s pain might be the anterolateral disc bulges, therefore a right-sided transforaminal epidural steroid injections (TFESI) with 4 mg of dexamethasone at L3–4 (figure 4) and L4–5 (figure 5) was performed. The transforaminal route was chosen in order to obtain access to the ventral epidural space, to specifically target the anterolateral disc bulges at those levels.
Transforaminal epiduralsteroid injection at right L3–4, lateral and PA views. The transforaminal route was chosen in order to obtain access to the ventral epidural space, to specifically target the anterolateral disc bulges. PA, Postero-Anterior.
Transforaminal epiduralsteroid injection at right L4–5, lateral and PA views. The transforaminal route was chosen in order to obtain access to the ventral epidural space, to specifically target the anterolateral disc bulges. PA, Postero-Anterior.
Outcome and follow-up
Following TFESI, the patient continued to pass both small and large keratin plugs; however, the pain associated with these episodes disappeared completely. The patient’s baseline back pain also was reduced by greater than 50%. The patient continued to experience relief several months post-procedure.
Discussion
The sympathetic innervation of the intervertebral disc is often not considered. It has been shown that discogenic pain can be transmitted by sympathetic afferent fibers through the sinuvertebral nerves, which innervate the posterior and posterolateral disc.7 The lateral disc is innervated by the grey ramus communicans, which is a sympathetic nerve of the autonomic nervous system; the anterior and anterolateral disc is innervated by branches of the sympathetic trunk.8 Thus, visceral pain sensations can originate from anterior or anterolateral intervertebral disc herniation.
Some authors have described resolution to visceral pain from sympathetic blockade at the level of intervertebral disc disease. In one study, 12 patients with chronic abdominal pain recalcitrant to conservative treatment were found to have anterior lumbar disc herniations. The authors hypothesised that the disc bulges were irritating the anterior sympathetic structures and documented pain relief in all 12 patients undergoing a sympathetic block at the level of disc pathology.9 Another group proposed that chronic pelvic visceral pain could be due to anterior disc herniation causing sympathetic dysfunction; their series of five case reports all benefited from sympathetic blockade at the level of disc disease.10
Our patient presented with a diagnosis of a rare kidney disease, with chronic pain attributed to that disease. Only upon close examination of the patterns of his pain did it become clear that the aetiology of his pain was perhaps not what it seemed. We wonder, had the patient been passing keratin plugs painlessly for years before the development of his intervertebral disc pathology? Was his kidney disease only discovered in 2011 due to his development of another pathology that presented as visceral pain? He developed right-sided low back pain around the same time he started having flank pain, which led to the discovery of mucinous tissues during multiple ureteroscopies. His presenting complaint was flank pain lasting from several minutes to several hours that would spontaneously resolve after he would feel ‘something’ traversing through the ureter; yet, this pain did not occur with every episode of keratinised squamous cell passage, and there were many instances when he passed big plugs without any pain. Ureteric colic should be consistent whenever a patient passes a calculus or keratinised epithelial cells. His discordant presentation of pain, in addition to his good response to lumbar transforaminal epidural steroid injections, point to a component of lumbar disc aetiology for his renal colic.
Treatment of this patient’s pain with TFESI avoided further, more involved intervention, which included the possibility of nephrectomy to alleviate his pain. His initial presentation to our clinic was to evaluate his options before pursuing surgical intervention. Further treatment for this patient could include repeating TFESI on as needed basis for symptom relief in both his lower back as well as visceral pain attributed to keratin plugs, or endoscopic discectomy of his disc bulges for long-term relief.
The take home message for readers should be to have an open mind and take into account all the possible scenarios. It is never a good practice to explain every clinical presentation with a single diagnosis.
Patient’s perspective
Before the steroid injection, I was not able to lie flat on my back. I would feel pain in the lower right area of my back and the longer I stayed in that position the worse the pain would get. This went away almost immediately after the injection. I am not sure if the injection was helpful with my kidney condition known as KDSM. During a span of 6 months after the injection, I passed keratin on four occasions without any pain. I usually have painful episodes about every two months. The pain did not return for about 6 months following the steroid injection.
Learning points
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Discrepancies within the clinical presentation should push the clinician to re-evaluate the source of the patient’s pain.
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The anterior and anterolateral surfaces of the intervertebral disc are sympathetically innervated, with pathology potentially mimicking visceral pain.
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We should not try to explain every clinical presentation in a patient with a single diagnosis. There could always be multiple coexisting pathologies causing the various symptoms and signs.
Footnotes
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Contributors ASB: prepared the initial draft. CMG: procured the images, marked and captioned the figures. Helped prepare the initial draft. RR and SK: were the attending nephrologist and pain medicine specialist, respectively, on this case who reviewed and revised the manuscript for critically important intellectual content.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.
References
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