Diagnosis and treatment of abdominal pain of spinal origin: a case report

Abstract

Background

Clinically, abdominal pain can also be caused by lesions of the vertebral bodies, intervertebral discs, and other structures. It is usually due to degenerative changes, injuries, or herniations of the intervertebral discs, as well as stimulation or compression of the sympathetic nerve plexus associated with the vertebral bodies, leading to nonspecific abdominal pain, medically referred to as "abdominal pain of spinal origin".

Case presentation

A 70-year-old Asian female presented with a 20-year history of unexplained right lower abdominal pain, initially managed as a gastrointestinal condition. Despite extensive evaluations (including CT and colonoscopy), the etiology remained elusive. Multidisciplinary collaboration eventually identified a right-sided L4–L5 disc herniation compressing the right L4 spinal nerve root. A diagnostic selective nerve root block of the right L4 root was performed, resulting in 80% pain relief within 30 minutes, confirming the spinal origin. Two days later, the patient underwent unilateral biportal endoscopic (UBE) discectomy. Postoperatively, the abdominal pain resolved significantly, and the Visual Analog Scale (VAS) score decreased to 2. At the 12-month follow-up, the patient remained pain-free.

Conclusions

Lumbar radiculopathy can mimic visceral abdominal pain. In patients with intractable abdominal pain, spinal screening is crucial. Diagnostic nerve blocks serve as a key tool to confirm the diagnosis and guide minimally invasive surgical treatment.

Background

Abdominal pain is a prevalent clinical symptom defined as discomfort experienced between the diaphragm and the pelvis. The etiology of abdominal pain is multifactorial and complex, typically classified by onset and duration into acute or chronic categories. The etiology of acute abdominal pain is usually straightforward, often identified by localization, allowing for effective diagnosis and management. In contrast, chronic abdominal pain is defined as persistent or recurrent pain lasting for more than 3 to 6 months. The nature and etiology of chronic abdominal pain can be more complex, with pain intensity varying from dull to cramping, burning, or vague \* MERGEFORMAT [1],and it may be localized or diffuse. Compared to acute abdominal pain, chronic abdominal pain necessitates careful diagnostic evaluation by clinicians to identify its underlying cause. Common etiologies include functional gastrointestinal disorders (FGIDs) or disorders of gut–brain interactions, such as functional dyspepsia (FD), irritable bowel syndrome (IBS), and centrally mediated abdominal pain syndrome (CAPS) [2]. However, lesions of the vertebral bodies, intervertebral discs, and other spinal structures can also induce referred abdominal pain. Nonspecific abdominal pain resulting from the irritation or compression of the vertebral sympathetic plexus due to spinal pathologies—such as degenerative disc disease, injury, or herniation—is medically referred to as "abdominal pain of spinal origin". This pain does not originate from intra-abdominal visceral pathology but is a form of referred pain resulting from neural reflexes. Given its rarity, abdominal pain of spinal origin is frequently misdiagnosed or overlooked. Therefore, this article reports the clinical presentation and management of a case treated at the Department of Spine Surgery in our hospital in September 2024. We also review and discuss relevant literature to enhance clinicians' understanding of this condition and provide clinical insights for the management of similar cases.

Case presentation

A 70-year-old Asian woman presented with a 20-year history of abdominal pain without an obvious precipitating cause. She described a dull, aching pain in the right lower quadrant, which was mechanically exacerbated by prolonged standing and walking, and partially relieved by lying supine. The pain occasionally radiated to the right lateral thigh. There was no history of fever, nausea, or changes in bowel habits. Twenty days prior to admission, the patient noted a persistent increase in abdominal pain accompanied by radiating pain in the lower back, prompting her admission to the gastroenterology department.

Physical examination revealed the patient was alert with clear respiratory sounds. The abdomen was flat and soft, with tenderness in the right lower quadrant but no rebound tenderness. No hepatosplenomegaly was palpable. Routine abdominal computed tomography (CT) revealed multiple liver cysts, a suspected duodenal descending diverticulum, mildly enlarged mesenteric and ileocecal lymph nodes, sigmoid colon and rectal wall thickening, and sacral cysts. Colonoscopy showed no significant abnormalities. Despite specialist examination and related imaging tests, the cause of the abdominal pain remained unclear. A multidisciplinary discussion was held after the pain management and gastrointestinal surgery departments ruled out related pathologies. The spinal surgery department reviewed the case and refining the imaging studies. Lumbar spine magnetic resonance imaging (MRI) revealed an old compression fracture of the L2 vertebral body, posterior bulging of the L4 vertebral body, and stenosis of the vertebral canal and right lateral recess. Additionally, there was evidence of lumbar disc degeneration, including L2–3, L3–4, and L4–5 disc bulging, L4–L5 disc herniation, and multiple cysts in the sacral canal (Fig. 1). Following consultation with the spine surgery department, considering the imaging features alongside the patient's right lumbosacral radiating pain and sciatica, a diagnosis of abdominal pain of spinal origin was suspected. The patient was subsequently transferred to the Department of Spine Surgery.

Fig. 1.

A, B Preoperative lumbar disc plain magnetic resonance imaging. A Sagittal T2-weighted image: the blue arrow indicates a strip-like shadow at the right posterior aspect of the L4 vertebral body. Consider the nucleus tissue of the L4/5 intervertebral disc prolapse. Disc bulging and herniation are observed at L3–L4 and L4–L5, along with hyperintense T2 signals (cysts) within the sacral canal. B Axial T2-weighted image at the L4 level: the red arrow indicates a strip-like shadow at the right posterior aspect of the L4 vertebral body protruding into the spinal canal, compressing the dural sac, and resulting in stenosis of the spinal canal and the right lateral recess

Upon transfer, the preliminary examination results indicated: there was mild tenderness in the lower right abdomen (indicating abnormal palpation), but no deep abdominal organ tenderness or rebound pain, mild tenderness and percussion pain over the lumbar spine, and slight tightness and tenderness in the right paravertebral and sacrospinalis muscles. The right Straight Leg Raise test and reinforcement test were positive ( +). The patient reported pain in the lateral aspect of the right lower leg and exhibited mild tenderness along the course of the right sciatic nerve. Muscle strength for dorsiflexion and plantar flexion of the right great toe was graded at approximately 4-, while bilateral Achilles tendon reflexes remained intact. Integrating the symptoms, physical signs, and auxiliary examination results, the specialist assessment further supported a spinal etiology. A diagnosis of abdominal pain of spinal origin and sciatica secondary to lumbar disc herniation was made. Therefore, we first performed a CT-guided selective nerve root block of the right L4 nerve root. Thirty minutes post-injection, resulting in 80% pain relief within 30 minutes, confirming a positive block test ( +). Two days after the association between the radicular pain and nerve root compression was established, the patient proceeded to unilateral biportal endoscopic (UBE) lumbar discectomy. Postoperatively, the abdominal pain resolved significantly, and the Visual Analog Scale (VAS) score decreased to 2 (Fig. 2). At the 12-month follow-up, she remained symptom-free with a VAS score of 0–1/10 and had returned to her normal daily activities without the need for analgesics. No recurrence of abdominal or leg pain was noted, thereby confirming the spinal lesion as the root cause of the abdominal pain.

Fig. 2.

A, B Lumbar magnetic resonance imaging on the third postoperative day. A Sagittal T2-weighted image: the blue arrow indicates a partial bony defect at the posterior aspect of the L4 vertebral body. Heterogeneous signals in the surgical area indicate that the herniated nucleus pulposus has been removed. B Axial T2-weighted image at the L4 level: the red arrow indicates a partial bony defect at the posterior aspect of the L4 vertebral body with surrounding soft tissue edema. The dural sac is decompressed, and the spinal canal stenosis is relieved

Surgical approach and procedure

• Spinal nerve root block (right L4). The patient was positioned prone, and the L4/L5 interspace was localized under fluoroscopic guidance. The needle insertion point was marked at the right side of the spinous process of the L4/L5 interspace, approximately 4 transverse finger widths away. After disinfecting the skin and draping with a sterile towel, the needle was inserted under fluoroscopic guidance. The needle tip was seen at the right intervertebral foramen of L4 and L5 under fluoroscopy (the orthogonal X-ray showed it at the lower edge of the L4 pedicle, and the lateral X-ray showed it at the lower edge of the L4 vertebral body). The patient complained of an electric shock sensation in the right thigh, prompting a slight retraction of the needle. When the needle reached the right intervertebral foramen of L4 (as seen on the orthogonal X-ray at the lower edge of the L4 vertebral body), the patient again reported an electric shock sensation in the right thigh. The needle was slightly retracted, and contrast agent was injected. Under fluoroscopic guidance, 2 mL of 2% lidocaine mixed with betamethasone was injected around the right L4 nerve root, resulting in 80% pain relief within 30 minutes, confirming the spinal origin.

• Unilateral biportal endoscopic (UBE) discectomy for lumbar intervertebral disc nucleus pulposus removal. The patient was placed in the prone position. The L4–L5 intervertebral space was localized using an extracorporeal Kirschner wire under C-arm fluoroscopic guidance. After the induction of satisfactory general anesthesia, routine disinfection and draping were performed, and neurophysiological monitoring was established. The entry points for the dual-channel approach were marked at the intersections of a vertical line 1 cm lateral to the right posterior midline and transverse lines 1.5 cm cranial and caudal to the center of the L4–L5 interspace. Skin incisions were made at these points. A guide wire was inserted 1 cm lateral to the right spinous process. The viewing portal was established through the proximal incision for the endoscopic system, while the distal incision served as the working portal. After tactile confirmation of the lamina and intervertebral space using the guide wire, serial dilators and the working sheath were inserted and secured. Fluoroscopy confirmed correct localization of the interspace. Soft tissue on the lamina was cleared using a radiofrequency plasma probe, and residual tissue was removed with forceps. A Kerrison rongeur was used to resect the lamina from the cranial and caudal aspects to expose the ventral attachment of the ligamentum flavum. The ligamentum flavum was detached from the ventral lamina using a curved curette and subsequently removed to decompress the spinal canal. Upon identifying the nerve root, it was gently separated and retracted medially using a nerve retractor to expose the intervertebral disc. Intraoperative findings revealed a central disc herniation protruding to the right with distal migration, causing significant compression of the right L4 nerve root. An incision was made in the prominent annulus fibrosus with a pointed blade, and the extruded and degenerated nucleus pulposus was removed using pituitary forceps. Radiofrequency ablation was applied to the intervertebral space to shrink the annular tissue. A partial laminectomy was extended inferiorly to open the lateral recess, ensuring thorough decompression of the spinal canal and nerve root canal. Following decompression, the nerve root tension was observed to be normal. After confirming hemostasis with no active bleeding, the incisions were sutured, and a closed suction drainage tube was placed. The wound was dressed, and the excised tissue was sent for histopathological examination (Fig. 3). The patient was safely returned to the ward.

Fig. 3.

Postoperative histopathological examination. The section reveals degenerated fibrocartilaginous tissue with scattered areas of minor fat necrosis and lymphocytic infiltration (hematoxylin and eosin [HE] stain, × 200 magnification)

Discussion

Clinically, cases of abdominal pain of spinal origin are rare, and it is uncommon for clinicians to investigate the spine, intervertebral discs, or related structures as potential sources of abdominal pain in patients presenting with visceral symptoms. Typically, lumbar disc herniation is recognized as a common cause of low back pain and radicular leg pain (sciatica) [3, 4]. However, abdominal pain as an atypical symptom of lumbar disc herniation is often overlooked or misdiagnosed in clinical practice. According to existing theories and related literature, the abdominal pain caused by a herniated disc is closely related to the compression of the spinal nerve roots by the prolapsed disc, the neuro-reflex interactions between the nerve roots and visceral organs, and the neuroanatomical pathways that traverse the lumbar spine. The concept of referred pain, or the "convergence theory", explains this phenomenon. According to this theory, sensory nerve fibers from different areas converge onto the same or adjacent spinal nerve roots or segments of the spinal cord. When one area experiences noxious stimulation, the pain is often perceived in another area that does not share the same direct stimulus [5, 6]. The innervation of the abdomen is complex, involving both the autonomic nervous system (sympathetic and parasympathetic nerves) and the somatic nervous system (thoracoabdominal nerves T7–T12 and lumbar nerves L1–L2). These nerves work in concert to regulate sensory and motor functions in the abdomen and the autonomic functions of internal organs [7]. Therefore, any pathology that stimulates or compresses the dorsal nerve roots between T7–L2 can cause somatic pain while simultaneously generating varying degrees of visceral pain [8].

In the case of this patient, lumbar spine MRI revealed. L3–4 and L4–5 disc bulging, L5–S1 disc herniation; L4 vertebral canal and right lateral recess stenosis, suggesting possible disc prolapse. Clinically, disc herniation between L4/5 is commonly associated with symptoms such as low back pain, buttock pain, and radiating leg pain, which affect the sensory and motor functions of the lower limbs. Although the herniated disc at L4/5 does not directly compress the T7–L2 nerve roots to cause abdominal pain, this does not rule out a potential connection between the disc herniation and abdominal pain. The mechanism by which L4 radiculopathy causes abdominal pain is complex, as the L4 dermatome typically involves the knee and lower leg. However, several anatomical pathways explain this phenomenon: 1. Compression of the L4 nerve root. The herniated L4/5 disc leads to compression of the L4 nerve root, which not only affects lower limb sensory and motor function but can also stimulate the sympathetic trunk, leading to autonomic dysfunction. This can result in referred pain in the abdominal region. Pain originating from L4 nerve root compression is transmitted via the paravertebral sympathetic chain to the L1 nerve root and then combines with the visceral sympathetic fibers conveyed by the L1 spinal nerve [9]. Through the mechanism of viscerosomatic convergence in the spinal cord, the brain misinterprets these spinal signals as visceral pain arising from the abdominal organs. Thus, abdominal pain is considered a type of referred pain from L4 nerve root compression. 2. Inflammatory response of the nerve root. The disc herniation may also trigger an inflammatory response in the nerve roots, which could lead to sensory disturbances in the abdominal viscera. Through neuro-reflex mechanisms, disc degeneration can influence the autonomic nervous system of the abdominal cavity, causing abdominal pain that worsens during activity or specific positional changes [10]. 3. The iliohypogastric and ilioinguinal nerves. These nerves, which arise from L1 and L2, primarily innervate the lower abdominal region [11]. Although the L1 and L2 nerve roots do not directly converge with the L4 nerve root, there is an anatomical connection, especially during the formation of the lumbar plexus. This case demonstrates that "abdominal pain" is not exclusive to T7–L2 pathologies. A positive response to a L4 selective nerve root block strongly implicates the L4 root as the pain generator, likely through the autonomic pathways described above. In summary, the pathogenesis of abdominal pain of spinal origin cannot be elucidated by a single mechanism; rather, it is likely the result of multiple interacting pathophysiological factors.

Due to the complex pathogenesis and nonspecific clinical presentation of abdominal pain of spinal origin, the rate of misdiagnosis in clinical practice is high. Therefore, an accurate diagnosis is more critical than immediate treatment. Spinal origin abdominal pain shares similar symptoms with many other systemic diseases, so careful differential diagnosis is necessary during clinical evaluation. Possible differential diagnoses include: 1. Gastritis or peptic ulcers. Often accompanied by acid reflux, nausea, and vomiting, confirmed by gastroscopy showing gastric mucosal changes. 2. Bowel obstruction. Characterized by abdominal pain, bloating, and cessation of gas and stool passage; imaging may show bowel distension and air–fluid levels. 3. Cholecystitis. Presents with right upper abdominal pain radiating to the shoulder or back; ultrasound typically shows gallbladder wall thickening. 4. Acute appendicitis. Characterized by right lower quadrant tenderness, rebound tenderness, and often accompanied by fever and nausea. 5. Somatization disorder. Can present with multi-site pain of varying causes, often related to psychological factors [12].

Therefore, establishing a diagnosis requires clinicians to carefully integrate the patient’s medical history, symptoms, physical examination findings, and auxiliary test results, while rigorously excluding systemic pathologies from other organ systems. Once abdominal pain of spinal origin is diagnosed, therapeutic approaches are varied and primarily focused on addressing the underlying etiology. For patients with mild symptoms, conservative treatments such as medication, physical therapy, and lifestyle changes are typically employed. Nerve block techniques, including spinal nerve root blocks, offer a non-surgical, trial-based approach to pain management and are widely used [13]. For patients with severe symptoms or those whose conditions continue to worsen, surgical intervention is often necessary. For example, posterior lumbar interbody fusion (PLIF), percutaneous endoscopic lumbar discectomy (PELD), and unilateral biportal endoscopic (UBE) discectomy for lumbar intervertebral disc nucleus pulposus removal are used to relieve the compression on the nerve roots, thereby alleviating the clinical symptoms. In the case presented in this article, a spinal nerve root block was initially used for experimental treatment [14, 15]. If the abdominal pain was relieved, visceral organ pathology could be excluded, followed by scheduled surgical intervention to remove the causative disc herniation. This combination of approaches yielded a satisfactory outcome for the patient.

Conclusion

In conclusion, while cases of abdominal pain of spinal origin are uncommon, they hold considerable clinical significance. Particularly in patients presenting with unexplained, intractable abdominal pain, it is crucial to maintain a high index of suspicion for the presence of spinal pathology. Clinicians must comprehensively evaluate the patient's medical history, symptoms, physical signs, and imaging findings to avoid misdiagnosis or oversight. Providing a timely and accurate diagnosis, followed by an appropriate treatment plan, is essential to alleviate suffering and enhance the patient's quality of life.

Abbreviations

FGIDs

Functional gastrointestinal disorders

FD

Functional dyspepsia

IBS

Irritable bowel syndrome

CAPS

Centrally mediated abdominal pain syndrome

CT

Computer tomography

MRI

Magnetic resonance imaging

PELD

Percutaneous endoscopic lumbar discectomy

PLIF

Posterior lumbar intervertebral disc fusion

UBE

Unilateral biportal endoscopic

SNRB

Spinal nerve root block

Author contributions

HDC provided the concept and reviewed the manuscript. CH drafted and conceptualized the manuscript. HZ contributed to drafting the manuscript and provided the initial idea for the study. YL assisted in data collection and compilation, while RZB contributed significantly to data collection.

Funding

There was no financial support or funding for this study.

Data availability

The data supporting the findings of this study are available in the records of Yichang Central People's Hospital, Yichang, Hubei, and can be accessed upon reasonable request.

Declarations

Ethics approval and consent to participate

This case report has been reviewed and approved by the Ethics Committee of Yichang Central People's Hospital. The patient has given written informed consent.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Competing interests

The authors declare no competing interests.