INTRODUCTION
Low back pain (LBP), the most prevalent musculoskeletal complaint globally, primarily attracts research attention to structures such as ligaments, facet joints, vertebral periosteum, paravertebral musculature and fascia, and spinal nerve roots. While lumbar degenerative disc disease is frequently associated with LBP1), advanced imaging modalities surprisingly reveal an absence of a definitive pathoanatomical diagnosis in 85% of patients presenting with isolated LBP (pain confined to the lumbar region without radiating symptoms or neurological deficits)2), and the clinical features and etiology of LBP remain poorly understood8). This necessitates moving beyond radiographic findings for accurate diagnosis, emphasizing an understanding of pain origin, meticulous clinical observation, and a focus on specific clinical features.
Maigne syndrome, also known as thoracolumbar syndrome, is a heterogeneous term that encompasses arthropathy of various facet joints, particularly T12-L1, and the entrapment of the medial branch of the superior cluneal nerve, causing unilateral LBP that involves the iliac crest and buttocks1,6,9); it is often misdiagnosed as a lumbar spine disorder. The authors present two cases of osteoporotic vertebral compression fractures (OVCFs) where patients displayed atypical pain patterns. Despite extended conservative treatment, both individuals reported persistent low back and buttock pain rather than pain at the fracture site in the thoracolumbar region. The authors analyze the surgical outcomes and explore potential etiologies contributing to this unusual symptom presentation.
CASE REPORT
Case 1
An 82-year-old woman presented with persistent low back and right buttock pain two months after a fall. She had been diagnosed with an L1 compression fracture (Fig. 1A) and treated conservatively elsewhere, experiencing mild improvement in her thoracolumbar back pain. However, upon sitting or rising, she developed significant right-sided low back and buttock pain radiating to the lateral iliac crest. This pain significantly impacted her daily activities, worsening with prolonged sitting and becoming intolerable. Physical examination revealed mild thoracolumbar tenderness, but severe pain arose from trigger points in the right buttock. Trigger point injections offered no relief, while right L1 selective nerve root and facet block provided dramatic but short-lived pain reduction. Lumbar computed tomography scan revealed a complex fracture line at L1 with Kummel disease, characterized by an intraosseous cleft and approximately 30% height loss on lateral imaging (Fig. 1B). Guided by the local block and imaging findings, we elected to proceed with surgery for L1 Kummel disease.
The patient underwent transpedicular cage insertion with posterior pedicle screw fixation for the lesion (Fig. 1C). This intervention resulted in a significant improvement in her preoperative symptoms. Postoperatively, there was a restoration of 80% of the pre-fracture vertebral body height. She experienced a substantial reduction in low back and buttock pain, allowing for prolonged sitting without discomfort and effortless transitions between sitting and standing. Notably, her numeric rating scale (NRS) pain score decreased from 8 to 1 immediately after surgery and remained stable at 8 months follow-up, demonstrating sustained pain relief.
Case 2
A 72-year-old woman presented with a two-month history of worsening lower back pain and bilateral buttock pain. These symptoms began after a fall and subsequent diagnosis of an L1 compression fracture at another hospital, where she underwent vertebroplasty. Despite the procedure, the patient experienced limited improvement and reported spending most of her day lying down due to severe bilateral buttock pain that made sitting extremely difficult. Notably, both the lower back and buttock pain completely resolved when lying down but worsened and limited her ability to bend backward. Neurological examination revealed no abnormalities, and physical examination showed mild direct tenderness in the thoracolumbar area but no specific trigger points in the lower back or buttocks. Her bone mineral density score was measured at -3.1, and radiographs at admission demonstrated progressive vertebral body height loss and a kyphotic deformity (Fig. 2A, B).
Upon detecting a progressive kyphotic deformity, the patient underwent L1 corpectomy and posterior pedicle screw fixation (Fig. 2C). This intervention resulted in immediate and significant improvement in her low back and bilateral buttock pain. Postoperatively, she was able to sit for prolonged periods and perform lumbar extension exercises without significant discomfort. Notably, her NRS pain score decreased from 8 preoperatively to 3 at the first follow-up and remained consistently low and stable throughout the 7-month follow-up period, with no evidence of recurrence.
DISCUSSION
OVCFs are the most common type of osteoporotic fracture, affecting an estimated 1.4 million people globally each year4). Notably, in Korea, OVCFs can occur spontaneously in individuals with osteoporosis, impacting roughly 25% of women aged 70 or older and nearly 50% of women aged 80 or older7). These fractures, most commonly seen in the thoracolumbar transition zone with a height reduction of over 15% in the vertebral body10), are a significant healthcare issue due to pain-induced physical and psychological impairment, as well as potential internal complications such as gastrointestinal and respiratory dysfunction caused by chronic thoracolumbar kyphosis5). In clinical practice, when a diagnosis is established, the typical initial treatment involves conservative pain management, possibly including back support and physiotherapy. This approach is favored for its noninvasive nature. Additionally, a significant number of patients experiencing fractures tend to see their chronic back pain resolve spontaneously within 8 to 12 weeks11). Minimally invasive vertebral augmentation techniques, percutaneous vertebroplasty, and balloon-assisted kyphoplasty, offer established methods for restoring vertebral height, alleviating pain, and mitigating spinal deformity. However, surgical intervention may become necessary when those therapies fail to achieve union, leading to avascular necrosis, or in cases of severe vertebral collapse progression, kyphosis, or neurological manifestations arising from spinal cord compression. In authors’ cases, the compression fracture deteriorated into Kummel disease after conservative treatment, or the kyphotic deformity progressed after vertebroplasty, leading to surgical treatment. However, before deciding on surgical treatment, it is important to note that the persistent pain was around the buttock area, away from the fracture site. This, along with the imaging findings, caused confusion and hesitation in the decision-making process.
Due to its non-specific presentation and overlap with other common causes of buttock pain, Maigne syndrome is often overlooked as a potential diagnosis. First described in 1957 by Strong and Davila13), who reported superior cluneal nerve pathology in nearly 10% of their patients hospitalized for buttock pain, the syndrome was further characterized by Dr. Maigne9). He observed a 40% prevalence of Maigne syndrome in a population of 350 patients presenting with buttock pain. Furthermore, his 2-year follow-up study on 19 patients who underwent surgical intervention for cluneal nerve entrapment at the iliac crest demonstrated positive outcomes in over two-thirds of the patients (13 out of 19)8).
Maigne syndrome can be divided into two distinct entities, the ‘central variant’ also referred to as thoracolumbar junction syndrome and the ‘peripheral variant’ also referred to as cluneal nerve entrapment syndrome. The central variant of thoracolumbar junction syndrome involves pathology at the thoracolumbar junction. The main pathology of the Maigne syndrome is a result of spinal nerve irritation secondary to ligamentous, capsule, and or facet joint degeneration. At the thoracolumbar junction, the T12 and L1 spinal nerves with their anterior and posterior rami are the main neural element in Maigne syndrome and have a distinct innervation pattern. The ventral ramus innervates the inferior abdomen, groin, and pubic area. The dorsal ramus innervates the subcutaneous tissues of the superior gluteal and inferior lumbar regions. This pattern of innervation explains the possible diffuse nature of symptoms associated with the referred phenomena and nerve irritation and the potential abnormal afferent input to the central nervous system in pain syndromes such as Maigne syndrome, including LBP, pseudo-sciatica, and hip pain.
The presented cases highlight the complexity of diagnosing LBP in the context of thoracolumbar fractures, particularly when non-specific symptoms, such as buttock pain, overshadow localized thoracolumbar discomfort. The phenomenon of persistent pain that is seemingly unrelated to the fracture site may be indicative of conditions like Maigne syndrome, which is often underdiagnosed due to overlapping symptoms with other lumbar disorders. This underscores the need for a thorough understanding of the anatomy and pathology of the superior cluneal nerves and their involvement in atypical pain presentations.
Maigne syndrome, or thoracolumbar junction syndrome, involves the entrapment of nerves such as the superior cluneal nerve, leading to buttock and iliac crest pain, which may mimic the pain experienced in lumbar disc disease or sacroiliac joint dysfunction. As noted by Isu and colleagues3), entrapment neuropathy of the superior cluneal nerve can often be a source of diagnostic confusion, particularly in elderly patients who present with OVCFs. The nerve entrapment mechanism, which can cause pain along the iliac crest and radiate towards the buttocks, is frequently overlooked, as seen in the described cases.
The identification of trigger points and response to nerve blocks proved pivotal in differentiating Maigne syndrome from other causes of LBP. Notably, the dramatic pain relief following the selective nerve root block or facet injections in our patients reinforced the role of nerve entrapment as a significant contributor to their pain. This observation aligns with findings by Randhawa et al.12), who reported that timely intervention could result in substantial symptom alleviation for patients with Maigne syndrome. Moreover, the progression of vertebral fractures into Kummel disease following conservative treatment suggests that initial management strategies might not always suffice, particularly in elderly osteoporotic patients. Surgical interventions, including corpectomy and pedicle screw fixation, were necessary to address both the mechanical instability and atypical pain syndromes resulting from these fractures. The success of these surgeries in alleviating both the local thoracolumbar pain and the referred buttock pain points to the importance of a comprehensive approach that integrates the treatment of both spinal fractures and associated nerve entrapments. In clinical practice, it is crucial to adopt a multi-faceted diagnostic approach that includes imaging studies, identification of atypical pain patterns, and nerve blocks. This strategy can improve outcomes by reducing the delay in addressing underlying conditions like Maigne syndrome, which are otherwise missed when focusing solely on radiographic findings.
CONCLUSION
The described cases emphasize the importance of considering atypical pain patterns and nerve entrapment syndromes, such as Maigne syndrome, in patients presenting with persistent low back and buttock pain following thoracolumbar fractures. The effective surgical outcomes following the identification of superior cluneal nerve entrapment highlight the role of targeted interventions in managing complex pain syndromes. Clinicians should remain vigilant for non-specific presentations of LBP and consider peripheral nerve involvement, particularly when conventional treatments fail to provide relief. Early diagnosis and intervention can significantly enhance patient outcomes, reduce chronic pain, and improve overall quality of life.
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