Baastrup's Disease: A Comprehensive Overview

Baastrup’s disease, also known as kissing spine syndrome and interspinous bursitis, results from adjacent spinous processes in the lumbar spine rubbing against each other and resulting in a degenerative hypertrophy and inflammatory changes. It was first described in 1933 and leads to enlargement, flattening and reactive sclerosis of interspinous surfaces. Baastrup disease is frequently missed by clinicians due to lack of knowledge or poor imaging technique. As a result, this relatively common pathology is largely underdiagnosed and subsequently mistreated [1].

Case INTRODUCTION

A 21 year old male college football lineman presents with low back discomfort over the past 2-3 months. He has been having low back discomfort while playing that gets worse while he is engaged with another opponent with his lumbar spine in extension. He does seem to get some relief leaning forward. There is some radiation up his spine, but no radiation down into his legs. On examination, he has no weakness. He is tender to palpation over the L4-L5 interspinous space and has some mild spasm on the left paraspinal musculature of the lumbar spine on the left. He did have plain film x-rays and an MRI of his lumbar spine that did not show any pars defect or spinal stenosis. There was moderate interspinous bursitis. What is the most likely diagnosis?

A) Spondylolysis
B) Central canal stenosis
C) Disc herniation
D) Baastrup’s disease

This disease is commonly seen among the elderly and has been described in thirteen percent of professional heavy motor vehicle drivers [2]. It is most commonly diagnosed at the L3 through L5 levels. The majority of cases affect one level, but as many as five levels have been reported. It is associated with older age, central canal stenosis, bulging discs and anterolisthesis [3]. Risk factors include excessive lordosis resulting in mechanical pressure and repetitive strain on the interspinous ligament, trauma and degenerative disc disease. What makes it interesting for sports medicine providers is that it has been noted in 6.3 % of college athletes with gymnasts being most common.

Etiology

Etiology is normally attributed to repetitive flexion and extension of the spine. Patients with Baastrup’s disease can have excessive lordosis with a resultant mechanical pressure that causes repetitive stress on the interspinous ligaments and adjacent spinous processes, which can lead to degeneration of the interspinous ligaments . The abnormal contact between adjacent spinous processes can also lead to pseudoarthrosis and formation of an adventitious bursa and intraspinal cysts or bursitis may also develop. The bursa is thought to appear as a result of synovial articulation formation.

Figure 1. Illustration of Baastrup’s disease. Adopted from [10].

Presentation

The most commonly presenting symptoms is pain with extension and relief with flexion. This, among other things, can cause some confusion with diagnosis, as there are other pathologies that worsen with extension. The pain is normally in the midline lumbar region with radiation along the spine with lateral radiation being very uncommon. There is often tenderness to palpation if the affected interspinous space. Axial loading of the spine in extension or hyperextension may also exacerbate symptoms on physical examination.

Diagnosis

Diagnosis can be challenging and imaging is usually needed. The “kissing” if closely approximated spinous processes can be seen on lateral plain films with sometimes visible sclerosis of the articulating surfaces. It may be beneficial to get flexion and extension views fir improved visualization. Computed Tomography (CT) can visualize the bony changes and show degenerative changes in greater detail. However, plain films and CT scans are not suitable for demonstrating pathological changes in the soft tissues of the spine.

This makes magnetic resonance imaging (MRI) the most sensitive imaging modality. Interspinous bursitis may precede the osseous changes of the spinous process, in which MRI has been shown to be superior for detecting when compared to other imaging modalities. MRI may show reactive sclerosis and hypertrophy of the spinous processes — which may have flattened and enlarged articulating surfaces. There may also be associated edema at the level of the interspinous ligament, and provides insight into the degree to which the posterior thecal sac is compressed.

Figure 2. Mild lumbar spondylosis with prominent, hypertrophic spinous processes, contacting one another between L3 and L5 with adjacent sclerosis. Adopted from [4].

Treatment

There is paucity of evidence in regards to the treatment for Baastrup’s disease. Physical therapy can be attempted and focus should be on reducing interspinous strain and lordosis, increasing core strength and improving hip mobility. This should be done while limiting any axial loading with the spine in extension. It can play an important role in long-term management and many will choose physical therapy as a first choice. Percutaneous injections with long-acting corticosteroids and/or local anesthetics have been used to treat inflammation and pain and can help localize pain [5-7]. In one series with 17 patients, fifteen of seventeen reported the treatment met expectations and had significant relief of pain at 1.4 years [7].

Likewise, in a larger study of 55 patients with Baastrup’s disease, patients underwent percutaneous injection of a long-acting corticosteroid with local anesthetic into the interspinous ligament between the adjacent spinous processes. Twenty-two percent of patients underwent a second infiltration within 7-10 days of the first. There was an overall decrease in pain and improvement in ambulation [8]. Surgical techniques have been employed including excision of the bursa and osteotomy to shorten the offending spinous processes [8]. Other studies suggest that these osteotomy-only techniques are ineffective in relieving symptoms [9]. Patients with satisfactory post spinous process resection results had undergone a diagnostic or therapeutic injection prior to surgical intervention [7].

Figure 3. (A) Profile view of X-ray films showed that these spinous processes did not contact in flexion position, (B) but did contact in extension position (arrows). (C) Magnetic resonance imaging showed low signal intensity on T1-weighted imagesand (D) high signal intensity on T2-weighted imagesof the interspinous ligament (arrows). Adopted from [11].

Summary

In summary, Baastrup’s disease is a largely underdiagnosed entity. Its incidence increases with age, but can be present in athletes in high school or college. It can occur either independently or together with symptoms and signs of other spine disorders, which can include spondylolithesis and spondylosis with osteophyte formation and loss of disc height. Pain usually worsens with extension and is relieved with flexion and there is typically tenderness with finger pressure at the level of interest. Lateral, flexion and extension plain films should be done, but MRI is the most sensitive imaging modality. Suspicion should increase if there is no spinal stenosis or spondylosis. It may be a process for diagnosis with diagnostic and therapeutic injections if there are associated conditions. Interspinous long-acting corticosteroid injections are frequently used and clear diagnosis should occur if surgical intervention is proposed.

– More Back Pain from Sports Medicine Review: https://www.sportsmedreview.com/by-joint/back/

Case Conclusion

D is the correct answer. Baastrup’s disease, also known as kissing spine syndrome and interspinous bursitis, results from adjacent spinous processes in the lumbar spine rubbing against each other and resulting in a degenerative hypertrophy and inflammatory changes. The most commonly presenting symptoms is pain with extension and relief with flexion. The pain is normally in the midline lumbar region with radiation along the spine with lateral radiation being very uncommon. There is often tenderness to palpation if the affected interspinous space. The MRI results mention no pars defect of spinal stenosis and there is no radiation of pain down into the legs, making the other diagnoses less likely.

Alonso, Fernando, et al. “Baastrup’s disease: a comprehensive review of the extant literature.” World neurosurgery 101 (2017): 331-334.

References

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