What is Baastrup disease?

Baastrup Disease (Kissing Spine Syndrome)

Baastrup disease is a degenerative condition of the spine characterized by close approximation or contact between adjacent spinous processes, most commonly affecting the lumbar spine at the L4-L5 level, resulting in chronic low back pain that worsens with extension and improves with flexion. 1

Epidemiology and Pathophysiology

• Baastrup disease is more prevalent in individuals over 70 years of age with no gender predilection 1
• Population-based studies show a decade-on-decade increase in incidence 2
• The male to female ratio is approximately 1.3:1 2
• Excessive lordosis is a common contributing factor, producing mechanical pressure that causes repetitive strains of the interspinous ligament with subsequent degeneration and collapse 1

Clinical Presentation

• The hallmark symptom is midline low back pain that:
  • Worsens during extension of the spine 1
  • Improves during flexion 1
  • Is exacerbated by direct finger pressure over the affected level 1
• Pain is typically chronic and persistent, often lasting for several years before diagnosis 3
• The condition is frequently underdiagnosed and misdiagnosed as other causes of low back pain 2

Diagnostic Approach

Imaging Studies

• Standard and dynamic flexion-extension radiographs of the lumbar spine are useful initial studies (used in 16.2% of cases in systematic review) 2
• MRI is the most commonly used diagnostic modality (56.2% of cases) and can identify:
  • Close approximation of adjacent spinous processes 2
  • Edema at contact surfaces 1
  • Cystic lesions between spinous processes 1
  • Sclerosis, flattening, and enlargement of the articulating surfaces 1
  • Bursitis and occasionally epidural cysts or midline epidural fibrotic masses 1
• CT scan is also frequently used (43.9% of cases) to evaluate bony changes 2
• FDG PET/CT has been used in some cases (5.9%) but is not a first-line imaging modality 2
• Bone scintigraphy with SPECT/CT can show increased uptake at affected levels and help distinguish from metastatic disease in patients with cancer history 4

Management Options

Treatment approaches for Baastrup disease include:

Conservative Management

• First-line treatment includes anti-inflammatory drugs and physical therapy (used in 35.7% of reported cases) 2
• Physical therapy focusing on core strengthening and posture correction may help reduce excessive lordosis 1

Interventional Procedures

• Percutaneous infiltrations with corticosteroids and local anesthetics (28.9% of cases) can provide diagnostic confirmation and therapeutic benefit 2, 3
• Interspinous injections target the inflamed bursa or pseudoarthrosis between spinous processes 1

Surgical Management

• Surgical decompression is utilized in more severe or refractory cases (70.7% of surgically treated patients) 2
• Surgical options include:
  • Excision of the bursa between spinous processes 1
  • Partial or complete osteotomy of the affected spinous processes 1
• Surgery may be considered when conservative measures and injections fail to provide adequate relief 3

Clinical Pitfalls and Special Considerations

• Baastrup disease must be distinguished from other causes of low back pain, including facet joint arthropathy, disc herniation, and spinal stenosis 1
• In patients with a history of cancer, Baastrup disease can be mistaken for spinal metastasis on imaging studies 4
• The condition may not always show obvious inflammation on imaging despite clinical symptoms, making diagnosis challenging in some cases 3
• There is a need for randomized clinical trials to establish optimal treatment protocols, as current evidence is largely based on case reports and retrospective studies 2

Prognosis

• With appropriate diagnosis and management, patients can experience significant pain relief and return to normal social and professional activities 3
• The condition is generally not associated with neurological deficits but can cause chronic pain and functional limitation if left untreated 1