Baastrup disease: Lumbar interspinous bursitis

This disease is named after Danish radiologist (1855 - 1950) Christian Ingerslev Baastrup.

Introduction & Epidemiology:
It is claimed that Baastrup disease is responsible for intractable LBA (1). Though it is reported in mostly lumbar spine it’s cervical spine variant is also reported (2). Gardella called Baastrup disease as spinous process syndrome (3). It is reported in many occupational areas such as miners (4) & heavy vehicle drivers (8). Among of much debate now it is considered mostly a case of aging related problem. Let us discuss in little more detail:

The Baastrup disease is characterized by the development of abnormal contact between adjacent spinous processes of the lumbar spine that results in rubbing against each other producing a bursitis which further result in focal midline pain and tenderness relieved by flexion and aggravated by extension.

Epidemiology:
It tends to be more common in the elderly. According to Maes et al (5) the prevalence of Baastrup disease is 8.2% (44 of 539) of the study population. In this study the lumbar spine was studied. This study also revealed that Baastrup disease is associated with age (P = 0.001), central canal stenosis (P = 0.0013), disc bulging (P = 0.0341), and anterolisthesis (P = 0.0429). There were no associations between Baastrup disease and disc degeneration, disc herniation, endplate findings, retrolisthesis, scoliosis, lordosis, or gender.
According to Kwong et al (6); Baastrup disease occurs with high frequency among the elderly. This study suggests that Baastrup disease develops with increasing age and is part of the expected degenerative changes in the aging spine. According to these researchers (6) in their CT scan based study of 1008 patients evidence of Baastrup disease was found in 413 patients (41.0%). A decade-on-decade increase in frequency was found with a peak of 81.3% among patients older than 80 years. As many as five spinal levels were found to be affected in some patients (4.1% of 413), but in most patients (35.4%), one level was affected. Baastrup disease was most common at L4-L5. Associated degenerative changes were found at almost all affected levels (899/901). Hence Kwong et al urged the clinicians that because of the nearly universal association with other degenerative changes, caution must be taken before diagnosing Baastrup disease as the cause of back pain.
According to Hanger (8) prevalence rate of this disease in a group of heavy automotive vehicles drivers is 13% of the test population.

Pathology
Patients with Baastrup disease may experience pain owing to irritation of the periosteum or adventitial bursae between abutting spinous processes. This process can result in a degenerative hypertrophy, inflammatory change and even a pseudarthrosis with bursa formation. This interspinous bursa may extend between the ligamentum flavae in the midline forming an epidural cyst and further contributing to the already existing canal stenosis.
This condition is usually seen patients with excessive lordosis of the lumbar spine. Often Baastrup lesions of the lumbar spine are located at L3-L4 and L4-L5 segments (8).

Palpation
I myself employ the following technique to find a Interspinous bursa is swollen or not.
First the spinous processes are palpated. The gap between the spinous process (Interspinous area) is located and palpating finger (usually the thumb) is slided on the slope following a parallel path way to that of laminas. Reaching on to the area between the spinous process from the side is easy & if Baastrup disease is present then obviously high degree of tenderness is elicited.This palpation also gives us the idea if the crowding of (kissing of ) spinous process as compared with other interspinous spaces & further it may reveal the tissue texture of the local tissue. Inflammed bursa with cyst may impart a "bouggy" feeling to the palpating hand. 

Radiographic features (9)
Plain film and CT
 •    often shows close approximation and contact of adjacent spinous processes (kissing spines)
•    there is resultant enlargement, flattening and reactive sclerosis of apposing interspinous surfaces.

MRI
May demonstrate interspinous bursal fluid and a postero-central epidural cyst(s). MRI can be very helpful in determining whether there is resulting posterior compression of the thecal sac.

Baastrup's sign: Also known as kissing spine, is an radiographic sign. It is characterized by posterior spinous processes 'kissing' and touching one another on sagittal plane.

Treatment (9)
Both conservative and surgical options are available for treatment. Local steroid injection into the interspinous processes will often ease the back pain. Surgical options include interspinous process decompression devices (e.g, Wallis system, X STOP), and steroid / local anaesthetic injection into the bursa.

Physiotherapy:

No references are there about physiotherapy. However electro-analgesia & thermo-analgesia are quite effective. SWD, PSWD, MWD & FIR exert powerful anti-inflammatory effect with thermo-analgesia. IFT gives anti-inflammatory effect with electro-analgesia. UST in pulsed mode directed appropriately to the focal tissue is both anti-inflammatory & analgesic.
Manual mobilization techniques are tried once the local tenderness is less. Contrast heat in acute inflammation & Hot fomentation thrice a day is also very effective in long standing cases which should be used as a home remedy. Egronomic corrective methods & postural awareness are of utmost importance as they may be primary factor that produced such a disorder. Manual therapists well versed with soft tissue & fascial techniques should try out techniques that may lengthen the thoracolumbar fascia.
The outcome of physiotherapy is so satisfactory that author opine on his clinical experience, steroid infiltration & surgery are rarest of rare probabilities to be employed. 

References:
1. FERNANDEZ DE LA MELA I; Medicamenta (Madr). 1951 Dec 10;9(210):404-5.[Lumbar interspinal nearthrosis (Baastrup disease) as responsible for some intractable backaches].

2. VIALLET P J Radiol Electrol Arch Electr Medicale. 1950;31(3-4):206-7. [Two cases of cervical localization of Baastrup disease].

3. GARDELLA G; Ann Radiol Diagn (Bologna). 1952;24(4):260-74.[Spinous process syndrome (Baastrup disease)].

4. Gajdek D; Chir Narzadow Ruchu Ortop Pol. 1976;41(2):171-4. Polish. No abstract available. [Baastrup syndrome of the lumbar spine in miners].

5. Maes R et al; Spine (Phila Pa 1976). 2008 Apr 1;33(7):E211-5. [Lumbar interspinous bursitis (Baastrup disease) in a symptomatic population: prevalence on magnetic resonance imaging.]

6. Kwong Y et al AJR Am J Roentgenol. 2011 May;196(5):1156-9. MDCT findings in Baastrup disease: disease or normal feature of the aging spine?

7. Pinto PS et al Clin Imaging. 2004 May-Jun;28(3):219-22. [Spinous process fractures associated with Baastrup disease.]

8. Hagner W; Med Pr. 1988;39(1):65-70. [Baastrup's disease of the lumbar segment of the spine among drivers of heavy motor vehicles].

9. http://radiopaedia.org/articles/baastrup_syndrome