Bertolotti Syndrome is a congenital spinal anomaly that often presents as a perplexing cause of chronic lower back pain, especially in younger adults. Named after Italian physician Mario Bertolotti, who first described it in 1917, the syndrome is a clinical diagnosis made when a specific anatomical variant is identified as the definitive source of a patient’s discomfort. This condition is frequently overlooked because the pain it generates can mimic more common spinal issues like sacroiliac joint dysfunction or disc degeneration.
Defining the Anatomical Abnormality
The syndrome is fundamentally linked to the presence of a Lumbosacral Transitional Vertebra (LSTV), a structural variation where the lowest lumbar vertebra, typically L5, displays characteristics of the sacrum. This occurs when the transverse process, a bony projection extending sideways from the vertebra, is abnormally enlarged. This enlarged process then articulates with, or partially fuses to, the sacrum or the ilium (pelvic bone).
This articulation creates an abnormal joint, known as a pseudoarthrosis or “false joint,” which lacks the cushioning and mobility of a normal spinal disc. The resulting bone-on-bone contact causes mechanical irritation, inflammation, and altered movement patterns in the lower back. This structural change is present from birth, but it usually becomes symptomatic in a person’s late twenties or early thirties as inflammation and degenerative changes accumulate.
Castellvi Classification
Anatomists use the Castellvi classification system to categorize the different presentations of LSTV, ranging from Type I, which involves an enlarged but non-articulating transverse process, to Type IV, which represents a mixed pattern. The most common types associated with the development of Bertolotti Syndrome are those that involve an articulation (Type II) or a complete fusion (Type III) between the L5 transverse process and the sacrum.
Recognizing the Specific Symptoms
The discomfort associated with Bertolotti Syndrome is commonly characterized by chronic, localized lower back pain that may be persistent or recurrent. This pain is often unilateral, occurring on the side of the enlarged transverse process that forms the pseudoarthrosis with the sacrum. The mechanical stress at this abnormal junction is the primary pain generator.
The pain can intensify with activities that involve prolonged standing, walking, or arching backward, as these movements increase pressure on the false joint. Patients may also experience pain that radiates into the buttock, hip, or groin area, which can sometimes be confused with sciatica or sacroiliac joint pain. The condition can also cause muscle spasms and stiffness in the lower back region.
The altered biomechanics of the spine can also lead to increased stress at the spinal segment immediately above the LSTV, potentially causing early degeneration of the L4-L5 disc. However, the specific pain felt by the patient is typically traced back to the inflamed pseudoarthrosis itself.
Confirmation Through Medical Imaging
A physical examination for Bertolotti Syndrome is often nonspecific, which makes medical imaging a mandatory step for accurate confirmation. The initial diagnostic tool is usually a standard radiograph (X-ray) of the lumbosacral region. These images are used to visualize the bony anatomy and clearly identify the enlarged transverse process of L5 and its articulation or fusion with the sacrum or ilium.
Advanced imaging techniques like a Computed Tomography (CT) scan can provide a more detailed, three-dimensional view of the bony structures, which is particularly helpful in classifying the LSTV and assessing the degree of articulation. However, the presence of an LSTV on imaging alone does not confirm the syndrome, as many people with LSTV remain asymptomatic.
The definitive step in diagnosis is a fluoroscopically-guided diagnostic injection of a local anesthetic, often combined with a corticosteroid, directly into the pseudoarthrosis. If the patient experiences a significant, temporary reduction in pain (typically 80% or more), this positive response confirms that the LSTV is the source of the chronic discomfort, establishing the clinical diagnosis.
Options for Pain Management
Management for Bertolotti Syndrome follows a tiered approach, beginning with conservative, non-invasive methods. Initial treatment often involves physical therapy aimed at strengthening the core muscles and improving posture to stabilize the spine and reduce mechanical strain on the abnormal joint. Anti-inflammatory medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), are often prescribed to manage the pain and reduce inflammation at the site of the pseudoarthrosis.
If conservative measures are not effective, the next step is often therapeutic injections. These interventional procedures, similar to the diagnostic injections, involve injecting a mixture of local anesthetic and corticosteroid directly into the painful pseudoarthrosis to provide longer-lasting relief. For patients who respond well to injections but whose pain returns, a minimally invasive procedure called radiofrequency ablation (RFA) may be considered, which uses heat to interrupt the pain signals from the joint. Surgical intervention is generally reserved for individuals whose pain is resistant to all conservative and interventional treatments and whose pain is definitively localized to the LSTV. The most common surgical approach is processectomy, which involves the removal of the enlarged transverse process and the painful pseudoarthrosis. Spinal fusion may be considered if the LSTV is associated with instability or significant degeneration at the adjacent disc level.