Pott’s disease is a serious form of tuberculosis infection that attacks the spine, representing the most common type of skeletal tuberculosis. Medically known as tuberculous spondylitis or spinal tuberculosis, this condition is named after the 18th-century English surgeon Percivall Pott. Early identification and treatment are important for managing the infection and preventing severe, long-term complications.
What Defines Pott’s Disease
Pott’s disease is caused by the bacterium Mycobacterium tuberculosis, the same organism responsible for pulmonary tuberculosis. It is classified as a type of extrapulmonary tuberculosis. The infection typically reaches the spine through hematogenous spread, where the bacteria travel through the bloodstream from a primary, often silent, site in the body, such as the lungs or lymph nodes.
The Mycobacterium tuberculosis bacteria settle in the highly vascularized anterior part of the vertebral bodies. The infection causes a destructive process known as osteomyelitis and discitis, leading to bone destruction and instability. This process involves inflammation and the formation of abscesses, which weaken the bony structure.
In adults, the infection often spreads from the vertebral body to the adjacent intervertebral discs, causing the disc tissue to die in a process called caseous necrosis. This destruction leads to a narrowing of the disc space and eventual collapse of the vertebrae. The lower thoracic and upper lumbar regions of the spine are the areas most frequently involved.
How the Infection Manifests
The clinical presentation of Pott’s disease is often insidious, developing slowly over months or even years. Patients may first experience systemic symptoms common to tuberculosis, such as low-grade fever, unexplained weight loss, loss of appetite, and drenching night sweats.
The earliest and most common local symptom is chronic, localized back pain, which often worsens with activity and may be more noticeable at night. This pain is frequently accompanied by stiffness and tenderness over the affected area of the spine. As the disease progresses and the vertebral bodies are destroyed, there is a risk of significant spinal deformity.
Vertebral collapse in the front of the spine causes an abnormal, sharp forward angulation known as kyphosis, or a gibbus deformity. Neurological compromise is a common complication. This involves compression of the spinal cord or nerve roots by abscesses, granulation tissue, or bone fragments from the collapsed vertebrae.
This compression can lead to symptoms like weakness, numbness, or even paralysis, a condition specifically termed Pott’s paraplegia. The severity and location of the infection determine the type of neurological deficit; for example, a cervical spine lesion can lead to serious consequences, including hemiparesis or quadriplegia. Large abscesses can also form and track down muscles, such as the psoas muscle in the lumbar region.
Confirmation and Course of Treatment
Confirming a diagnosis of Pott’s disease involves a combination of clinical assessment, laboratory tests, and advanced imaging. A physical examination may reveal local spinal tenderness, muscle spasm, or an established kyphotic deformity. Blood tests often show elevated inflammatory markers like Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP).
Imaging studies are essential for assessing the extent of spinal damage and potential cord compression. X-rays can show vertebral destruction and collapse, while Computed Tomography (CT) scans provide better detail of the bone structure. Magnetic Resonance Imaging (MRI) is the preferred method for evaluating soft tissue involvement, such as abscesses and the degree of spinal cord compression.
A definitive diagnosis requires obtaining a tissue sample, typically through an image-guided needle aspiration or surgical biopsy, to perform mycobacterial cultures and histological analysis. This confirms the presence of Mycobacterium tuberculosis and determines the susceptibility of the bacteria to different drugs.
The primary treatment for Pott’s disease is a prolonged course of multi-drug anti-tuberculosis therapy. The standard regimen often involves four first-line drugs—isoniazid, rifampin, pyrazinamide, and ethambutol—administered together for an initial period, followed by a continuation phase with a reduced number of drugs. The total duration of this chemotherapy typically ranges from 6 to 18 months, depending on the severity of the disease and the patient’s response.
Surgical intervention may be necessary for specific indications, such as significant spinal instability, a severe kyphotic deformity, or a worsening neurological deficit. The surgical procedure may involve debridement to remove infected tissue and abscesses, as well as stabilization of the spine using instrumentation.