Pott disease or Pott's disease is a form of tuberculosis that occurs outside of the lungs whereby disease is seen in the spinal vertebrae. Tuberculosis can affect several tissues outside of the lungs including the spine, a kind of tuberculous arthritis of the intervertebral joints. The disease is named after Percivall Pott ,a British surgeon. The lower thoracic and upper lumbar vertebrae are the areas of the spine most often affected. The formal name for the disease is tuberculous spondylitis and it is most commonly localized in the thoracic portion of the spine.

Pott’s disease results from haematogenous spread of tuberculosis from other sites, often the lungs. The infection then spreads from two adjacent vertebrae into the adjoining intervertebral disc space. If only one vertebra is affected, the disc is normal, but if two are involved, the disc, which is avascular, cannot receive nutrients and collapses. The disc tissue dies and is broken down by caseation, leading to vertebral narrowing and eventually to vertebral collapse and spinal damage. A dry soft tissue mass often forms and superinfection is rare.

Progressive bone destruction leads to vertebral collapse and kyphosis. The spinal canal can be narrowed by abscesses, granulation tissue, or direct dural invasion, leading to spinal cord compression and neurologic deficits.

The kyphotic deformity is caused by collapse in the anterior spine. Lesions in the thoracic spine are more likely to lead to kyphosis than those in the lumbar spine. A cold abscess can occur if the infection extends to adjacent ligaments and soft tissues. Abscesses in the lumbar region may descend down the sheath of the psoas to the femoral trigone region and eventually erode into the skin.

The presentation of Pott disease depends on the following :

Stage of disease

Affected site

Presence of complications such as neurologic deficits, abscesses, or sinus tracts

Potential constitutional symptoms of Pott disease include fever and weight loss. The reported average duration of symptoms at diagnosis is 4 months but can be considerably longer. This is due to the nonspecific presentation of chronic back pain.

Back pain is the earliest and most common symptom of Pott disease, with patients usually experiencing this problem for weeks before seeking treatment. The pain caused by Pott disease can be spinal or radicular.

Neurologic abnormalities occur in 50% of cases and can include spinal cord compression with paraplegia, paresis, impaired sensation, nerve root pain, and/or cauda equina syndrome.

Cervical spine tuberculosis is a less common presentation but is potentially more serious because severe neurologic complications are more likely. This condition is characterized by pain and stiffness. Patients with lower cervical spine disease can present with dysphagia or stridor. Symptoms can also include torticollis, hoarseness, and neurologic deficits.

The clinical presentation of spinal tuberculosis in patients infected with the human immunodeficiency virus (HIV) is similar to that of patients who are HIV negative; however, spinal tuberculosis seems to be more common in persons infected with HIV.

The physical examination in Pott disease should include the following:

Careful assessment of spinal alignment

Inspection of skin, with attention to detection of sinuses

Abdominal evaluation for subcutaneous flank mass

Meticulous neurologic examination

Although the thoracic and lumbar spinal segments are nearly equally affected in persons with Pott disease, the thoracic spine is frequently reported as the most common site of involvement. Together, these segments make up 80-90% of spinal tuberculosis sites, with the remaining cases of Pott disease occurring in the cervical spine. Almost all patients with Pott disease have some degree of spine deformity (kyphosis).

Examination should reveal local pain related to the affected area or radicular pain. Muscle spasm and rigidity can also be associated.

Large, cold abscesses of paraspinal tissues or psoas muscle may protrude under the inguinal ligament and may erode into the perineum or gluteal area.

Neurologic deficits may occur early in the course of Pott disease. Signs of such deficits depend on the level of spinal cord or nerve root compression.

Pott disease that involves the upper cervical spine can cause rapidly progressive symptoms. Retropharyngeal abscesses occur in almost all cases affecting this part of the spine. Neurologic manifestations occur early and range from a single nerve palsy to hemiparesis or quadriplegia.

A large proportion of patients with Pott disease do not present with extraskeletal disease. In reported series, only 10-38% of cases of Pott disease are associated with extraskeletal tuberculosis.