Pots disease

Pott’s disease, also known as spinal tuberculosis, is a form of extrapulmonary tuberculosis that primarily affects the vertebral column. It is a significant cause of spinal deformities and neurological complications worldwide, particularly in regions with high tuberculosis prevalence. Early recognition and treatment are crucial to prevent permanent disability.

Introduction

Pott’s disease is named after Sir Percivall Pott, who first described the association between spinal deformities and tuberculosis of the spine. The disease results from infection of the vertebrae by Mycobacterium tuberculosis, leading to bone destruction, spinal instability, and potential neurological deficits. It commonly affects the thoracic and lumbar regions of the spine and can present with a variety of systemic and local symptoms.

Etiology and Pathogenesis

Mycobacterium tuberculosis infection

The primary causative agent of Pott’s disease is Mycobacterium tuberculosis. The bacteria typically originate from a primary focus, often the lungs, and spread to the spine through hematogenous dissemination. Rarely, direct extension from adjacent infected tissues can also lead to spinal involvement.

Route of infection

• Hematogenous spread: The most common pathway, where bacteria travel through the bloodstream from a primary site to the vertebral bodies.
• Direct extension: Infection spreads from adjacent structures, such as psoas abscesses or infected lymph nodes, to the vertebral column.

Pathophysiology

• Vertebral body involvement: The infection usually begins in the anterior portion of the vertebral body, leading to gradual bone destruction.
• Intervertebral disc destruction: The intervertebral discs are often affected secondarily, causing collapse and segmental instability.
• Paravertebral abscess formation: Caseous necrosis and abscesses can form adjacent to the affected vertebrae, sometimes tracking along fascial planes to distant sites.

Risk Factors

Pott’s disease can affect individuals of any age, but certain factors increase susceptibility to spinal tuberculosis. Identifying these risk factors is important for early detection and prevention.

• Immunocompromised states: Conditions such as HIV infection, diabetes mellitus, or prolonged corticosteroid therapy can impair immunity and increase the risk of tuberculosis infection.
• Malnutrition: Poor nutritional status weakens the immune system, making individuals more vulnerable to Mycobacterium tuberculosis.
• Previous tuberculosis exposure: A history of pulmonary or extrapulmonary tuberculosis increases the likelihood of secondary spinal involvement.
• Socioeconomic factors: Overcrowding, poor sanitation, and limited access to healthcare contribute to higher incidence of tuberculosis in certain populations.

Clinical Features

General symptoms

• Fever
• Night sweats
• Weight loss
• Fatigue and malaise

Spinal manifestations

• Localized back pain, often progressive and worse at night
• Kyphotic deformity due to vertebral collapse
• Paravertebral swelling or palpable masses from abscess formation
• Reduced spinal mobility and stiffness

Neurological complications

• Radiculopathy characterized by pain, numbness, or tingling along the nerve distribution
• Myelopathy resulting in weakness, spasticity, or sensory deficits
• Severe cases may progress to partial or complete paralysis if spinal cord compression occurs

Diagnosis

Clinical examination

• Inspection and palpation: Evaluation for spinal deformities, localized tenderness, and paravertebral swelling.
• Neurological assessment: Examination of motor strength, sensory function, reflexes, and gait to detect nerve involvement.

Laboratory investigations

• Complete blood count: May reveal anemia or leukocytosis.
• ESR and CRP: Elevated erythrocyte sedimentation rate and C-reactive protein indicate active inflammation.
• Tuberculin skin test and Interferon Gamma Release Assay (IGRA): Support evidence of tuberculosis infection.

Imaging studies

• X-ray: Can show vertebral body destruction, disc space narrowing, and kyphotic deformity.
• MRI: Preferred modality for early detection, evaluation of soft tissue involvement, and spinal cord compression.
• CT scan: Useful for assessing bony destruction and planning surgical intervention.

Microbiological and histopathological confirmation

• Biopsy: Tissue sampling from the affected vertebra or abscess to confirm tuberculosis.
• Culture for Mycobacterium tuberculosis: Confirms diagnosis and allows drug susceptibility testing.

Differential Diagnosis

Several conditions may mimic the clinical and radiological features of Pott’s disease. Accurate differentiation is essential to guide appropriate management.

• Pyogenic spondylitis, typically caused by bacterial infections such as Staphylococcus aureus
• Metastatic spinal disease from primary cancers of the breast, lung, or prostate
• Osteoporotic vertebral collapse, especially in elderly patients
• Other granulomatous infections, such as brucellosis or fungal spondylitis

Management

Medical treatment

• Anti-tubercular therapy (ATT) regimen: Standard first-line treatment includes a combination of isoniazid, rifampicin, pyrazinamide, and ethambutol.
• Duration of therapy: Typically extends for 9 to 12 months, depending on severity and response to treatment.
• Monitoring: Regular assessment for drug side effects, liver function tests, and adherence to therapy is essential.

Surgical management

• Indications: Severe neurological deficits, spinal instability, progressive deformity, or failure of medical therapy.
• Procedures: Options include decompression, abscess drainage, spinal fusion, and instrumentation for stabilization.
• Postoperative care: Includes continued ATT, physiotherapy, and monitoring for surgical complications.

Rehabilitation

• Physiotherapy to maintain mobility and strengthen paraspinal muscles
• Use of spinal support or bracing to prevent deformity
• Gradual return to functional activities under supervision

Complications

• Neurological deficits: Weakness, sensory loss, or paralysis due to spinal cord or nerve root compression.
• Spinal deformities: Kyphosis or gibbus formation resulting from vertebral collapse.
• Chronic pain: Persistent back pain even after treatment.
• Relapse or drug-resistant tuberculosis: Risk of recurrence if therapy is incomplete or if resistant strains are present.

Prognosis

The prognosis of Pott’s disease depends on the severity of spinal involvement, the presence of neurological deficits, and the timeliness of treatment. Early diagnosis and appropriate anti-tubercular therapy significantly improve outcomes.

• Factors affecting recovery: Age, nutritional status, extent of vertebral destruction, and presence of comorbidities.
• Long-term outcomes: Most patients achieve good functional recovery with proper treatment, although some may have residual spinal deformity or mild neurological impairment.

Prevention

Preventing Pott’s disease involves reducing the overall burden of tuberculosis and minimizing risk factors for spinal involvement.

• BCG vaccination: Provides partial protection against severe forms of tuberculosis in children.
• Early detection and treatment of pulmonary tuberculosis: Reduces the risk of hematogenous spread to the spine.
• Public health measures: Improving sanitation, reducing overcrowding, and increasing awareness about tuberculosis transmission.

References

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