Spinal Tuberculosis (TB)
Spine is most commonly affected bone by tuberculosis infection. It primarily affects thoracic spine; however, tuberculosis of lumbar spine, cervical spine and sacrum are not uncommon. Primary lesion in spine tuberculosis is infection of the disc and adjacent vertebral bones. This gradually involves vertebral bodies causing destruction and collapse of vertebra. Occasionally, infection starts in vertebral body or posterior part of bony vertebral ring. Spinal tuberculosis can also involve spinal cord and it’s coverings (Meninges).
Symptoms of Spine Tuberculosis:
Patients usually presents with pain at the site of infection. Typical symptoms of tuberculosis (fever, night sweat, loss of appetite, weight loss) are many times absent in spinal tuberculosis. If vertebral destruction is significant, patient may have localized deformity (kyphosis) at that level. In advance cases, patients may have symptoms of spinal cord compression (loss of sensation and weakness in arms/ legs, loss of bladder-bowel control, loss of dexterity and weakness in hand grip, loss of balance and spasticity in legs), which happens due to compression by:
- Displaced bone fragments from vertebral body destruction and collapse,
- Pus and granulation tissue in spinal canal,
- Compression of spinal cord by deformed spine,
- Direct involvement of spinal cord by infection
Risk Factors for Developing Spine Tuberculosis:
- Contact with person having tuberculosis
- Poor nutrition,
- Living in overcrowded places,
- Debilitating medical illnesses,
- Immunosuppressant therapy,
- HIV and other illnesses suppressing immunity.
Diagnosis of Spine Tuberculosis:
Any patient presenting with above-mentioned signs and symptoms and having risk factors should be suspected of having spine tuberculosis. A thorough physical examination with special attention to neurological status is done. Following tests are recommended for final diagnosis confirmation:
- X-ray: An x-ray will show loss of disc height in early phase of disease as spinal tuberculosis usually starts with involvement and destruction of the disc material. It will also reveal vertebral collapse and spinal deformity in advanced cases.
- MRI Scan: An MRI is usually done early in cases suspected to be having spinal tuberculosis. It will reveal infection affecting disc and adjacent vertebral bodies in detail. Vertebral body destruction, amount of spinal cord compression, presence of infection at other levels, infection inside the spinal cord will also be evident on an MRI. MRI is also done to assess patient’s response to treatment. Though spinal tuberculosis has typical MRI picture, it cannot confirm whether it is tuberculosis, or bacterial infection, or some other lesion. A biopsy is required for that.
- Biopsy: A biopsy of the lesion seen on MRI is of great importance. It will give us final confirmation about the diagnosis of the lesion. A microscopic histopathology examination will differentiate between infection due to bacteria/ tuberculosis and a tumor. Collected sample is also used for culture and sensitivity to know which antibiotics will work on given infection. There are different ways to collect biopsy:
- CT Guided Biopsy: A needle is inserted under local anesthesia with CT guidance and required material is retrieved.
- Fluoroscopy Guided Biopsy: Under local/ general anesthesia, target material is collected with help of intra-operative x-ray TV machine. This procedure is done in operation theater.
- Surgical Biopsy: Sample is collected by surgical intervention when 1) previous biopsy attempts have failed, 2) it is difficult to reach the lesion by CT/ Fluoroscopy, 3) when surgery is any way required for other reasons.
- CT Scan: A CT is performed to assess bony anatomy in detail and when MRI is not possible. CT scan is also used to assess bone healing in post-operative patients.
- Culture and Sensitivity: Tuberculosis can be of different kind based on the antibiotics it responds to. To know whether it’s a normal/ multi drug resistant (MDR)/ extreme drug resistant (XDR) TB and to guide spine specialist to choose right medications, a culture and sensitivity test is done. In this test bacteria is first grown in lab and then different drugs are tested on this to see which drugs inhibit growth of the bacteria. Those same drugs are then given to patient to treat him/ her.
- Other tests: A chest x-ray and sputum test is done to rule out lung infection. Several blood tests (e.g. ESR) can be done to assess severity and progress/ resolution of infection.
Treatment of Spine Tuberculosis:
TB is a medical disease. Even if a surgery is done, it is absolutely must to take anti-tubercular drugs to eradicate TB infection. TB bacteria responds slowly to drugs, hence a long duration of treatment is required. This may range from 12 -24 months depending on the type of infection (resistant TB versus normal TB), response to drugs, site of infection etc. For patients who are diagnosed in early phase, and who do not have any indication for surgery (please see below), a medical treatment with appropriate drugs is usually sufficient. This should be accompanied by good nutrition, adequate rest, bracing of the affected spine segment, symptomatic treatment for pain and nutritional supplements. A close watch on patient’s response to drug therapy is necessary by clinical examination, blood tests and imaging to ensure gradual resolution of the patient’s symptoms/ progressive healing of the lesion and to catch any complication caused by medicines/ disease process to treat them early.
Surgery is required when patient presents with any of the followings, either at first presentation or during the course of medical treatment:
- Signs of severe spinal cord compression (loss of sensation and weakness in arms/ legs, loss of bladder-bowel control, loss of dexterity and weakness in hand grip, loss of balance and spasticity in legs),
- Progressive worsening of spinal cord compression symptoms during treatment,
- X-ray/ MRI evidence of severe bone destruction which can cause spine instability, increased pain, deformity and spinal cord compression,
- Severe pain not responding to medical treatment,
- To obtain biopsy in difficult cases.
Usually a spine decompression and fusion surgery is required in these cases. Spine fusion will give pain relief, correct and prevent progression of spine deformity, allow adequate spinal decompression to take place and prevent recurrence of spinal stenosis, stabilize spine to help in infection healing, allow early mobilization and prevent need of bed rest after surgery. In rare instances, where vertebral destruction is not significant and primary symptoms are of spine stenosis, a decompression only procedure can be done. Also, a TB lesion inside the spinal cord might also need only decompression surgery if not responding to medical treatment/ and to confirm diagnosis.