Tuberculosis of spine was first described by Percivall Pott. He noted this as a painful kyphotic deformity of the spine associated with paraplegia. Since then condition is also referred to as Pott’s disease.
Tuberculosis of spine is the most common site of skeletal tuberculosis. It accounts for 50 percent of the cases. Tuberculosis of spine occurs most commonly in lower thoracic region followed by lumbar, upper dorsal, cervical and sacral regions in decreasing order of frequency.
Tuberculosis of spine is also referred as tuberculous spondylitis. Tuberculosis of the spine used to be a disease of early childhood in the past. But with improved public health measures, this age incidence has changed, and adults are more frequently affected.
Pathology of Tuberculosis of Spine
The focus of infection usually begins in the cancellous bone of the vertebral body. Occasionally it is in the posterior neural arch, transverse process, or subperiosteally deep to the anterior longitudinal ligament in front of the vertebral body.
As the disease progresses, the area of infection gradually enlarges and spreads to involve two or more adjacent vertebrae by extension beneath the anterior longitudinal ligament or directly across the intervertebral disc.
Sometimes there may be multiple vertebrae involved with multiple foci of involvement separated by normal vertebrae termed as skip lesions. The infection may be disseminated to distant vertebrae via the paravertebral abscess.
As the tuberculosis of spine progresses, vertebral bodies loose their mechanical strength as a result of progressive destruction under the force of body weight and eventually collapse leading to an angular kyphotic deformity. The severity of the deformity depends upon the extent of destruction, the level of the lesion, and the number of vertebrae involved.
Kyphosis is most marked in thoracic area because of the normal dorsal curvature. In the lumbar area it is less because of the normal lumbar lordosisbecasue of which the body weight is transmitted posteriorly and collapse is partial
The collapse is minimal in cervical spine because most of the body weight is borne through the articular processes.
Healing takes place by gradual fibrosis and calcification of the granulmatous tuberculous tissue. Eventually the fibrous tissue is ossified, with resulting bony ankylosis of the collapsed vertebrae.
Paravertebral abscess formation occurs in almost every case. With collapse of the vertebral body, tuberculous granulation tissue, caseous matter, and necrotic bone and bone marrow are extruded through the bony cortex and accumulate beneath the anterior longitudinal ligament.
These cold abscesses gravitate along the fascial planes andpresent externally at some distance from tee site of the original lesion.
- In the lumbar region the abscess gravitates along the psoas fascial sheath and usually points into the groin just below the inguinal ligament.
- In the thoracic region, the longitudinal ligaments limit the abscess, which is seen in the radiogram as a fusiform radiopaque shadow at or just below the level of the involved vertebra.
- Thoracic abscess may reach the anterior chest wall in the parasternal area by tracking via the intercostal vessels.
Neurological complications may arise due to compression of the cord by the abscess, caseating or granulating mass, intervertebral disc or edge of bone c. Other contributory factors may be thrombosis of the local vessels and edema of the cord.
Neural deficit can be paraparesis to begin with and eventually lead to paraplegia. It occurs most often in the mid-or upper-thoracic region, where the kyphosis is most acute, the spinal canal is narrow, and the spinal cord is relatively large.
Clinical Features of Tuberculosis of Spine
The onset of is usually insidious. Initial symptoms are vague, consisting of generalized malaise, easy fatiguability, loss of appetite and weight, and loss of desire to play outdoors in children. There may be an afternoon or evening fever.
Backache is usually minimal and may be referred segmentally.
Muscle spasm makes the back rigid. Motion of the spine is limited in all direction. The patient may complain of inability to flex spine when picking an object up from the floor. For doing this, the patient flexes his hips and knees, keeping the spine in extension.
Spasm of the paravertebral muscles in the lumbar region is also elicited by passive hyperextension of the hips with the patient in prone position-this also puts stretch on the iliopsoas muscle, which is in spasm and contracture owing to psoas abscess.
A kyphus in the thoracic region may be the first noticeable sign. As the kyphosis increases, the ribs will crowd together and a barrel chest deformity may develop.
When the lesion is situated in the cervical or lumbar spine, a flattening of the normal lordosis is the initial finding.
Tenderness is often present in the affected vertebral levels. The abscesses may be palpated as fluctuant swellings in the groin, iliac fossa, retropharynx, or on the side of the neck, depending upon the level of the lesion.
The gait of the person with Pott’s disease is peculiar, reflecting the protective rigidity of the spine. His steps are short, as he is trying to avoid any jarring of his back. In tuberculosis of the cervical spine, he holds his neck is extension and supports his head with one hand under the chin and the other over the occiput.
If paraplegia develops, there will be spasticity of the lower limbs with hyperactive deep tendon reflexes, a spastic gait, a varying degree of motor weakness, and disturbances of bladder and anorectal function.
Radiographic Features of Tuberculosis of Spine
Findings are suggestive, but not pathognomonic. In addition to the routine anteroposterior and lateral views of the spine, linear tomograms, CAT scan, and nuclear magnetic resonance imaging are used to delineate bone and spinal cord pathology in detail. Chest radiograms are taken to rule out outer foci of systemic disease in case of a suspected person.
Initially, the vertebral body becomes rarefied with loss and haziness of its bone trabecular pattern. Soon the vertebral body expands and its borders are indistinct. With progressive destruction of bone the vertebral body collapses. The intervertebral disc space first narrows and later is obliterated. Paraspinal abscesses may be seen quite early, presenting as fusiform or rounded shadows of water density.
In the differential diagnosis one should consider conditions that may causes destruction and collapse of the vertebral body, narrowing and obliteration of intervertebral disc spaces, and paraspinal soft-tissue swelling. These conditions are bacterial infections of spine, leukemia, Hodgkin’s disease, eosinophilic granuloma, aneurysmal bone cyst, and Ewing’s sarcoma.
Treatment of Tuberculosis of Spine
As soon as the diagnosis of tuberculous of spine is suspected, the patient is placed on bed rest and chemotherapy is initiated immediately. Patient is observed for response of the disease. A number of patients recover on chemotherapy.
Some of the patient may require surgical debridement or decompression of the cord.
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