NEURORADIOLOGY


Case 34 :
Diagnosis please!

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Diagnosis

Koch's Spine.

Discussion

It is also the commonest form of skeletal tuberculosis with an incidence of up to 50% of all skeletal tuberculosis. In general it is a disease of the young adult in the developing countries. In developed countries it affects more commonly, the elderly. The spinal disease is always secondary to a primary lesion and occurs due to hematogenous spread. The primary focus may be active or quiescent and may be in the lungs, mediastinal lymph nodes, kidneys and other viscera.
Clinically there are four types :
1. Para discal lesion begins in the metaphysis, erodes the cartilage and destroys the disc, resulting in narrowing of the disc space.
2. Central type begins in the midsection of the body which gets softened and yields under gravity and muscle action, leading to compression, collapse and bony deformation.
3. Anterior lesions lead to cortical bone destruction beneath the anterior longitudinal ligament. Spread of the infection is in the subperiosteal and sub ligamentous planes resulting in the loss of periosteal blood supply to the body with resultant collapse. Other factors such as periarteritis and endarteritis contribute to the collapses.
4. In appendicle type, the infection settles in the pedicles, the laminae, the articular processes or the spinous processes and causes initial ballooning of the structure followed by destruction.

Tuberculous spondylitis commonly occurs in the thoracic, followed by lumbar and cervical spines which more often occurs in the pediatrics group. With its high resolution, direct multiplanar imaging, detection of early lesions and also associated lesions such as abscesses, skip lesions and epi and intradural involvement, MRI is the obvious choice of investigation. Contrast MRI aids in better delineation and also in differentiating the lesion from the surrounding edema. T1 images show decreased signal from the lesion within the 30 days and narrowing of the disc space and also loss of signal from the nuclear pulpous. T2 may show increased signal from the involved body and the disc narrowing with normal decreased or increased signal higher than normally seen.


Dr Ashok Raghavan, Manipal Hospital, Bangalore

References
http://www.thamburaj.com/spinal_tuberculosis.htm