Tropical Medicine Central Resource

The spongy tissue of the vertebral body is a frequent site for hydatid bone disease. In the early stages, cystic areas may be seen in the vertebral body and often extend into the pedicle, lamina and transverse process (Figs. 3.140 and 3.141). Contiguous posterior rib involvement usually accompanies the vertebral disease in the thoracic area (Fig. 3.142A,B). In many patients, however, instead of cystic areas, there is more generalized bone destruction, yet the vertebral height is usually maintained and the intervertebral disc space is spared. Later in the disease, especially when there is complicating secondary infection, partial collapse of the vertebra and narrowing of the disc space are not uncommon. Occasionally, a cystic lesion in a vertebra may cross the disc space to involve an adjacent vertebra, causing collapse of both vertebral bodies and disc space obliteration. When secondary infection sets in, sclerotic changes develop in the affected vertebra, surrounded by hypertrophic bony overgrowth (Fig. 3.142A).

Fig. 3.140 Hydatid disease affecting the body and neural arch of the second lumbar vertebra and the adjacent disc space. A lateral tomogram clearly shows the well defined cystic area in the posterior portion of the vertebral body extending into the pedicle and lamina. There is narrowing of the LI-2 disc space as well. (Courtesy of the University of Cape Town Radiology Library).

Fig. 3.141 Hydatid disease involving T12 and LI with extension posteriorly into the extradural space, causing complete block on myelography in a patient from India with signs of paraplegia. (A) Lateral and (B) AP views of the dorsolumbar spine obtained during myelography with the patient in a 70 degree Trendelenburg position show a complete block at LI from an extradural hydatid mass. Cystic radiolucent defects are seen in the T12 and LI vertebral bodies with a slight surrounding rim of sclerosis on the lateral view (A). There is minimal narrowing of the T12-L1 and L1-2 disc spaces compared with the normal discs above and below those levels. (Courtesy of Dr. A. C. Johnson, Tulsa, Oklahoma).

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Fig. 3.142 Paraspinal abscesses due to extension of hydatid disease of the spine into the adjacent paravertebral soft tissues in three different patients. (A) A hydatid cyst arising from the lower thoracic spine with large paraspinal abscess extending ftom the top of T11 to the bottom of T12. The right pedicles and neural arches of T11 and T12 are involved and there is marked hypertrophic bony overgrowth on the right side of the T11-12 disc space, which is moderately narrowed. There is also erosion, splaying, and slight dislocation of the costovertebral aspects of the right 11th and 12th ribs. There is slight scalloping of the right lateral aspect of T12 due to erosion. (B) Hydatid disease involving the right lateral aspect of T11 with destruction of the pedicle and extension into the right paravertebral soft tissues, producing a well-defined paraspinal abscess at TIO-11. There is dislocation of the costovertebral aspect of the right 11th rib and there is erosion with resulting scalloping of the lateral margin of T11. (C) Hydatid disease of the transverse process of L4 in a 30-year-old Syrian man with a sinus in the lumbar region. A sinogram shows the contrast medium leading to a lucent defect in the right transverse process of L4. (D) The appearance of hydatid disease of the lumbar spine at operation. Note the large number of daughter cysts and small vesicles around the dura mater, and invasion of the surrounding paravertebral muscles and soft tissues. (C and D courtesy of Dr. M. K Booz and J Bone Joint Surgery, 1972).