Patient Case - AIDS Complicated Bacterial Infection of Spinal Cord

Case history and clinical manifestations

It is a case of AIDS definitely diagnosed by CDC, a male aged 48 years, who had progressively severe asthenia of both lower extremities with accompanying gatism for more than 1 month, decreased plain perception at 10^th~12^th thoracic vertebra, III degrees of right muscle strength, II degrees of left muscle strength and existing muscular reflex. Bacteria culture found it was Staphylococcus aureus infection. MR imaging demonstrates strip liked abnormal high T₁ and high T₂signals in vertebral canal of thoracic and lumbar spine and intravenous injection of Gd-DTPA for contrast-enhanced imaging demonstrates griller enhancements of paravertebral abscess wall with obvious compression to the spinal cord.

Imaging demonstrations

Fig. 3-3-1. Contrast-enhanced saggital MR imaging demonstrating strip liked abnormal high T₁ and high T₂ signal in vertebral canal of thoracic and lumbar spine. Contrast-enhanced imaging by intravenous injection of Gd-DTPA demonstrates griller enhancement of paravertebral abscess wall and obvious compression of spinal cord in thin strip shape.

Diagnosis

AIDS complicated bacterial infection of spinal cord.

Discussion

This is a case of Staphylococcus aureus infection due to hematogenic infection of deep skin ulcer entering vertebral canal, which causes flowing pillar liked abscess in extradural space and formation of strip liked vomica of different sizes. The patient had obvious symptoms and signs of spinal cord compression and root compression and suffered from chronic abscess. Its MR imaging demonstrations are closely related to the location of infection. Due to large extradural space of thoracic spine, cellulitis frequently occurs to form abscess that tends to spread and accumulates extradurally to extend and compress structures in vertebral canals. The key points for differential diagnosis are: 1) acute myelitis without obvious obstruction of the subarachnoid cavity; 2) metastatic neoplasm of spine with osseous damage and significantly increased white blood cell count in cerebral fluid of acute spinal cord abscess or purulent myelitis, early and severe functional disturbance of nervous system; 3) arachnoiditis of spinal cord with no space-occupying effect; 4) extradural fat, which should be differentially diagnosed from AIDS complicated bacterial infection of spinal cord in the cases of abscess bleeding of thoracic spine.