HIV Myelitis


KEY FACTS

Terminology

  • Myelopathy resulting from primary HIV infection

    • Most common cause of spinal cord disease in AIDS patients; prevalence of 20-55%

Imaging

  • Most common: Atrophy

  • Spinal cord T2 hyperintensity ± patchy enhancement

    • Thoracic > cervical; ↑ rostral as disease progresses

Top Differential Diagnoses

  • B12 deficiency

  • Infection (varicella-zoster virus, human T-cell leukemia/lymphoma virus)

  • Multiple sclerosis

  • Transverse myelitis

  • Delayed radiation myelopathy

Pathology

  • DNA lentivirus/retrovirus attacks spine monocytes, macrophages

    • Disease of cord and brain often occurs separately, suggesting different pathogenetic mechanisms

  • Opportunistic CNS and PNS infections and malignancies

Clinical Issues

  • Insidious progressive spastic paraparesis with ataxia, urinary problems, and sensory loss

    • May have acute myelitic syndrome shortly after seroconversion

  • Immune reconstitution inflammatory syndrome → myelopathy

  • Diagnosis of exclusion based on clinical, laboratory, and radiologic findings

    • MR excludes other extrinsic or intrinsic processes

Diagnostic Checklist

  • Important to exclude other treatable causes of myelopathy

  • Spinal cord atrophy is most common MR abnormality, typically involving thoracic spinal cord ± cervical cord involvement

High signal intensity abnormalities are seen in the cervical spinal cord on sagittal FLAIR MR
. The cord is not swollen. The findings are consistent with HIV-related changes in the spinal cord.

Axial T2WI MR demonstrates hyperintense signal in the right hemicord
. The cord is not swollen. No enhancement was observed on postcontrast T1WI (not shown). The findings are consistent with HIV-related changes in the spinal cord.

Micropathology, low power with Luxol fast blue stain, shows extensive spongiform changes within white matter from vacuolar myelopathy
. Disease of cord and brain often occur separately, suggesting different pathogenetic mechanisms.

(Courtesy R. Schmidt, MD.)

Micropathology, high power with Luxol fast blue stain, shows marked vacuolation within white matter from HIV myelopathy.

(Courtesy R. Schmidt, MD.)

TERMINOLOGY

Synonyms

  • AIDS or HIV → myelopathy or myelitis, vacuolar myelopathy (VM)

Definitions

  • Myelopathy resulting from primary HIV infection

IMAGING

General Features

  • Best diagnostic clue

    • Spinal cord (SC) T2 hyperintensity ± patchy enhancement

  • Location

    • Thoracic > cervical; mid to low thoracic cord with ↑ rostral involvement as disease progresses

  • Morphology

    • Most common: Atrophy (72%)

    • Common

      • Diffuse nonspecific T2 hyperintensity of SC without definite pattern (29%)

      • Atrophy + diffuse abnormality (14%)

    • Classic: Symmetric T2 hyperintensity involving white matter (WM) tracts laterally

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