eMedicine Specialties > Neurology > Neurological Infections
HIV-1 Associated Vacuolar Myelopathy
Updated: Mar 14, 2007
Introduction
Background
Vacuolar myelopathy is the most common chronic myelopathy associated with HIV infection. It occurs during the late stages of HIV infection, when CD4+ lymphocyte counts are very low, often in conjunction with AIDS dementia complex, peripheral neuropathies, and opportunistic central nervous system and peripheral nervous system infections or malignancies (eg, cytomegalovirus, progressive multifocal leukoencephalopathy, lymphoma).
Pathophysiology
Several hypotheses have been proposed to explain the development of this common complication of HIV-1 infection.
- One hypothesis is infiltration by HIV-infected mononuclear cells that secrete neurotoxic factors including cytokines, possibly in conjunction with neurotoxic astrocyte factors. A significant amount of scientific support exists for this paradigm.
- Neurotoxic HIV proteins: Transgenic mice that express HIV gene products in oligodendrocytes develop clinical and histologic features that resemble the human disease.
- Direct HIV infection of astrocytes and neurons: While this is reported in the brain and dorsal root ganglia, it is not a major feature in vacuolar myelopathy.
- The impaired ability to utilize vitamin B-12 as a source of methionine in transmethylation metabolism for myelin maintenance in the spinal cord may be a contributing factor.
Frequency
United States
Before the introduction of highly active antiretroviral therapy (HAART), vacuolar myelopathy was seen in 5-20% of adult HIV patients in clinical studies and in 25-55% of adult HIV patients in histologic studies.
Since the introduction of HAART, it is estimated that fewer than 10% of AIDS patients develop HIV myelopathy.
Mortality/Morbidity
Most patients die within 6 months of developing symptoms of myelopathy.
Clinical
History
- Patients have a history of slow progression, painless leg weakness, stiffness, sensory loss, imbalance, and sphincter dysfunction.
- Relapsing-remitting courses have also been described.
- Vacuolar myelopathy is often seen in conjunction with cognitive decline, distal limb pain, and numbness from peripheral neuropathy.
- Back pain is not a prominent feature.
- Arm function is usually normal except for advanced vacuolar myelopathy.
Physical
- Slowly progressive spastic paraparesis
- Hyperreflexia and extensor plantar responses
- Sensory ataxia
- Incontinence
- Rarely, asymmetric features and involvement of upper extremities
- Often associated with AIDS dementia complex and neuropathy
- A discrete sensory level is usually absent; if present, this strongly suggests other causes of myelopathy.
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References
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Further Reading
Keywords
HIV-1 associated myelopathy, AIDS myelopathy, AIDS dementia complex, peripheral neuropathies, opportunistic central nervous system infections, opportunistic peripheral nervous system infections, central nervous system malignancies, cytomegalovirus, progressive multifocal leukoencephalopathy, lymphoma, HIV-1 infection complications, neuropathy, HAART, highly active antiretroviral therapy
