The role of somatosensory evoked potentials in the diagnosis of AIDS-associated myelopathy.
BACKGROUND
Although AIDS-associated vacuolar myelopathy is detected in >50% of autopsy cases, it is often unrecognized during life. The clinical assessment is often difficult because of concurrent peripheral neuropathy and lack of specific diagnostic markers. Somatosensory evoked potentials (SEPs) have been successfully used to evaluate central conduction in a number of diseases involving the spinal cord.


OBJECTIVE
To assess the diagnostic yield of SEPs in AIDS-associated myelopathy.


METHODS
We recorded tibial and median nerve SEPs in 69 HIV-infected subjects referred for evaluation of lower extremity neurologic abnormalities. Stimulation of the peroneal nerve at the popliteal fossa was performed in patients with absent response to ankle stimulation.


RESULTS
HIV-infected subjects had significantly delayed latencies of both peripheral and central potentials, suggesting a combination of peripheral and CNS abnormalities. Analysis of peripheral and central latencies allowed us to discriminate between neuropathy and myelopathy in individual patients. Abnormalities of tibial central conduction time (CCT) correlated with clinical diagnosis of myelopathy. There was no significant difference in median CCTs between patients and controls, suggesting that conduction abnormalities were restricted to the thoracolumbar spinal cord. A derived spinal conduction time was a sensitive indicator of central conduction abnormalities in AIDS patients with myelopathy.


CONCLUSIONS
The combination of median, posterior tibial, and peroneal SEPs is a valuable tool in the diagnosis of AIDS-associated myelopathy, particularly when myelopathy and peripheral neuropathy coexist. The use of a derived spinal conduction time improves the diagnostic yield of SEPs in AIDS-associated myelopathy.
Tagliati
M
M
Department of Neurology, Clinical Neurophysiology, The Mount Sinai Medical Center, New York, NY 10003, USA. mtagliat@bethisraelny.org
Di Rocco
A
A
Danisi
F
F
Simpson
D M
DM
D000163:Acquired Immunodeficiency Syndrome / Q000150:complications*; D000328:Adult; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D015658:HIV Infections / Q000150:complications; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D020335:Paraparesis / Q000209:etiology; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology; D013118:Spinal Cord Diseases / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D013979:Tibial Nerve / Q000503:physiopathology