Thermosensory threshold: a sensitive test of HIV associated peripheral neuropathy?

The purpose of the study was to assess the prevalence of thermosensory abnormalities in patients infected with HIV infection. Using a Thermo Sensory Analyser, we assessed thermosensory threshold for warm sensation (WS) and cold sensation (CS) of the forearm and foot in 40 controls and 75 HIV positive patients, including five patients with clinically evident peripheral neuropathy, three with AIDS-related dementia and 20 with AIDS. We found that thermosensory threshold is a reproducible test. The 95th centile for normal WS of the forearm was 1.4 degrees C above and CS 0.9 degrees C below the baseline temperature of 32 degrees C, and for WS of the foot was 5.3 degrees C and CS 4.4 degrees C respectively. The median WS of the foot for controls was 1.4 (IQR 0.7-2.8) degrees C, for asymptomatic HIV positive patients was 1.9 (1.1-4.2) degrees C, for patients with AIDS was 3.5 (1.6-5.7) degrees C and for those with peripheral neuropathy was 5.4 (1.7-14.9) degrees C (P< 0.05 compared to controls). A higher threshold was also evident for CS in patients with advanced HIV disease. These findings suggest that thermosensory testing is a sensitive tool in detecting early, small nerve fibre disease before the onset of clinically evident peripheral neuropathy.