Fig 1.
Vestibular-evoked myogenic potential triggered by galvanic vestibular stimulation (galvanic-VEMP) recording positions and equipment.
It shows the right position of the participant to capture galvanic-VEMP; the equipment used for stimulus generation (a), the electrode positions for GVS (b), the electrode position to capture an electromyographic response on the gastrocnemius muscle (c), the equipment for processing the signal (d), and the computer for recording the responses (e).
Fig 2.
A normal vestibular-evoked myogenic potential triggered by galvanic vestibular stimulation (galvanic-VEMP) tracing.
These recordings were obtained from an uninfected individual with his head rotated to the left and electromyographic (EMG) response recorded from the right gastrocnemius muscle. The black line indicates the trace recorded with the cathode and anode on the right and left side (CRAL), respectively, whereas the gray line indicates the opposite stimulation polarity (CLAR). SL, short-latency response (47 ms); ML, medium-latency response (100 ms); SL-amp, SL amplitude (12.5 μV); ML-amp, ML amplitude (62.5 μV).
Table 1.
General characteristics of human T-cell lymphotropic virus type 1 (HTLV-1)-infected and -uninfected groups (n = 122).
Table 2.
Comparative analysis of the latency and amplitude of short-latency (SL) and medium-latency (ML) responses between human T-cell lymphotropic virus type 1 (HTLV-1)-infected and -uninfected groups.
Fig 3.
Short-latency (SL) and medium-latency (ML) response receiver operating characteristic (ROC) curves for detecting spinal cord injury in patients infected with human T-cell lymphotropic virus type 1 (HTLV-1).
AUC, area under the curve; IC, confidence interval.
Fig 4.
Frequency comparisons between normal and altered vestibular-evoked myogenic potential triggered by galvanic vestibular stimulation (galvanic-VEMP) for each group.
The type of response (normal, delayed latency, or absent) and its frequency (%) is shown for each group. G1, uninfected control group; G2, human T-cell lymphotropic virus type 1 (HTLV-1)-asymptomatic group; G3, possible HTLV-1-associated myelopathy (HAM) group; G4, HAM group; n, number of participants. aDelayed latency of short-latency (SL), medium-latency (ML), or both responses. bAbsent SL, ML, or both responses. *p<0.001, chi-square or Fisher’s exact test.
Fig 5.
Vestibular-evoked myogenic potential triggered by galvanic vestibular stimulation (galvanic-VEMP) tracings.
(A) Delayed short-latency (SL) and medium-latency (ML) waves in an individual with asymptomatic human T-cell lymphotropic virus type 1 (HTLV-1) infection. (B) Absent SL response with delayed ML response latency in an individual with possible HTLV-1-associated myelopathy (HAM). (C) Absent SL and ML responses in an individual with HAM. These recordings were obtained from subjects with their heads rotated to the left and electromyographic (EMG) responses recorded from the right gastrocnemius muscle. The black line indicates the trace recorded with the cathode and anode on the right and left side respectively, whereas the gray line indicates the opposite stimulation polarity. SL, short-latency response onset; ML, medium-latency response onset.