Vestibular-evoked myogenic potential (VEMP) to evaluate cervical myelopathy in human T-cell lymphotropic virus type I infection.
METHODS
Cross-seccional analysis.


OBJECTIVE
To define the clinical usefulness of vestibular-evoked myogenic potential (VEMP) in detecting cervical medullar involvement related to human T-cell lymphotropic virus type 1 (HTLV-1) associated myelopathy/tropical spastic paraparesis (HAM/TSP).


BACKGROUND
VEMP is generated by acoustic or galvanic stimuli, passing through the vestibulo-spinal motor tract, the spinal nerves and recorded by means of surface electrodes on the sternocleidomastoid muscle. HAM/TSP is a progressive inflammatory myelopathy with predominant lesions at the thoracic spinal cord level, although the cervical spine can be affected. VEMP may be of value to investigate cervical myelopathy.


METHODS
Seventy-two individuals were evaluated of whom 30 HTLV-1 were seronegative and 42 HTLV-1 seropositive (22 asymptomatic, 10 with complaints of walking difficulty without definite HAM/TSP and 10 with definite HAM/TSP). VEMP was recorded using monaural delivered short tone burst (linear rise-fall 1 millisecond, plateau 2 milliseconds, 1 KHz) 118 dB NA, stimulation rate of 5 Hz, analysis time of 60 milliseconds, 200 stimuli, band pass filtered between 10 and 1.500 Hz.


RESULTS
VEMP was normal in the seronegative group (30 controls). In the seropositive, abnormal VEMP was seen in 11 of 22 (50%) of the HTLV-1 asymptomatic carriers, in 7 of 10 (70%) of those with complaints of walking difficulty and in 8 of 10 (80%) of the HAM/TSP patients. In this last group, the pattern of response was different. No VEMP response was more frequent when compared with the HTLV-1 asymptomatic group (2-tailed P-value = 0.001).


CONCLUSIONS
VEMP may possibly be useful to identify patients with cervical myelopathy and to distinguish variable degrees of functional damage. Minor injury would be related to latency prolongation and major injury to no potential-evoked response.
Felipe
Lilian
L
Faculty of Medicine of Federal University of Minas Gerais, Brazil.
Gonçalves
Denise Utsch
DU
Santos
Marco Aurélio Rocha
MA
Proietti
Fernando Augusto
FA
Ribas
João Gabriel Ramos
JG
Carneiro-Proietti
Anna Bárbara
AB
Lambertucci
José Roberto
JR
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D002574:Cervical Vertebrae / Q000502:physiology / Q000821:virology; D003430:Cross-Sectional Studies; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D015490:HTLV-I Infections / Q000175:diagnosis / Q000503:physiopathology; D015368:Human T-lymphotropic virus 1; D006801:Humans; D008297:Male; D008875:Middle Aged; D015493:Paraparesis, Tropical Spastic / Q000175:diagnosis / Q000503:physiopathology*; D014722:Vestibule, Labyrinth / Q000502:physiology*