The N3 potential compared to sound and galvanic vestibular evoked myogenic potential in healthy subjects and in multiple sclerosis patients.
Both sound (s-) and galvanic (g-) vestibular-evoked myogenic potential (VEMP) enable us to study the saccular pathways. However, the VEMP can be abnormal for non-vestibular factors, such as insufficient activation of the sterno-cleido-mastoid (SCM) muscle or a lesion that involves the accessory nucleus and/or nerve or the SCM muscle. These drawbacks do not affect another technique that evaluates the saccular function: the N3 potential. We recorded both the s- and the g-VEMP and the N3 potential in a group of 31 healthy subjects to establish a reference range. The N3 potential and the s-VEMP were recordable bilaterally from all the subjects, whereas the g-VEMP was undetectable uni- or bilaterally in 7 subjects. The latency and amplitude values of the s-VEMP did not differ from those of the g-VEMP. For all three techniques, the latency and amplitude values from the right and from the left recording and/or stimulation side were the same. We suggest using normative latency and amplitude values based on the mean and ratio of the right- and left-side values. The s-VEMP, the N3 potential and the auditory evoked response (ABR) were compared in 15 subjects suffering from multiple sclerosis. The three techniques detected a similar number of abnormalities, but these abnormalities were not correlated. This suggests that these different techniques should be regarded as complementary in evaluating saccular function.
Versino
Maurizio
M
Fondazione Istituto Neurologico C.Mondino, IRCCS and Dipartimento Scienze Neurologiche Università di Pavia, Pavia, Italy. mversino@unipv.it
Ranza
Laura
L
Colnaghi
Silvia
S
Alloni
Roberto
R
Callieco
Roberto
R
Romani
Alfredo
A
Bergamaschi
Roberto
R
Pichiecchio
Anna
A
Bastianello
Stefano
S
Cosi
Vittorio
V
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000503:physiopathology*; D009119:Muscle Contraction / Q000502:physiology*; D009334:Neck Muscles / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*; D012016:Reference Values; D012444:Saccule and Utricle / Q000502:physiology* / Q000503:physiopathology