Previously, we demonstrated that patients with adductor spasmodic dysphonia (ADSD) have a disinhibition of laryngeal responses to sensory input. In this study, sensorimotor responses to stimulation of the superior laryngeal nerve were compared between 10 subjects with abductor spasmodic dysphonia (ABSD) and 15 normal volunteers. The groups had similar latency and frequency characteristics of their unconditioned adductor responses (p > .05). The conditioned R1 (early) responses of the subjects with ABSD were greater and more variable in amplitude than those of the normal volunteers (p ≤ .008). Similar R2 (late) conditioning effects were found in both groups, with a nonsignificant trend toward reduced inhibition of contralateral R2 responses at lower interstimulus intervals (p = .01) in the patient group. Thus, inhibitory mechanisms that modulate the R1 laryngeal sensorimotor pathway in the brain stem may be abnormal in subjects with ABSD. Abnormal modulation of laryngeal sensorimotor responses seems present in both types of spasmodic dysphonia.
AronsonAE. Clinical voice disorders: An interdisciplinary approach. 2nd ed.New York, NY: Thieme-Stratton, 1985.
2.
ParnesSMLavoratoASMyersEN. Study of spastic dysphonia using videofiberoptic laryngoscopy. Ann Otol Rhinol Laryngol1978;87:322–6.
3.
NashEALudlowCL. Laryngeal muscle activity during speech breaks in adductor spasmodic dysphonia. Laryngoscope1996;106:484–9.
4.
LudlowCL. Pathophysiology of the spasmodic dysphonias. In: Bell-BertiFRaphaelLJ, eds. Producing speech: Contemporary issues for Katherine Safford Harris. Woodbury, NY: American Institute of Physics, 1995:291–308.
5.
LudlowCLNauntonRFTeradaSAndersonBJ. Successful treatment of selected cases of abductor spasmodic dysphonia using botulinum toxin injection. Otolaryngol Head Neck Surg1991;104:849–55.
6.
WatsonBCSchaeferSDFreemanFJDembowskiJKondraskeGRoarkR. Laryngeal electromyographic activity in adductor and abductor spasmodic dysphonia. J Speech Hear Res1991;34:473–82.
7.
KimuraJ. Electrodiagnosis in diseases of nerve and muscle: Principles and practice. Philadelphia, Pa: FA Davis, 1983:323.
8.
SanesJNIsonJR. Habituation and sensitization of components of the human eyeblink reflex. Behav Neurosci1983;97:833–6.
9.
CohenLGLudlowCLWardenM. Blink reflex curves in patients with spasmodic dysphonia. Neurology1989;39:572–7.
10.
TolosaEMontserratLBayesA. Blink reflex studies in focal dystonias: Enhanced excitability of brainstem interneurons in cranial dystonia and spasmodic torticollis. Mov Dis1988;3:61–9.
11.
PanizzaMLelliSNilssonJHallettM. H-reflex recovery curve and reciprocal inhibition of H-reflex in different kinds of dystonia. Neurology1990;40:824–8.
12.
LudlowCLVan PeltFKodaJ. Characteristics of late responses to superior laryngeal nerve stimulation in humans. Ann Otol Rhinol Laryngol1992;101:127–34.
13.
SessleBJ. Presynaptic excitability changes induced in single laryngeal primary afferent fibres. Brain Res1973, 53:333–42.
14.
SessleBJ. Excitatory and inhibitory inputs to single neurones in the solitary tract nucleus and adjacent reticular formation. Brain Res1973;53:319–31.
15.
LudlowCLSchulzGMYamashitaTDeleyiannisFW-B. Abnormalities in long latency responses to superior laryngeal nerve stimulation in adductor spasmodic dysphonia. Ann Otol Rhinol Laryngol1995;104:928–35.
16.
KarnellMP. Abductor and adductor spasmodic dysphonia: Related until proven otherwise. Am J Speech Lang Pathol1992;1:17–8.
17.
MillerRHWoodsonGEJankovicJ. Botulinum toxin injection of the vocal fold for spasmodic dysphonia. Arch Otolaryngol Head Neck Surg1987;113:603–5.
18.
BlitzerABrinMF. Laryngeal dystonia: A series with botulinum toxin therapy. Ann Otol Rhinol Laryngol1991;100:85–9.
19.
LudlowCLNauntonRFSedorySESchulzGMHalletM. Effects of botulinum toxin injections on speech in adductor spasmodic dysphonia. Neurology1988;38:1220–5.
20.
LudlowCL. Treatment of speech and voice disorders with botulinum toxin. JAMA1990;264:2671–5.
21.
NIH Consensus Development Conference statement: Clinical use of botulinum toxin. Arch Neurol1991;48:1294–8.
22.
TruongDDRontalMRolnickMAronsonAEMisturaK. Double-blind controlled study of botulinum toxin in adductor spasmodic dysphonia. Laryngoscope1991;101:630–4.
23.
LudlowCLBagleyJAYinSGKodaJ. A comparison of different injection techniques in the treatment of spasmodic dysphonia with botulinum toxin. J Voice1992;6:380–6.
24.
BlitzerABrinMStewartCAvivJEFahnS. Abductor laryngeal dystonia: A series treated with botulinum toxin. Laryngoscope1992;102:163–7.
25.
HiranoMOhalaJ. Use of hooked-wire electrodes for electromyography of the intrinsic laryngeal muscles. J Speech Hear Res1969;12:362–73.
26.
LudlowCL. Neurophysiological assessment of patients with vocal motor control disorders. In: CooperJA, ed. Assessment of speech and voice production: Research and clinical applications. Bethesda, Md: NIDCD Monograph, 1991:161–71.
27.
FergusonGA. Statistical analysis in psychology and education. New York, NY: McGraw-Hill Book Company, 1966:110.
28.
TanakaYLudlowCLYoshidaYHiranoMSelbieWS. Expression of Fos-like immunoreactivity in the laryngeal reflex pathway of the cat's lower brainstem. In: FletcherNDavisP, eds. Controlling complexity and chaos: 9th Vocal Fold Physiology Symposium. San Diego, Calif: Singular Press, 1996:91–106.
29.
MochidaA. Reflex control on laryngeal functions: Vibration effect of the laryngeal mucosa on recurrent laryngeal nerve reflexes. J Otolaryngol Jpn1990;93:938–47.
30.
KunaSTSmicklyJSInsalacoG. Posterior cricoarytenoid muscle activity during wakefulness and sleep in normal adults. J Appl Physiol1990;68:1746–54.
