Frances J. Freeman

Linguistic performance deficits in stutterers : relation to laryngeal reaction time profiles

Abstract Converging evidence suggests that stuttering is associated with deficits in the planning and execution of speech. Evidence also suggests that the onset, development, and loci of stuttering are related to demands language places on speech motor planning and execution. We combined linguistic and vocal motor assessments to address two questions: 1) Can we identify a subgroup of adult stutterers who demonstrate linguistic deficits? and 2) Do linguistically normal and impaired stutterers show different patterns of laryngeal reaction time (LRT) as a function of response complexity? Linguistic performance was evaluated using tasks that assess relatively high-level production and comprehension processes. Responses used to record LRT differed in linguistic and motoric complexity. Only linguistically impaired stutterers showed significant increases in LRT for complex responses. Findings suggest that linguistic and motor processes affect the efficiency and fluency of speech motor control and that both processes be made explicit in models of stuttering.

Brainstem Conduction Abnormalities in Spasmodic Dysphonia

Twelve spasmodic dysphonia patients were evaluated by three different auditory brainstem response parameters; 75 % were abnormal. Three of the 12 had prolonged wave I-V interpeak latency. Seven had pathologic wave V latency shifts at a high stimulus rate. Amplitude ratios were normal for all subjects. The authors hypothesize that spasmodic dysphonia is a disorder of variable cranial nerve symptom presentations, and offer several possible models to account for its sporadic representation in the nervous system.

Auditory brainstem response abnormalities in adductor spasmodic dysphonia

Six patients with adductor spasmodic dysphonia were evaluated for evidence of brainstem dysfunction using the auditory brainstem response (ABR). In four, abnormally large increments in wave V latencies were found at high stimulus repetition rates. Latency increments exceeded three standard deviations above the mean in a normative adult population. A fifth patient had the prolonged interpeak latencies described previously by other investigators. In five of six patients the capacity of the auditory brainstem to conduct impulses was compromised. These results suggest a central nervous system abnormality in adductor spasmodic dysphonia.

Are mothers of stutterers different? An investigation of social-communicative integration☆

Abstract Many speech-language pathologists assume that parent-child communicative interactions are critical precipitating or maintaining factors in the onset and development of stuttering. Although parents are frequently counseled to alter their attitudes or behaviors, no studies have pinpointed specific parental behaviors as increasing childrens disfluency. The purpose of this study was to analyze differences between 12 mothers of stutterers and 12 mothers of nonstutterers in their social-communicative interactions with their own child, an unfamiliar stutterer, and an unfamiliar nonstutterer. Ten minutes of free-play interaction between each mother and child were video recorded from behind a one-way mirror. Results indicate that the two groups of mothers differed significantly only in their use of routine statements. Other findings indicate that stuttering children used significantly more positive and imperative statements than nonstuttering children. All children asked significantly more questions of their own mothers than of unfamiliar mothers.

Abnormal Parasympathetic Vagal Function in Patients with Spasmodic Dysphonia

Gastric vagal function was assessed in 15 patients with spasmodic dysphonia by measuring gastric acid output in response to sham feeding. Patients secreted significantly less acid than controls (p less than 0.001). Cardiac vagal function was assessed in 11 patients by measuring heart rate during deep respiration and also during and after Valsalva maneuver. Patients with spasmodic dysphonia had a significantly reduced fluctuation of heart rate during deep respiration (sinus arrhythmia). The expiratory to inspiratory R-R interval averaged 1.08 +/- 0.08 (mean +/- SD) in patients and 1.22 +/- 0.10 in controls (p less than 0.005). The ratio of tachycardia during Valsalva maneuver to bradycardia after Valsalva maneuver was also lower in patients than in controls (p less than 0.005). The auditory brainstem response was abnormal in 11 of 15 patients. Our results show either a central brainstem abnormality or several cranial nerve abnormalities in some patients with spasmodic dysphonia.

Multichannel electromyographic observations in spasmodic dysphonia patients and normal control subjects.

Spasmodic dysphonia is primarily a disorder of vocalization. Increasing evidence, however, suggests that individuals with this disorder comprise a heterogeneous population characterized by abnormal motor control throughout the vocal tract. Multichannel simultaneous electromyography was performed on 11 spasmodic dysphonia patients and 10 normal awake subjects to investigate both the distribution of neuromotor abnormality within the vocal tract (eg, intrinsic and extrinsic laryngeal muscles, tongue, and palate) and the contribution of activation of higher central nervous system centers to observed abnormality. Experimental tasks ranged from vegetative (quiet breathing) to simple linguistic (short sentences). Digitized electromyographic signals were analyzed to compute the amplitude envelope and extract a set of parameters that represent amplitude characteristics. Electrode insertions were cross-validated by quantitative analysis of patterns of activation across selected reference tasks and by traditional qualitative methods. Between-group differences were found for measures of normalized median and peak token amplitudes. These differences are both task- and measure-dependent. Results highlight the complex and interactive effects of muscle, task, and quantitative measures on between-group differences.

Respiratory/Laryngeal Coupling and Complexity Effects on Acoustic Laryngeal Reaction Time in Normal Speakers

Summary The simple reaction time paradigm was used to investigate effects of peripheral (respiratory/laryngeal coupling) and central (task complexity) requirements on average acoustic laryngeal reaction time (LRT) values in normal speakers. Respiratory/laryngeal coupling at response onset varied from glottal stop to aspirate. Complexity varied from isolated vowel to short sentence. The range from shortest to longest average LRT value across all tasks was 69 ms. Significant differences among tasks indicate that acoustic LRT values are sensitive to relatively small magnitude effects associated with respiratory/laryngeal coupling and task complexity. Results led to formulation of two hypotheses, which, while consistent with present findings, require further investigation: First, LRT increases directly with increasing glottal resistance. Second, LRT increases directly with increases in the number of stressed syllables in the response.

Stuttering onset after laryngectomy

Abstract Two cases of onset of stuttering subsequent to laryngectomy are reported. These patients demonstrate that the existence of a larynx is not necessary for the generation of stuttering. The findings support the hypothesis that neuromotor control of sound source (laryngeal or alaryngeal) plays a critical role in the generation of stuttering-type dysfluencies and, perhaps, even in the onset of stuttering. They also suggest that dramatic alteration in sound source has the potential for dramatically altering fluency.

Episodic reactive dysphonia: a case study.

This case study exemplifies successful diagnosis through stroboscopic fiberoptic examination, illustrates the critical importance of a careful case history, and demonstrates potential hazards of supposedly benign environmental substances for hypersensitive individuals.