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Biomedical subjects

C L Ludlow

Publications and source records attributed to C L Ludlow.

At least 55 records · Page 3Linked to original sources
PubMed1992

Single motor unit activity of human intrinsic laryngeal muscles during respiration.

Individual motor units in the thyroarytenoid (TA) and cricothyroid (CT) muscles were studied in 10 normal human volunteers during quiet respiration. Both tonic and phasic firing patterns were found in both TA and CT units. The rate of firing was higher during inhalation than during exhalation in phasic TA units and in tonic CT units. Tonically active units had a higher firing frequency than phasically active units in both TA and CT muscles. Phasically active units corresponded with the respiratory cycle, with firing associated with inhalation in both the TA and CT muscles. A variety of firing patterns were found between units in both the TA and CT muscles, and in one subject, units recorded from the same muscle had very different firing patterns. The results suggest that although laryngeal motoneurons are modulated by the respiratory cycle, they do not respond uniformly to respiration.

Action Potentials↗
PubMed1992

An evaluation of laryngeal muscle activation in patients with voice tremor.

Eight patients with voice tremor were studied to characterize laryngeal muscle involvement. Electromyographic (EMG) recordings were made from intrinsic laryngeal muscles, simultaneously with some extrinsic laryngeal muscles, respiratory movement, and voice recordings during respiration, whisper, and phonation. Spectral measures were used to determine the tremor frequency and the prominence of spectral peaks in the EMG, respiratory and acoustic signals, while correlation coefficients were computed between pairs of tremulous EMG signals to measure the synchrony of tremor between muscles. The intrinsic laryngeal muscles were tremulous during respiration and speech, with the thyroarytenoid most often involved. Tremor was also detected in some of the extrinsic muscle recordings and the percentage of muscles with tremor was higher during phonation than during whisper or respiration. Time delays were found between tremor oscillations in laryngeal muscles. Because the thyroarytenoid was affected in all the patients studied, botulinum toxin injections may be beneficial in treatment of this voice disorder.

Aged↗
PubMed1992

Genetic aspects of idiopathic speech and language disorders.

At the outset of this article, we posed the question of whether or not the current evidence from genetic studies of DLD and stuttering indicate that it would be fruitful to conduct studies aimed at determining the gene location for each of these disorders. As we pointed out, because these are behavioral development disorders, phenotypic variations and changes in characteristics through the life span pose problems when attempting to determine who is and is not affected. Further, because these disorders can be either idiopathic or secondary to a variety of causes, any genetic study must rule out or take account of cases secondary to other factors. Few studies conducted thus far have taken these problems into account, and the results must be considered tentative. Given these reservations, the results certainly point to a genetic component in both disorders, although the data collected thus far on DLD suggest a mendelian form of transmission. If further more intensive studies continue to support this model for DLD, linkage studies on this disorder are likely to be productive.

Articulation Disorders↗
PubMed1991

Successful treatment of selected cases of abductor spasmodic dysphonia using botulinum toxin injection.

Ten patients with abductor spasmodic dysphonia, who exhibited spasmodic bursts and heightened activity of the cricothyroid muscle during speech, were selected for participation. Between 5 and 20 U of botulinum toxin type A were injected into both right and left cricothyroid muscles. Six patients benefited substantially, whereas four did not. Acoustic analyses of voice patterns showed similar changes to the clinical impressions. Significant group improvements were found in sentence duration while selected patients improved in the proportion of their speech that was voiced and the duration of their voiceless consonants. Those patients with abductor spasmodic dysphonia and other muscle abnormalities in addition to the cricothyroid and with constant breathiness did not benefit.

Adult↗
PubMed1990

Spasmodic dysphonia: botulinum toxin injection after recurrent nerve surgery.

The purpose of this study was to determine if botulinum toxin injections into the thyroarytenoid muscle would reduce symptoms in adductor spasmodic dysphonic patients who had experienced symptom recurrence after recurrent laryngeal nerve surgery. Five patients were seen between 3 to 10 years after surgery with a return of speech symptoms and persistent unilateral vocal fold paralysis. Before injection, comparisons with controls on spectrographic measures of pitch and voice breaks, aperiodicity, and sentence length demonstrated significant symptoms of spasmodic dysphonia (p less than or equal to 0.02). Electromyographic measures demonstrated equal levels of thyroarytenoid muscle activation on the operated and non-operated sides with bipolar needle electrodes, and heightened activity in both muscles relative to normal. Therefore, symptom return was associated with thyroarytenoid innervation after recurrent nerve surgery. In all patients, the thyroarytenoid muscle on the side operated on was injected with type A botulinum toxin. In two patients, toxin was also injected on the side not operated on. Significant (p less than or equal to 0.002) reductions in all speech symptoms occurred after injection. Electromyographic measures demonstrated significant reductions in the percent activation levels of both the injected muscle and noninjected muscles (p less than or equal to 0.01). Botulinum toxin injections were an effective treatment of post-surgical symptom recurrence in adductor spasmodic dysphonia.

Adult↗
PubMed1989

Stop consonant production in isolated and repeated syllables in Parkinson's disease.

To determine if Parkinson's disease (PD) patients have increasing difficulty as speech tasks become longer or more complex, the timing and accuracy of isolated syllables and repeated sequences of syllables were studied. Acoustic measures of PD patient's syllables were similarly impaired relative to normal controls for both isolated and repeated syllable sequences. Listeners' identification scores were equally high for both types of productions. Unlike previous studies of other types of movements in PD, speech accuracy and timing does not deteriorate as items become longer or more complex.

Aged↗
PubMed1989

Blink reflex excitability recovery curves in patients with spasmodic dysphonia.

We studied 12 patients with spasmodic dysphonia (SD) and 12 healthy control subjects. The patients, who had no symptomatic involvement of the eyes, were evaluated for increased excitability of blink reflexes, which is characteristic of blepharospasm and generalized dystonia. We measured symptom severity from sound spectrograms of five sentences, including sentence production time, number of pitch phonatory breaks, and percentage of aperiodic phonation. We evoked blink reflexes by electrical and mechanical stimulation, and assessed excitability by obtaining excitability recovery curves and responses to trains of stimuli. Patients and controls differed from each other in test R2 amplitude attenuation across all intervals from 150 to 1,000 msec to electrical and mechanical stimulation. Our results indicate that patients with SD have increased excitability of blink reflexes, which suggests that the dystonia involves not only the larynx but also other anatomical structures.

Adult↗
PubMed1989

A new surface electrode for recording from the posterior cricoarytenoid muscle.

A new pharyngeal surface electrode for recording posterior cricoarytenoid muscle activity through the hypopharyngeal mucosa has been evaluated. The electrode was passed through one nasal passage into the hypopharynx. Correct electrode location was verified by increased activity during inhalation, with decreased activity during phonation. The procedure was evaluated in 45 subjects, 10 normal speakers and 35 patients with dysphonia. Accurate recordings were obtained in 25 subjects (56%). Problems encountered were lack of pharyngeal descent, electrode dysfunction, and signal interference due to phonatory vibration or interarytenoid activity. Signal validity was evaluated in four normal speakers with accurate electrode placement. Significant (p less than or equal to 0.001) increases in PCA activity occurred during tasks requiring vocal fold abduction. The electrode proved to be a useful, noninvasive clinical tool for recording PCA activity in some patients.

Adult↗
PubMed1988

Effects of botulinum toxin injections on speech in adductor spasmodic dysphonia.

Adductor spasmodic dysphonia involves an overadduction of the vocal folds during speech causing uncontrolled voice and pitch breaks and slow, effortful speech. The disorder is resistant to speech therapy and often recurs following initial benefit from unilateral recurrent laryngeal nerve resection. Botulinum toxin injections into multiple sites of the thyroarytenoid muscle on one side were performed in 16 patients. Speech was recorded prior to injection and three times post-injection. Symptoms were measured by two examiners from speech spectrograms without knowledge of speaker identity or recording session. Significant (p less than or equal to 0.03) reductions in pitch and voice breaks, phonatory aperiodicity, and sentence time occurred only when injections resulted in unilateral vocal fold paralysis. Symptoms returned with the restoration of vocal fold movement, 3 months later. Reduction in speed of swallowing without aspiration was reported in 80% of cases. Although speech volume was reduced, there were no instances of aphonia.

Adult↗
PubMed1987

Site of penetrating brain lesions causing chronic acquired stuttering.

Ten subjects exhibited acquired stuttering that had persisted for 10 to 15 years following penetrating missile wounds sustained during the Vietnam War. None had a history of developmental or chronic adult stuttering. In comparison with other head-injured subjects and normal control subjects, the subjects with acquired stuttering had significant deficits in skilled rapid hand movements and oral and speech movements, suggesting a motor control disorder. The identified brain lesions of the acquired stuttering group were on the right in 5 subjects, on the left in 4, and bilateral in 1. The internal and external capsules, the frontal white matter, and the striatum were more frequently involved in the acquired stuttering group than in other head-injured subjects (p less than or equal to 0.05). This speech rhythm and rate disorder was not associated with evident cortical lesions in either hemisphere but with predominantly unilateral lesions of the subcortical pyramidal and extrapyramidal systems.

Adult↗
PubMed1987

Speech timing in Parkinson's and Huntington's disease.

The purpose was to determine the effects of two different basal ganglia diseases on speech planning, initiation, and production. Patients with Parkinson's Disease (PD) and Huntington's Disease (HD) were compared with normal subjects on speech timing tasks. Speech reaction time was unimpaired, while changes in duration at different speech rates were affected differently in the two patient groups. In HD, changes in the duration of syllables, of pauses between phrases, and of sentences were all reduced, while in PD only the control of sentence duration was impaired. The HD patients had reduced syllable repetition rates, but both patient groups maintained their repetition rates over 5 sec. The ratios of word to phrase time, and of phrase to sentence time, remained constant across regular and fast speaking rates and did not differ from normal in either patient group. The results suggest that PD and HD patients are not impaired in speech planning or initiation, but have poor control over the duration of speech events.

Basal Ganglia↗
PubMed1987

Dynamic aspects of phonatory control in spasmodic dysphonia.

To understand the voluntary laryngeal movement disorder in spasmodic dysphonia (SD), SD patients were compared with normal controls on speech tasks with different laryngeal motor-control demands. Nine patients with idiopathic chronic SD and no other speech, otolaryngologic, neurologic, or psychiatric disorders were compared with 15 control subjects who were free of such disorders. Speech production tasks required different degrees of dynamic and precise control of vocal fold movement. Phonatory off times were increased in the SD patients, while maximum phonation time, phonatory on time, frequency and intensity control, and reaction times for CV syllables were not affected. On a reaction-time task, the onset of laryngeal movement was not delayed in the SD patients, however, the time between the onset of laryngeal movement and phonatory onset was significantly increased in the SD patients in comparison with the controls. Therefore, SD patients had no difficulty with the onset of laryngeal movement but were slow to achieve phonation, indicating a movement-control disorder affecting vocal fold adduction for phonation onset.

Adult↗
PubMed1986

Lesion locations associated with speech perception deficits following penetrating head injury.

Speech discrimination and identification tasks assessing voicing and place distinctions were given to 16 unilaterally brain injured subjects free of aphasic or dysarthric symptoms 12-15 yr post head injury. Seven subjects did not demonstrate any difficulty with these speech tasks, while five left- and four right-brain-injured subjects showed moderate difficulties. These difficulties were more pronounced on the discrimination than on the identification tasks. Analysis of CT scans demonstrated that the lesion locations most clearly associated with the speech discrimination deficits were upper levels of the white matter subjacent to cortical regions in either hemisphere.

Brain↗
PubMed1986

The use of perceptual methods by new clinicians for assessing voice quality.

The purpose of this study was to determine the validity and reliability of using perceptual ratings for assessing voice quality in patients with vocal fold nodules or polyps. A 13-dimension perceptual rating system was modeled after systems currently in clinical use. To meet the criterion of 80% mean interjudge reliability, eight hours of training were required for four previously inexperienced listeners. Extended vowel phonations of patients and controls were then rated blindly by the same listeners. Interjudge reliability was greater than .90 for three dimensions judged in the pathological phonations, while intrajudge test-retest agreement was less than 75% on five dimensions. Validity was demonstrated with 100% correct assignment to group by computing a discriminant function employing all dimensions. Despite the extensive training procedures used, our reliability data were not comparable to those reported when highly experienced judges have been used, suggesting that the task of perceptually rating voice quality is difficult and requires extensive professional experience.

Humans↗
PubMed1986

Brain lesions associated with nonfluent aphasia fifteen years following penetrating head injury.

Men who sustained penetrating head injuries resulting in nonfluent aphasia within six months following injury, were examined fifteen years later and classified into two groups, 13 with persistent nonfluent aphasia, and 26 without symptoms of aphasia. Relative to a normal control group on a comprehensive battery of speech and language tests, the chronic nonfluent aphasics demonstrated syntactic processing deficits in all language modalities, with only mild or no impairment in other language faculties. The recovered group demonstrated deficits only in written expressive syntax. The CT lesions of the two groups differed in the extent of left hemisphere lesion volume and the degree of posterior and deep lesion extension within the left hemisphere. The nonrecovered group did not have greater right hemisphere damage. Broca's area was equally involved in 77 per cent of patients in both groups. All patients in the nonrecovered group had posterior extension of their lesions in Wernicke's area with some involvement of the underlying white matter and basal ganglia in the left hemisphere.

Adolescent↗
PubMed1984

Speech symptoms associated with early signs of Shy Drager syndrome.

Speech disturbances reflecting impaired laryngeal control were found in ten patients whose autonomic dysfunction was associated with central neurological disease (Shy Drager Syndrome). In contrast, ten patients with progressive autonomic failure without evidence of CNS involvement had no difficulties on speech function tasks in comparison with normal controls. Presence of speech symptoms may aid in the clinical differentiation between patients with pure autonomic dysfunction and those with central neurological involvement.

Adult↗