Katrin Neumann

How the brain repairs stuttering

Stuttering is a neurodevelopmental disorder associated with left inferior frontal structural anomalies. While children often recover, stuttering may also spontaneously disappear much later after years of dysfluency. These rare cases of unassisted recovery in adulthood provide a model of optimal brain repair outside the classical windows of developmental plasticity. Here we explore what distinguishes this type of recovery from less optimal repair modes, i.e. therapy-induced assisted recovery and attempted compensation in subjects who are still affected. We show that persistent stuttering is associated with mobilization of brain regions contralateral to the structural anomalies for compensation attempt. In contrast, the only neural landmark of optimal repair is activation of the left BA 47/12 in the orbitofrontal cortex, adjacent to a region where a white matter anomaly is observed in persistent stutterers, but normalized in recovered subjects. These findings show that late repair of neurodevelopmental stuttering follows the principles of contralateral and perianomalous reorganization.

Severity of dysfluency correlates with basal ganglia activity in persistent developmental stuttering

Previous studies suggest that anatomical anomalies [Foundas, A. L., Bollich, A. M., Corey, D. M., Hurley, M., & Heilman, K. M. (2001). Anomalous anatomy of speech-language areas in adults with persistent developmental stuttering. Neurology, 57, 207-215; Foundas, A. L., Corey, D. M., Angeles, V., Bollich, A. M., Crabtree-Hartman, E., & Heilman, K. M. (2003). Atypical cerebral laterality in adults with persistent developmental stuttering. Neurology, 61, 1378-1385; Foundas, A. L., Bollich, A. M., Feldman, J., Corey, D. M., Hurley, M., & Lemen, L. C. et al., (2004). Aberrant auditory processing and atypical planum temporale in developmental stuttering. Neurology, 63, 1640-1646; Jancke, L., Hanggi, J., & Steinmetz, H. (2004). Morphological brain differences between adult stutterers and non-stutterers. BMC Neurology, 4, 23], in particular a reduction of the white matter anisotropy underlying the left sensorimotor cortex [Sommer, M., Koch, M. A., Paulus, W., Weiller, C., & Buchel, C. (2002). Disconnection of speech-relevant brain areas in persistent developmental stuttering. Lancet, 360, 380-383] could be at the origin of persistent developmental stuttering (PDS). Because neural connections between the motor cortex and basal ganglia are implicated in speech motor functions, PDS could also be associated with a dysfunction in basal ganglia activity [Alm, P. (2004). Stuttering and the basal ganglia circuits: a critical review of possible relations. Journal of Communication Disorders, 37, 325-369]. This fMRI study reports a correlation between severity of stuttering and activity in the basal ganglia and shows that this activity is modified by fluency shaping therapy through long-term therapy effects that reflect speech production improvement. A model of dysfunction in stuttering and possible repair modes is proposed that accommodates the data presented here and observations previously made by us and by others.

Evidence for compensation for stuttering by the right frontal operculum

There is recent evidence of focal alteration in fibre tracts underlying the left sensorimotor cortex in persistent developmental stuttering (PDS) [Lancet 360 (2002) 380]. If, as proposed, this anatomical abnormality is the cause of PDS, then overactivation in the right hemisphere seen with functional neuroimaging in stutterers may reflect a compensatory mechanism. To investigate this hypothesis, we performed two functional magnetic resonance imaging (fMRI) experiments. The first showed systematic activation of a single focus in the right frontal operculum (RFO) in PDS subjects during reading, which was not observed in controls. Responses in this region were negatively correlated with the severity of stuttering, suggesting compensation rather than primary dysfunction. Negative correlation was also observed during the baseline task that consisted in passive viewing of meaningless signs, indicating that RFO compensation acts independently of specific demands on motor speech output. The second experiment, that involved a covert semantic decision task, confirmed that RFO activation does not require overt utterances or motor output. In combination these findings suggest that the RFO serves a nonspecific compensatory role rather than one restricted to the final stages of speech production.

Carbon Dioxide Field Flooding Reduces Neurologic Impairment After Open Heart Surgery

BACKGROUND Air emboli released from incompletely deaired cardiac chambers may cause neurocognitive decline after open heart surgery. Carbon dioxide (CO2) field flooding is reported to reduce residual intracavital air during cardiac surgery. A protective effect of carbon dioxide insufflation on postoperative brain function remains unproven in clinical trials. METHODS Eighty patients undergoing heart valve operations by median sternotomy were randomly assigned to either CO2 insufflation (group I, n = 39) or unprotected controls (group II, n = 41). Preoperative evaluation included neurocognitive test batteries consisting of six different tests, and objective measurements of brain function by means of P300 wave auditory-evoked potentials (peak latencies, ms). Neurocognitive testing and P300 measurements were repeated on postoperative day 5. Neurocognitive deficit (ND) was defined as a 20% decrement in two or more tests. RESULTS Preoperatively, P300 peak latencies did not differ between groups (374 +/- 75 vs 366 +/- 72 ms, not significant [n.s.]). Five days after surgery, P300 peak latencies were significantly shorter with CO2 protection as compared with the unprotected control group (group I: 390 +/- 68 ms, group II: 429 +/- 75 ms, p = 0.02). Clinical outcome was comparable as for mortality (group I: 1 patient; group II: 2 patients) and cerebrovascular events or confusional syndromes (group I: 5 patients; group II: 4 patients) or other clinical variables as intubation time or hospital stay. Neurocognitive test batteries did not reveal differences between groups. CONCLUSIONS Shorter P300 peak latencies after surgery indicate less brain damage in patients who underwent heart valve operations with CO2 flooding of the thoracic cavity. Even if these findings were not supported by clinical results or neurocognitive test batteries in our cohort, carbon dioxide field flooding has proven efficiency and should be advocated for all patients undergoing open heart surgery.

Effectiveness and Efficiency of a Universal Newborn Hearing Screening in Germany

The decision to mandate, finance, and implement a universal newborn hearing screening (UNHS) requires the evaluation of its therapy-directed benefit by comparing (1) a procedure employing a UNHS with (2) a targeted screening for at-risk babies for neonatal hearing disorders and (3) a procedure without systematic screening. In a cohort study the outcome of the UNHS program of Hessen in 2005 with 17,439 screened newborns was analyzed. Validity, effectiveness, and efficiency were evaluated and compared to a sample of 98 Hessian and 355 German children who were detected in 2005 as hearing-impaired but not by an UNHS. The UNHS group had a PASS rate of 97.0%. Forty-nine hearing-impaired children were diagnosed at a median age of 3.1 months and treated at a median age of 3.5 months. Corresponding values for the Hessian non-UNHS group were 17.8 and 21.0 months. For Germany the median age at diagnosis was 39.0 months. The age at therapy onset correlated negatively with parameters of speech/language and psychosocial development. A targeted screening would have resulted in a low sensitivity of 65.3%. Hence, a UNHS is the most effective way to an early therapy of neonatal hearing disorders with an optimal outcome.

Event-related fMRI for the suppression of speech-associated artifacts in stuttering

The purpose of this study was to establish functional magnetic resonance imaging (fMRI) for the investigation of brain function during overt speech production in stuttering. Up to now this technique has rarely been used for the investigation of speech production paradigms because artifacts related to overt speaking largely impair the sensitivity toward task-related activation. Recently, the temporal delay of the hemodynamic response has been exploited to achieve a suppression of speech-related artifacts. By the limitation to very short utterances (one word), a temporal segregation of the respective effects was accomplished by means of an event-related experimental design. However, the investigation of speech production in persons who stutter requires a more extensive speaking situation. Since longer and more complex utterances evoke more symptoms of stuttering than reading of single words, a useful task should at least include the reading of full sentences. In this study we performed simulations to investigate the correlation of speech-related artifacts with the respective hemodynamic response in dependency on speech duration and rate of data sampling. Furthermore, we show that prolonged stimulus durations and repetition times of 3 s still allow an effective suppression of speech-related artifacts in fluent as well as in nonfluent speakers. Not only were obvious false activations at high contrast cerebrospinal fluid tissue borders widely eliminated, subjects also displayed consistent activation in speech-related and motor areas. As these results widely resemble those obtained by earlier neuroimaging studies on language production, event-related fMRI seems to be capable of recording neurophysiological correlates of overt speech production.

Alport syndrome with diffuse leiomyomatosis

Alport syndrome (AS) is a hereditary nephropathy with hematuria progressing to end‐stage renal failure (ESRF), sensorineural deafness, and specific eye signs (lenticonus, macular flecks, and congenital cataracts). Inheritance is X‐linked in about 85% of the cases, caused by different mutations in the COL4A5 gene. Rarely AS is seen in combination with diffuse leiomyomatosis (DL). DL is a tumorous process involving smooth muscle cells, mostly of the esophagus, but also of the tracheobronchial tree and the female genital tract. Characteristically, the patients have deletions of the 5′‐end of both the COL4A5 and the COL4A6 genes, respectively. We here present a 9‐year‐old boy who was admitted because of a newly diagnosed sensorineural deafness. He was born with cataracts and presented symptoms of dysphagia and bronchial irritation in the first year of life. Macroscopic hematuria was first noticed at 2 years during a febrile infection. Since early childhood the boy suffered from severe constipation. Taking together these symptoms, the diagnosis of Alport syndrome with diffuse leiomyomatosis (AS‐DL) has to be considered. Genetic analysis demonstrated the predicted deletion of the COL4A5/COL4A6 genes.

The Interplay between Glottis and Vocal Tract during the Male Passaggio

The transition between ‘chest’ and ‘head’ register is essential for male opera singers in order to reach the higher pitches. The ‘passaggio’, which is a scale passage where this transition takes place, but also a maneuver of register equalization, is typically difficult to learn. Studies on parameters for a definition of this transition are restricted to a small number of singers so far. Audio, electroglottographic, and equivalent subglottic pressure signals of 11 male opera singers were recorded while singing scales on open back vowels and passing the register transition. A spectrum analysis of the audio signal revealed that the second harmonic (H₂) dominates in ‘chest’, resonated by the first formant (F₁), together with the fourth harmonic (H₄), supported by the second formant (F₂). During the passaggio, H₂ level decreases because it loses the resonance of F₁, while the third harmonic (H₃) gains the resonance of F₂. At this point the H₄ level drops because that harmonic is no longer supported by F₂. The transition from ‘chest’ to ‘head’ register is marked by characteristic changes in the amplitude patterns of the partials H₂, H₃, and H₄, and the frequency progressions of the first two formants, defining an objective distinction between the two registers.

High prevalence of hearing disorders at the Special Olympics indicate need to screen persons with intellectual disability

BACKGROUND Persons with intellectual disabilities (ID) are at increased risk for hearing impairment which often remains undetected. If left untreated, such hearing impairments may worsen the social and communicative problems of these persons. The aims of this study are to determine the prevalence of hearing impairment, to specify type and degree of hearing loss, and to evaluate the sensitivity and specificity of the screening in this population. METHODS During the German Special Olympics Summer Games 2006, 552 athletes with ID had their hearing screened according to the international protocol of Healthy Hearing, Special Olympics. This screening protocol includes otoscopy, measurement of distortion product otoacoustic emissions, and - if necessary - tympanometry and pure tone audiometry (PTA) screening at 2 and 4 kHz. Additionally, 195 athletes underwent a full diagnostic PTA. The results of the screening and diagnostic PTA were compared. RESULTS Of the 524 athletes who completed the screening protocol, 76% passed and 24% failed it. Ear wax was removed in 48% of all athletes. 42% of the athletes were recommended to consult an otolaryngologist or an acoustician. Of the 99 athletes whose screening-based suspicion of a hearing loss was confirmed with diagnostic PTA, 74 had an undetected hearing loss. The correlation (Cramers V) between screening and diagnostic PTA was .98. The sensitivity of the screening was 100% and the specificity 98%. DISCUSSION The screening reliably detects hearing disorders among persons with ID. The prevalence of hearing impairment in this population is considerably higher than in the general population, and the proportion of undetected hearing impairments is large, even among people with only mild and moderate ID, as examined in this study. Therefore, a screening is highly recommended, and special attention from caregivers and professionals as well as regular hearing assessment and standard therapy programmes are required for persons with ID.

Auditory status of persons with intellectual disability at the German Special Olympic Games

Among persons with intellectual disability, the prevalence of hearing impairments is high. During the German Special Olympics Summer Games 2004, a hearing screening was conducted on 755 athletes with intellectual disabilities. Obligatory screening included ear inspection and recording of otoacoustic emissions, and optional screening included tympanometry and brief pure-tone audiometry. 38.0% of the athletes failed the screening. 53.0% needed ear wax removal. 56.1% of the fails indicated sensorineural hearing loss and 13.6% indicated mixed hearing loss. 12.5% of the fails were caused by unremovable ear wax, 1.4% by ear canal affections, and 16.4% by middle ear problems. Left ear fails were more frequent than right ear fails. A peripheral hearing disturbance can thus be expected in every third subject. The high failure rate, a considerable percentage of previously undetected profound hearing loss (1.1%), and the frequent need for ear wax removal, suggest that nearly half of persons with intellectual disabilities need regular otological or audiological consultations. Sumario La prevalencia de hipoacusia entre personas con discapacidad auditiva, es alta. Durante los juegos olímpicos de verano 2004 en Alemania, se realizó un tamiz auditivo en 755 atletas con discapacidad intelectual. Éste incluyó otoscopia, prueba de emisiones otoacústicas y opcionalmente una timpanometría y una audiometría breve. El 38% de los atletas no pasaron el tamiz y a 53% se les retiró cerumen. El 56.1% de los que no pasaron el tamiz presentaban hipoacusia sensorineural y 13% hipoacusia mixta; a 12.5% no fue posible retirarles el cerumen, 1.4% presentaban alteraciones del conducto auditivo externo y 16.4% tenían algún problema del oído medio. Fueron más frecuentes las alteraciones en el oído izquierdo que en el derecho. Se puede esperar una alteración auditiva periférica en un tercio de los sujetos. El alto índice de falla en el tamiz, un porcentaje considerable de hipoacusia profunda no detectada (1.1%) y la necesidad frecuente de remoción de cerumen, sugiere que casi la mitad de las personas con discapacidad intelectual necesitan consulta audiológica u otológica regular.