Two patients participated in dichotic listening training. "Michael" participated in dichotic listening therapy for two clinic semesters. "Thomas" lives in another state and participated in dichotic listening therapy with his speech-language pathologist.
In dichotic training, stimuli are presented at different interaural intensities with a higher intensity directed to the poorer (dichotic scoring) and lower intensity directed to better (dichotic scoring) ear. Initial presentation level is at a comfortable level to the poorer scoring ear, and a soft level to the better (dichotic scoring) ear. When the individual's target ear's score reaches >70%, the intensity level delivered to the poorer ear is increased by 1, 2, or 5 dB. This continues until there are equal intensities presented to both ears. Because of the limited amount of dichotic listening materials, available, new recordings of digits, words, sentences, CVs and short stories were created and used in the training sessions.
Case One: Michael
Michael was the product of a normal pregnancy and birth. All developmental milestones were developing appropriately until the age of three. At that time, Michael's speech and language skills began to decline. Initially, this decline in speech and language was attributed to sibling jealousy as this decline coincided with the birth of a younger sibling. Michael was sent for a hearing evaluation which established normal peripheral hearing. As Michael had a history of otitis media, the lack of progression in speech and language was next related to his history of ear infections. Subsequently, autism and pervasive developmental disorder were also erroneously diagnosed. With the onset of seizure activity at the age of three and a half years, the diagnosis of LKS was made after a characteristic spiking EEG. Nocturnal seizure activity continued until Michael was eleven years old, even though anticonvulsants were prescribed. At age 11, Michael had his first normal EEG.
Our involvement with Michael began when he was 12.5 years old, as he was a subject in a study examining pre and post behavioral and electrophysiological measures after Fast ForWord® training, provided by Michael's local school system. Approximately four weeks after Michael completed the Fast ForWord® program, Dichotic listening therapy began weekly for a total of twenty one hour dichotic listening training sessions.
Post-testing showed improvement in dichotic scores after dichotic listening training, as well as improvements in electrophysiologic responses (auditory late response). In addition, unsolicited parental reports were positive. Extended family member, as well as Michael's teachers, commented that his speech was improving and that he was speaking in complete sentences and thoughts, rather than in a telegraphic-type speech. They also reported that he rarely used signs. This cannot be validated, as we did not measure pre and post mean length utterance.
Case Two: Thomas
Thomas was the product of a normal pregnancy and birth history was normal. Gross motor development milestones were achieved at appropriate times. At age 3, Thomas had a speech-language evaluation to address articulation concerns. This assessment yielded normal results. Sleep concerns were noted as early as age 3 ½; at age 5 ½, a tonsillectomy/ adenoidectomy was performed for sleep apnea.
Early behavioral, attention, language and hearing were first noted when Thomas was in pre-school. A speech-language assessment at that time (age 6.25) indicated a severe receptive language delay. Language regression and concerns continued over the next few years.
Thomas had an abnormal EEG at age 8 years, 2 months indicated bilateral abnormalities, but left temporal lobe activity greater on the left side. Approximately six months later, an EEG indicated abnormalities on the right side, as well. Thomas is currently managed medically for his abnormal nocturnal EEG. In July, 2009, Thomas was formally diagnosed with Landau-Kleffner Syndrome (LKS). Thomas began dichotic listening in October, 2009. He was seen at the LSU Health Sciences Center in July, 2010. Because of the geographical distance, Thomas has been working with his speech language pathologist on dichotic listening via recorded compact discs. Training began 20 minutes, twice per week, and is now listening weekly. Although we do not have comprehensive pre and post (C)APD test results, we have dichotic test scores from an assessment in July, 2009. Scores previously abnormal are now within normal limits.
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