A peer-reviewed, evidence-based journal for clinicians in the field of neuroscience
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[ V O L U M E 1 2 , N U M B E R 7 – 8 , J U L Y – A U G U S T 2 0 1 5 ] Innovations in CLINICAL NEUROSCIENCE 33 suspicion of an auditory processing disorder. The diagnosis of ANSD was made based on the audiological findings of absent ABR and acoustic r eflex in the presence of bilateral mild- to-moderate degree of hearing loss and the presence of cochlear microphonics on ABR with poor speech identification score disproportionate to the hearing loss. The presence of cochlear microphonics in this patient, which is a pre-neural response, suggested the integrity of outer hair cells. However, this was not evidenced on OAE. Space-occupying lesions at the brainstem level were ruled out through neurological examination and radiological investigations. Although the OAE is used as a differential diagnostic tool and is often present in patients with auditory nerve dys-synchrony, it was absent in this patient, making our diagnosis challenging. Starr et al 5 report that in 30 percent of patients with ANSD, the OAE is absent. Deltenre et al 6 attribute the loss of OAE in the presence of preserved cochlear microphonics to the dysfunction of the cochlear amplifier, which would add to the initial synchronization deficit in such patients. This could be the possible mechanism for the absence of OAE in our patient too. The patient also demonstrated impaired temporal resolution (gap detection >20m.sec in both ears). Being one of the basic components for speech perception, impaired temporal resolution may significantly alter an individual's ability to perceive speech. This factor along with poor dichotic perception (inability in binaural separation) may have contributed to the significant impairment in verbal comprehension by Mr. B. Mr. B also reported erectile dysfunction, which was possibly related to the escitalopram he was taking for anxiety. Medications were reassessed by the clinical team, and Mr. B was started on mirtazapine 30mg/day; the escitalopram was discontinued. In addition, education regarding his disability and incorporation of behavioral modifications that included practicing speechreading (i.e., lip reading) skills, a sking his secretary to take down notes for him, and participating in yoga therapy were initiated. After these measures were in place, Mr. B reported a better level of functioning in his day-to-day office work. However, his most distressing symptom, autonomic arousal on hearing telephone ringtones, persisted. This symptom was possibly confounded by Mr. B's inability, when speaking on the phone, to use visual cues (i.e., speechreading) from the person with whom he was speaking. While Mr. B's difficulty in comprehending speech made a formal cognitive behavior therapy approach difficult, his autonomic arousal symptom did improve with a technique of thiopentone-assisted systematic desensitization. 7 Mr. B was seen for follow-up on two occasions over a three-month period after initiation of the desensitization sessions. On his final follow-up visit, he subjectively reported a 75-percent improvement in his anxiety symptoms and phone ringing phobia by utilizing a combination of mirtazapine, behavioral interventions, yoga therapy, and five desensitization sessions. His sexual dysfunction had also resolved. CONCLUSION Presence of psychiatric symptoms that have been long-standing and unresponsive to conventional pharmacotherapy and the presence of defects in perceiving speech should raise clinical suspicion of a possible underlying neuro-developmental condition. Our patient's severe anxiety symptoms initially masked the presence of ANSD. Once the proper diagnosis was made, the ANSD was effectively managed through an interdisciplinary and multimodal treatment approach, and the patient improved significantly. In cases of ANSD with comorbid psychiatric symptoms, we recommend an individualized treatment plan that incorporates the use of alternative communication strategies and b ehavioral modifications (e.g., enhancing the patient's speechreading skills and utilization of face-to-face conversations, reducing competing noices in certain auditory environments, and speaking more slowly while conversing), along with appropriate pharmaco- and psychotherapies. REFERENCES 1. Northern J (ed). Guidelines for Identification and Management of Infants and Young Children with Auditory Neuropathy Spectrum Disorder. Aurora, CO: The Children's Hospital; 2008. 2. Starr A, Picton TW, Sininger Y, et al . Auditory neuropathy. Brain. 1996;119:741–753. 3. World Health Organization. International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10). Geneva: WHO; 1992. 4. Shivashankar N, Satishchandra P, Shashikala HR, Gore M. Primary auditory neuropathy—an enigma. Acta Neurol Scand. 2003;108(2):130–135. 5. Starr A, Sininger Y, Nguyen T, et al. Cochlear receptor (microphonic and summating potentials, otoacoustic emissions) and auditory pathway (auditory brain stem potentials) activity in auditory neuropathy. Ear Hear. 2001;22:91–99. 6. Deltenre P, Mansbach AL, Bozet C, et al. Auditory neuropathy with preserved cochlear microphonics and secondary loss of otoacoustic emissions. Audiology. 1999;38:187–195. 7. Pearlman T. Behavioral desensitization of phobic anxiety using thiopental sodium. Am J Psychiatry. 1980;137:1580–1582.