Transcript The Auditory Nervous System

The Auditory Nervous System
SPA 4302
Spring 2007
The Ascending Auditory
Pathway
Primary Auditory Cortex
Medial Geniculate Body
Inferior Colliculus
Lateral Lemniscus
Superior Olivary Complex
Cochlear Nucleus
VIIIth Nerve
The Descending Auditory
Pathways
• Olivo-cochlear Neurons
• Cortical Neurons
• Innervation of Middle Ear Musculature
Olivo-Cochlear Efferent Neurons
Descending Pathways from Auditory Cortex
Efferent
Innervation of
Tensor Tympani
& Stapedius
Muscles
Development: VIIIth N. and
Central Auditory Nervous System
• VIIIth nerve initially: days 25 to 45
• Spiral Ganglion, Vestibular Ganglia
identifiable by day 35
• Little else known about dev. of CANS
Hearing Loss and the CANS
• VIIIth N: some SNHL, some normal
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Tinnitus!
Unilateral SNHL, Initially high frequency
Possibly poor Word Recognition
Facial Nerve Symptoms
• Disorders of the Auditory Nerve
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Vestibular Schwannoma
Neuritis
Multiple Sclerosis
Auditory Neuropathy: a new dx category
• Normal OAEs, Abnormal ABR
Disorders of the Cochlear Nuclei
• Kernicterus:
– Result of Rh incompatibility
– Hyperbilirubinemia
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Cerebrovascular Accident: A brainstem stroke
Congenital trauma, malformation
Pressure (trauma, increased CSF pressure)
Syphilis
Aging
Disorders of the Higher Auditory
Pathways
• Brainstem Tumors:
– Intra-axial: contralateral or bilateral deficits
– Extra-axial: ipsilateral deficits
• Higher level lesions
– CVA/Stroke/Aneurysm
– produce contralateral deficits
Tests for Auditory Processing Disorder
• PI-PB
• Filtered Speech
• Speech with Competition
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SSI
Competing Sentence Tests
Dichotic Digits Test
Staggered Spondaic Word Test
• Masking Level Difference Test
Therapeutic Management
• Classroom Modifications
– Improve Signal To Noise Ratios
– Pre-Teaching
• Remediation Activities
– Listening “Games”
– Computer Based Auditory Training
• Compensatory Strategies
– Homework Buddy