Tumors of the 8th Nerve, retrocochlear disorders Flashcards
What is the brainstem?
Relay between the brain and the sensory/motor systems
What is the cortex?
Controls higher order functions and interprets signals
What is a neoplasm?
Tumor arising from the alteration of normal cells with subsequent uncontrolled growth
What are intra-axial tumors?
Tumors occurring in, and affecting the brainstem
What are extra-axial tumors?
Tumors occurring in, and affecting, the cortex
Neoplasms can develop …
Anywhere in the CANS from the 8th nerve to the auditory cortex
Characteristics of intra-axial tumors
The closer the tumor is to the cochlea, the more auditory symptoms are present
Characteristics of extra-axial tumors
Associated with normal hearing thresholds and good speech recognition in quiet
Speech recognition breaks down in noise or with a competing message
Unilateral tumors are expressed as abnormalities on the contralateral side
VIIIth nerve tumors are more accurately called…. and arise from …
Vestibular schwannomas
Arise from neural sheath surrounding the vestibular branch of the VIIIth nerve
What is the most common type of vestibular schwannomas?
-Sporadic unilateral vestibular schwannomas
What are the treatment options for vestibular schwannomas?
- Surgery: priority is to maintain facial nerve function, preserve hearing, remove the whole tumor
- Radiation
- Amplification: necessary for patients with hearing loss after surgery or for those that surgery is not an option
Subjective characteristics of auditory nerve tumors
- Age: most common in older adults
- Chief complaint: progressive unilateral hearing loss
- Duration of symptoms: more than 1 year
Auditory nerve tumor presentation with otoscopy
WNL, not a middle or outer ear problem
Auditory nerve tumor presentation with tympanometry
WNL, not a middle ear or outer ear problem
Auditory nerve tumor presentation with acoustic reflexes
Absent in the affected ear, abnormal reflex decay
