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
Auditory nerve tumor presentation with OAEs
WNL
Auditory nerve tumor presentation with audiometry
Varies by patient
Unilateral or significantly asymmetric high-frequency SNHL
Auditory nerve tumor presentation with speech perception
Poorer than expected*****
Key red flag
Key red flags for an auditory nerve tumor
Sloping hearing loss, word and speech understanding does not match the audiogram, unilateral hearing loss paired with tinnitus and unsteadiness
