”GoId standard” investigation for Acoustic Neuroma

”GoId standard” investigation for Acoustic Neuroma is? 

A. Contrast enhanced CT 
B. Contrast enhanced MRI
C. Evoked potential 
D. PET scan

Ans. B. Contrast enhanced MRI 

VESTIBULAR SCHWANNOMA

Tumors origination from cranial nerves account for 6-8 % of primary intracranial tumors and most are benign neoplasms arising from Schwan cell schwannomas; of the nerve sheaths; 

• Vestibular Schwannoma arises eccentrically from the sheath and compress the parent nerve rather than invading it; 

• It is the most common CP angle tumor, followed by meningioma and epidermoid cyst 

All cranial nerves except I and II, which are in fact white matter tracts of the cerebrum, have nerve sheaths, but schwannomas usually grow on the sensory nerves, most frequently from the superior vestibular division of vestibulocochlear nerve acoustic neuroma; and with decreasing frequency, from trigeminal, glossopharyngeal and lower cranial nerves; Pure motor cranial nerves rarely form schwannomas;

- Multiple cranial nerve schwannomas are found in neurofibromatosis type 2 and bilateral vestibular Schwannomas are pathognomonic sine qua non; of NF-2; Recently, NF-2 is called as MISME complex multiple inherited Schwannomas, Meningiomas and ependymomas;; Cranial nerve tumors almost invariably show marked contrast enhancement; 

-Acoustic vestibular; schwannomas .  neuromas; account for 80% of cerebellopontine lesions 

- Plain skull radiograph or conventional tomography shows widened internal auditory meatus IAM. ; 

- CECT shows enhancing mass in posterior fossa with widening of IAM; Although medium sized and large vestibular schwannomas may easily be detected by CECT, MRI is much more sensitive than CT in detection of small lesions;

- MRI is now the method of choice for the investigation of suspected vestibular schwannomas than can be diagnosed or excluded on high-resolution, thin section, T2 weighted fast spin-echo images of CP angles, capable of resolving the 7th and 8th nerves in detail; If the findings are equivocal, gadolinium-enhanced images can refuse or confirm the suspicion of a tumor, since it almost always shows marked enhancement; 

- Audiometry is often the initial diagnostic test; Unilateral pure-tone sensorineural hearing loss with disproportionate loss of speech is suggestive of a retrocochlear lesion; Auditory brain stem response detects 95% of tumors- a delay in the latency of the V wave of 0.2 msec or greater is considered abnormal;

-  MAGNETIC RESONANCE IMAGING WITH GADOLINIUM ENHANCEMENT is the GOLD STANDARD for diagnosing Acoustic neuromas.