Acoustic+neuroma

|| MRI of Acoustic Neuroma || **Grade I** - Tumor is small, occurring only within the internal auditory canal itself. **Grade II** - Tumor extends into the fluid spaces around the brainstem **Grade III** - Larger tumor (usually up to 2.5 cm in diameter). Extends up to the brainstem. **Grade IV** - Very large tumor (up to 5 cm in diameter). Compresses the brainstem, often involves the nerves of swallowing and the 5th cranial nerve (face and eye sensation)(4) || **Stage II** tumor protrudes through the opening of the IAC on the brain side, in the area called the cerebellopontine angle (CPA), not yet touching the cerebellum of brainstem **Stage III** the tumor has grown large enough to contact the cerebellum and/or the brainstem, but not compressing these brain structures. This may impact on the the trigeminal nerve having loss of facial sensation. Other nerves can be affected resulting in paralysis of the soft palate, a hoarse voice and paralysis of the tongue. Finally in **Stage IV**, if left untreated the tumor will press into the cerebellum/brainstem, possibly resulting in walking and writing issues. At this point cerebrospinal fluid (CSF) flow could be blocked, causing hydrocephalus (pressure on the brain) and eventually lead to coma or even death. (5) ﻿ || The most common treatment of AN is microsurgical resection. Primary treatment of AN with external-beam irradiation is reported to be successful. Radiosurgery has been proposed as an alternative to microsurgical resection. Its well-circumscribed nature and typical intense enhancement of MRI facilitate localization and treatment by stereotactic techniques. Another treatment option is adjuvant external irradiation used in conjunction with subtotally resected AN. The dose is 50-66 Gray (Gy) in 1.8-2.0Gy fractions in 5 to 6 weeks. [1]  || Acoustic Neuroma: Standard dose, 50-66Gy. [1]
 * Epidemiology: || The National Institute of Health (NIH) places the incidence at 1 per 100,000 individuals per year in theUnited States, which translates to 2000 to 3000 new cases diagnosed per year in the United States; however, three large autopsy series have identified these tumors in 0.8% to 1.7% of patients. The incidence of NF-2, on the other hand, is well documented to be at 1 in 40,000.(1)
 * Etiology: || Acoustic neuroma (AN) occurs in all parts of the world without ethnic predilection. One known risk factor is the genetic risk of neurofibromatosis type I.(2) ||
 * Signs & Symptoms: || Common symptoms are Hearing Loss, vertigo, and tinnitus (ringing in the ear). The less common symptoms include dizziness, difficulty understanding speech, headaches, the loss of balance, numbness and weakness in face. Also pain in the face and vision problems can be a less common symptom.(3) ||
 * Diagnostic Procedures: || Tests done for detection of AN include Magnetic resonance imaging (MRI) imaging demonstrates excellent soft tissue visualization but does not show bony details. enhanced MR imaging with gadolinium enhancement continues to be the gold standard diagnostic tool.(2) computed tomography (CT) scan of the head has limited use due to its high bony detail that may obscure views of the acoustic neuroma. A hearing test with auditory evoked response is done to determine the eighth nerves involvement and function. Electronystagmography (equilibrium and balance test) are also performed to see the extent of the disease on a patients balance.(2)
 * Histology: || Acoustic neuromas, also known as vestibular schwannomas, are non-malignant tumors of the 8th cranial nerve. Most commonly they arise from the covering cells (Schwann cells) of the inferior vestibular nerve.(2) They can also arise within the labyrinth.(2) ||
 * Lymph Node Drainage: || <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 16px;">An acoustic neuroma is not cancer. The tumor does not metastasize to other parts of the body. However, it may continue to grow and press on important structures in the skull. ||
 * Metastatic Spread: || <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">They do not Metastasize. ||
 * Grading: || <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">Size determines therapeutic outcome.
 * Staging: || <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%; line-height: 13.5pt;">**stage I** tumor slowly impede the inter auditory canal (IAC), auditory and balance nerves are being compressed. This is when the first symptoms occur of tinnitus and unilateral hear.
 * <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%; line-height: 13.5pt;">0 to 10 mm: stage 1
 * <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%; line-height: 13.5pt;">10 to 20 mm: stage 2
 * <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%; line-height: 13.5pt;">20 to 35 mm: stage 3
 * <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%; line-height: 13.5pt;">more than 35mm: stage 4
 * Radiation Side Effects: || <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">The acute side effects are minimal and most patients can continue normal daily activities. Late effects of radiation treatments may occur to a small percentage of patients, most often headache, fullness of the ear, or decreased balance. These effects, if they occur, are usually modest and resolve over a few months. There is a very high rate of facial nerve preservation with radiation. The majority patients with good hearing will retain useful hearing in the treated ear, but hearing loss is the most common permanent side effect.(6) ||
 * Prognosis: || <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">Since acoustic neuromas are not malignant they will have no effect on the survival of the patient if treatment is done before stage IV issues arise. Hearing can be lost and other nerves can be impinged on by the growth of the acoustic neuroma causing facial droop like what is seen with Bell palsy. Other quality of life issues may arise if untreated and tumor growth continues.(5) ||
 * Treatments: || <span style="color: #00b050; font-family: 'Times New Roman',serif; font-size: 12pt;">Treatment of acoustic neuroma (AN) should offer a high chance of local control and preservation of cranial nerve function. Preservation of hearing is a realistic goal in up to one-third of patients with “useful hearing” preoperatively.
 * TD5/5: || <span style="color: #00b050; font-family: 'Times New Roman',serif; font-size: 12pt;">TD 5/5: Normal Tissue Tolerances (Gy) (1.8-2.0 Gy per fraction). [2]

<span style="color: #00b050; font-family: 'Times New Roman',serif; font-size: 12pt;"> || <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 14px; line-height: 21px;"> References:

<span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 14px; line-height: 21px;">(1)Ho, Steven Y. MD,. Kveton, John F. MD. //Acoustic Neuroma: Assesment and Management//. Available at: [] Accessed June 1, 2011. <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">(2)Chao C, Perez C, Brady L .//Radiation Oncology.2nd ed//. Philadelphia, PA: Lippincott Williams & Wilkins; 2002:153-154. <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">(3) PubMedHealth, //Acoustic Neuroma.// Available at: [] June 2, 2011. <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">(4)Brain-Surgery.com, Brain and Neurosurgery infomation center. //Acoustic Neuromas//. Available at: []Accessed May 31, 2011. <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">(5)The Acoustic Neuroma World Site. //A guide for acoustic neuroma patients//. Available at: []Accessed June 1, 2011. <span style="color: #ff5200; font-family: 'Times New Roman',Times,serif; font-size: 110%;">(6)John Hopkins Medicine, //Stereotatic Radiosurgery//. Available at: []Accessed June 2, 2011. <span style="color: #00b050; font-family: 'Times New Roman',serif; font-size: 12pt;">[1] Chao C, Perez C, Brady L. Brain, Brainstem, and Cerebellum. //Radiation Oncology.// //2nd ed//. Philadelphia, PA: Lippincott Williams & Wilkins; 2002: 129-156. <span style="color: #00b050; font-family: 'Times New Roman',serif; font-size: 12pt;">[2] Vann A, Dasher B, Chestnut S, Wiggers N. Central Nervous System Tumors. //Portal Design in Radiation Therapy. 2nd ed.// Columbia, SC: The R.L. Bryan Company; 2006: 59-69.