Acoustic neuroma pathophysiology: Difference between revisions
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==Overview== | ==Overview== | ||
Acoustic neuroma arises from [[Schwann cells]], which are the cells that are normally involved in the conduction of nervous impulses along [[axons]], nerve development and regeneration. On microscopic [[histopathological]] analysis, acoustic neuroma may display two types of growth patterns Antoni type A and Antoni type B.<ref name="radio"> | Acoustic neuroma arises from [[Schwann cells]], which are the cells that are normally involved in the conduction of nervous impulses along [[axons]], nerve development and regeneration. On microscopic [[histopathological]] analysis, acoustic neuroma may display two types of growth patterns Antoni type A and Antoni type B.<ref name="radio">Acoustic Schwannoma. Radiopedia(2015) http://radiopaedia.org/articles/acoustic-schwannoma Accessed on October 2 2015</ref> Antoni type A growth pattern is composed of elongated cells with cytoplasmic process arranged in fascicles, little stromal [[matrix]] and verocay bodies. Antoni type B growth pattern is composed of loose meshwork of cells, less densely cellular matrix, microcysts and myxoid change. | ||
==Pathophysiology== | ==Pathophysiology== | ||
Acoustic neuromas are [[benign]] tumors ([[WHO]] grade 1), which usually arise from the intracanalicular segment of the vestibular portion of the [[vestibulocochlear]] [[nerve]] (CN VIII), near the transition point between glial and Schwann cells (Obersteiner-Redlich zone). An acoustic neuroma arises from a type of cell known as the Schwann [[cell]]. These cells form an insulating layer over all nerves of the [[peripheral nervous system]] (i.e., nerves outside of the [[central nervous system]]) including the eighth [[cranial]] nerve. The eighth [[cranial nerve]] is separated into two branches the cochlear branch, which transmits sound to the brain and the vestibular branch, which transmits balance information to the [[brain]]. Most acoustic neuromas occur on the vestibular portion of the eighth cranial nerve. Because these tumors are made up of [[Schwann cells]], and usually occur on the vestibular portion of the eighth cranial nerve, many physicians prefer the use of the term vestibular schwannoma. However, the term acoustic neuroma is still used more often in the medical literature.<ref name="radio"> | Acoustic neuromas are [[benign]] tumors ([[WHO]] grade 1), which usually arise from the intracanalicular segment of the vestibular portion of the [[vestibulocochlear]] [[nerve]] (CN VIII), near the transition point between glial and Schwann cells (Obersteiner-Redlich zone). An acoustic neuroma arises from a type of cell known as the Schwann [[cell]]. These cells form an insulating layer over all nerves of the [[peripheral nervous system]] (i.e., nerves outside of the [[central nervous system]]) including the eighth [[cranial]] nerve. The eighth [[cranial nerve]] is separated into two branches the cochlear branch, which transmits sound to the brain and the vestibular branch, which transmits balance information to the [[brain]]. Most acoustic neuromas occur on the vestibular portion of the eighth cranial nerve. Because these tumors are made up of [[Schwann cells]], and usually occur on the vestibular portion of the eighth cranial nerve, many physicians prefer the use of the term vestibular schwannoma. However, the term acoustic neuroma is still used more often in the medical literature.<ref name="radio">Acoustic Schwannoma. Radiopedia(2015) http://radiopaedia.org/articles/acoustic-schwannoma Accessed on October 2 2015</ref> | ||
They are well circumscribed encapsulated masses, which unlike neuromas, arise from but are separate from nerve fibers, which they usually splay and displace rather than incorporated. | They are well circumscribed encapsulated masses, which unlike neuromas, arise from but are separate from nerve fibers, which they usually splay and displace rather than incorporated. | ||
== Genetic == | |||
One the most knowable causes of acoustic neuroma is Neurofibromatosis type 2 (NF2). Neuro bromatosis Type 2 is an autosomal dominant disease caused by loss of function mutations. Approximately 50% of reported NF2 cases represent new mutations for which no other affected family member can be identified. NF2 gene is on chromosome 22q12.2 that encodes a 595–amino acid protein named “moesin- ezrin-radixin–like protein,” otherwise known as “merlin” or “schwannomin.” Merlin protein linked with other proteins in cell and are involved in linking cytoskeletal components with the plasma membrane and are located in actin-rich surface projections such as microvilli, membrane ruf es, and cell contact regions. | |||
===Microscopic Pathology=== | ===Microscopic Pathology=== | ||
They can display two types of growth patterns: | They can display two types of growth patterns: | ||
Revision as of 18:00, 21 May 2018
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Acoustic neuroma Microchapters | |
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Diagnosis | |
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Treatment | |
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Case Studies | |
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Acoustic neuroma pathophysiology On the Web | |
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American Roentgen Ray Society Images of Acoustic neuroma pathophysiology | |
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Risk calculators and risk factors for Acoustic neuroma pathophysiology | |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
Acoustic neuroma arises from Schwann cells, which are the cells that are normally involved in the conduction of nervous impulses along axons, nerve development and regeneration. On microscopic histopathological analysis, acoustic neuroma may display two types of growth patterns Antoni type A and Antoni type B.[1] Antoni type A growth pattern is composed of elongated cells with cytoplasmic process arranged in fascicles, little stromal matrix and verocay bodies. Antoni type B growth pattern is composed of loose meshwork of cells, less densely cellular matrix, microcysts and myxoid change.
Pathophysiology
Acoustic neuromas are benign tumors (WHO grade 1), which usually arise from the intracanalicular segment of the vestibular portion of the vestibulocochlear nerve (CN VIII), near the transition point between glial and Schwann cells (Obersteiner-Redlich zone). An acoustic neuroma arises from a type of cell known as the Schwann cell. These cells form an insulating layer over all nerves of the peripheral nervous system (i.e., nerves outside of the central nervous system) including the eighth cranial nerve. The eighth cranial nerve is separated into two branches the cochlear branch, which transmits sound to the brain and the vestibular branch, which transmits balance information to the brain. Most acoustic neuromas occur on the vestibular portion of the eighth cranial nerve. Because these tumors are made up of Schwann cells, and usually occur on the vestibular portion of the eighth cranial nerve, many physicians prefer the use of the term vestibular schwannoma. However, the term acoustic neuroma is still used more often in the medical literature.[1] They are well circumscribed encapsulated masses, which unlike neuromas, arise from but are separate from nerve fibers, which they usually splay and displace rather than incorporated.
Genetic
One the most knowable causes of acoustic neuroma is Neurofibromatosis type 2 (NF2). Neuro bromatosis Type 2 is an autosomal dominant disease caused by loss of function mutations. Approximately 50% of reported NF2 cases represent new mutations for which no other affected family member can be identified. NF2 gene is on chromosome 22q12.2 that encodes a 595–amino acid protein named “moesin- ezrin-radixin–like protein,” otherwise known as “merlin” or “schwannomin.” Merlin protein linked with other proteins in cell and are involved in linking cytoskeletal components with the plasma membrane and are located in actin-rich surface projections such as microvilli, membrane ruf es, and cell contact regions.
Microscopic Pathology
They can display two types of growth patterns:
- Antoni A
- Elongated cells with cytoplasmic processes arranged in fascicles
- Little stromal matrix
- Verocay bodies: nuclear free zones of processes lying between regions of nuclear palisading
- Antoni B
- Loose meshwork of cells
- Less densely cellular
- Microcysts and myxoid change
References
- ↑ 1.0 1.1 Acoustic Schwannoma. Radiopedia(2015) http://radiopaedia.org/articles/acoustic-schwannoma Accessed on October 2 2015