Central Nervous System Cyst

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A central nervous system cyst is a cyst that primarily presents itself in the tissue of the central nervous system.They are usually benign and could be filled with cerebrospinal fluid, blood, or tumor cells. There are two categories; cysts that originate from non-central nervous system tissues, and cysts that originate from central nervous system tissues.[1][2]

Classification

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 Originating from non-central nervous system tissues

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This classification of cysts are embedded in the endoderm and the ectoderm of cranial and spinal cord germ layers. They normally take over the neuraxis, which allows them to infiltrate the central nervous system tissues.[3]They are most commonly found in the area near the pineal gland, the supracellar cistern, and the cerebelloponitine angle space. Some examples include Teratomas, dermoid cysts, and Rathke’s cleft cysts.

Originating from the central nervous system tissues

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This category of cysts takes over areas of necrotic tissue in the brain from injuries, diseases, or abnormalities, which will happen due to the central nervous systems nonregenerative nature. These cysts can affect all germ layers of the central nervous system, but are most common in the arachnoid mater, and the ventricular space. Some examples are arachnoid cysts, ependymal cysts, cystic cerebellar astrocytomas[4][5]

Signs and symptoms

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Some of the cysts can be asymptomatic depending on the location in the brain or spinal cord. If the cysts do develop into critical areas of the central nervous system they will present the following symptoms[6]:

  • pressure in the spinal cord or brain  
  • Rupture of nerves around the cyst
  • Weakness in area controlled by brain affected by the cyst
  • Inflammation
  • Can be asymptomatic depending on type and location of cyst
  • Hydrocephalus
  • Brainstem hemorrhage

Symptoms tend to vary depending on the type of cyst as well as the location, and are assessed on a case by case basis[7].

Causes

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Many brain cysts form in the womb during the first few weeks of development as a result of congenital defects.[8]  Cyst may also form later in life due to a head injury or trauma, and sometimes can be associated with cancerous tumors or infection(s) in the brain. However for the most part, the underlying reason(s) for cyst formation are still unknown[8].

Diagnosis

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Healthcare professionals will typically diagnosis a brain cyst via an imaging scan/test. These imaging tests include CT scans and MRIs. The diagnosis process typically begins with a medical history workup followed by a medical exam. In some cases a primary health care provider will refer a patient to a neurologist or neurosurgeon. Other diagnostic methods include the usage of Immunohistochemistry, used to differentiate between epithelial and and arachnoid cysts, and radiological and macroscopic examinations. These examinations are useful to get a baseline idea, but can be unsatisfactory to diagnosis CNS cysts.[7][3]


Classification

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 Ordinary cysts found in different regions of the body, not including the central nervous, are classified depending on how they look under a microscope.[4] As of 2016 the World Health Organization (WHO) announced genetic testing would be used to further classify cysts found in the CNS.  Further understanding of a cysts genetic makeup will shed further light on how to treat cysts.


References

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  1. ^ Schiff, David (June 2010). "Cysts" (PDF). American Brain Tumor Association. Retrieved 3 March 2017.
  2. ^ Hirano, Asao; Hirano, Michio (2004-03-01). "Benign cysts in the central nervous system: Neuropathological observations of the cyst walls". Neuropathology. 24 (1): 1–7. doi:10.1111/j.1440-1789.2003.00526.x. ISSN 1440-1789. PMID 15068166. S2CID 35936716.
  3. ^ a b Greenfield, Jerry (January 2015). "Surgery for an Arachnoid Cyst". Retrieved 2017-03-11.
  4. ^ a b Chen, Yong; Fang, Hong-Juan; Li, Zhi-Feng; Yu, Sheng-Yuan; Li, Chu-Zhong; Wu, Zhe-Bao; Zhang, Ya-Zhuo (2016-08-01). "Treatment of Middle Cranial Fossa Arachnoid Cysts: A Systematic Review and Meta-Analysis". World Neurosurgery. 92: 480–490.e2. doi:10.1016/j.wneu.2016.06.046. PMID 27319312.
  5. ^ Chen, Yong; Fang, Hong-Juan (August 2016). "Treatment of Middle Cranial Fossa Arachnoid Cysts: A Systematic Review and Meta-Analysis". World Neurosurgery. 92. Elsevier Inc.: 480–490. doi:10.1016/j.wneu.2016.06.046. PMID 27319312.
  6. ^ "Brain Cyst". www.saintlukeshealthsystem.org. June 2015. Retrieved 2017-03-26.
  7. ^ a b Sundaram C, Paul T R, Raju B V, Ramakrishna Murthy T, Sinha A K, Prasad V S, Purohit A K. Cysts of the central nervous system : a clinicopathologic study of 145 cases. Neurol India [serial online] 2001 [cited 2017 Apr 11];49:237. Available from: http://www.neurologyindia.com/text.asp?2001/49/3/237/1247
  8. ^ a b "Brain and spinal cord cysts - Canadian Cancer Society". www.cancer.ca. Retrieved 2017-04-11.