Arachnoid cyst

(Código CIE-9-CM: 348.0)

Arachnoid cyst, also known as cysts leptomeningeal.

Arachnoid cysts (QA) are benign pathological structures of features that could define as clear fluid filled cavities similar to cerebrospinal fluid (LCR), contained within a histologically indistinguishable healthy arachnoid.

Occur during the division of the arachnoid.

The most accepted hypothesis speaks of changes in the separation of endomenix in the third quarter of the neonatal period. The membrane is endomenix mesenchymal tissue surrounding the neural tube. In the third quarter, when the roof of the fourth ventricle is broken, CSF pressure waves flowing through it, the dissected into two layers and result pial, arachnoid and subarachnoid space. Alterations of this mechanism may lead to the formation of separate cavities that, growth in, form cysts.

Other hypotheses are saying that are secondary to focal brain hypoplasia, in which occupy the space provided or produced by alterations of the secretion of substances from the subarachnoid space to the venous system. Also, to explain the subsequent growth of the cyst were raised various theories; between them, the most accepted, because there are cases where it has been demonstrated in vivo, is the formation of valve mechanisms . Have also been described in the literature sometimes cysts associated with meningeal infections and trauma, called secondary, as opposed to those for which the cause is unknown and suspected congenital malformation, and designated primary.

Really it is intraaracnoideos cysts. When diagnosed at the level of media were called ” sindrom ” temporal lobe agenesis. (This term is now obsolete).

Others are caused by trauma.

An fracture Simple linear, without immediate complications, can cause the development of a cyst , hence the need to maintain a proper monitoring of the evolution of consolidation fracture and an etiologic alert to the onset of neurological symptoms.


Constitute a typical diagnosis of childhood, especially in the first two years of life, which represent approximately 1% of the expansive intracranial. The most common locations found in various series are the Sylvian fissure and posterior fossa.

5 by 1000 autopsias.son characteristic lesions in childhood, slightly more common in males.

Also found at the spinal level, although they are rare.


  • Cisura de silvio 49%
  • APC 11%
  • Supracolicular 10%
  • Vermiano 9%
  • Sellar and suprasellar 9%
  • Interhemisférico 5%
  • Convexity 4%
  • Clivus 3%

Histological types

Simple cysts: Cell line appear to be capable of secretion CSF. The cysts of the middle fossa speak exclusively of this type

Complex cysts that may also contain glia, epéndimo, and other types of tissue.

Quiste Aracnoideo

Quiste Aracnoideo

Clinical Presentation

The symptomatology is variable depending of the central compress, the most striking focal symptoms are signs of hypertension , as are headache ( headlong), hemiparesis,diplopia (double vision), irritability, mood swings, apathy (emotionless), and impaired intellectual performance.

Trench Media suprasellar with fuzzy supra or infratentorial hydrocephalus hydrocephalus

,headache,hemiparesia HTE,Craneomegalia,late development,loss of visual acuity,precocious puberty HTE,craneomegalia,late development

Most cysts are symptomatic in infancy.

Can be diagnosed by the presence of:

  • Symptoms of increased intracranial pressure (Headache, sickness…)
  • Epilepsy.
  • Sudden deterioration: due to bleeding (in cyst or subdural): pit medial cysts are prone to bleeding due to the increased possibility of rupture of bridging veins; due to rupture of the cyst
  • Protrusion in the skull
  • Focal neurological signs.
  • Incidental finding.
  • Hydrocephalus (Probably due to compression of the third ventricle)
  • Endocrine symptoms: occurring in a 60%. Includes precocious puberty.
  • Visual impairment
  • In posterior fossa usually produce nonspecific symptoms such as hearing loss and tinnitus sometimes even difficult to distinguish from Meniere's disease and the most characteristic often cerebellar ataxias.


Are diagnosed primarily by TAC.

The ideal method of diffusion MRI sequences (Maybe it will raise the differential diagnosis with epidermoid cysts or neoplastic hemangioblastomas).

Differential diagnosis

  • Cystic astrocytomas.
  • Wemer cistern
  • Hydatid cyst – Cisticercosis
  • Myocardial old crebral
  • Porencefalia.
  • Hollow Line Media.


Size is recommended to treat only the symptoms that occur regardless of the location and. Treatment is still controversial.

Therapeutic options have endoscopic fenestration or craniotomy into the ventricle or subarachnoid space and the implantation of a shunt.

Probably the best treatment consists in the derivation of cyst peritoneum.

Method Advantages Disadvantages

Aspiration- drill and fast Recurrence

Craniotomy with excision of the quísticay wall fenestration to subarachnoid or ventricular space allows inspection of the cyst and vascular structures. Evita in some cases permanent shunt. Possible re-accumulation and more invasive.

Cystoperitoneal Simple Derivation Procedure Unit Shunt and risks of carrying Shunt.

Dr. J. Sales Llopis

Department of Neurosurgery, University General Hospital of Alicante.

To consult:

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157 Replies

  1. humberto says:

    Hello I have my grandfather 81 ala years time that he made a magnetic resonance the result of the interpretation is as follows :
    multiple pulse sequences were performed T1, T2 , FLAIR , Diffusion , AND , getting multiplanar images which shows :
    ocupativas symmetrical brain parenchyma lesions not identified, with decrease in brain volume widely , grooves comprominencia .
    draws attention aranoideo the presence of cyst in the left parietal region , with measures 20x18x21 mm.
    the nuclei of the base with adequate volume and intensity as well as morphology concervados .
    the optic chiasm , pituitary gland and pituitary stalk with volume and signal intensisad consercados .
    corpus callosum present without alteriaciones in their morphology
    the supratentorial ventricular system with bulging breaks , increased volume of compensatory and sisternas way to the base with increased volume .
    mesencefalo , pons and medulla unchanged .
    craniocervical junction is concervada and normal caraccteristicas.
    cerebellar hemispheres and vermis size , form , situation and normal signal intensity .
    the fourth ventricle is Central and adequate volume .
    no restriction areas are observed to superspreading .
    After administration of intravenous contrast material , no zones are observed normal refuerso .
    estruccturas unaltered orbits .
    estruccturas of the internal auditory canals are symmetric and normal signal intensity .
    the tissue is normal .
    decrease in brain volume in relation to cortico subcortical atrophy
    arachnoid cyst in the left parietal region.
    suggested correlation with clinical studies.

  2. taco says:

    hello my name gladly Jose and I am from Honduras well I just want to know or ask you if you know or that al-aware of any medical natura, since there is a patient who was operated three times head since he had an arachnoid cyst and operations will be obstructed the occipital nerve, and many suffer from constant headaches and that leads him to take a lot of medication, ay sele put a valve and valve did not work was the agrarecere much contact me blessings:

  3. Xavier says:

    Hello, I have a child 5 years old,in February 2011, he slipped and hit his head, he did take him to the doctor, they did a scan and was diagnosed with the following:

    The computerized tomographic brain injury is done through continuous axial slices 5 m.m.s. thick, I agree to planar obtained in digital panoramic radiography, substance without using iodized contrast and supplemented with bone algorithm, pairs of Mostar:

    The normality of the supratentorial parenchymal structures with adequate differentiation of gray and white matter and brainstem while large central posterior fossa cyst homogeneous seen the occipital bone remodeling, centrally bilateral extension of the fourth ventricle and communicates, the latter of increased volume. The cerebellar hemispheres are reduced toward the midline.

    Supratentorial ventricular system topography, dimensions and normal morphology with long occipital horns and fourth ventricle volume increased.
    A cisternal level emphasizes the preservation of cerebral and cerebellar cortical sulci and the basal cisterns and peritroncals.

    Centromedial structures without deviations relative to the midline.
    No extra axial intracranial collections.
    Bony structures of cranial vault base and post-traumatic disorders.

    Normal Brain. Great posterior fossa cyst in communication with the fourth ventricle.
    Absence of parenchymal lesions and extra-axial post-traumatic intracranial.

    We took him to several of the best specialists in the country and they have all told us the same thing, which is very common, that their behavior is normal, and leave everything, except some reaction.
    Not to operate, and you should do your normal life.

    Although the cyst is approximately 5cm to date has not complained about any of the topics listed in the previous comments as vomiting, head pain severe, etc.

    About a year ago we realized that when trying to look closely, one eye is deviated and took him to the doctor and was diagnosed,"Accommodative esotropia with ac / a high", and the doctor says he has nothing to do with your cyst.

    My questions are:
    1.- How to know if a cyst or a mega cisterna.
    2.- It has something to do with accommodative esotropia with ac / a high.
    3.- I have to give a test to see if the cyst has grown or may have any complications.
    4.- I have to take special care in school, or when playing?

    I am a father of Lima, Peru, worried about my only son and I get very sad this whole issue.
    Muito Obrigada.

    • catalina says:

      my daughter is having the same and also will detour eye started to wear glasses always tell you that it has nothing to do with it but it is no coincidence that three people I know, the same thing happens only faith in God and do not let the operate the mine were detected a year and already has four and thank GOD is living a normal life

    • VICTORIA says:

      Hello, I have 33 years old, several arachnoid cysts, and even one intramural. To this day, Thank God, I have made my life as normal, to the point of almost not think cysts. I understand your concern because I'm a mother, but the only recommendation I can give, is to calm down and try to influence him that calm your child, for trouble us no benefit in these cases. Teach your child to live life fully and accountability. Much encouragement and strength. A huge

  4. chateante says:

    Male, 40 years old. I suffer headaches since last May, and I take Lyrica 25 (morning and evening) and Sirdalud (night). He has been diagnosed me arachnoid cyst (see the transcript of the two tests). I am waiting for an appointment with the neurosurgeon. What is your opinion?. I am particularly concerned about a possible operation. Do you think it will be necessary?.

    Thank you very much.

    TC SKULL WITHOUT Constraste
    F. realization: 13/06/2012.
    Headache three weeks in male 40 years without interest AP, especially when trying to concentrate or exercise. The pain is localized to left parietal level. I pray rule out organic (commented with neurology).
    Cranial CT without IV contrast administration.
    A hypodense large image which occupies the anterior portion of the left temporal fossa is identified, adapting to the rest of the time the injury parenchyma without conditioning effect apparent mass. On the characteristics and location that image probably corresponds to arachnoid cyst without evidence of associated complications. However, existence of symptoms given complete study assessing MRI.
    Rest of the brain parenchyma without evidence of relevant findings.
    Likely arachnoid cyst left temporal without apparent complications.

    F. realization: 29/06/2012.
    Tensional headache. Nonspecific dizziness.
    MRI of the head without contrast administration IV.
    The image is identified in the most anterior portion of the left temporal fossa described in previous TC. This injury has similar signal intensities of the LCR in all sequences. Adjacent parenchyma temporary adapts to the presence of the lesion, changing its shape even without obvious mass effect or perilesional edema or other changes in the parenchyma adjacent. Nor associated hemorrhagic component or alterations in the next bony structures. No diffusion restriction sequence. All findings described corresponds to arachnoid cyst without evidence of associated complications.
    Rest of the brain parenchyma without evidence of relevant findings.
    Arachnoid cyst left temporal no associated complications.

  5. Marco Delatorre says:

    Doctor Good Night, known to have a son 14 and a half years and when I was 1 year eight months they left him some 6 arachnoid at the height of the left brain the neurosurgeon who treated him side cysts will I operate and put a valve which almost completely drain the cysts, but more happens that for the month of February this year he began to ache and give constant vomiting at the beginning were each 15 days after each week and then almost spending a day, they began to treat chronic migraines in the electroencephalogram apparently there was nothing, but then a month ago I kept vomiting and take him to the hospital and gave convulsions and in a magnetic resonance which made him realize a cyst in the left front, apparently as we put child valve on the left side said was fulfilling its mission, but all could be due to this new detected cyst, began to administer this will Keppra 250 milligrams, but a week like you turned the table begins with headache, right arm and then start throwing up every hour for about a day with pseudoseizures until triggered a seizure in which he lost consciousness, for a few minutes and often returned well but back problems in language and motor skills but recovered in a day, in this situation followed him up the drug because they said they needed to get to the exact dosage being with keppra (levetiracetam) 500 mg in the morning and 500 mg at night and 1 hour after this medicine 1 capsule epamin 100 milligrams (phenytoin sodium) morning and evening, but this last time gave on Thursday morning the table hard 1 day and a half of vomiting and headache, but Dr.. Neurology is very professional treating you said the four crises were not giving him convulsive but could be anxiety attacks and we will do a videoencefalograma, for activity when the box having, I'm worried Doctor is that after these pictures my son is struck even in the penultimate box levetiracetam you went to 750 on day milligrams, but began to have suicidal thoughts and turned to the dose indicated above, but equally so acudio psychiatrist and was prescribed these drugs paroxetine 10 grams to 8 Morning and Olanzapine quarter tablet to 21H00 and when you start the tables 6 clonazepam drops each 12 hours 3 drops the 3 following days like every twelve hours, what worries me that this is occurring every 8 days and my son is with 38 increasingly more weight down by constant vomiting and according to the treating neurologist and kilos states that seizures would be neutralized by the amount of drug administered, but what worries me is the onset of symptoms with headaches and vomiting which are of one and a half although no trigger seizures in, but if these depressive crisis not lose consciousness, but if it is gone with his clueless eyes, Doctor ask me any advice about it and God Bless You

  6. sergio says:

    hi, my son 14 years was operated arachnoidal cyst left parietal “giant”, neurosurgeon used a system that involves making a avertura in the skull of no more than 7 millimeters in diameter by which introduces an instrument with which camera “breaks” this bag of fluid that it is responsible for eliminating horganismo naturally, not needing any element llamese “tube” to remove fluid from the cyst, thank God it turned, the cyst is shrinking considerably and the brain is no longer making dough (is not compressed by the size of the cyst”, Days neurosurgeon will Avaria Base Hospital Los Angeles, besides being a very good professional is very good person, very human and we are very grateful to him and his team.
    I would also add that my son did not nungún symptom, was a finding, when my son we took a scanner appeared this cyst and when we went to another neurosurgeon Concepción told us we had to put a tube from the cyst to the thorax, which thankfully was not necessary for this new advancement in medicine, greetings and trust in God at all times.



  8. LUCY says:

    my husband has 67 years it detected a arachnoid cyst left temporal and left frontal subcortical ischemic focus when he made a resonance Magnetic, I am very worried because in a period of 1 time forgot what to , Now this normal , however painful arms

  9. Agnes says:

    I have 47 years and the scan says: “image is observed 14 mm x 7 mm located in the deep valley left sylvian sector under and behind the basal ganglia which could correspond to arachnoid cyst” I wonder if this has any treatment to dissipate or have to be removed with ciruía?? Thank you for your contribution.

  10. Roxana Rodriguez says:

    I was diagnosed with arachnoid cyst of 6.3 cm of diameter, is located in the anterior aspect of the left middle fossa and fissure silvio. Could enviarne information about this. Not if m have q operate. But many dolored d m gives head and precione.

  11. I have my seven 7 years is restless made him an electroencephalogram result was mild bioelectric hase 5 Magnetic days made him resonanci result is arachnoid cyst 40 by 20 mm left side of the brain and are intact celebrero I want to know what treatment arachnoid cyst worried mom jumps

  12. claudia says:

    hello my name is claudia. do 6 years my son had surgery for a left temporal cyst and make approximately 2 months suffered a seizure,repeat studies and resonance he goes again or small cyst. I question big question is, may reappear if the doctor tell you anymore volveira happen and would love someone help me by answering what the next step. quisa a new ciruguia??? thank you

  13. my son is 7 years has learning disability ,speaking he was made an electroencephalogram ,Light result disorganization biolectrica ,and also a resonance Magnetic result is observed ensanchamientofocal the subarachnoid space left middle fossa support arachnoid cyst .reaches the 40 by 20 mm diameter de maximo . focale no lesions are identified at the cerebral parenchyma ,cerebellar or brainstem , basal cisterns,sylvian and convexity subarachnoid spaces gauge preserved ventricular morphology .System of ,position and size respected media focused .linea. my son is medicated with valproic acid syrup logical āveśe has severe headache treatment .that is made to the cyst I await your response and I am very concerned since we thank you for your response jumps am a mom worried



  15. luis says:

    Hello I have 31 years when I was the age of 8 years found me a great arachnoid cyst on the right side of my head (en attracted to wear) in all my life I spent a clear normal life if in pain (referred to) in low season for example hours and then disappears and vulve to me in months or years now today 7 June 2012 and I have 3 days with more or less intense pain and not let me sleep besides wanting to sleep and this dizzy,to pass? will be growing?? it opens broken?

  1. 10 February 2013

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