Arachnoid Cyst, Surgical Indications And Surgical Approach

Objective;Intracranial arachnoid cyst is a kind of benign cyst,which is closely related with arachnoid.The cystic fluid is usually colorless,transparent,like cerebrospinal fluid and seldom yellow stained.The ICA can be classified into two kinds;primary ICA and secondary ICA.The primary ICA is also called congenital ICA,which is caused by embryogenesis dyspasia.The cyst is formed by arachnoid cleavage or duplication and closely related with subarachnoid cavity and cistern.The secondary ICA is also called fake ICA,which is featured with inflammatory cell and Hemosiderin pigmentation.It is caused by brain trauma,brain hemorrhage or intracranial infection. The inflammatory reaction of subarachnoid cavity made CSF gathered pathologically. All the patients in this study had no history of brain trauma or intracranial infection, so the primary ICA is considered.The natural case history of ICA is not in detail.Many patients may show no symptom all their lives,and some patients became Symptomatic many years after the cyst was detected.There are also reports of the spontaneous disappear of the cyst. There are also patients who were admitted because of clinical symptoms as follows; regional prominence of cranial skull,headache,vomiting,epileptic attack,blurred vision,distracted attention,hypomnesia,diminished eyesight,papilledema and hydrocephalus.In recent years,with the development of the radiological techniques,the clinically detectable rate of IAC seemed to have a tendency to increase.But whether all the patients diagnosed by imageology need surgical therapy? For this goal,we collect 72 ICA cases from January 2006 to April 2007,and decide the suitable surgical indications by comparing Clinical symptoms,imaging examination and follow-up. Methods;1.Collect clinical data of ICA patients.2.hnageology examination,including CT and CTC.3.Follow-up of the patients,detect the change of symptoms and the imaging.4.Choose the suitable surgical indications by comparing the data.Result;All the 72 patients were diagnosed of ICA after brain CT scan.45 patients underwent surgery,while the other 36 patients did not undergo operation.CTC was taken in 46 cases,out of which 13 cases were CIAC and 33 cases were NCIAC.After surgery,all the patient's clinical symptoms improved to different degrees,and there were no serious complications.The CT scans indicated the cyst decreased in 41 cases. Conclusion;1.Brain CT scans and CTC are of great importance for the diagnosis and choose of surgical indication.2.The absolute surgical indication is the NCIAC patients with definite clinical symptoms.3.The relative surgical indication is CIAC patients whose clinical symptom keep on aggravating or CT scans show tendency of the cyst to increase. Objective;If the ICA patients have definite surgical indications,the surgery will be needed. It is very important to choose the proper modus operandi.The pathological cause of ICA is the pressure difference.The intracystal pressure is higher than the pulsation pressure of brain tissue and subarachnoid cavity,so the surrounding brain tissue will be compressed and clinical symptoms appear.The best way to resolve the pressure is to make a pathway of the cyst fluid to release the intracystal pressure.The goal of surgery is to relieve the compression to normal brain tissue,improve the surrounding blood circulation,promote brain development,release clinic symptom and avoid recurrence of the cyst.The existing modus operandi contains direct surgery and indirect surgery.The direct surgery is to remove the cyst wall or make the cyst communicating with subarachnoid cavity,cistern or ventricle through craniotomy or under neroendoscope.The indirect surgery is to drain the cyst fluid into cistern or abdominal cavity by shunt equipment.Theoretically,the cyst wall excision is the most reasonable.It can release clinic symptom and following CT scans demonstrate the cyst decreased.But the cyst wall can seldom be removed completely,because it sticks to normal nervous structures very tightly.It is very difficult to operate and the wounds and risk may be a little bigger.The advantages of shunt surgery are minimally Invasive,easy to operate and save,but the disadvantages are infection and the obstruction of shunt tube.The neroendoscope therapy can not only remove most of the cyst wall,but also open the cistern.So it avoids the dependence on shunt tube,and worth for recommendation.The final goal of ICA therapy is not only to release the compression and reform the anatomic structure,but also to recover and.retain the neurophysiologic function.On the whole,how to chose modus operandi depends on the individual difference of patients,the doctor's experience and the operational equipment,so there should not be rigid criterion.What's important is to accumulate cases and reinforce follow-up,then assess the therapeutic effect of different modus operandi and come to a common conclusion.For this sake,we collected 45 ICA cases who have underwent surgical therapy from January 2001 to April 2006,and decided the most proper different modus operandi by comparing different modus operandi,clinical effect, complications and follow-up.Methods;1.Collect the clinic data of surgical patients.2.Introduce 3 different modus operandi respectively.3.Introduce the typical cases.4.Decide the most proper different modus operandi by comparing the data collected.Result;45 patients underwent surgery,out of which 4 cases underwent cystoperitoneal shunt,15 cases underwent craniotomy cyst excision and cistern communication,26 cases underwent neuroendoscopic cyst excision and cistern communication.During surgery,we can find that the cyst wall was membraneous and a little pale.The contents of cyst are colorless,transparent and CSF-like.The tissue pathological examination of the cysts walls revealed fibrous connective tissue and small amount of lymphocytes infiltration.The chemical examination of the cyst fluid was like CSF.Conclusion;1.The modus operandi should be confirmed according to the location of cyst, the characteristic of the disease and the surgeon's erperience.2.For the patients with ICA complicated with other.diseases,the craniotomy is firstly considered;For the patients with cystslocated-in saddle area or ventricle,the ventriculoscope should be firstly chosen;For the CICA and huge ICV,the cyst-peritoneal shunt is the best;For the ICA in posterior cranial fossa,it's better to take craniotomy cyst excision and cistern communication,then make the cyst-peritoneal shunt.3.For the ICA located in hemisphere,ventriculoscope is better than craniotomy.4.EMA and ECM indicate the direction of microinvasive therapy of ICA,and can be used in ICA in different locations.