Arachnoid Cysts Causes, Symptoms ,Diagnosis, Treatment, Prevention

Arachnoid Cysts Causes, Symptoms ,Diagnosis, Treatment, Prevention

What are Arachnoid Cysts?

Arachnoid cysts are cerebrospinal fluid-filled sacs that are located between the brain or spinal cord and the arachnoid membrane, one of the three membranes that cover the brain and spinal cord. Primary arachnoid cysts are present at birth and are the result of developmental abnormalities in the brain and spinal cord that arise during the early weeks of gestation. Secondary arachnoid cysts are not as common as primary cysts and develop as a result of head injury, meningitis, or tumors, or as a complication of brain surgery. The majority of arachnoid cysts form outside the temporal lobe of the brain in an area of the skull known as the middle cranial fossa. Arachnoid cysts involving the spinal cord are rarer. The location and size of the cyst determine the symptoms and when those symptoms begin. Most individuals with arachnoid cysts develop symptoms before the age of 20, and especially during the first year of life, but some people with arachnoid cysts never have symptoms.

Arachnoid cysts in children are usually congenital, or present at birth. These cysts are called primary arachnoid cysts. Arachnoid cysts that are not congenital, but develop later in life, are called secondary arachnoid cysts. Primary arachnoid cysts are more common than secondary arachnoid cysts. Men are more likely to develop arachnoid cysts than females.  Males are four times more likely to have arachnoid cysts than females.

Read more: Arboviral Encephalitides

What causes arachnoid cysts?

Primary arachnoid cysts, the congenital version, are usually caused by an abnormal growth of the brain and spinal column while the baby is developing in utero. This can be genetic. However, the exact cause of these growths is not known.

Non-congenital arachnoid cysts in both children and adults can have several causes. These include trauma or injury to the head, meningitis, and tumors. They may also occur as a reaction to brain surgery. Arachnoid cysts are most common in children.

What are the risk factors for arachnoid cysts?

A number of factors increase the risk of developing arachnoid cysts. Not all people with risk factors will get arachnoid cysts. Risk factors for arachnoid cysts include:
  • Brain infection such as meningitis (infection or inflammation of the sac around the brain and spinal cord)
  • Brain or spinal cord surgery
  • Brain or spinal cord tumor
  • Head injury
  • Male gender

What are the symptoms of arachnoid cysts?

Small arachnoid cysts are usually symptomless and may not require treatment. If arachnoid cysts grow significantly, they may cause symptoms, such as headache, weakness and fatigue. In serious cases, symptoms may become life threatening. Serious symptoms of arachnoid cysts include seizures, developmental problems, sensory or motor impairment, and hydrocephalus (fluid buildup in the skull). The symptoms of arachnoid cysts depend on which part of the brain they affect.

Early symptoms of arachnoid cysts

Arachnoid cysts that are small in size may cause no symptoms or mild symptoms. If arachnoid cysts are large enough, you may experience arachnoid cyst symptoms daily or just once in a while. At times any of these symptoms can be severe:
  • Dizziness or vertigo
  • Headache
  • Malaise or lethargy
  • Nausea with or without vomiting

Later symptoms of arachnoid cysts

  • Larger arachnoid cysts can put pressure on the brain, leading to serious symptoms including:
  • Changes in hearing
  • Developmental delays and failure to thrive
  • Difficulty hearing
  • Head bobbing
  • Impaired balance and coordination
  • Loss of vision or changes in vision
  • Muscle twitching, spasms or seizures

Serious symptoms that might indicate a life-threatening condition

In some cases, arachnoid cysts can be life threatening. Seek immediate medical care if you, or someone you are with, have any of these life-threatening symptoms including:
  • Seizure
  • Worst headache of your life

How are arachnoid cysts diagnosed?

There are two main methods used to diagnose an arachnoid cyst:

MRI - An MRI (magnetic resonance imaging) test is a non-invasive scan that reveals detailed images of the brain and its surrounding nerves and tissue. Since an MRI can identify the exact location and size of a cyst and its proximity to important structures within the brain and spine, it is the preferred method of diagnosis for both children and adults.

Ultrasound - In infants and young children, another non-invasive procedure known as an ultrasound is an alternative method of diagnosing arachnoid cysts. During an ultrasound, reflective sound waves create images of internal structures within the body.

How are arachnoid cysts treated?

An arachnoid cyst with no symptoms or other complications may not be treated. A doctor will monitor the cyst over time to watch for growth or changes in the cyst.

For symptomatic cysts, removal is common. Cysts in the brain may not be taken out with surgery because of the risks. Rather, one of two procedures will be used. The first involves a small incision near the cyst and insertion of an endoscope with a small camera on the end. The endoscope is used to gently open the cyst, allowing the fluid to drain. The fluid will mix in with the cerebrospinal fluid and redistribute through the body. This procedure is called fenestration.

The second possible procedure for an arachnoid cyst includes putting a small tube, or catheter, through an incision into the cyst. The shunt allows the fluid to drain to another part of the body, such as the belly.
For symptomatic cysts on the spinal column, removal might be possible. If not possible, fenestration or shunting are the best solutions.

Surgery for arachnoid cysts

The goals of surgery are to drain the cyst and prevent it from refilling.

To prevent the cyst from refilling, doctors remove the outer membrane of the cyst or open a small window on the cyst (fenestrating the capsule) to create wide communications with the normal surrounding subarachnoid space.

Certain arachnoid cysts of the skull base, such as sellar and suprasellar cysts, can be accessed directly using the Endoscopic Endonasal Approach (EEA).

This state-of-the-art, minimally invasive approach allows surgeons to access the tumor through the natural corridor of the nose, without making an open incision. Surgeons then remove the cyst through the nose and nasal cavities.

EEA offers the benefits of no incisions to heal, no disfigurement, and a faster recovery time.

What are the potential complications of arachnoid cysts?

Early detection and treatment of arachnoid cysts will help prevent symptoms from developing. If the cyst is allowed to grow, it may put pressure on the brain and spinal cord, leading to permanent neurological complications. Complications of untreated arachnoid cysts can be serious, even life threatening in some cases. You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications of arachnoid cysts include:
  • Brain damage
  • Failure to thrive in infants and children
  • Hydrocephalus (fluid buildup in the skull)
  • Permanent nerve damage including paralysis
  • Seizures and tremors

Prevention for Arachnoid Cysts

Unfortunately there is no prevention for the arachnoid cyst. The best thing you can do is stay fit and healthy and maintain a healthy diet.

Arachnoid Cyst Prognosis

Generally, treatment of a symptomatic cyst will resolve the symptoms. For asymptomatic cysts, a doctor will continue to monitor the cyst and treat if symptoms appear, but the affected patient should be able to enjoy a normal life with the cyst.

If arachnoid cysts are left untreated but are bleeding or growing rapidly, there could be permanent neurological damage. This is a severe outcome.