Arachnoid cyst
An arachnoid cyst is a fluid-filled sac that develops between the brain or spinal cord and the arachnoid membrane, one of the protective layers surrounding the central nervous system. Arachnoid cysts are most commonly congenital and present at birth (primary arachnoid cysts), but they can also develop later in life (secondary arachnoid cysts). Secondary arachnoid cysts may occur as a result of brain surgery, trauma, tumours, head injury, or infection.
These cysts usually contain cerebrospinal fluid (CSF), the fluid that cushions and protects the brain and spinal cord. In some cases, they may interfere with the normal circulation or drainage of cerebrospinal fluid.
Symptoms
Symptoms may remain undetected for many years. However, if the cyst grows large enough, it can place pressure on nearby areas of the brain or spinal cord and cause symptoms such as:
- Headaches
- Nausea and vomiting
- Lethargy
- Dizziness
- Seizures
- Hearing problems
- Neurological symptoms
- Difficulty with balance and walking
- Muscle spasms or weakness
- Bowel and bladder control problems
- Back pain
- Tingling, numbness, or loss of sensation in the arms and legs
Diagnosis and Treatment Options
To diagnose an arachnoid cyst, we will review your child’s medical and family history and perform a physical and neurological examination. Diagnostic imaging tests, such as X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans, may also be recommended.
Treatment depends on the size and location of the cyst, as well as the severity of symptoms. Most arachnoid cysts do not cause symptoms and require only regular monitoring to assess for growth or changes over time.
Cysts that cause symptoms may require surgical treatment. Brain cysts are commonly treated with fenestration, a procedure in which a small opening is created in the cyst wall to allow excess fluid to drain and circulate normally within the cerebrospinal fluid pathways.
In some cases, a shunt may be required. This involves inserting a catheter (thin tube) to divert excess fluid to another area of the body where it can be absorbed. For cysts affecting the spinal cord, treatment options may include surgical removal, fenestration, or shunt placement.
Recovery
Recovery varies depending on the size and location of the cyst and the treatment performed. Recovery may include:
- Temporary confusion or neurological deficits
- Rehabilitation
- Follow-up MRI scans
- Possible additional surgery
- Physiotherapy
- Occupational therapy
- Psychological support, if required
- Pain medication as needed
- Speech therapy, if required
