What are the other Names for this Condition? (Also known as/Symptoms)

• Arachnoid Cyst of the Spinal Cord
• Arachnoid Cyst of the Spine
• SAC (Spinal Arachnoid Cyst)

What is Spinal Arachnoid Cyst? (Definition/Background Information)

• Arachnoid cysts are uncommon benign cysts with cerebrospinal fluid that form between the layers of the arachnoid membranes. These cystic lesions may arise anywhere in the central nervous system (CNS); however, most are seen in the brain
• The involvement of the spinal cord is infrequently noted, in which case it is known as a Spinal Arachnoid Cyst (SAC). Most of these lesions are observed among the pediatric population, usually having a congenital origin. In adults, these are mostly observed against a background of trauma, other tumors, or spinal infections
• These cysts are classified based on the cause as:
  • Primary Spinal Arachnoid Cyst: The cause of formation of the cyst is unknown, but it is known to form due to certain developmental issues during fetal growth
  • Secondary Spinal Arachnoid Cyst: It develops due to certain underlying factors, such as meningitis, trauma to the brain, or surgical complications
• The exact cause of formation of a Spinal Arachnoid Cyst is unknown; a majority of these lesions are diagnosed in males and are present in the thoracic region. When present in children, they may occur due to certain spinal abnormalities such as spina bifida or split cord malformation (diastematomyelia)
• Small-sized Spinal Arachnoid Cysts may not present any significant signs and symptoms. Large cysts may cause pain at the site of the lesion, weakness in upper and lower limbs, one-sided paralysis, and loss of bowel or bladder control
• In some cases, the treatment of Spinal Arachnoid Cyst may involve surgery. In a majority, the prognosis is good with appropriate early treatment, since it is a benign lesion. Occasionally, large cysts may result in severe complications and permanent damage to the spine, particularly if these are undetected or left untreated

According to classification of meningeal cysts, Spinal Arachnoid Cysts are classified as type IA spinal meningeal cysts, since they are extradural and contain neural tissue (or nervous tissue). Extradural means “outside the dura mater, but within the spine”. Some intradural arachnoid cysts are classified as type III spinal meningeal cysts, meaning they develop within the spinal canal.

Who gets Spinal Arachnoid Cyst? (Age and Sex Distribution)

• Spinal Arachnoid Cysts are seen in both children and adults across all age groups; most cases are observed in children
• Both males and females are affected; however, males are affected much more than females
• No specific racial or ethnic group predilection is noted

What are the Risk Factors for Spinal Arachnoid Cyst? (Predisposing Factors)

The following factors may increase one’s risk for Spinal Arachnoid Cysts:

• A family history of primary arachnoid cysts is a known risk factor
• Primary Arachnoid Cysts of the Spinal Cord have been associated with certain congenital abnormalities such as:
  • Diastematomyelia, a type of spinal cord malformation
  • Spina bifida
  • Syringomyelia (a form of syrinx)
• Occasionally, the following factors may lead to the development of Secondary Arachnoid Cysts of the Spinal Cord:
  • Head injury; it is the most common factor noted
  • Meningitis or inflammation of the meninges that may occur from various factors
  • Presence of other spinal tumors in the region
  • Iatrogenic factors, such as complications (intracranial hemorrhage) that develop from invasive procedures to the spinal region

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Spinal Arachnoid Cyst? (Etiology)

Spinal Arachnoid Cysts are a benign collection of cerebrospinal fluid (CSF) in the subarachnoid space, usually of congenital origin. Currently, a host of factors are thought to contribute towards its formation; however, no definitive cause has been identified.

• Spinal Arachnoid Cysts can either occur sporadically or form in association with other congenital defects or malformations of the spinal cord
• Spinal Arachnoid Cysts may develop due to other underlying conditions or factors, such as trauma, CNS tumor, infections, or complications from invasive procedures to the spine

According to scientific research, there is a malformation/splitting of the arachnoid membranes in the spinal meninges owing to some of the factors mentioned above, which causes the subarachnoid space to be filled with cerebrospinal fluid.

What are the Signs and Symptoms of Spinal Arachnoid Cyst?

The signs and symptoms of Spinal Arachnoid Cysts can vary from one individual to another and depends on the size and location of the cystic tumor. Most of the cysts presents symptoms at birth (congenitally) or during infancy, typically before the child is 12 months old. Some cysts are diagnosed in early childhood, into adolescence, or even during young adulthood. Occasionally, they may even be diagnosed during pregnancy, during routine USG screening of the developing fetus.

In general, most small tumors are asymptomatic and no significant symptoms may be observed, while large tumors are known to present symptoms. In many individuals, tumors that grow slowly and remain asymptomatic, are only diagnosed during certain radiological imaging studies of the spinal cord region, which are performed for unrelated health conditions. In some rare cases, no significant symptoms are noted even from large-sized cysts.

Most of the Spinal Arachnoid Cysts i.e., over 80% of the cysts are found in the thoracic region (chest or upper back region), affecting the spinal canal. 15% of them affect the cervical region (neck) and about 5% are observed in the lumbar region (lower back). These cystic tumors may be intramedullary (arising from inside the spinal canal) or extramedullary (from outside the spinal canal).

Generally, the signs and symptoms of the cysts depend on several factors that include:

• Size of the cyst
• Characteristics of the cyst, which is observed on imaging studies
• Exact location of the cyst
• Age of the affected individual (whether it is a child or an adult)

The signs and symptoms of Spinal Arachnoid Cyst may include:

• Presence of visible lump in the affected region
• Back pain and/or chest pain
• Numbness and tingling sensation
• Weakness of the body or lower extremities; loss of strength in the arms of legs
• Pain in the arms and legs, depending on the nerves that are compressed by the tumor
• Spinal cord compression leading to numbness and pain, due to mass effect of the tumor
• Severe cases may result in loss of bowel and bladder control
• Paralysis

The signs and symptoms of other coexistent congenital spinal anomalies may be noted.

How is Spinal Arachnoid Cyst Diagnosed?

There are a variety of tests and exams the healthcare provider may employ to diagnose Spinal Arachnoid Cyst, which may include:

• Physical examination and complete medical history screening
• Assessment of the presenting signs and symptoms
• Prenatal ultrasound scans, which are performed during pregnancy; usually the second trimester scans reveal the presence of cysts, if any present
• Amniocentesis: A medical procedure that involves removal of a small amount of amniotic fluid from the amnion for prenatal diagnosis; it may be performed if the healthcare provider suspects any genetic abnormalities
• Alpha fetoprotein (AFP) blood test in pregnancy: A screening test that is performed to determine the apparent risk for certain congenital abnormalities, such as spina bifida or chromosomal disorders, and not to confirm any diagnosis
• Neurological, motor skills, and cognitive assessment:
  • Checking intellectual ability, memory, mental health and function, language skills, judgment and reasoning, coordination and balance, reflexes, and sensory perceptions (space, sight, hearing, touch, etc.)
  • The healthcare provider/neurologist may use the Karnofsky Performance Scale in order to assess the neurological functioning of the individual’s central nervous system (CNS)
• Electroencephalography (EEG)
• Electromyography with nerve conductivity tests
• Imaging studies that may be performed include:
  • X-ray of the vertebral column
  • Computerized tomography (CT) scan of the vertebral column; CT with contrast
  • Magnetic resonance imaging (MRI) scan of the central nervous system (brain and spine); MRI with contrast agents such as gadolinium
  • Cerebral angiographic studies or MR angiography: An angiogram involves injecting dye into the bloodstream, which makes the blood vessels to appear visually on X-rays. The X-ray may show a tumor in the brain or the blood vessels leading into the tumor
  • Magnetic resonance spectroscopy: This radiological technique is used to study the chemical profile of the tumor. It is often performed with and compared to corresponding MRI scan images of the affected region
• Cerebrospinal fluid analysis, where a spinal tap or lumbar puncture procedure may be performed: This diagnostic test is used to remove a sample of cerebrospinal fluid (CSF) from the spaces in and around the brain and spinal cord. The sample is removed from the lower spinal cord using a thin needle, and it is then checked for the presence of cancer cells
• Molecular studies, if necessary

Tissue biopsy: A biopsy of the affected region (spinal cord) is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy sample under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy sample under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis.

A differential diagnosis to eliminate other conditions or tumor types may be considered, before arriving at a definitive diagnosis.

The clinical differential diagnosis may include:

• Dandy-Walker malformation
• Empty sella syndrome
• Porencephaly

The radiological differential diagnosis may include:

• Cysts of ligamentum flavum
• Extradural spinal cysts
• Focal spinal cord deformity
• Herniated ventral cord
• Intervertebral disc cysts
• Spinal cysticercosis
• Spinal dermoid cyst
• Spinal epidermoid cyst
• Spinal ganglion cyst
• Spinal hydatid cyst
• Synovial cyst of the spine

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Spinal Arachnoid Cyst?

The complications of Spinal Arachnoid Cyst may include the following:

• Stress and anxiety due to fear of an intraspinal tumor
• Congenital lesions, those that are present at birth, may cause developmental delays in the child
• Paraplegia or paralysis of the lower limbs
• Large-sized cysts may also cause spinal bone malformations in infants and young children
• Large tumors may also press against the vertebral bones causing it to expand or break easily when subjected to minor trauma including falls and accidents
• Severely affected physical health may lead to the overall quality of life being greatly reduced
• Large undetected tumors can severely affect spinal cord function and be disabling or even life-threatening, due to mass effect/compression of surrounding tissue
• Tumor rupture may cause a form of meningitis
• Miscarriage and stillbirths, may take place in very rare cases
• Occasionally, recurrence of the tumor following its incomplete surgical removal
• Damage to the muscles, vital nerves, and blood vessels, during surgery
• Post-surgical infection at the wound site

How is Spinal Arachnoid Cyst Treated?

The treatment of Spinal Arachnoid Cyst may involve the following:

• In some cases of small asymptomatic tumors, the healthcare provider may consider conservative ‘wait and watch’ measures, instead of immediately recommending surgery to remove them
• Symptomatic treatment may involve the use of medications, painkillers, steroids (to reduce inflammation), and administration of anti-depressants
• Microsurgery: The surgery is performed using microsurgical techniques, which can help minimize damage to the accompanying nerve. Since the tumor mostly affects the covering around the nerves, it can be completely removed without affecting the nerve in most cases
• Osteoplastic laminotomy: It is a minimally-invasive procedure to treat spinal cord tumors. The technique also helps minimize post-operative complications and provides increased spinal stability. If necessary, osteoplastic laminotomy may be followed up by a spinal column reconstruction procedure
• Laminectomy: An invasive procedure that is performed to relieve compression on the spinal cord or spinal nerves caused by the tumors, by widening the spinal canal through removal of the laminae (part of the vertebra)
• Follow-up care with regular screening and check-ups are important and encouraged

How can Spinal Arachnoid Cyst be Prevented?

Currently, there are no known methods to prevent the development of Spinal Arachnoid Cyst.

• If there is a family history of the condition (Primary Spinal Arachnoid Cyst), then genetic counseling will help assess risks, before planning for a child
• Genetic testing of the expecting parents and prenatal diagnosis may help in understanding the risks better during pregnancy

Even though the Secondary Spinal Arachnoid Cysts have underlying causes, it is often difficult to prevent them.

What is the Prognosis of Spinal Arachnoid Cyst? (Outcome/Resolutions)

• The prognosis of Spinal Arachnoid Cyst is usually good with suitable treatment, since it is a benign cyst
• In the absence of treatment, large cysts may cause severe neurological disabilities and permanent morbidity

In general, the prognosis of Spinal Arachnoid Cysts depends on a variety of factors including:

• Whether it is primary or secondary
• Size of the cyst
• The combination of signs and symptoms noted

Additional and Relevant Useful Information for Spinal Arachnoid Cyst:

The following article link will help you understand other cancers and benign tumors:

http://www.dovemed.com/diseases-conditions/cancer/