In most cases, arachnoid cysts are present at birth (congenital), but usually do not cause any symptoms (asymptomatic) throughout an individual’s life. Less often, arachnoid cysts may develop because of head injury, the presence of a tumor, infection or surgery on the brain
Whether symptoms develop depends upon the size and the specific location of the cyst within the brain. Small cysts usually do not cause symptoms. However, cysts can increase in size causing symptoms to appear, especially if they press against a cranial nerve, the brain, or the spinal cord.
Most cases of arachnoid cysts that are associated with symptoms occur in childhood. The specific symptoms present vary from case to case. It is important to note that affected individuals will not have all of the symptoms listed below.
The most common symptoms associated with arachnoid cysts are usually nonspecific and include headaches, nausea, vomiting, dizziness and the accumulation of excessive cerebrospinal fluid in the brain (hydrocephalus), resulting in increased intracranial pressure In rare cases, in some children, an arachnoid cyst can cause malformation of certain cranial bones, resulting in an abnormally enlarged head (macrocephaly). .
A variety of additional symptoms occur in some individuals with arachnoid cysts depending upon the size and location of the cyst. Most cysts occur near the middle fossa region of the brain. Such symptoms include lethargy, seizures, vision abnormalities and hearing abnormalities. Neurological signs may be present because arachnoid cysts may cause increased pressure on structures of the brain. Such neurological findings may include developmental delays, behavioral changes, an inability to control voluntary movements (ataxia), difficulties with balance and walking and cognitive impairment. Weakness or paralysis on one side of the body (hemiparesis) has also been reported.
In addition to hydrocephalus, cysts located in the suprasellar region may be associated with vision disturbances, continuous bobbing of the head, and abnormalities affecting certain hormone-producing glands that help to regulate the rate of growth, sexual development, and certain metabolic functions (endocrine system).
Although they occur much less often than those found within the skull (intracranial), arachnoid cysts may also arise near the spine (spinal arachnoid cysts). Spinal arachnoid cysts may be associated with progressive weakness of the legs, tingling or numbness in the hands or feet, abnormal side-to-side curvature of the spine (scoliosis), back pain, and involuntary muscle spasms (spasticity) that result in slow, stiff movements of the legs. In rare cases, these cysts may cause paralysis of the legs (paraplegia). Urinary tract infections may also occur in individuals with spinal arachnoid cysts.
Other symptoms and physical findings have been reported to be associated with arachnoid cysts including migraine headaches, attention-deficit disorder and difficulties understanding or expressing language (aphasia). The exact cause and effect relationship between these findings and arachnoid cysts is not clear.