General DiscussionArachnoiditis is a disease characterized by an acute inflammatory stage that occurs in the dura (exterior) and the arachnoid (interior), two of the three membranes that cover and protect the brain, the spinal cord and th...

Arachnodactyly-abnormal ossification-intellectual disability syndrome is a rare genetic disorder characterized by the presence of arachnodactyly (long, thin fingers and toes), abnormal ossification (abnormal bone formation), and intellectual disab...

Arachnodactyly-intellectual disability-dysmorphism syndrome is a rare genetic disorder characterized by the presence of spider-like fingers and toes (arachnodactyly), intellectual disability, and dysmorphic facial features. It is caused by a mutat...

An arachnoid cyst is a type of cyst that forms in the arachnoid membrane, which is one of the three layers of tissue that cover the brain and spinal cord. Arachnoid cysts are usually filled with cerebrospinal fluid (CSF) and can range in size from...

Arachnoid cysts are fluid-filled sacs that occur on the arachnoid membrane that covers the brain (intracranial) and the spinal cord (spinal). There are three membranes covering these parts of the central nervous system: the dura mater, arachnoid, ...

Arachnoid cysts are cerebrospinal fluid-filled sacs that form between the brain and the arachnoid membrane, one of the three membranes that cover the brain and spinal cord. They are usually benign and asymptomatic, but can cause neurological sympt...

Meningiomas are benign, slow-growing tumors, classified as brain tumors, but actually growing in the three protective membranes that surround the brain (meninges). Sometimes they cause thickening or thinning of adjoining skull bones. Meningiomas d...

Arachnoiditis is a pain disorder caused by the inflammation of the arachnoid, one of the membranes that surround and protect the nerves of the spinal cord. It is characterized by severe stinging, "burning pain", and neurological problems....

Arachnoiditis is a rare, chronic, and often debilitating neurological disorder caused by inflammation of the arachnoid, one of the membranes that surround and protect the nerves of the spinal cord. Symptoms of arachnoiditis can include pain, numbn...

Chikungunya is a rare viral infection transmitted by the bite of an infected mosquito. It is characterized by a rash, fever, and severe joint pain (arthralgias) that usually lasts for three to seven days. Because of its effect on the joints, Chiku...

Arcus senilis is a white or gray arc or circle that appears around the outer edge of the cornea of the eye. It is a normal part of aging and is usually seen in people over the age of 60. It is caused by a deposit of lipids in the cornea and is har...

AREDYLD syndrome is a rare genetic disorder characterized by intellectual disability, seizures, and delayed development. It is caused by a mutation in the AREDYLD gene, which is responsible for the production of a protein involved in the developme...

Regenerative anemia is a type of anemia in which the body is unable to produce enough red blood cells to replace those that are lost. This type of anemia is caused by a decrease in the production of red blood cells in the bone marrow, which is the...

Argentine hemorrhagic fever (AHF) is a rare and potentially fatal viral disease caused by the Junin virus, a member of the Arenaviridae family. It is found in rural areas of Argentina, where it is spread by contact with infected rodents. Symptoms ...

Arginase deficiency is a rare inherited disorder characterized by complete or partial lack of the enzyme arginase. Arginase is one of six enzymes that play a role in the breakdown and removal of nitrogen from the body, a process known as the urea ...

Arginase-1 deficiency is a rare genetic disorder caused by a mutation in the arginase-1 gene. This gene is responsible for producing the enzyme arginase-1, which is necessary for the body to break down the amino acid arginine. Without this enzyme,...