A syrinx is a rare, fluid-filled

neuroglial Glia, also called glial cells (gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. They maintain homeostasis, form myel ...

cavity within the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...

(

syringomyelia Syringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. Often, syringomyelia is used as a generic term before an etiology is determined. This cyst, called a syrinx, can expand and elongate ...

), in the

brain stem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is conti ...

(

syringobulbia Syringobulbia is a medical condition in which syrinxes, or fluid-filled cavities, affect the brainstem (usually the lower brainstem). The exact cause is often unknown, but may be linked to a widening of the central canal of the spinal cord. Thi ...

), or in the nerves of the elbow, usually in a young age.

Presentation

Symptoms usually begin insidiously between adolescence and age 45. Syringomyelia develops in the center of the spinal cord, causing a central cord syndrome. Pain and temperature sensory deficits occur early but may not be recognized for years. The first abnormality recognized may be a painless burn or cut. Syringomyelia typically causes weakness, atrophy, and often fasciculations and hyperreflexia of the hands and arms; a deficit in pain and temperature sensation in a capelike distribution over the shoulders, arms and back is characteristic. Light touch and position and vibration sensation are not affected. Later, spastic leg weakness develops. Deficits may be asymmetric. Syringobulbia may cause vertigo, nystagmus, unilateral or bilateral loss of facial sensation, lingual atrophy and weakness,

dysarthria Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effectively ...

, dysphagia, hoarseness, and sometimes peripheral sensory or motor deficits due to medullary compression.

Cause

A syrinx results when a watery, protective substance known as

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

, that normally flows around the spinal cord and brain, transporting nutrients and waste products, collects in a small area of the spinal cord and forms a

pseudocyst Pseudocysts are like cysts, but lack epithelial or endothelial cells. Initial management consists of general supportive care. Symptoms and complications caused by pseudocysts require surgery. Computed tomography (CT) scans are used for initial ima ...

. A number of medical conditions can cause an obstruction in the normal flow of

, redirecting it into the spinal cord itself. For reasons that are only now becoming clear, this results in syrinx formation.

Cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

fills the syrinx. Pressure differences along the spine cause the fluid to move within the cyst. Physicians believe that it is this continual movement of fluid that results in cyst growth and further damage to the spinal cord. In the case of

, the syrinx can expand and elongate over time, destroying the spinal cord. Since the spinal cord connects the brain to nerves in the extremities, this damage may result in pain, weakness, and stiffness in the back, shoulders, arms, or legs. Other symptoms may include headaches and a loss of the ability to feel extremes of hot or cold, especially in the hands. Each patient experiences a different combination of symptoms. These symptoms typically vary depending on the extent and, often more critically, to the location of the syrinx within the spinal cord. Syrinxes usually result from lesions that partially obstruct CSF flow. At least ½ of syrinxes occur in patients with congenital abnormalities of the craniocervical junction (e.g. herniation of cerebellar tissue into the spinal canal, called

Chiari malformation Chiari malformation (CM) is a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull). CMs can cause headaches, difficu ...

), brain (e.g. encephalocele), or spinal cord (e.g. myelomeningocele—see Congenital Neurologic Anomalies: Brain Anomalies). For unknown reasons, these congenital abnormalities often expand during the teen or young adult years. A syrinx can also develop in patients who have a spinal cord tumor, scarring due to previous spinal trauma, or no known predisposing factors. About 30% of people with a spinal cord tumor eventually develop a syrinx. Syringomyelia is a paramedian, usually irregular, longitudinal cavity. It most often affects the cervical and thoracic regions but may extend further down or up into the brainstem (syringobulbia). Syringobulbia, which is rare, usually occurs as a slitlike gap within the lower brain stem and may disrupt or compress the lower cranial nerves or ascending sensory or descending motor pathways.

Diagnosis

A syrinx is suggested by an unexplained central cord syndrome or other characteristic neurologic deficits, particularly pain and temperature sensory deficits in a capelike distribution. MRI of the entire spinal cord and brain is done. Administration of intravenous Gadolinium during the MRI examination is useful for detecting any associated tumor.

Treatment

Underlying problems (e.g. craniocervical junction abnormalities, postoperative scarring, spinal tumors) are corrected when possible. Surgical decompression of the foramen magnum and upper cervical cord is the only useful treatment, but surgery usually cannot reverse severe neurologic deterioration.

Etymology

Syrinx is taken directly from the ancient Greek word for "tube." It is the root of the word "syringe."

References

External links

* https://www.merckmanuals.com/professional/neurologic-disorders/spinal-cord-disorders/syrinx-of-the-spinal-cord-or-brain-stem?query=syrinx {{DEFAULTSORT:Syrinx (Medicine) Rare diseases Congenital disorders of nervous system