An abnormal, growing, longitudinal cavity that forms within the spinal cord, most frequently in the cervical or neck region. A syrinx may extend into the gray matter (as in syringomyelia) or into the lower brain stem (as in syringobulbia). A common symptom of an invading syrinx is loss of pain and temperature sensations. There may also be weakness of the hands or arms and serious respiratory abnormalities, including hoarseness, stridor (harsh, obstructed breathing), hypoventilation (breathing at an abnormally slow rate, which increases the amount of carbon dioxide in the blood), and apnea (a total cessation of breathing, either momentarily or for a prolonged period]. Sudden death as a result of sleep apnea syndrome is a risk of syrinx. Neurological examination and tests such as myelography, MRI (magnetic resonance imaging], and CT (computed tomography] scanning are useful in the diagnosis of a syrinx. Management of sleep apnea syndrome (such as the use of a mask over the nose or a dental device to force the jaw forward) is vital. The only specific treatment for the syrinx itself is surgery. However, the results of surgery are varied and unpredictable. A syrinx is often seen in association with a Chiari malformation, trauma, and spinal cord or skull-based abnormalities.
An unusual hollow space in either the brainstem or spinal cord, characteristic of the condition known as syringomyelia.