The spinal cord is connected to a region below the brain, called the brainstem. Normally, the spinal cord ends at the approximate level of first lumbar vertebra in the adult. The spinal canal is surrounded and protected by the bony structures of the spinal column (spinal vertebra). The cerebrospinal fluid (CSF) surrounds the entire brain and spinal cord. Normally, there is no collection of cerebrospinal fluid with the spinal cord. The function of the CSF is to bathe, cushion and nourish the brain and spinal cord.
Syringomyelia is defined as an abnormal fluid cavity within the spinal cord. This abnormal fluid cavity within the spinal cord results in pressure within the cord, which can disrupt neurological function. In the normal spine there is not a collection of fluid within the spinal cord but there is fluid which surrounds the spinal cord referred to as the cerebrospinal fluid. The most common cause of syringomyelia is a Chiari Malformation. Other causes of a syrinx and syringomyelia include trauma to the spinal cord, spinal tumors or other mass lesions.
The exact development of syringomyelia is unknown, although there are many theories about the formation of a syrinx cavity. This changes the fluid pressure around the spinal cord and causes fluid to be driven into the spinal cord substance. The cerebrospinal fluid pulsates with each heartbeat contributing to CSF flow into a syrinx, which communicates with the CSF surrounding the spinal cord. A syrinx may enlarge over time, thus resulting in pressure upon delicate nerves pathways that traverse the spinal cord. There is no real predictable pattern of change involving the syrinx cavity.
The test of choice for diagnosis of a syrinx is a spine MRI. The spinal syrinx is more often found in the cervical spine followed infrequency of occurrence in the thoracic spine. As a syrinx progresses in size, it may contribute to the development of scoliosis (abnormal curvature of the spine). During the early stages of syringomyelia the symptoms may be vague and fleeting.
The symptoms associated with syrinx development or syringomyelia includes pain, which often involves the arm, hand or leg. Some people experience a burning type of pain around the ribs or in the neck or back. Pain may be present for months to years before an accurate diagnosis is made. The pain may be experienced as dull, aching, or stabbing. Symptoms may also include numbness and/or tingling (paresthesia). Some individuals experience extremity weakness, which may initially seen to be limited to the foot or the hand. The weakness is generally progressive over time. Some will experience hand clumsiness. Weakness and reduced sensation contribute to ataxia. Lower extremity ataxia walking (gait) disturbances. This is generally described as an unusual gait or dragging of one leg. Some people will stagger and report frequent falling due to the weakness of a limb.