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4 July, 2009

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Syringomyelia

Syringomyelia is the formation of a fluid-filled cyst (syrinx) within the spinal cord. The most common site is the cervical spine in the neck region. As the syrinx grows, it presses on the spinal cord and interferes with the transmission of nerve impulses. The condition affects approximately eight out of every 100,000 people and men are more at risk than women (for reasons unknown). The average age of onset is about 30 years.

There are broadly three types of syringomyelia. The most common type is associated with congenital (from birth) brain abnormalities, while the second type develops as a complication following spinal trauma, infection or tumour. The third type is caused by unknown factors and is called idiopathic syringomyelia. Without treatment, syringomyelia may result in paraplegia or quadriplegia. Treatment options include surgery.

Symptoms
The symptoms of syringomyelia vary from one individual to the next, depending on the severity and location of the cyst. Symptoms can develop slowly and this may delay the diagnosis. They include:

Pain and weakness in the back, shoulders, arms or legs
Headaches
Reduced skin sensations, such as not being able to feel extremes of heat and cold
Loss of sensation in the hands, including sensations of pain
Muscle atrophy (wasting), usually beginning in the hands and spreading to include the arms and shoulders
Severe pain in the shoulders and neck
Reduced bowel and bladder control (in the later stages)
Sexual dysfunctions.

Three broad categories
The brain and spinal cord (central nervous system) are bathed in a clear fluid known as cerebrospinal fluid. Some of the functions of cerebrospinal fluid include nourishing and cushioning the central nervous system. The three broad categories of syringomyelia include:

Congenital brain defects – such as Arnold-Chiari malformation. The bottom part of the brain (cerebellum) lies in the upper part of the neck instead of within the skull. This obstructs the flow of cerebrospinal fluid.
Injury to the spinal cord – including trauma, ruptured aneurysm, infection (such as HIV), certain degenerative diseases or some brain tumours. The cyst forms at the damage site.
Idiopathic syringomyelia – the cause is unknown.

Formation of the cyst
Cerebrospinal fluid normally circulates around the brain and spinal cord. If the flow of cerebrospinal fluid is obstructed and turned back on itself, a cyst (syrinx) may form within the delicate tissue of the spinal cord. The cyst may be small at first; it is thought that the differences in pressure between the skull and spinal cord gradually force cerebrospinal fluid into the cyst. Over time, the cyst grows larger and presses on the surrounding spinal cord nerves. This can eventually damage the nerves.

Syringomyelia usually progresses slowly over years, but symptoms can sometimes advance rapidly after straining or coughing. This is because the temporary increase in cerebrospinal pressure forces fluid into the cyst.

The brain may be affected
The brain stem is the bridge between the brain and the spinal cord. Messages relay from the brain to the motor and sensory nerves of the body, and vice versa, in a constant ‘conversation’. In some cases of syringomyelia, the cyst grows into the brain stem and interferes with vital functions such as breathing and heartbeat. This complication is called syringobulbia.

Some of the symptoms may include:

Swallowing difficulties
Involuntary flickering of the eyes
Tongue ‘wasting’, which results in speech problems.

Diagnosis
The symptoms of syringomyelia can mimic those of other conditions, so diagnosis can be difficult. Some of the tests for syringomyelia include:

Medical history
Physical examination
Magnetic resonance imaging (MRI)
Computed tomography (CT) scans
Electromyography – to test muscle strength
Tests of cerebrospinal fluid pressure
Lumbar puncture – to take a sample of cerebrospinal fluid
Myelogram – an x-ray requiring injection of contrast dye into the cerebrospinal fluid.

Treatment
Treatment depends on the cause and severity of the condition but may include:

Wait-and-see approach – if the cyst is small and not causing any symptoms, your doctor may prefer to simply monitor the condition.
Medications – syringomyelia can’t be treated with drugs, but pain killers and muscle relaxants may help to ease some of the symptoms.
Shunting – a thin tube is inserted into the cyst to drain the fluid into the abdominal cavity. The shunt contains a one-way valve to prevent backflow. This type of treatment is often used if hydrocephalus (build-up of cerebral fluid inside the brain) is also present.
Surgery – to remove the tumour or repair the damage caused by the trauma. In the case of Arnold-Chiari malformation, surgery aims to give the cerebellum more room in the base of the skull and neck, and improve the flow of cerebrospinal fluid at the same time.

Where to get help

Your doctor
Neurologist

Things to remember

Syringomyelia is the formation of a fluid-filled cyst (syrinx) within the spinal cord.
As the cyst gets larger, it presses on the spinal cord and interferes with the transmission of nerve impulses.
Causes include congenital (from birth) brain defects, spinal cord trauma and infection.
Treatment options include surgery.

You might also be interested in:
Cysts explained.

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