Syringomyelia

What happens in syringomyelia

The spinal cord is bathed in cerebrospinal fluid (CSF), which flows around the brain and cord. When something blocks or disturbs this flow, pressure waves can push fluid into the cord, where it collects in a cavity. Over months to years, the syrinx may lengthen and widen, pressing on nerve fibers from the inside.

Because the syrinx usually begins near the center of the cord, it first damages the fibers that cross there carrying pain and temperature signals. Touch, vibration and position sense travel in other parts of the cord and are often spared at first. This "dissociated" sensory loss is a classic clue.

Causes

• Chiari malformation type I: the lower part of the brain (cerebellar tonsils) sits low and blocks CSF flow at the base of the skull. This is the most common cause.
• Post-traumatic syringomyelia: develops months to many years after a spinal cord injury, from scar tissue that blocks flow.
• Arachnoiditis: scarring of the membranes around the cord after infection, bleeding, surgery or injections.
• Spinal cord tumors: some tumors form or cause a syrinx.
• Tethered cord syndrome and other congenital spinal problems.
• Idiopathic: no cause is found in some people.

A very small, thin fluid space in the center of the cord (a dilated central canal) is sometimes found by chance on MRI. It often causes no symptoms and does not grow.

Syringomyelia symptoms

Symptoms often start in young adulthood and progress slowly. They vary with the size and location of the syrinx.

Sensory symptoms

• Loss of pain and temperature feeling in a cape-like distribution across the shoulders, back and arms
• Painless burns and cuts on the hands
• Numbness and tingling
• Burning, aching nerve pain (neuropathic pain) in the neck, shoulders or arms

Motor symptoms

• Weakness and wasting of hand and arm muscles, clumsy fingers
• Stiffness, spasticity and weakness in the legs, with unsteady walking
• Brisk reflexes in the legs and reduced reflexes in the arms

Other symptoms

• Headache at the back of the head made worse by coughing or straining (with Chiari)
• Scoliosis, sometimes the first sign in children
• Bladder and bowel problems, sexual dysfunction
• A drooping eyelid and small pupil on one side (Horner syndrome)
• Damaged, unstable joints in the shoulder or elbow (Charcot joints)
• Syringobulbia: if the cavity reaches the brainstem, facial numbness, trouble swallowing, hoarseness, tongue weakness and dizziness

Diagnosis

• MRI of the brain and whole spine is the key test. It shows the syrinx, its size and extent, and causes such as Chiari malformation, tumors or tethering. Contrast may be given to look for a tumor.
• CSF flow MRI (cine MRI) can show blocked flow around the base of the skull or a scarred segment.
• Neurological examination and sometimes nerve conduction studies to map nerve damage.
• Spine X-rays for scoliosis.

Treatment

Watchful waiting

Small syrinxes without symptoms, or with stable mild symptoms, are often monitored with periodic MRI and examination.

Surgery

The goal is to restore normal CSF flow so the syrinx shrinks or stops growing.

• Posterior fossa decompression: for Chiari-related syringomyelia. Bone at the back of the skull and top of the spine is removed, often with a patch to enlarge the covering of the brain. Most syrinxes shrink after this.
• Untethering or removal of scar tissue: for post-traumatic syringomyelia and arachnoiditis, sometimes with a graft to reconstruct the space around the cord.
• Tumor removal when a tumor is the cause.
• Shunting: a small tube drains the syrinx into another space. It is used when other approaches fail, as shunts can block over time.

Symptom management

• Medicines for nerve pain, such as gabapentin, pregabalin or certain antidepressants
• Physical and occupational therapy for weakness and spasticity
• Protecting numb skin: check water temperature with an elbow or thermometer, wear gloves for cooking and cold weather, inspect hands daily for injuries
• Some specialists advise avoiding heavy lifting and repeated straining, which raise spinal fluid pressure

Outlook

Syringomyelia often progresses slowly, and some people stay stable for years. Surgery usually stops progression and may improve pain, weakness and numbness, especially when done before long-standing damage. Sensation that has been lost for a long time often does not fully return. Regular follow-up with MRI is needed because a syrinx can recur.

Frequently asked questions

What are the first symptoms of syringomyelia?

Early symptoms often include neck, shoulder or arm pain, numbness in the hands, and loss of the ability to feel hot or cold across the shoulders and arms. People may first notice painless burns or cuts on their hands. Hand weakness and leg stiffness usually come later.

Is syringomyelia serious?

It can be. Untreated, a growing syrinx can cause permanent weakness, numbness, chronic pain and disability. Many cases progress slowly, and small stable cysts may never cause problems. Surgery that corrects the cause stops progression in most people, so regular monitoring is important.

What causes a syrinx in the spinal cord?

A syrinx forms when the normal flow of cerebrospinal fluid around the spinal cord is obstructed. The most common cause is Chiari I malformation. Others include previous spinal cord injury, scarring of the spinal membranes, spinal tumors and tethered cord. Sometimes no cause is found.

Can syringomyelia go away on its own?

Rarely. Small syrinxes occasionally shrink without treatment, particularly in children, but most stay the same or slowly grow. Surgery to restore spinal fluid flow is the main way to make a syrinx shrink, and the cyst usually decreases in size after successful decompression.

What is the difference between syringomyelia and hydromyelia?

Hydromyelia is widening of the central canal of the spinal cord, which is lined by normal canal cells. Syringomyelia is a cavity that can extend beyond the canal into the cord tissue. On MRI they can be hard to tell apart, so the term syringohydromyelia is often used.