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In syringomyelia there is fluid-filled tubular cavitation (syrinx formation) within the central, usually cervical, spinal cord. The syrinx can elongate, enlarge and expand into the grey and white matter and, as it does so, it compresses the nervous tissue of the corticospinal and spinothalamic tracts and the anterior horn cells. This leads to the various neurological symptoms and signs. If the syrinx extends into the brainstem, syringobulbia results.
- A blockage in the circulation of cerebrospinal fluid (CSF) is the most common cause of syringomyelia. The most common reason for this blockage is the presence of a Chiari malformation. This is a developmental abnormality occurring in the fetus causing the cerebellum to protrude from its normal position through the foramen magnum and into the cervical portion of the spinal canal. There are 2 main types - type I and type II. Type I has no other associated cause and type II is associated with spina bifida.
Other causes of disruption/blockage of CSF circulation include:
- Spinal dysraphism: this is incomplete closure of the neural tube (neural tube defects including spina bifida). It is associated with syringomyelia. Identification and treatment of the dysraphism can arrest progression of syringomyelia.
- Spinal cord injury: this can occur secondary to trauma, radiation, haemorrhage, ischaemic injury or infection.
- Idiopathic syringomyelia: this occurs in some cases.
- Prevalence is 8.4 per 100,000 in the USA.
- It is more common in men than in women.
- Most commonly presents in the 20s and 30s but can present in childhood or later life.
- The primary lesion may have been present since birth but the condition progresses very slowly. Progression of symptoms and deterioration seem to occur over many years.
- Syringomyelia usually affects the cervical region.
- Sudden exacerbations can occur and are thought to be caused by rupture of the syrinx because of raised venous pressure, as seen in sneezing or violent coughing.
- Pain and temperature sensation are lost due to spinothalamic tract damage. One side may be affected more than the other. Classically, the sensation loss is experienced in a shawl-like distribution over the arms, shoulders and upper body.
- Dysaesthesia (pain experienced when the skin is touched) is common.
- Light touch, vibration and position senses in the feet are affected as the syrinx enlarges into the dorsal columns.
- These begin to occur as the syrinx extends and damages the lower motor neurones of the anterior horn cells.
- There is muscle wasting and weakness that begins in the hands and then affects the forearms and shoulders.
- Tendon reflexes are lost.
- Claw hand may be present.
- There may be respiratory muscle involvement.
- Bladder, bowel and sexual dysfunction can occur.
- Horner's syndrome may be present.
SyringobulbiaThis occurs if the syrinx extends into the medulla of the brainstem. The cranial nerves become affected:
- Facial sensory loss can occur as the trigeminal nerve becomes involved.
- Vestibulocochlear nerve involvement causes vertigo and nystagmus.
- Facial, palatal and laryngeal nerve palsy can occur as the VIIth, IXth, Xth and XIth cranial nerves become involved.
- Weakness and atrophy of the tongue is caused by XIIth nerve involvement.
Other possible features
- Charcot joints: shoulder, elbow or wrist are most commonly affected.
- Scoliosis: presentation can be with scoliosis. It has been suggested that patients due for surgery for correction of scoliosis should have an MRI scan first to exclude syringomyelia.
- Painless ulcers on the hands.
- Extension of the syrinx into the lumbar region and involvement of the legs.
- Respiratory insufficiency can occur: there seems to be a multifactorial aetiology involving muscle weakness, central control and chemoreceptors.
- CT scanning is better at showing abnormalities of bony spinal canal, whilst MRI scanning is better at showing soft tissue. Plain X-rays can show a widened cervical canal.
- Lumbar puncture is best avoided because of risk of herniation.
- It is important to identify the cause of the syrinx formation.
- Physiotherapy and rehabilitation can help to preserve neurological function. The patient must be taught to avoid damage which may result from absence of pain.
- No drugs can retard or reverse the condition but analgesics may be required for pain.
- There are a number of neurosurgical approaches that can be used to retard or halt the progress of the condition. They include insertion of a shunt, laminectomy and syringotomy (drainage of the syrinx).
- The procedure used will depend on the nature of the lesion.
- In Chiari malformation, surgical decompression at the foramen magnum is performed to promote the free flow of CSF.
- In one study, the majority of participants who underwent posterior fossa surgery for a Chiari type I malformation reported significant improvement in their quality of life afterwards.
- Delay in surgical treatment may result in irreversible spinal cord injury.
- It may be necessary to repeat surgery.
- As myelopathy progresses in syringomyelia, the patient can become wheelchair-bound or confined to bed.
- Complications that can occur due to the immobility caused by the myelopathy are recurrent pneumonia, pressure sores and pulmonary embolism.
- Paraplegia, quadriplegia and bowel or bladder dysfunction can result from the myelopathy itself.
- Respiratory failure can occur and is thought to be secondary to extension of the syrinx into the medulla.
- This depends on where the syrinx is, how far it extends, its underlying cause and the resulting neurological disability it causes.
- Those with moderate or severe neurological features do worse.
- Early surgical intervention may improve the outcome.
Further reading & references
- Al-Shatoury HAH; Syringomyelia, eMedicine, Mar 2010
- Fuller R, Stanners A; A cough, then respiratory failure. Lancet. 2000 Jan 22;355(9200):284.
- Mueller D, Oro' JJ; Prospective analysis of self-perceived quality of life before and after posterior fossa decompression in 112 patients with Chiari malformation with or without syringomyelia. Neurosurg Focus. 2005 Feb 15;18(2):ECP2.
- Attal N, Parker F, Tadie M, et al; Effects of surgery on the sensory deficits of syringomyelia and predictors of outcome: a long term prospective study. J Neurol Neurosurg Psychiatry. 2004 Jul;75(7):1025-30.
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Dr Michelle Wright
Dr Gurvinder Rull