Syringomyelia is one of two conditions involving cerebrospinal fluid (CSF) within the spinal cord, common in patients with Chiari I malformation. Whereas simple distention of the ependymal-lined central canal is classically termed hydromyelia, syringomyelia often involves dissection of CSF through the ependyma to form cavitation within the substance of the spinal cord. Since the distinction may not be clear using standard imaging techniques, the term syrinx, or syringohydromyelia, is used to describe any abnormal accumulation of CSF within the spinal cord. Extension upward into the brainstem is termed syringobulbia. Syringomyelia may develop as a delayed complication of spine or spinal cord injuries, and rarely after meningitis.

Symptoms: Syringomyelia presents slowly over the years, with variable symptoms. One is sensory loss in a "cape" distribution (over the tops of the shoulders) and loss of pain and temperature sensation with preserved touch and position sense. Other symptoms include cervical and occipital pain, extremity pain, hand and arm weakness and atrophy, and spasticity.

Diagnosis: MRI is the diagnostic study of choice, since it will accurately depict the structure of the spinal cord.

Treatment: Options to treat syringomyelia depend on its underlying cause and include posterior fossa decompression, which is the procedure of choice when posterior fossa anomalies are present (Chiari I malformation), and shunting the syrinx. Primary spinal syringomyelia is often treated by laminectomy and expansion of the subarachnoid space.