Figure 4. Extensive cervical and upper thoracic syrinx associated with Chiari I malformation (same patient as on Figures 1-3)
2. Noncommunicating Syringomyelia: cyst arises in the cord substance and does not communicate with central canal or subarachnoid space. May be due to trauma, neoplasm (mostly gliomas), or arachnoiditis. True syrinx cavities contain fluid of the same constituency as CSF, whereas tumour cyst fluid is usually highly proteinaceous.
Aetiology probably lies in the outlet obstruction (partial or complete) of the fourth ventricle (foramina of Luschka and Magendie), as mentioned above. Congenital conditions like Chiari malformation type I or II, cerebellar ectopia, basilar impression, Dandy-Walker syndrome, and acquired conditions such as adhesive arachnoiditis are associated with high incidence of syrinx. Major theories of syrinx formation are the hydrodynamic ("water-hammer") theory of Gardner and William's theory of "hydrodissection". The former states that systolic pulsations are transmitted with each heartbeat from the intracranial cavity to the central canal and the latter assumes that manoeuvres, which raise CSF pressure (valsalva, coughing, etc.) cause "hydrodissection" through the spinal cord tissue.
The clinical syndrome is non-specific and may characterize any intramedullary spinal cord pathology. It may include sensory loss (similar to central cord syndrome) with a "cape" of dissociated sensory loss (loss of pain and temperature sensation with preserved touch and joint position sense; may result in painless ulcerations from unperceived injuries), cervical and occipital pain, lower motor neuron hand and arm weakness and painless (neurogenic) arthropathies (Charcot's joints) seen in less than 5 % of the cases.
The investigation of choice is MRI scanning in sagittal and axial planes. If for some reason MRI is not possible, CT myelography with water-soluble contrast is performed.
The first choice of surgical treatment is posterior fossa decompression when posterior anomalies (e.g. Chiari malformation) are present. Various shunting procedures may be performed if posterior fossa decompression is not warranted (no posterior anomaly present) or not successful in reducing the size of the syrinx. Shunting the fluid from the syrinx to the peritoneal, pleural or subarachnoidal spaces may be performed. Other procedures, like plugging the obex, syringostomy (opening the syrinx to the subarachnoid space without leaving a tube), and percutaneous syrinx aspiration (may be used repeatedly) are rarely indicated.
Assessing treatment outcome is difficult due to rarity of the condition, variability of natural history (which may arrest spontaneously), and too short follow-up.
Posttraumatic Syringomyelia is a form of Noncommunicating Syringomyelia. It may occur following penetrating injury or non-penetrating "violent" trauma to the spinal cord as well as a result of post-spinal anaesthesia or following thoracic disc herniation. They often present late (years or even decades after the injury) and may affect about 0.3-3 % of cord injured patients. The late appearance of upper extremity symptoms in a paraplegic or paraparetic patient should raise high index of clinical suspicion of posttraumatic Syringomyelia. Surgical management involves intradural lysis of arachnoid adhesions to the inner surface of the dura at the level of the spinal column fracture or abnormal angulation followed by expansive duraplasty and various shunting procedures of the syrinx.
Syringobulbia is the central cavitation of the medulla. It is commonly associated with a syrinx extending to involve the brain stem. The clinical features of Syringobulbia include: facial pain and dissociated sensory loss vertigo and nystagmus - VIII cranial nerve, facial palatal or laryngeal palsy - VII, IX, X, XI cranial nerves dysfunction, wasted tongue - XII cranial nerve dysfunction, Horner's syndrome - sympathetic loss
The above article was kindly donated by;
Mr. Karoly M. David FRCS (SN)